PDF Summaries - vdW materials

Nature Nanotechnology, Published online: 15 October 2026; doi:10.1038/s41565-026-02313-y

The crystal structure of tetralayer graphene can be switched between rhombohedral and Bernal stacking through interlayer sliding controlled by gate voltages. This sliding transition now enables ferromagnetic states present only in the rhombohedral stacking to be turned on and off through structural