PDF Summaries - vdW materials

Nature, Published online: 14 October 2026; doi:10.1038/s41586-026-11109-y

Two-dimensional graphene films with unusual folded surfaces are synthesized through a modular assembly strategy and show enhanced strength, toughness and elastic strain owing to stress distribution between interlayer folds.

Nature Nanotechnology, Published online: 14 October 2026; doi:10.1038/s41565-026-02306-x

Gate-voltage sweeps drive a first-order sliding transition between Bernal-dominant and rhombohedral–Bernal mixed stacking in marginally twisted double-bilayer graphene, which allows for non-volatile on/off switching of the low-temperature ferromagnetic phase.

Superconducting phases have recently been discovered both in twisted bilayers of transition metal dichalcogenide WSe$_2$ (tWSe$_2$) and in rhombohedral multilayer graphene (RMG). While both have generated extensive interest, they appear to be driven by qualitatively different physics. Here, we propose a unified picture in which the superconductivity in RMG arises from a strongly correlated metallic state with a spatial length scale that is compatible with the moir\'e length scale of tWSe$_2$. Central to this mechanism is a Wigner crystal phase in RMG that is metallic, driven by a "W"-shaped dispersion in the flat part of the underlying graphene band structure. We demonstrate this effect through calculations of Wigner crystal states in pentalayer RMG, focusing on dilute electrons in the quarter-metal regime relevant to experiment. In a region of the phase diagram we find the Wigner crystal breaks three-fold rotation symmetry, which guides our construction of a $t$-$V$ model on a triangular lattice as an effective description of the low-energy electronic physics. This construction suggests a surprisingly similar low-energy description of RMG and tWSe$_2$. Broader implications for superconductivity in dilute carrier systems are also discussed.

Low infrared emissivity materials (i.e., metallic materials) are of significance for thermal radiation regulation. However, the easy‐corrosion susceptibility and poor chemical stability are common bottleneck issues that affect their applications. We report a versatile electronic structure modulation strategy for low infrared (IR) emissivity graphene by engineering the surface chemistry of precursor graphene oxide and the followed reduction/doping process. The fabrication protocols minimize the irreparable disruption of the intrinsic graphitic structure and enable controllable assembly of nanosheets by suppressing formation of carboxyl groups. More significantly, the convenient reduction and halogen doping effects synergistically minimize electron scattering and enhance interfacial charge transport. The low‐defective graphitic structure and the ordered multiscale architecture, as well as halogen doping effect, afford exceptional carrier mobility (∼27.1 cm 2 V −1 s −1 ), carrier density (5.73 × 10 20 cm −3 ), and electrical conductivity comparable to highly oriented pyrolytic graphite. Surprisingly, the anomalous metallic response gives the lowest IR emissivity (0.15, 8–14 µm) for carbon materials, comparable to MXene and traditional metallic materials. The large‐scale processability and outstanding long‐term stability under chemical conditions offer new insights for the potential infrared applications of graphene materials.

npj Computational Materials, Published online: 14 October 2026; doi:10.1038/s41524-026-02358-6

Switchable altermagnetism and Luttinger-compensated ferrimagnetism in graphene-MnPS₃ heterostructures

Author(s): Weipeng Chen, Jin Wang, Quanshui Zheng, and Zhanghui Wu

Robust superlubricity in commensurate moirapos{e} patterns is experimentally demonstrated for the first time.

[Phys. Rev. Lett. 137, 166201] Published Wed Oct 14, 2026

Nature Nanotechnology, Published online: 14 October 2026; doi:10.1038/s41565-026-02293-z

Wafer-scale growth of a metastable rhombohedral boron nitride polytype takes sliding ferroelectricity from handcrafted structures in the laboratory towards integrated devices.

Author(s): Harley D. Scammell and Oleg P. Sushkov

Exciton condensation, a collective phase-coherent state of bound electron-hole pairs, is expected to enable phenomena such as dissipationless counterflow and novel broken-symmetry states but has remained difficult to realize in zero magnetic field. In semiconductors, exciton condensation requires th…

[Phys. Rev. B 114, 194508] Published Tue Oct 13, 2026

We show that graphene nanoflakes realize a previously unexplored form of orbitronics in which orbital currents emerge in the absence of intrinsic angular momentum of the constituent atoms. Starting with a hexagonal graphene nanoflake, we demonstrate the presence of energy-degenerate eigenstates with opposite non-zero expectation values of the angular momentum. Placing electrodes in an appropriate configuration on the flake couples the reservoirs more strongly to one of the two opposite-angular-momentum states, yielding a chiral current that carries a net orbital angular momentum. The resulting circulating orbital currents generate magnetic fringe fields that are experimentally accessible with spin centers or superconducting quantum interference magnetometers, providing avenues for their experimental realization. Finally, our work establishes a new platform for exploring and studying orbitronics in zero-dimensional systems.

Graphene nanoribbons support a variety of electronic phases that can be tuned via external stimuli. In particular, zigzag graphene nanoribbons exhibit an antiferromagnetic insulating ground state which can transition to a half-metallic phase under a transverse electric field or when embedded in hexagonal boron nitride. Here, we develop a simple model of a heterostructure composed of a half-metallic zigzag graphene nanoribbon coupled with an Ising superconductor. We demonstrate that an Ising superconductor's s-wave spin-singlet pairing gap component can induce a spin-triplet, odd-parity pairing gap in the half-metallic phase of the nanoribbon via proximity coupling. The resulting superconducting phase is topologically nontrivial, with gate-tunable transitions that enable the emergence of Majorana zero modes.

Unconventional superconductivity can emerge in various forms in strongly correlated systems. Historically, the most extensively studied examples include nodal and triplet pairing, which were experimentally detected in cuprates and superfluid helium-3, respectively. Beyond these canonical cases, there are also nematic superconductors, in which the rotational symmetry of the lattice is broken in the superconducting state. While there are several examples of nematic superconductors whose pairing emerges inside a preexisting nematic normal state, experimental evidence for superconducting states that intrinsically break rotational symmetry on their own has been exceedingly scarce. Here, we report the experimental realization and identification of an intrinsic multi-component nodal nematic superconducting state in magic-angle twisted trilayer graphene (MATTG). By integrating tunneling spectroscopy with quantum transport measurements, we directly probe the symmetry of low-energy superconducting quasiparticles. Deep inside the superconducting state, we observe a pronounced two-fold anisotropy in the zero-bias tunneling conductance under an in-plane magnetic field, which is strongly suppressed together with superconductivity as the temperature or perpendicular magnetic field is increased. Remarkably, the major axis of anisotropy rotates by up to $90^{\circ}$ across the superconducting dome, indicating an intrinsic, field- and density-tunable symmetry of the low-energy excitations. These behaviors imply a nodal superconducting state in MATTG that spontaneously breaks the six-fold rotational symmetry of the moir\'e superlattice. Our results establish moir\'e graphene as a versatile platform for realizing and interrogating nodal nematic superconductivity, opening a new avenue for exploring unconventional symmetry-breaking superconducting states in two-dimensional materials.

We investigate electron wave-packet transport in monolayer graphene subjected to photonic-crystal-inspired electrostatic superlattices composed of periodically arranged circular barriers and wells with zero net potential. Using the time-dependent Dirac equation combined with a split-operator propagation method, we systematically examine how lattice geometry, barrier-well ordering, propagation direction, carrier energy, and scatterer radius govern transient dynamics and long-time transmission behavior. Three representative superlattice configurations are analyzed: square, staggered, and triangular superlattices. While all systems exhibit a universal temporal evolution characterized by an initial transient regime followed by transmission saturation, the saturated transmission strongly depends on structural geometry and propagation direction (i.e., forward and backward). In particular, square and triangular lattices display pronounced directional asymmetry, whereas the staggered configuration serves as an isotropic system in both the forward and backward directions. By introducing the normalized asymmetry coefficient η , we demonstrate that both the magnitude and sign of directional preference can be controllably tuned—and even reversed—through variations in electrostatic potential strength and incident wave-packet energy. These findings establish circular electrostatic superlattices as a versatile platform for geometry-programmable Dirac-fermion transport, opening pathways toward graphene-based directional filters, tunable energy-selective transport elements, and advanced electron-optical devices.

Magnetic proximity effects in transition metal dichalcogenide (TMD)/2D-magnet heterostructures are often described in terms of the magnetization of the interfacial magnetic layer. Here, we show that this picture is sufficient to describe the neutral-exciton valley splitting of the TMD, but incomplete for its hole-doped electronic structure. We study a gate-tunable van der Waals heterostructure composed of monolayer WSe$_2$ in direct contact with trilayer CrI$_3$. By combining spatially and helicity-resolved reflection-contrast spectroscopy with magnetic circular dichroism, we identify two distinct magnetic domains in the trilayer CrI$_3$: one with purely antiferromagnetic interlayer coupling and one with a mixed antiferromagnetic (AFM)/ferromagnetic~(FM) coupling. In both domains, the sign of the neutral-exciton valley splitting of WSe$_2$ switches with the magnetization reversal of the adjacent CrI$_3$ layer. In contrast, helicity-resolved positive-trion spectroscopy of WSe$_2$ reveals a qualitatively different response. While the AFM domain shows a strongly helicity-selective trion resonance, the mixed AFM/FM domain exhibits trion resonances in both helicities. This behavior disappears when all CrI$_3$ layers are aligned in a parallel magnetization direction. Our results demonstrate that charged excitons are sensitive to the full layer-resolved magnetic sequence of the adjacent 2D-magnet, revealing magnetic proximity beyond the interface.

We investigate Pauli-consistent ensemble Monte Carlo simulations of graphene with explicit intraband electron-electron scattering. To reduce the cost of electron-electron proposal-rate evaluation, we introduce a sampled-partner approximation that replaces the full partner-cell sum by uniform sampling from the instantaneous ensemble, while leaving the event-level collision step unchanged. Comparison with the full-sum reference shows close agreement together with a substantial reduction in computational cost, enabling large-ensemble low-noise simulations. In this regime, systematic oscillatory components become clearly resolved in ensemble-averaged time traces. We show that these oscillations are numerical and originate from deterministic drift on the discretized momentum-space grid. We also discuss a procedure for reducing their impact in recorded observables without modifying the underlying Monte Carlo dynamics.

Resonantly driven nonlinear systems, from superconducting circuits to nanomechanical resonators, are often described in a rotating frame, where amplitude and phase evolve slowly within a fixed landscape of stable and unstable states. How such systems behave when this landscape moves on their intrinsic timescale remains to be understood. Here, we exploit the strong tension sensitivity of a graphene drum's resonance frequency to reshape the rotating-frame phase space of a bistable mechanical mode in real time, combining an MHz-frequency resonant drive with kHz-frequency tension modulation. When the modulation rate becomes comparable to the mechanical relaxation rate, adiabatic tracking of the fixed points breaks down. Instead, parametric instabilities emerge in the slow dynamics at frequencies set by libration around these points rather than by the mechanical resonance; stronger modulation drives period doubling and chaos. A slow-variable theory predicts where the instabilities occur, and Melnikov analysis captures the onset of chaos. These results show that the rotating frame itself can be parametrically driven, offering a general route to controlling nonadiabatic dynamics in systems ranging from Josephson bifurcation amplifiers to cold atoms.

Advances in polymer synthesis and computational modeling are expanding the block-copolymer architecture space accessible for phase-behavior design. Machine learning can accelerate this exploration, yet a common representation capable of learning across diverse chain topologies remains lacking. Here, we present a graph neural network (GNN) representation of acyclic AB multiblock architectures, tested by random-phase approximation (RPA) instability prediction. Each chain is represented as a graph, enabling a common model to learn across diverse topologies. This representation, which organizes RPA-related information, retains predictive capability when extrapolated to architectures with more blocks and demonstrates its potential for reuse across tasks through transfer to instability-wavenumber prediction. By effectively linking block-copolymer chain architecture to field-theoretic response, this graph representation not only reconstructs stability-limit curves but also provides a practical route for future self-consistent field theory exploration of ordered phase space across complex topologies.

Excitons in monolayer transition metal dichalcogenides (TMDs) are highly sensitive to external stimuli, allowing control of resonance energies and lifetimes through electric and magnetic fields, heterostructures, moire potentials and mechanical strain. Observations of single-photon emission (SPE) near sample edges, wrinkles, and strained nanobubbles have motivated strain-engineering aimed at realizing localized emitters in 2D materials. The origin of these emitters remains unclear and prior studies have relied on far-field spectroscopy with strain profiles inferred separately through topography, limiting direct correlation between local strain and excitonic response. We directly probe strain-modified excitonic spectra in monolayer WSe$_2$ using cryogenic scattering-type scanning near-field optical microscopy (s-SNOM). We compare two strain-engineering techniques, nano-indentation and patterned substrates, used to produce SPEs. At 9 K, we spatially resolve exciton resonance shifts with sub-diffraction limit resolution, simultaneously measuring near-field optical response and topography. We observe that strain transferred from nano-indentation into a deformable polymer substrate differs from that produced by draping TMDs over patterned dielectric pillars. Adhesion and tearing during plastic deformation drive a compressive exciton blueshift, while draping produces dominant tensile strain. Comparing the strain model results to the experimentally observed energy shifts shows that the nano-indentation strain is over an order of magnitude smaller than previously inferred, due to puncturing of the fragile monolayer, whereas pillar-strained devices remain intact under more modest strain. These differences suggest SPE arises from complex, strain-mediated interactions rather than simple confinement potentials, establishing s-SNOM as a powerful probe of quantum emission in strained 2D materials.

Advanced Materials, Volume 38, Issue 57, 13 October 2026.

Solids that are stiff to most loads and extremely compliant to one are normally built, not found. That internal atomic relaxation lowers elastic constants is textbook; what has remained untested is whether it can be driven far enough to separate the elastic scales of a crystal by an order of magnitude while leaving it mechanically stable. Density functional theory calculations of the complete in-plane elastic tensor of four non-hexagonal carbon monolayers sharing a square lattice metric show that it can: their longitudinal stiffnesses agree to within a factor of two while their shear constants span more than a factor of fifty. Twin T-graphene, previously reported as elastically isotropic from normal strains alone, is the extreme case, with $C_{66}=3.03$~N\,m$^{-1}$, nearly fifty times below graphene, at an axial stiffness typical of semiconducting monolayers, and a soft Kelvin eigenvalue a factor of $29$ below the others while the Born criteria hold. Symmetry confines the strain-induced relaxation to the $B_{2g}$ sector, a counter-torsion of the carbon sublayers about the short mid-plane bonds that removes $96\%$ of the clamped-ion shear stiffness with almost no bond stretching and leaves the semiconducting gap intact. Transverse acoustic phonons, finite-temperature dynamics, and large-deformation simulations show that the channel survives beyond the harmonic, zero-temperature limit. Because the selection rule is a point-group statement rather than a chemical one, it yields a screening criterion for other crystals and other strain components.

Tracing my scientific path from many-body physics in semiconductor nanostructures to topological quantum matter, this Habilitation \`a diriger des recherches (HDR) memoir presents only part of my research since defending two PhD theses in Toulouse and Nizhny Novgorod in 2011. Focusing on pseudo-relativistic fermions and topological states in zinc-blende semiconductors and their heterostructures, it highlights my independent research program: identifying physical problems, developing predictive theories, and initiating new directions with experimentalists. The first part addresses Kane fermions in bulk HgCdTe: temperature-driven band inversion, domain-wall states, the collapse of Landau levels in crossed electric and magnetic fields, and disorder-induced topological transitions. The second examines pressure-, temperature-, and disorder-driven phase transitions in single and double HgTe quantum wells (QWs), including bilayer-graphene-like semimetals and a two-dimensional higher-order topological insulator (2D HOTI) phase beyond the minimal BHZ model. The third develops three-layer InAs/Ga(In)Sb QWs as a III-V platform for massless Dirac fermions, large-gap quantum spin Hall insulators, 2D HOTI phases, and semimetals with quadratic band touching, and discusses InAs$_{x}$Sb$_{1-x}$/InAs$_{y}$Sb$_{1-y}$ heterostructures as a promising alternative. Several of these predictions are supported by experimental observations, including quantized helical edge transport up to 60 K and the unconventional quantum Hall effect. Defended on March 25, 2026, at the University of Montpellier. Jury: Michel GOIRAN (chair and rapporteur, LNCMI-CNRS, Toulouse); Alexey KAVOKIN (rapporteur, Westlake University, Hangzhou); Robson FERREIRA (rapporteur, LPENS-CNRS, Paris); Alexei BARANOV (member, IES-CNRS, Montpellier); Benoit JOUAULT and Fr\'ed\'eric TEPPE (members, L2C-CNRS, Montpellier).

The escalating threat of multidrug‐resistant (MDR) bacteria, especially methicillin‐resistant Staphylococcus aureus (MRSA), urgently demands integrated multimodal therapies. However, it remains challenging to develop all‐in‐one platforms that synchronize photothermal therapy (PTT), photodynamic therapy (PDT), and ion release under a single near‐infrared (NIR) trigger. Herein, a van der Waals composite AgPor/Hj, assembled from Ag(II) porphyrin and graphene‐TiO 2 heterojunction, is reported. Synergistic hot hole injection from the heterojunction to the porphyrin macrocycle greatly enhances NIR absorption, achieving an ultrahigh photothermal conversion efficiency of 64.5% for porphyrin‐based systems. Crucially, under a single 808 nm NIR irradiation, the engineered interface synchronizes PTT, PDT, and ultrafast Ag(II) release. This single‐NIR‐triggered triple‐modal synergy enables outstanding biofilm eradication and potent MRSA inhibition both in vitro and in vivo. AgPor/Hj effectively eliminates bacteria in infected wounds and accelerates tissue repair, significantly outperforming vancomycin, the first‐line antibiotic for MRSA. Combined with excellent biocompatibility, low cost, and easy preparation, this synergistic platform provides a highly promising strategy for treating MDR bacterial wound infections.

$\rm{TiSe_{2}}$ is a candidate of high temperature excitonic condensates with spontaneous exciton formation in addition to its charge density wave (CDW). However, direct observation and manipulation of this electron-hole paring state formation is still lacking. Here, using varying-temperature angle-resolved photoemission spectroscopy (VT-ARPES), we observe a distinct odd-to-even-layer switch of spontaneous exciton state formation with the evident correlated band structure in $\rm{TiSe_{2}}$ thin films. While the odd-layer $\rm{TiSe_{2}}$ films show a sharp band structure in single-particle picture superimposed by CDW renormalization, in the even-layer $\rm{TiSe_{2}}$ films, the full-filling valence band (VB) opens a distinct notch at the top, and the conductive band (CB) shows a significant extra signal extending above Fermi level with spectra broadening. These features indicate that the extra holes (notched VB) and electrons (broadening CB above Fermi level) form spontaneous excitons in even-layer $\rm{TiSe_{2}}$. Based on a correlated electron-hole model extracted from the tight-binding description, we reproduce the characterized band structures with spontaneous exciton formation, where the interlayer inter-band coupling in $\rm{TiSe_{2}}$ plays a key role, which leads to an odd-to-even-layer switch of the excitonic state formation. Our results provide direct evidences of the spontaneous exciton formation, promising an excitonic condensate as versatile platform for realizing Bose-Einstein condensate (BEC) and investigating novel correlated phenomena.

Author(s): Ce Bian, Hengxin Tan, and Wenhui Duan

A widespread experimental realization of quantized anomalous transport in the intrinsic magnetic topological insulator ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$ is hindered by its elusive surface magnetic gap. Uncovering the origin of the gapless states is thus essential for accessing its topological p…

[Phys. Rev. Lett. 137, 166401] Published Wed Oct 14, 2026

Semiconductor moir\'e superlattices, owing to strongly bound excitons and pronounced electronic correlation, have emerged as an intriguing solid platform for exploring correlated bosonic phenomena, where the moir\'e potential landscape plays a central role. Hydrostatic pressure allows continuous, in-situ tuning of this landscape, but remains underexplored because of experimental challenges. Here we integrate a diamond anvil pressure cell with high quality dual gated WSe2/WS2 twisted bilayers and perform cryogenic optical spectroscopy. We observe distinct pressure evolutions of moir\'e intralayer excitons, which reveal drastic modulation of the excitonic moir\'e-potential landscape captured by a continuum model and suggest the capability of engineering the exciton-band topology. Moreover, we demonstrate efficient pressure control over the interplay between charges and both intralayer and interlayer excitons: the intralayer charge-transfer exciton becomes less sensitive to doping, likely due to reduced charge-transfer character; in contrast, the interlayer exciton exhibits enhanced exciton-charge repulsion. Our results establish hydrostatic pressure as a powerful tuning knob for engineering bosonic quasiparticles and Bose-Fermi interactions in moir\'e materials.

Maximizing the absorption of exciton-polaritons in transition-metal dichalcogenides (TMDCs) under critical coupling conditions is crucial for developing high-efficiency polariton-based photodetectors, solar cells, and perfect absorbers. Here, we propose a polaritonic critical self-hybridized coupling between Brillouin zone folding driven quasi-bound states in the continuum (BZF-QBIC) mode and A excitons in a bulk WS2 metasurface. This polaritonic critical coupling shows robust behavior with respect to the asymmetric parameters of the involved BZF-QBIC mode, in contrast to the asymmetry-sensitive conventional QBIC-based critical coupling. By changing the height of WS2 metasurfaces, we observe a typical anti-crossing behavior with a Rabi splitting of 246.5 meV. Moreover, the maximum absorption value of 0.5 for exciton-polaritons is achieved at the polaritonic critical coupling condition. The large population of excitons provided by bulk WS2 is essential for achieving polaritonic critical coupling and can further enhance polaritonic absorption. This work enables the realization of robust, high-absorption self-hybridized polaritonic critical coupling in TMDCs, and further expedite their applications in high-absorption low-dimensional polaritonic devices.

Author(s): Satyabrata Bera, Sudipta Chatterjee, Suman Kalyan Pradhan, Subhadip Pradhan, Arnab Bera, Sk Kalimuddin, Ashis K. Nandy, and Mintu Mondal

The interplay between spin reorientation and topological electronic structure in two-dimensional (2D) van der Waals (vdW) ferromagnets (FMs) is a core issue for understanding how magnetic anisotropy couples to nontrivial topological charge transport. Although spin reorientation transitions (SRTs) ar…

[Phys. Rev. B 114, 194408] Published Tue Oct 13, 2026

We investigate multilayer d-wave altermagnetic metals with odd-parity helical p-wave pairing. In the minimal bilayer system, interlayer tunneling reconstructs the spin-split Fermi surfaces and generates two layer-hybridized sectors with distinct effective chemical potentials. Without Rashba spin-orbit coupling (RSOC), the emergent mirror symmetry and subsystem chiral symmetry stabilize phases with different numbers of helical Majorana edge-mode pairs and additional counterpropagating pairs, jointly characterized by the mirror Chern number and the winding numbers defined along high-symmetry lines. The combination of RSOC and the altermagnetic exchange field gaps out the helical Majorana pairs while, in a certain parameter regime, leaving another pair of counterpropagating Majorana edge modes gapless, giving rise to second-order topological phases with isolated or twofold Majorana corner modes, as well as a hybrid-order phase in which gapless Majorana edge modes coexist with Majorana corner modes. We identify a layer symmetry that elucidates the physical origin of these phases. For an arbitrary N-layer system, such a symmetry naturally arises from the interlayer-coupling matrix, allowing N-fold Majorana corner modes to emerge when all layer-hybridized sectors enter the nontrivial second-order regime. Our results establish the interplay among the layer degree of freedom, odd-parity pairing, and Fermi-surface configurations as a controllable route to engineering topological superconductivity in layered altermagnetic systems.

Metasurface-based bound states in the continuum (BICs) enable exceptional spatiotemporal control of light and substantially enhance light–matter interactions, making them highly attractive for applications in sensing, nonlinear optics, and integrated photonics. However, conventional BICs in single-layer metasurfaces rely on in-plane symmetry and are highly susceptible to structural perturbations, offering limited design flexibility and constraining both their robustness and functional diversity. To overcome these limitations, we theoretically propose and experimentally demonstrate a new class of symmetry-protected quasi-BICs in bilayer terahertz metasurfaces. These states are realized by coupling in-plane rotational and out-of-plane reflective symmetries through S4 point-group operations. Moreover, we show that such QBICs exhibit strong robustness against structural defects and fabrication imperfections. This work overcomes the robustness limitations of conventional single-layer metasurface BICs and establishes a general design paradigm for photonic devices that harness BICs with enhanced stability and scalability.

Flat polar phonon bands in ferroelectrics have been envisioned to realize irreducibly small domains for achieving the highest memory density. However, such bands are extremely rare, with only a one-dimensional flat polar band discovered in ferroelectric hafnia, which gives rise to irreducibly narrow, line-type domains with a half-unit-cell width of 2.7 Angstrom. Here, we report the discovery of a two-dimensional flat polar band in the ferroelectric (BaTiO$_3$)$_1$/(BaXO$_3$)$_1$ superlattice (X = Zr, Sn), which generates extremely localized, noninteracting dipoles within its quarter-unit-cell area that form quasi-degenerate states of irreducible sub-nm$^2$ ferroelectric domains. The estimated ferroelectric domain density, exceeding 300 Tbit/cm$^2$ (assuming one bit per domain) represents a record high among the known ferroelectrics, with independently switchable dipoles at low voltages. The ferroelectric phase hosting two-dimensional flat bands constitutes a competing ground state across superlattice stacking directions and thus can be experimentally realized in both freestanding structures and epitaxial growth on MgO substrates. This discovery opens unprecedented opportunities to explore multidimensional flat polar bands in ferroelectrics and to engineer ultra-dense and low-power memory devices.

Highly selective oxidation of methane to liquid oxygenates under mild conditions remains challenging because of the difficulty in controlling overoxidation at highly reactive sites. Here, we demonstrate remote control of single-atom Cu reactivity through outer-shell coordination engineering in Zr-based metal-organic frameworks (MOFs). By anchoring Cu 1 to Zr-oxo nodes in UiO-66-X (X = -NO 2 , -H, and -CH 3 ), remote X-BDC ligands systematically modulate the electronic properties of Cu 1 sites and the catalytic microenvironment. In situ characterization combined with ab initio molecular dynamics in an explicitly solvated aqueous environment reveals a dynamic outer-shell-to-inner-shell regulation that reshapes the active structure and reactive oxygen species around Cu 1 sites, thereby facilitating CH 4 activation. In particular, the electron-withdrawing NO 2 -BDC ligand creates electron-deficient Cu 1 - • OH* sites, while adsorbed water further regulates active-site conformation. Consequently, Cu 1 /U6-NO 2 achieves a turnover frequency of 322.4 h −1 with nearly 100% oxygenate selectivity under mild conditions, establishing a general strategy for overcoming activity-selectivity trade-offs in methane conversion.

Thermoelectrics turn waste heat into electricity, but finding new ones requires transport calculations too costly for whole databases. Searches therefore choose what to calculate from the electronic density of states (DOS), increasingly predicted by machine learning, yet such choices are rarely tested. We test them on all 106,235 Heusler structures in the DXMag database, screening 51,257 on density-functional spectra and 54,978 on neural-network predictions, and judging both by 3,625 band-structure and transport calculations. A DOS-derived Seebeck indicator ranks most compounds passing every transport and stability test within the top 1% of their population, and ten of the eleven established half-Heusler thermoelectrics calculated pass. Predicted spectra lose most band gaps, unnoticed by spectral-similarity metrics, yet still rank passing compounds near the top. The screen certifies 80 computational candidates, 61 without reported measurements. Computed or predicted, the DOS can choose what to calculate; only a band structure shows whether a gap exists.

Atomically well-defined interfaces are essential for realizing functional interlayer coupling in stacked and twisted oxide heterostructures, yet transferred freestanding oxides can develop structural inhomogeneities, including local curvatures, interfacial voids, and incomplete contacts with substrates. Here, we demonstrate that these transfer-induced structural disorders and imperfections evolve substantially and can be suppressed by post-transfer thermal treatments, yielding bulk-like crystalline freestanding oxide nanomembranes. Using freestanding SrTiO3 membranes as a model system, we report a systematic understanding of the role of "atomic ironing" and the associated evolution of lattice mosaicity, interfacial roughness, and optical bandgap. We further demonstrate atomically bonded conformal interfaces in twisted SrTiO3 heterostructures, highlighting the importance of post-transfer thermal processes. These results establish a synthetic strategy to restore the structural integrity and intrinsic bulk-like functionality of freestanding oxide nanomembranes, enabling stacked, twisted, and heterogeneously integrated oxide architectures with atomically well-defined interfaces for emerging quantum functionalities.

Nickelate superconductors, sharing a similar electronic environment with cuprate superconductors, offer a promising platform for unraveling the mechanism of high-temperature superconductivity. However, the realization of superconductivity in these systems has so far been restricted to thin films or bulk samples under high-pressure. This limits the applicability of various experimental probes to study the mechanism of superconductivity, and hinders the potential application of the nickelate superconductors. Exploring bulk superconductivity at ambient pressure is therefore essential to understand its origin and enable broader experimental research. Here, we report the realization of bulk superconductivity at ambient-pressure in quintuple-layer square-planar (SP) nickelate La6Ni5O12. The SP phase is obtained by performing topotactic reaction on the quintuple-layer Ruddlesden-Popper (RP) compound La6Ni5O16. Optimized reduction condition endows La6Ni5O12 with a superconducting state that exhibits onset transition temperature of ~ 18 K, as verified by both zero resistance and diamagnetic shielding effect. Pronounced hysteresis loops revealed by magnetization and torque magnetometry demonstrate the occurrence of vortex pinning. Specific heat measurements on a polycrystalline pellet of La6Ni5O12 reveal a clear superconducting transition at ~18 K and a superconducting volume fraction of ~ 25%, which strongly supports the presence of bulk superconductivity. Our results establish an unprecedented bulk sample platform for investigating superconductivity in nickelates at ambient pressure, which paves the way for further experimental studies into the superconducting mechanism.

We present the theory of the Landau levels of $C_3$ high-fold fermions in honeycomb lattices. These fermions arise as a generalization of the tight-binding model in a honeycomb lattice with one orbital per site, known to describe graphene, to a family of models with several orbitals per site transforming according to representations of $C_3$, relevant for triangulene two-dimensional crystals. The models are defined by the number of orbitals $n_a$ and $n_b$ at the $a$ and $b$ sites of the unit cell. They feature energy bands that combine flat bands and Dirac cones, that are isomorphic to those of graphene, the Lieb, $p_{xy}$ honeycomb, and the Kagome tight-binding models. Combining tight-binding and $k\cdot p$ methods, here we compute the Landau levels of the $(1,1)$, $(1,2)$, $(2,2)$ and $(3,3)$ models, we compare them to those of the reference models, and we explore the similarities and differences with the Landau levels in graphene. Our findings reveal that the nature of $C_3$ high-fold fermions combine Dirac-type Landau quantization, originating from the linear crossings and associated relativistic band dispersion, with anomalous Landau quantization rooted in the quantum geometry of the singular flat bands.

Author(s): Spenser Talkington and Eugene J. Mele

Two-dimensional moiré materials feature widely tunable electronic structures. When these materials are illuminated by light, they exhibit optical gyrotropy in the form of circular dichroism and birefringence. Here, the authors show that this gyrotropy naturally decomposes into an intrinsic contribution due to interlayer electronic coupling and an extrinsic contribution due to the twisted embedding of the material in physical space. The authors conduct a general symmetry analysis applicable to moiré materials and identify regimes in which the intrinsic, and in which the extrinsic contributions dominate the gyrotropy. Finally, they apply the analysis to twisted bilayer graphene and twisted MoTe${}_2$.

[Phys. Rev. B 114, 235408] Published Tue Oct 13, 2026

We introduce a compact Topological-Geometrical Descriptor (TGD) for planar two-dimensional carbon networks. Atomic coordinates are mapped to a periodic planar graph and represented through ring populations, topological-charge statistics, projected ring geometry, and dual-graph defect adjacency. The resulting modeling vector contains 19 physically interpretable features. We evaluate TGD on 120 published planar carbon allotropes using the DFT relative energy per atom with respect to graphene as the target. Repeated five-fold cross-validation with gradient boosting yields a mean absolute error (MAE) of 0.0826 +/- 0.0138 eV/atom and R2 = 0.803 +/- 0.074. Under the same validation protocol, TGD gives a mean MAE of 0.0828 eV/atom, compared with 0.0929 eV/atom for a 203-feature Matminer representation. We further analyze 360 vacancy-defected graphene configurations spanning 12 vacancy concentrations from 2 to 24 percent. When entire vacancy concentrations are held out, TGD gives a pooled MAE of 0.269 eV/vacancy and R2 = 0.861, outperforming simple baselines based on vacancy concentration alone or non-hexagonal-ring fraction alone. Sensitivity tests show that the inferred edge sets are stable to moderate changes in the adaptive bond factor. Finally, the mean absolute topological charge is examined as a one-variable empirical surrogate for the allotrope dataset and is treated explicitly as dataset-specific rather than universal. These results show that TGD combines compact prediction with direct structural interpretation while making clear the present restriction to single-layer planar carbon networks.

The recent discovery of long-sought dice-lattice bands in layered electride YCl opens up unprecedented opportunities for studying correlated electrons in real dice lattice systems. While the weakly dispersive band at the Fermi level is partially filled and density-wave states are expected due to Fermi surface nesting based on conventional theories, the ARPES measurement nevertheless revealed a uniform flat band splitting of 0.5 eV, suggesting unusual ferromagnetism (FM) borne out of the metallic 2D dice lattice. In this Letter, we propose that the uniform metallic FM order is stabilized by the prominent quantum metric near topological band crossing points at K and K', which reconstructs the magnetic instability in the dice metal and tips the density-wave instability toward a uniform FM order. Importantly, our analysis based on random phase approximation (RPA) and Hartree-Fock theory predicts a remarkably high Curie temperature above room temperature for the 2D FM order. These findings establish the first example of a room-temperature 2D metallic magnet stabilized by quantum metric, which not only exemplifies the fundamental significance of quantum geometry in solids but also bears far-reaching applications in energy-efficient high-density magnetic memories.

Topological boundary states offer a platform for guided-wave propagation within bulk bandgaps. Their propagation characteristics depend not only on the spectral extent of the states but also on their dispersion within the operating bandwidth. A nearly linear dispersion provides more uniform group velocity across frequency, whereas a reduced slope enables slow-wave propagation. Despite advances in inverse design of prescribed dispersion relations and topological dispersion tuning, application-oriented characteristics of boundary-state dispersion have rarely been direct inverse-design objectives. Here, we develop a supercell-enabled, surrogate-assisted framework for the inverse design of boundary-state dispersion in a phononic crystal with pseudomagnetic fields. Area-preserving anisotropic deformation shifts the local Dirac points, and independent variation of 21 rows within the supercell provides distributed control over the boundary-state branch. A constraint-preserving surrogate reconstructs the dispersion from an initial frequency and positive frequency increments, with first- and second-difference losses introduced to capture local slope and curvature. Coupled with a genetic algorithm, the framework targets two prescribed-bandwidth design tasks: highly linear dispersion and slow-wave dispersion. For the former, finite-element verification yields relative group-velocity variations of 0.142% to 1.183% over prescribed bandwidths of 4% to 6%. For slow-wave designs, mean group velocities of 190 to 385 m/s are obtained over bandwidths of 0.2% to 0.8% while satisfying a 5% group-velocity variation limit. These results establish boundary-state dispersion as a direct inverse-design target beyond conventional bandwidth optimization, opening a flexible route to group-velocity control through application-oriented dispersion engineering over prescribed relative bandwidths.

Symmetry-protected electronic states in correlated oxides offer a route to combining topology, lattice tunability, and many-body interactions, but creating such topological electronic states in complex oxides remains challenging. Here, we show that oxygen octahedral rotations provide a symmetry-control parameter for stabilizing Dirac-related electronic states in epitaxial CaNbO3 films. By comparing compressively strained tetragonal films and relaxed orthorhombic films, we demonstrate that distinct octahedral rotation patterns preserve nonsymmorphic symmetry and lead to distinct transport signatures consistent with Dirac-like electronic states. The films exhibit metallic transport with high mobility of 138,000 cm2 V-1 s-1, multichannel conduction, and Shubnikov-de Haas oscillations from small high-mobility Fermi pockets. Landau-fan diagram analysis indicates finite Berry-phase contributions, while first-principles calculations reveal a strain-driven evolution from nodal-line band crossings in the orthorhombic phase to Dirac-electron band features in the tetragonal phase. These results establish oxygen octahedral symmetry as a design knob for engineering topological electronic states in correlated perovskite oxides.

Author(s): Y. J. Lü, C. C. Jin, Y. J. Hou, K. Yang, H. R. Qin, Z. W. Wu, and W. H. Wang

Understanding the dramatic slowdown of dynamics in glass-forming liquids remains one of the central challenges in glass physics. Using extensive molecular dynamics simulations, we uncover a topological origin of this phenomenon. Vortices in the hopping displacement vector fields are identified as th…

[Phys. Rev. Lett. 137, 166101] Published Wed Oct 14, 2026

Widely used methods for identifying crystal structure in atomistic simulations are limited in practice to a handful of simple structures, leaving many important crystalline systems without automated classification techniques. Voronoi topology analysis offers a route to classifying arbitrary crystalline and defect environments, but realizing this potential first requires enumerating the Voronoi cell topologies that can arise under thermal perturbation of a structure of interest. We present an algorithm that deterministically enumerates all Voronoi cell topologies arising from generic infinitesimal perturbations of an arbitrary crystal structure, producing structural classifiers that extend automated identification to general crystalline systems. We demonstrate the approach on several structures of general interest.

Quantum gas microscopy provides single-shot access to many-body configurations, but their microscopic reconstruction has so far largely relied on a predefined discrete spatial basis during fluorescence readout. Here we realize ultrafast atom-resolved fluorescence microscopy of an ultracold $^{162}$Dy gas directly in continuous space, with all external confinement removed during imaging. Exploiting the large mass and broad optical transition of dysprosium together with a high numerical aperture in-vacuum objective, we detect single atoms within $4\,\mu\mathrm{s}$ while maintaining an effective point-spread function with a full width at half maximum of $254.8(3)\,\mathrm{nm}$, and an isolated single-atom classification fidelity of $99.72(3)\%$. We use the measured single-atom response to construct a statistical configuration-inference model that recovers atomic positions and multiplicities, coming from overlapping atoms, directly from single fluorescence snapshots. Benchmarking our model on Monte-Carlo generated images shows a total reconstruction fidelity of $98.7\%$. Our approach extends quantum gas microscopy beyond predefined detection lattices, enabling atom-resolved measurements of counting statistics and higher-order spatial correlations directly on the intrinsic length scales of continuum many-body systems.

Phonon-photon coupling in quantum materials is commonly treated as an effective direct interaction, neglecting the crucial role played by electrons. Here we develop a gauge-invariant theory of cavity phonon polaritons that captures electronic screening, dissipation, and hybridization. We show that screening can suppress polariton formation in metals, severely constraining cavity control of phonon-mediated superconductivity. By contrast, interband electronic resonances in time-reversal-symmetric gapped systems can strongly enhance phonon-photon coupling, enabling robust polariton formation down to the monolayer limit despite electronic absorption. We illustrate these effects in NbSe2, hBN, and gapped graphene. Finally, we show that gauge invariance enforces photon decoupling from a critical soft phonon, establishing a general no-go mechanism for photon condensation.

Simulating defects of every dimension together is expensive, and the savings of adaptive methods are rarely tested at equal accuracy. We present a variational framework in which fields, dislocation lines and defect densities share one free energy, one dissipation law and exact ledgers of mass and Burgers vector, so that a region can change its representation without gaining or losing defects. On this basis, an allocator switches the dislocations themselves between discrete particles, where they are sparse, and a continuous density, where they are dense. The switch is made block by block from local counts, conserves the Burgers vector exactly and is controlled by a single threshold. For $5\times10^5$ dislocations, the allocator reproduces the discrete model to within 1% in the sparse region at 14-37 times lower cost, depending on the machine; the advantage grows to 81 times at $10^6$ dislocations, and a threshold calibrated on one ensemble meets its error target on an independent one. For an idealized array of dislocation walls in copper, the allocator is 37.5 times cheaper than particle dislocation dynamics and, at almost the same cost, six times more accurate than continuum dislocation dynamics between the walls. In a three-dimensional copper model coupling grain-boundary cavitation with damage, ligaments left at nominal coalescence delay creep rupture by 25-48% (post hoc sweep). By contrast, grids refined at interfaces gain less than twofold once the active region exceeds about 30% of the domain, so representation switching, rather than grid refinement, is the effective form of adaptivity for defect-rich microstructures.

We investigate the effects of substrate temperature and Al flux, at a fixed N flux, on the polarity, electrical properties, and structural quality of AlN films grown on high-resistivity Si(111) by plasma-assisted molecular beam epitaxy. N-rich conditions result in relatively highly resistive Al-polar AlN/Si, whereas Al-rich conditions promote N-polarity and improved structural quality but simultaneously lead to increased p-type conductivity of AlN/Si stacks, consistent with unintentional Al doping of the Si substrate during AlN growth. Increasing the substrate temperature further improves the structural quality while enhancing the unwanted conductivity, revealing a growth-induced trade-off among polarity, electrical isolation, and structural quality. By reducing the substrate temperature to 575{\deg}C while maintaining slightly Al-rich conditions, an N-polar AlN/Si stack with a sheet resistance of 276 k{\Omega}/sq is achieved. These results provide guidelines for optimizing AlN/Si templates for various nitride device heterostructures.

Author(s): Maitrayee Ghosh, Shuai Zhang, S. X. Hu, Armin Bergermann, Arianna Gleason, and Siegfried Glenzer

In the depths of ice giant planets such as Neptune and Uranus, and in inertial confinement fusion targets, chemical reactions can be significantly affected by the extreme pressure and temperature conditions. One of the most intriguing phenomena is the possible formation of diamond from hydrocarbon f…

[Phys. Rev. B 114, 214202] Published Tue Oct 13, 2026

Topological wave systems have largely evolved along two distinct paradigms: gapless topological semimetals and gapped topological insulators. While topological semimetals support bulk transport, they generally lack intrinsic selectivity among propagation channels; topological insulators enable robust transport but confine it to narrow interfaces, limiting spatial utilization. Here, we theoretically demonstrate and experimentally realize time-reversal-invariant spin-valley photonic half-semimetals (HSMs), which exhibit a dual semimetal-insulator topology within a single bulk band structure. In HSMs, the bandgap closes selectively in spin-valley space: for a given spin (valley), one valley (spin) is semimetallic while the other remains insulating. This coexistence of spin- and valley-resolved gapless and gapped band structures makes HSMs fundamentally distinct from both conventional semimetals and insulators. As a defining bulk phenomenon, an HSM functions as a spin-valley-locked beam splitter, intrinsically enabling valley-selective spin routing. Moreover, when four complementary HSMs are assembled into a periodic superlattice, the same dual topology enables reciprocal spin-valley-resolved multilane helical transport with 100% spatial utilization. These results establish HSMs as a platform for selective bulk wave control and multichannel topological transport beyond conventional topological phases.

Interlayer excitons (IXs) in transition metal dichalcogenide bilayers possess unique dipolar properties, providing a path for exploring correlated many-body phases, electrically tunable dipole-dipole interactions, and long-range exciton transport. However, the large electron-hole separation underlying their dipolar character also results in a significantly reduced oscillator strength, limiting their direct optical interaction with light, and thus the direct probing of their dynamics and many-body interactions. Here, we show that by using Purcell engineering of critical coupling, a weak interlayer transition can absorb as strongly as the dominant intralayer transition, despite its much smaller intrinsic oscillator strength. Using this approach, in an open cavity architecture we demonstrate an order of magnitude IX absorption modulation in bilayer and trilayer MoS2, with doubling of the IX to A-exciton interaction strength weight from ~23% to ~53%. Furthermore, we demonstrate that in a tailored closed cavity architecture, the IX enhancement can reach beyond an order of magnitude, from ~5% to ~83% excitonic absorption, enabling IX absorption similar to intralayer excitons. An analytical description of the interaction is obtained via a closed-form transmission-line model which separates the excitonic and photonic contributions to the optical response, revealing how cavity architecture can be designed towards critical coupling. Our findings establish Purcell engineering of critical coupling as a general route to controlling and enhancing weak excitonic transitions.

Recent progress in programmable quantum simulators motivates exact benchmarks for nonequilibrium dynamics in topological quantum matter. We study the Kitaev honeycomb model driven through its critical regions by a linear ramp of the bond coupling $J_z$ over a ramp time $\tau$, comparing zigzag and armchair ribbons with fully periodic tubes. The production of excitations exhibits a geometry-dependent finite-size crossover controlled by $N_2/\sqrt{\tau}$, the ratio of the ribbon width to the Kibble--Zurek length. Periodic tubes obey the expected critical-line Kibble--Zurek scaling and serve as the boundary-free benchmark. Zigzag ribbons follow the same scaling until defect production is exponentially suppressed by a finite-width algebraic gap floor associated with the formation of Majorana edge modes, whose occupation is pinned by inversion parity. Armchair ribbons instead support transient Majorana edge modes with exponentially small gaps, producing width-parity-dependent defect plateaus: exactly one defect per unit length for odd widths and an approximate, transient plateau near one half for even widths. The quench-generated entanglement entropy and fermionic logarithmic negativity inherit the same geometry-dependent structure, and the negativity further distinguishes the coherence-borne entanglement of the Kibble--Zurek regime from the population-borne entanglement of the edge-mode plateaus. These results identify boundary Majorana modes as the mechanism controlling departures from ideal Kibble--Zurek dynamics and provide geometry-resolved benchmarks for programmable simulations of topological matter.

Author(s): Federico Malizia, Andrés Guzmán, Federico Battiston, and István Z. Kiss

Higher-order interactions can induce abrupt collective transitions, yet the microscopic mechanisms controlling macroscopic critical behavior remain unclear. Here we show that nested hyperedges generate a dual effect on dynamical processes: they promote the onset of collective behavior while suppress…

[Phys. Rev. Lett. 137, 167402] Published Wed Oct 14, 2026

Topological insulators host exotic quantum phenomena such as the quantum spin Hall (QSH) effect, which enables dissipationless one-dimensional edge conduction. Realizing such states at room temperature and on a macroscopic scale is essential for energy-efficient electronics and quantum technologies, yet remains a fundamental challenge due to material limitations. Here, using microwave impedance microscopy, we directly visualize robust conductive channels persisting up to 300 K in α-Bi₄Br₄ nanowires. Their stability and scalability are likely enabled by a “stair-stepped” stacking configuration on the side facets, a multilayer geometry in which QSH edge states from individual layers remain spatially decoupled. This configuration circumvents the stringent alignment and layer-number constraints of previous proposals, allowing robust stair-stepped QSH (SS-QSH) conduction in structures several micrometers long and hundreds of nanometers high. Magnetic-field- and temperature-dependent measurements are consistent with the topological nature of these conductive channels, as further supported by our theoretical analysis. Crucially, the conductance peaks and bulk signals scale with nanowire height, verifying the stair-stepped origin. Our results are also successfully reproduced by finite-element analysis simulations. This work establishes α-Bi₄Br₄ as a practical platform for high-temperature topological electronics and demonstrates a generalizable stacking strategy for designing scalable QSH systems.

At fixed bulk criticality, every fixed nonsingular real single-end potential preserves a growing local population of real eigenvalues in an open analytic family of non-Hermitian chains. An open region of two-end real potentials removes this population. A boundary-amplitude criterion fixes the minimum number of controlled ends. The population grows as $\sqrt N$, where $N$ is chain length, although its normalized spectral weight vanishes and the local limiting bands remain unchanged. For a representative chain's four zero-detuning settings, an independent passive Hermitian double chain converts this distinction into separated resonances at one fixed local port under a common coupling scan at fixed probe carrier. Its absolute reflection contrast and stability margin both scale as $N^{-1}$, with explicit sufficient resource budgets. Boundary amplitudes thus fix a minimum control requirement that limiting bands and thermodynamic spectral density do not specify.

The formation and motion of small polarons are ubiquitous in energy materials and influence photoinduced processes. Polaron transport is governed by thermally activated lattice dynamics and rare hopping events, requiring spatial and temporal scales only attainable with machine-learning molecular dynamics, which enables extensive sampling of atomic trajectories and polaron configurations over nanoseconds. Moreover, the Born-Oppenheimer approximation underlying standard ab initio molecular dynamics cannot describe the nonadiabatic coupling between electronic states mediated by nuclear motion, which controls energy exchange and excited-state relaxation. Here, we develop a simulation framework that combines machine-learning-assisted polaron dynamics with nonadiabatic molecular dynamics to bridge these complementary aspects of polaron physics, and determine how different polaron-hopping mechanisms affect excited-state dynamics. The enlarged trajectory space allows us to provide the first direct dynamical confirmation of the adiabatic or nonadiabatic classification of polaron hopping regimes originally proposed on the basis of static Marcus-theory arguments, and to connect individual hopping events directly to nonadiabatic electronic transitions. In bulk TiO$_2$, nonadiabatic hoppings occur preferentially when the energy of the polaron-induced gap state approaches the conduction-band manifold, promoting both electronic de-excitation and, via a Landau-Zener mechanism, excitation from the ground state. In MgO, the predominantly adiabatic character of hole-polaron hopping suppresses these effects, leading to longer charge-carrier lifetimes and an absence of thermally activated excitations. At the rutile TiO$_2$(110) surface, hopping events are rarer than in bulk because the excess electron is strongly stabilized in the subsurface region, leading to correspondingly longer de-excitation times.

Non-Abelian anyons, strange particles forming the basis of fault-tolerant topological quantum computing, are predicted to emerge in fractional quantum Hall states at even-denominator filling factors. Identifying which topological order is realized has proven to be a challenging problem that requires an accurate, non-perturbative treatment of realistic Landau level mixing, which has so far been missing from theoretical studies. Here we present the first complete solution of non-Abelian quantum Hall problem that includes all electrons and all Landau levels, for spin-polarized electrons at filling factor $\nu = 3/2$. We develop a momentum-resolved neural-network variational wave function, optimized solely on the microscopic Hamiltonian, which gives direct access to the topologically degenerate ground states. Without any physics input about the expected outcome, it discovers a degenerate ground-state manifold whose entanglement reveals anyons with quantum dimension $\sqrt{2}$, the hallmark of Ising-type non-Abelian order. By directly computing the overlap with trial wave functions, we further show that Landau level mixing favors the anti-Pfaffian over other candidate states. Our results demonstrate the power of neural-network wave functions in finding and characterizing non-Abelian anyons from first principles, in regimes of strong Landau level mixing, relevant to many recent experiments.

Amorphous alkali oxychlorides are fast ion conductors, but their atomic structure remains unresolved. Total scattering sums all partial pair correlations into one curve that has no unique inversion, so the structure must be modeled. Melt-quench molecular dynamics builds a model from the interatomic potential alone, and reverse Monte Carlo (RMC) builds one from the measurement alone. The two have rarely been compared with all else held fixed. We benchmark both routes and two hybrid schemes on amorphous \ce{Li_{0.9}NbO_{0.9}Cl_{4.1}} against one neutron pair distribution function with one foundation potential. The hybrid schemes put the energy either in the acceptance rule (inline) or in short relaxations between blocks of refinement (alternating). Each refinement starts from a melt-quench glass or from a random packing of isolated units. The glass has the lowest energy and places the first-shell peaks correctly, but carries almost none of the oscillation beyond 6~\AA{} (goodness of fit $R^{2} = 0.29$). Pure RMC fits the measurement to within its counting noise ($R^{2} = 0.99$), but at more than $1.3$~eV/atom above the glass, and niobium loses about half of its first-shell chlorine. Started from the glass, both hybrid schemes reach $R^{2} = 0.92$ within $0.1$~eV/atom of its energy and keep its coordination chemistry. Structures from the two inputs fit almost equally well and differ in energy by a tenth of the RMC penalty, yet they differ in whether their polyhedra are connected. The input is therefore part of the method. We recommend quenching a glass with a foundation potential and refining it against the measurement with a hybrid scheme. The resulting structure carries both the local chemistry and the medium-range order, and it is the starting point for modeling ion transport in these conductors.

The zero modes of the Aharonov-Casher Hamiltonian form an exactly flat, vortexable Chern band in any nonuniform magnetic field, analogous to the lowest Landau level. We ask which local Hamiltonians host exactly flat higher-vortexable bands. For a scalar Hamiltonian, an exactly flat first-vortexable band requires a mass proportional to the local field; the Dirac analogue has the same structure. For periodic Bernal bilayer graphene with nonzero mean flux, the exact zero-mode pair is genuinely first-vortexable if and only if the interlayer hopping has nonzero mean; zero-mean hopping instead gives a decomposable pair. Multiorbital models yield exact higher-vortexable chains to arbitrary order, while remaining first order in momentum.

Chern insulators have optical properties that are strikingly different than ordinary chiral media. Unlike the natural optical activity of the latter, which is a finite-wavelength effect arising from spatial dispersion, the optical activity of a Chern insulator is already present in the long-wavelength limit, and exhibits a striking directional asymmetry in the propagation of circularly polarized light. We study this unnatural optical activity using a recently developed field theory for Chern insulators. For bulk Chern insulators, we derive the normal-incidence transmission and reflection coefficients of multilayer structures, identify the associated Faraday and Kerr angles, and show that these optical rotations provide a direct optical signature of topology at low frequencies. We also show that an interface between bulk Chern insulators can act as a kind of mirror, completely reflecting light at normal incidence when the Chern invariants have opposite signs. Moving to a more realistic model of a two-dimensional current sheet, we study the Faraday and Kerr effects in a thin film of $\mathrm{Mn}\mathrm{Bi}_2\mathrm{Te}_4$ in its Chern insulator phase. The predicted rotations are many orders of magnitude larger than those of optically active media of comparable thickness that are topologically trivial.

Existing machine-learning models for perovskite solar cells struggle to predict devices made from new materials. Most treat device layers as arbitrary categorical labels and represent perovskite absorbers either through featureless composition vectors or through rigid crystal graphs that require a pre-solved unit cell. As a result, they cannot generalize to unrecorded alloys or unfamiliar cell architectures. We present the Virtual-Alloy Physics-Aware Semantic System (V-PaSS), an architecture built around the physical continuity of perovskite solid solutions. V-PaSS represents arbitrary mixed-cation, mixed-halide absorbers by interpolating relaxed crystal graphs of 23 pure $ABX_3$ endpoint compounds via Vegard's law with learned bandgap bowing. For the device stack, it couples layer sequence and cell polarity (n-i-p or p-i-n) with interfacial band offsets and encodes chemical descriptions with a scientific language model. Evaluated under an institution-grouped protocol where test devices come exclusively from unseen laboratories, an untuned default configuration of V-PaSS achieves the lowest error among fourteen tested models (2.861% MAE, a 5.2% relative reduction over a gradient-boosted baseline at 3.017%, and outperforming the best tuned benchmark at 2.912%). V-PaSS pulls furthest ahead where test devices differ most from training: reducing error by 15.7-19.0% on unseen absorber alloys, by 16.1% on mixed absorbers from new laboratories, and widening its lead over the baseline by 3.6$\times$ on devices with unobserved transport layers. Combined with tree ensembles, V-PaSS sets a new state of the art across all five benchmark splits.

Nature, Published online: 14 October 2026; doi:10.1038/d41586-026-03081-4

Governments around the world have pledged to conserve 30% of the terrestrial realm by 2030, but official data suggest that the target is barely halfway to being met. A combined global and national-level data set now shows that up to 27% of land area is conserved, but gaps in ecological representation remain.

Electrical control of orbital magnetism is a central goal of orbitronics. While current-induced orbital polarization has recently been demonstrated in inversion-asymmetric systems, nonvolatile electrical control of an equilibrium orbital moment has remained elusive. Here, using x-ray absorption spectroscopy with \textit{in situ} electric-field control of the FE polarization, we demonstrate non-volatile switching of the equilibrium orbital magnetization of the oxide q2DEGs formed at the LaAlO$_3$/EuTiO$_3$/Ca-STO (001) interface. X-ray linear dichroism reveals a reversible modulation, driven by the FE-polarization direction, of the Ti-3$d$ crystal-field splitting and orbital occupancy, establishing a ferroelectric-like metallic state. X-ray magnetic circular dichroism shows a polarization-controlled switching of the Eu$^{2+}$ orbital magnetic moment induced by the orbital magnetization of the q2DEG projected onto Eu-5$d$ states and detected at the Eu-$M_{4,5}$ edge through Eu-5$d$/Eu-4$f$ hybridization in the inversion-symmetry-broken interface. These results provide spectroscopic evidence of ferroelectric control of orbital magnetism in an oxide q2DEG.

Recent photoluminescence experiments in twisted MoTe$_2$ have reported signatures of anyons binding to trapped trions. The measured binding energies near the fractional Chern insulators at fillings of $\nu=-2/3$ and $-3/5$ have a ratio close to the fractional-charge ratio $5/3$, even though such scaling is not generally guaranteed for the expected short-range trion-anyon interaction. We model the trapped trion as a fixed impurity, and investigate anyon-impurity binding using a lowest-Landau-level model with exact diagonalization and Jain wavefunctions. Surprisingly, we find that the anyon-impurity binding energy ratio between $\nu=-2/3$ and $-3/5$ is close to $5/3$ for either short- or long-ranged impurity-electron interactions. However, the ratio departs strongly from the charge ratio at intermediate ranges or different Jain states. Remarkably, we also uncover "wrong-sign" binding, whereby both quasiholes and quasiparticles can bind to either sign of a short-range impurity potential by selecting orbital channels with favorable local density oscillations. Our findings show that localized excitons or trions can be used to probe the internal density profile of anyons.

In this paper, we derive the spin polarization and the spin Chern number in momentum and real spaces in terms of the Wilson loop in each spin sector. For these derivations, the spin matrix in the subspace of occupied or unoccupied states is generalized by the unitary rotation to prevent the spectral gap from closing. In the presence of a finite spin gap, the spin eigenvectors recompose the eigenstates of the Hamiltonian in two spin sectors. A dimensional reduction leads to the charge polarization in each spin sector in terms of the Wilson loop along the effective Brillouin zone (BZ) in one dimension (1D). A linear combination of the charge polarizations defines the spin polarization, which naturally quantifies the spin Chern number in momentum space. It is also shown that the spin Chern number is directly derived from the local Wilson loops on a discrete 2D BZ. The theoretical treatment is further generalized for real space in a supercell framework, which can deal with ordered and disordered systems in a unified manner. In this framework, the spin Chern number in real space is formulated in terms of the Wilson loop around the BZ boundary. These formulations are used to numerically evaluate topological phases in the Bernevig-Hughes-Zhang model. Numerical results show an equivalence of the spin Chern number and the ${\mathbb{Z}_2}$ index.

In Kitaev magnets, frustration arises from bond-dependent spin anisotropic interactions, which can potentially realize sought-after quantum spin liquid phases. However, material realizations with dominating Kitaev exchange are scarce and the broad parameter space of extended Kitaev models remains largely unexplored experimentally. Here, we use density-functional theory, cluster many-body, spin-wave, and density-matrix renormalization calculations to show that the recently discovered honeycomb rhodate Ag$_3$LiRh$_2$O$_6$ hosts an off-diagonal exchange $\Gamma_1'$ that is second in magnitude only to the ferromagnetic Kitaev exchange $K_1$. This combination of $K_1$ and $\Gamma_1'$ explains key experimental observations, an unusually high magnetic ordering temperature of 94 K at ambient pressure and its rapid decrease under hydrostatic pressure as Ag$_3$LiRh$_2$O$_6$ evolves from ferromagnetic toward zigzag order within the honeycomb planes. Our spin-wave calculations further predict an unusual topology of the magnon bands arising from the $\Gamma_1'$ term in the spin Hamiltonian of the honeycomb layer. We show that the large trigonal splitting of $t_{2g}$ states enhances $\Gamma_1'$, the hitherto underappreciated term in Kitaev magnets, and opens the way to new interesting regimes of the extended Kitaev model.

Universal conductance fluctuations are conventionally organized by symmetry class, but crystalline anisotropy introduces additional structure in spin transport. Here we demonstrate orientation-dependent universal spin-transport fluctuations in disordered two-dimensional $d$-wave altermagnets without spin-orbit coupling. Rotating the altermagnetic orientation changes both longitudinal spin-conductance and transverse spin-Hall conductance fluctuations, while each conserved-spin sector remains in class AI. Altermagnetic orientation controls both the fluctuation amplitudes and the development of disorder-insensitive plateaus. These plateaus become flatter and less sensitive to the altermagnetic strength over the studied parameter ranges as the orientation approaches $45^\circ$, with representative fluctuation amplitudes of approximately $0.60e/(4\pi)$ for the longitudinal spin conductance and $0.40\,e/(4\pi)$ for the spin-Hall conductance. The longitudinal fluctuation amplitude correlates strongly with anisotropy of the clean-band Fermi-velocity tensor. Spin-sector covariances explain how the conserved channels combine into total fluctuations. Our results extend anisotropy-sensitive universal-fluctuation physics to conserved-spin altermagnetic transport and establish crystalline orientation as a control parameter within a fixed symmetry class.

arXiv:2508.20487v2 Announce Type: replace-cross Abstract: Topology is a powerful framework for controlling and manipulating light, minimizing detrimental perturbations on the photonic properties. Combining nanophotonics with topological concepts presents opportunities for both fundamental physics and technological applications. Although most topological photonic realizations have been inspired by condensed-matter analogue models, new topological ideas have just begun to be realized at the nanoscale. Nanophotonics is characterized by subtle phenomena that are not usually considered in other topological models' realizations, such as nonlocality, strong field confinement, and light radiating to the far-field continuum. In this perspective, we will discuss how standard topological band theory for photonic crystals needs to be extended by a more comprehensive approach that properly treats such nanophotonic intrinsic effects and, in particular, the interplay of polarization and far-field radiation. We highlight the emerging role that polarization singularities might play in defining the topological invariants in the far field, which are not fully captured by bulk observables alone. We conclude by outlining a set of open questions and promising directions for exploring novel concepts in topological nanophotonics and shaping next-generation photonic devices.

Yttrium oxyhydride (YHO) thin films are synthesised by reactive magnetron sputtering of \b{eta}-YHx precursor films onto single-crystalline yttria-stabilised zirconia (YSZ) (111) and (100) substrates at 200 {\deg}C, followed by post-deposition oxidation in air. For comparison, reference films are also prepared on amorphous SiO2 and soda-lime glass substrates at both 200 {\deg}C and room temperature (RT). The structural (X-ray diffraction and scanning electron microscopy), compositional (elastic recoil detection analysis), and optical properties, including photochromic behaviour, of the films are systematically investigated. The results reveal a strong influence of substrate orientation on the film microstructure and crystallographic texture, leading to epitaxial-like growth with a mosaic spread of ~3-4{\deg}. YHO deposited on YSZ(100) exhibits larger crystallite sizes (10-20 nm) than YHO grown on YSZ(111) (~8 nm) and exhibits residual in-plane compressive strain while remaining largely relaxed with respect to the substrate. Compositional analysis revealed that the O/Y and O/H atomic ratios ranged from 0.71 to 0.82 and from 0.33 to 0.44, respectively, for films deposited under optimised conditions. These films exhibit photochromic behaviour under solar simulator illumination, with relative transmittance changes ranging from 7 to 22 % after 10 min of illumination. Despite the pronounced structural differences, the epitaxial-like films show no systematic improvement in photochromic response, indicating that the effect is governed primarily by composition. The study shows that the bleaching time constant increases exponentially with increasing contrast reached during illumination, rather than representing an intrinsic material constant of YHO.

Photon chirality is inherently sensitive to structural handedness and magnetism, which break spatial inversion and time-reversal symmetries, respectively. Ferroaxial order, by contrast, hosts two-dimensional chirality while preserving both symmetries, thereby precluding its direct coupling to photon chirality. Intertwining ferroaxiality with magnetic order, however, may lift such constraints and enable unconventional coupling to photon chirality. Nevertheless, the optical response arising from such intertwined order has yet to be demonstrated experimentally. Here, we demonstrate transverse magneto-gyrotropy arising from spin-driven ferroaxiality in the Weyl magnet EuCd2Sb2. Whereas the conventional polar magneto-optical Kerr effect is governed by magnetization parallel to the light-propagation direction, we observe a gyrotropic response associated with magnetization transverse to the light-propagation direction. The optical rotation exhibits a characteristic 120-degree periodicity upon rotation of the in-plane magnetic field, reflecting the threefold symmetry of the emergent ferroaxial state and revealing the ferroaxial origin of the transverse gyrotropic response. This coupling to photon chirality enables vectorial control of the gyrotropic response through the magnetic field direction. Our findings establish an interaction between photon chirality and transverse magnetization enabled by intertwined ferroaxial and magnetic orders, demonstrating a novel form of multiferroicity with functional light-matter interaction.

We summarize previously published computer simulation studies of a metal electrodeposition model that considers diffusive cation flux, a fast reaction in contact with the electrode or with the growing deposit, and adsorbed atom diffusion in finite time windows. Simulations with various parameters show compact, fractal, dendritic deposits, and dynamic transitions between different morphologies during the growth of individual samples. The dendritic shapes are characterized by hierarchical organizations in which branches of a given order reproduce the shape and crystalline orientation of the branches of the previous order, in contrast to the random branching of the fractal deposits formed by DLA and related models. The simulations show dendrites with maple leaf shape in SC lattices, pine tree shape in FCC lattices, and flower-like shape in HCP lattices, with surfaces predominantly oriented in the lowest-energy configurations of each lattice. Simulations with nucleation restricted to a nanoscale seed show the initial formation of faceted particles followed by dendrite formation, in agreement with silver electrodeposition on substrates patterned with gold nanoparticles. A quantitative application to faceted and dendritic silver obtained in the same experiment provides values of the model parameters which are consistent with the characteristic widths of these structures being of the same order of magnitude of the diffusion lengths of atoms on (111) and (001) surfaces. Using an extended model for iron electrodeposition on Si(100), the simulations qualitatively reproduce the initial formation of multilayer islands, small oscillations of the roughness of a polycrystalline compact film after island coalescence, and instability development. Possible directions for applying this modeling to the electrodeposition of other materials are suggested.

Classical film theory predicts a finite diffusion-limited current at porous electrodes. However, over-limiting currents (OLCs), which exceed this limit, are often observed and have been attributed to surface charge, confinement, or electrokinetic effects. Here, we use a frequency-domain framework to identify a different mechanism governed by the time scale of concentration variation. For perfectly reactive interfaces, the spectral Sherwood number, a frequency-dependent dimensionless measure of interfacial mass transfer relative to molecular diffusion, grows as $\Shnd\sim\omega^{1/2}$ at high frequency, while its phase approaches $\pi/4$. This response corresponds to the semi-infinite Warburg limit of the electrochemical impedance. A scaling analysis shows that the exponent and prefactor are determined by diffusion within a thin layer adjacent to the interface and are therefore independent of the global pore geometry. Numerical results for parallel plates, circular tubes, and twelve porous microstructures confirm this scaling. Geometry, flow strength, and flow direction affect the low-frequency response and crossover frequency, but not the asymptotic scaling in the high-frequency limit. This temporal route to OLCs requires neither surface charge nor confinement and could inform the design of systems for pulsed electrodeposition, mineral recovery and renewable-energy storage.

Chiral topological order is incompatible with strictly two-dimensional local commuting-projector Hamiltonians on finite-dimensional tensor-product Hilbert spaces. Invertible subalgebras (ISAs) provide an alternative framework. We construct an ISA supporting chiral semions, together with its anti-semion commutant, on a square lattice with one qubit per edge. We give explicit non-Pauli generators for both algebras and prove that together they generate all local operators on the Hilbert space. Starting from the $\mathbb{Z}_4$ toric code, we condense the boson $e^2m^2$ and identify the semion and anti-semion algebras. We then decompose each $\mathbb{Z}_4$ qudit into two qubits and use a finite-depth circuit to disentangle one qubit per edge fixed by the condensation constraints. Pumping the semion ISA along the $z$ direction defines an explicit three-dimensional non-Clifford quantum cellular automaton (QCA). We show that pumping eight times is equivalent to a translation followed by a finite-depth quantum circuit with ancillary qubits. We also give an explicit finite-depth circuit relating this construction to the semion QCA previously obtained from topological quantum field theory. A similar condensation construction yields a $U(1)_4$ ISA on a square lattice. Together with the semion and earlier odd-prime ISAs, finite stacking realizes every pointed Witt class of bosonic Abelian anyon theories. Finally, we extend both constructions to all spatial dimensions $d=4k{-}2$, with one qubit or $\mathbb{Z}_4$ qudit on each $(2k{-}1)$-cell for the semion or $U(1)_4$ ISA, respectively.

Fluorite-structured ferroelectrics, such as hafnium zirconium oxide ($Hf_{1-x}Zr_{x}O_{2}$), are among the most promising materials for developing the next generation of low-power nonvolatile memories. Emulating realistic operating scenarios for ferroelectric memories requires performing access rate-dependent endurance tests. The access rate-dependent reduction of the switched polarization cannot be described as a mere superposition of fatigue and imprint effects, which are observed in conventional endurance and retention tests, respectively. The interplay between these degradation mechanisms and its correlation with the delay time in between the programming pulses remains unclear. Combining electrical testing through voltage pulses with ab initio and drift-diffusion simulations provides a comprehensive perspective on the microscopic origin of the access rate-dependent reduction of the switched polarization of ferroelectric capacitors based on product-relevant 5 nm thick $Hf_{0.5}Zr_{0.5}O_{2}$ films. The role of oxygen vacancy defects accumulating at the electrode-ferroelectric interface with delay time in reducing the fraction of switchable domains is elucidated considering electron transfer processes which change the defect charge state. Building upon this theoretical understanding, a physics-based model to extrapolate the long-term access rate-dependent endurance performance is developed and experimentally verified for temperatures up to 135{\deg}C and delay times up to 2 ms.

Onsager solved the two-dimensional Ising model in zero field, but no solution is known in a magnetic field. We prove that in any dimension $d\ge2$, at every fixed dimensionless field outside a countable set, the free energy obeys no algebraic differential equation in the coupling, even locally. The obstruction arises from droplet geometry: the maximal droplet volume grows as the $d/(d-1)$ power of its boundary size, while an integer band in the pressure coefficients protects the extremal contributions against cancellation. Our result excludes Onsager-type solutions and closed forms in elliptic, hypergeometric, or Painlev\'e functions of the coupling at these fields.

Medium-range order (MRO) is an important feature of amorphous materials, but its nature in terms of atomic arrangement has remained elusive. Here, using large-scale machine-learning-driven atomistic simulations of amorphous silicon, we probe the MRO of this archetypal network glass. By characterizing the structure in three dimensions, we reveal that the symmetry of the atomic arrangement around a central atom shows a crossover as a function of distance. At short distances, the structure is determined by local bonding constraints, which evolve from predominantly tetrahedral environments in low-density amorphous silicon to highly coordinated and strongly disordered local environments in very-high-density amorphous silicon. At larger distances, however, distinct cubic- and octahedral-symmetry patterns emerge in the three-dimensional atomic-density distribution, despite the absence of these symmetries at shorter length scales. We find that this crossover is accompanied by a quasi-periodic spatial organization of the topological rings in the structure. The characteristic spacing between ring centers matches the length scale of the first sharp diffraction peak (FSDP) in the structure factor, establishing a direct connection between this reciprocal-space signature of MRO and its real-space organization. These results demonstrate that the FSDP, the spatial correlation of the rings, and emergent orientational symmetries are not independent manifestations of MRO, but reflect different aspects of a common structural organization. Our findings provide a unified real-space picture of MRO in amorphous silicon and suggest that intermediate-range structural order in network glasses emerges from the interplay between local bonding constraints and extended atomic arrangements driven by efficient packing.

Non-Abelian anyon chains whose interactions favor a single fusion channel host quantum critical ground states described by minimal-model conformal field theories (CFTs) protected by a topological symmetry. We show that their measurement-only counterpart, where non-commuting fusion charge measurements act locally on the anyons of a chain of $L$ sites, provides a fundamental example of a non-unitary CFT controlling a non-Abelian learning problem. Mapping the monitored dynamics to a random tensor network, we numerically find $1/L$ scaling Lyapunov gaps, logarithmic entanglement scaling with the chord length, and an effective central charge in the Shannon entropy of the measurement record. The conserved topological charge sharpens with dynamical exponent $z= 1$ and is learnable by a decoder on an $O(L)$ time scale. As the topological symmetry is a non-invertible symmetry of the $SU(2)_k$ anyon theories, we establish the monitored golden chain $(k=3)$ as a non-Abelian generalization of the weakly (Kramers-Wannier) self-dual quantum critical point of the toric code $(k=2)$, and the first of a family for $k\geq 3$.

Author(s): Zhenlin Zhang, Wei Hu, Enrico Perfetto, and Gianluca Stefanucci

Extension of the Bethe-Salpeter equation to open quantum systems predicts that engineered photonic environments induce exceptional points in the excitonic spectra of transition-metal dichalcogenides, providing a pathway for non-Hermitian quantum devices with controllable optical and valleytronic properties.

[Phys. Rev. X 16, 031020] Published Tue Jul 28, 2026

When a long liquid drop is confined in a Hele-Shaw cell, the pull of surface tension produces a rapid retraction of its tip, causing it to bulge out as it draws up the excess liquid. Using numerical simulations, we demonstrate that this retraction is self-similar at long times, with the speed of retraction slowing like $t^{-1/2}$, where $t$ is the duration of retraction. After showing how this scaling can be understood using force and mass balance, we perform an asymptotic analysis of the Hele-Shaw equations to derive both the shape of the retracting drop, as well as prefactors of the scaling laws. Excellent agreement is found between our simulations and theory, and the experimental consequences are pointed out.

We extend Mark Kac's kinetic framework from single-species Euclidean spaces to a two-species, non-linear interaction space on the open cone $(0, \infty)^2$ governed by the Matsumoto--Yor rational collision involution. We identify a non-linear conserved energy $E(x,y) = x + y + 1/x$ and an invariant conic metric measure $d\mu = \frac{dx \, dy}{x(x+y)}$. By establishing a two-species $H$-theorem, we prove that entropy production vanishes if and only if post-collision velocities are statistically independent ($I(U;V)=0$). In contrast to the transform-domain proof of Letac and Weso{\l}owski~\cite{letac2000}, which relies on joint Laplace transforms of general measures, our approach yields a direct physical derivation in state space via the transformation law for logarithmic gradients and separation of variables. This uncouples the functional-differential system to uniquely characterize the Generalized Inverse Gaussian (GIG) and Gamma distributions as the non-equilibrium thermodynamic equilibria.

Author(s): Ross Glew

We introduce a family of polytopes—in-in zonotopes—whose boundary structure organizes the contributions to scalar equal-time correlators in flat space computed via the in-in formalism. We provide explicit Minkowski sum and facet descriptions of these polytopes, and show that their boundaries factori…

[Phys. Rev. Lett. 137, 161603] Published Wed Oct 14, 2026

Coupling of itinerant electrons to non-collinear spin structures in frustrated rare-earth magnets leads to unusual transport properties. While these complex magnetic orders are expected to modify the electronic structure, underlying microscopic mechanisms have been rarely identified. Using magnetoreflectance spectroscopy and \textit{ab initio} calculations, we reveal reconstructions of the electronic structure across the magnetization plateaus of the kagome spin-ice HoAgGe. We find an unusual optical anisotropy: a larger conductivity perpendicular to the kagome planes originating from the hybridization of Ho $4f$ flat bands with conduction electrons. Moreover, these flat bands are also responsible for the pronounced magnetoreflectance observed at the metamagnetic transitions. Most importantly, the magnetoreflectance behaves completely differently for excitations near the Fermi level and higher-energy interband transitions. The former, expected to sensitively probe variations in band topology near the Fermi level, shows abrupt non-monotonous changes between the magnetic states, while the interband excitations mimic the field dependence of the magnetization. These observations imply that in HoAgGe, the unusual magnetotransport likely reflects variation of band topology between plateau states. More generally, our study shows that heavy-electron bands near the Fermi level offer an efficient way to control the band structure and thereby the transport and optical properties of non-collinear magnets.

Active flows are often confined by soft, deformable boundaries that they can push against, reshape, and in turn get reorganized by. Motivated by this interplay, we combine theory and numerical simulations to analyze the morphodynamics of an elastic vesicle enclosing a dilute suspension of extensile active particles. We model the two-dimensional vesicle as a weakly extensible elastic ring with bending rigidity, immersed in a Stokesian fluid, and describe the confined active suspension using a kinetic theory. The vesicle and the suspension are coupled hydrodynamically, through the kinematic and dynamic boundary conditions at the interface, and energetically, through a single alignment interaction that simultaneously aligns active particles with the membrane and the membrane with the particles. We show that this interaction reduces to a weak-anchoring boundary condition familiar from passive liquid crystals and derive a closed-form quiescent equilibrium state in which the nematic order in the suspension organizes into a vortex with a +1 defect core. A stability analysis of this state predicts an ordered hierarchy of activity thresholds at which successive shape modes of the vesicle are destabilized, as well as a purely passive, anchoring-driven instability of floppy vesicles. Nonlinear simulations, performed with a volume-conserving immersed boundary method, reveal that each threshold crossing gives rise to a distinct emergent state: a static spindle with boundary-pinned defects, a rotor that tank treads against its own rotation, a fluctuating spinner, and a turbulent state in which the vesicle acts as a self-stirring compartment. Beyond demonstrating how boundary deformability sculpts, and is sculpted by, confined active matter, our results open the door to study hydrodynamic interactions between such active vesicles and to use membrane fluctuations as a probe of activity of suspensions.

Accurate electronic band structures are essential for predicting material properties, but high-fidelity calculations are computationally demanding. We introduce O-kRystal, a dual-space orbital-learning framework that uses a lower-cost Perdew-Burke-Ernzerhof (PBE) calculation as both an energy baseline and a source of structured orbital information. Combining PBE band energies with real- and reciprocal-space orbital matrices, O-kRystal predicts higher-level corrections for individual electronic states as a function of crystal momentum and spin. For states within 5 eV of the band-edge midpoint, it predicts Heyd-Scuseria-Ernzerhof (HSE06) band energies with a mean absolute error of $0.171 \pm 0.009$ eV across nearly 6,000 three-dimensional materials spanning insulating, metallic, magnetic, and nonmagnetic systems. On a separate benchmark of six strongly correlated materials, it reduces the corresponding PBE band-energy MAE by 68.7% and resolves orbital-dependent changes in the relative placement of transition-metal d and ligand p states. Despite training only at high-symmetry points, it maintains comparable accuracy at unseen points along band paths and reconstructs HSE06 densities of states from dense Brillouin-zone predictions. Finally, training O-kRystal on $G_0W_0$ quasiparticle energies for two-dimensional materials demonstrates its applicability across levels of theory and the potential of orbital learning for higher-fidelity, momentum-resolved electronic-structure prediction beyond density functional theory.

Reticular chemistry allows metal-organic frameworks (MOFs) to be designed from their building units, yet their synthesis remains constrained by sparse experimental data, noisy crystallization outcomes, and the absence of benchmarks for comparing active-learning strategies. While data-driven approaches such as Bayesian optimization (BO) can improve synthesis success rates, selecting appropriate optimizers beforehand for mapping MOF crystallization landscapes remains largely empirical. Here we present ActMOF, an experiment-grounded benchmark for comparing search strategies in aluminum-carboxylate MOF synthesis. ActMOF is emulated from experimentally measured microwave syntheses with each encoded condition assigned a crystallinity index calculated based on diffraction peak intensity and full width at half-maximum. By benchmarking policies guided by Gaussian processes (GP), tree ensembles and large language models (LLM), ActMOF placed the GP family among the leading policies for active learning in sparse synthesis landscapes. It then demonstrated transferability by guiding the microwave synthesis of six reticularly related aluminum MOFs. All six campaigns gave crystalline products within a fixed budget of 12 experiments each, and established a reusable testbed for AI-driven MOF synthesis.

Author(s): Wenbin Zhao, Volker Koch, and Feng Yuan

We study particle correlations in high energy jets by comparing the measured energy-energy correlator with that constructed from two individual energy flows with respect to the jet axis. This comparison demonstrates that the genuine correlations are stronger at moderate or large angles across all je…

[Phys. Rev. Lett. 137, 162301] Published Wed Oct 14, 2026

Author(s): Dmitriy Zhigunov and Jacob Page

Exact unstable solutions of the Navier-Stokes equations are thought to underpin the dynamics of turbulence but are usually computed in minimal computational domains. Here, we extend this dynamical systems approach to spatially extended turbulent flows featuring multiple interacting “substructures” a…

[Phys. Rev. Lett. 137, 164001] Published Wed Oct 14, 2026

Author(s): Shahram Panahiyan

We investigate how quantum correlations in squeezed driving fields determine scaling laws in dissipative multiphoton quantum sensing. Independently squeezed fields yield factorized scaling, with separate absorption and emission contributions and nonlinear thresholds that suppress exponential scaling…

[Phys. Rev. Research 8, 043035] Published Tue Oct 13, 2026

Author(s): Ying-Jen Yang and Ken A. Dill

Biomolecular machines operate as stochastic flows on networks. Here, we develop a principled approach to network design where local transition rates are systematically tuned to achieve global dynamical objectives. Based on the fluctuation-response duality in caliber force theory, our formalism unifi…

[Phys. Rev. Research 8, 043039] Published Tue Oct 13, 2026

Acute kidney injury (AKI) is a life-threatening condition with notably high in-hospital mortality, characterized by a three-phase progression: a relatively stable state (without imminent life threat), a critical pre-deterioration state (the time window which may be identified and in which timely intervention could prevent upcoming irreversible deterioration), and a deteriorated state (severe conditions such as death or rescue events). Accurate early prediction of AKI deterioration and deciphering the critical transition remain challenging because of complex, high-dimensional, noisy, and incomplete clinical data, as well as limited mechanistic understanding of disease progression. To solve this problem, we propose STIfuse (Spatiotemporal Information fusion), a unique dual-view framework that integrates deep learning (DL) and spatiotemporal information transformation (STI) based on Takens’ embedding theorem and critical slowing down (CSD) theory. The DL backbone encodes multi-dimensional static representations to capture structural dependencies, while the STI branch transforms high-dimensional spatial information into a low-dimensional dynamic representation. These views are fused by a multivariate Gaussian distribution: the means capture statistical levels for diagnosis, and the covariances reflect collective physiological fluctuations for early deterioration prediction. An optimal-transport-distance-based contrastive loss is employed to learn discriminative dynamic features between ˈcriticalˈ and ˈstableˈ states. Pretrained on the MIMIC-IV dataset and validated on five external cohorts (including MIMIC-III (with two independent cohorts), eICU, HiRID, and NWICU), STIfuse demonstrated superior performance in predicting 72-hour deterioration. Further analysis of single-cell multi-omics data study uncovered inflammatory cascades linking comorbidities to AKI. STIfuse provides an interpretable, robust and scalable framework for early warning of AKI deterioration prediction, highlighting its potential in utility and scalability for clinical foundation models.

Interactions turn a gas into a fluid. We show that two-body loss can take their place. Correlated loss induces elastic scattering, as required by the optical theorem, which dominates at strong loss via the quantum Zeno effect. A nondegenerate gas with only two-body loss thus flows hydrodynamically, with viscosity and thermal conductivity close to those of the unitary Fermi gas. As loss heats the gas, both grow in time with a universal exponent 3/8. Unlike single-particle loss, two-body loss can engineer collisions, and hence transport, in quantum matter.

Recovering the interaction structure of complex stochastic dynamical systems from sparse time-series observations is an inherently ill-posed inverse problem. The posterior over network configurations is high-dimensional, highly degenerate, and shaped by the non-equilibrium nature of the available data. To address this, we propose a fully Bayesian, ensemble-based inference framework. Our approach grounds a continuous-time Stochastic Differential Equation (SDE) likelihood formulation---acting mathematically as an Onsager-Machlup quasi-potential for non-equilibrium paths---within a non-parametric Minimum Description Length (MDL) structural prior. This framework rigorously penalizes model complexity and avoids kinetic overfitting by forcing continuous parameters into a finite vocabulary of discrete categories. The joint posterior is optimized using a block-coordinate scheme combining sub-quadratic Markov Chain Monte Carlo (MCMC) topological sampling with deterministic Nelder-Mead parameter optimization. Using highly non-linear macroscopic population dynamics as a benchmark, we demonstrate that inference requires non-stationary transient data to resolve causal information. Furthermore, we prove that propagating structural uncertainty via ensemble-based posterior analysis produces significantly more robust and reliable predictions for downstream perturbation outcomes than traditional single-point (MAP) estimates. The framework is highly generalizable, capturing fundamental topological constraints even under severe generative model mismatches, offering a robust tool for uncertainty-aware inference in complex stochastic systems.

Extracting the London penetration depth, $\lambda(T)$, from the measured magnetic susceptibility, $\chi(T)$, of a superconducting platelet in a perpendicular magnetic field requires knowing the function $\chi(\lambda)$ computed for the actual sample geometry. Thin films are increasingly important in quantum computing and superconducting electronics, most of which operate at ultra-low excitation fields in the vortex-free regime. Understanding their electromagnetic response in the Meissner--London (finite-$\lambda$, no vortices) state is therefore essential for extracting intrinsic properties such as the London penetration depth and superfluid phase stiffness. While numerous prior works have addressed different aspects of this problem, here we focus on providing an analytical semi-empirical representation of $\chi(\lambda)$ based on the 2D sheet-current model and establishing the limits of its applicability using two independent full 3D numerical solutions: finite-element modeling and a volume-current integral equation. As a result, we provide $\chi(\lambda)$ for a disc of radius $a$ and thickness $d$ in closed form, valid for all $\lambda$ and for aspect ratios $\delta\equiv d/(2a)\le0.05$, and accurate to $0.1\%$. The two-dimensional sheet description with Pearl length $\Lambda=2\lambda^2/d$ is adequate for $\delta \lesssim10^{-4}$ and $\lambda \gtrsim 4d$. Thicker films require the full closed form, which includes the three-dimensional corrections. Using the same numerical analysis, we provide an empirical formula that maps rectangular samples---the geometry most commonly used in experiments---onto a disc with an ``effective radius'' for subsequent calculation of $\chi(\lambda)$, and formulate a complete calibration protocol for whole-sample susceptibility measurements.

Fractional Brownian motion (fBM) is a model of anomalous diffusion parameterised by a Hurst exponent $H \in (0,1)$ and a generalised diffusion coefficient $D_H 0$. We jointly estimate $H$ and $D_H$ using maximum likelihood (MLE) from density measurements with Poisson counting noise and single-particle trajectory with Gaussian localisation error. We show that one density measurement in time cannot infer both $H$ and $D_H$ and that several time points are needed, which matters most for inference precision. For trajectories, we show that a neural network trained with a squared error loss approximates the posterior mean of $H$, which can be computed exactly at negligible cost. Paired with the profile-likelihood estimate of $D_H$, the posterior mean has the lowest root mean squared error in both $H$ and $D_H$, except near $H=0$ and $H=1$ where MLE estimates $H$ better. In vesicle trajectories from two cell types, $H$ and $D_H$ form a continuum rather than distinct modes of motion. The posterior probability that each window within a track is subdiffusive or superdiffusive shows that $26\%$ of MRC5 fibroblast and $21\%$ of HeLa vesicle trajectories contain both subdiffusive and superdiffusive windows, against $2\%$ and $7\%$ expected from estimation uncertainty alone. Intracellular cargoes therefore switch between subdiffusion and superdiffusion over time rather than forming populations with fixed $H$.

Echo State Networks (ESNs) are fundamentally important from the conceptual perspective of AI, because they provide simple and tractable frameworks for understanding temporal information processing, memory, and learning in dynamical systems. They are composed by an interconnected reservoir whose connectivity matrix remains constant over time and only the output weights are updated during the training period. In particular, ESNs employing online training allow the incremental adaptation of the output weights as data is received, making them particularly suitable for applications in which new input data becomes available over time (non-stationary environments). A key objective in the study of such learning structures is to determine which statistical properties of the reservoir enhance computational efficiency and maximize prediction performance. To this end, we investigate the effects of reservoir topology on learning performance, considering weight matrices generated from Erdos-Renyi random networks and Watts & Strogatz small-world networks. As test data we use the Lorenz and Rossler models in the chaotic regime and the FitzHugh-Nagumo model in the limit cycle regime. In the case of random Erdos-Renyi reservoirs, our simulations show that best performances are obtained for sparse reservoirs and especially when the link-density is near and immediately above the critical point of mean-field bond percolation. Watts & Strogatz reservoirs are shown to demonstrate best performance also for small values of link-density, compatible with the mean-field bond percolation when taking into account the specific nonlocal ring structure of the Watts & Strogatz reservoirs. These studies on the influence of the reservoir architecture and hyperparameters on enhancing the accuracy of ESN predictions provide an efficient framework for real-time forecasting in dynamically evolving systems.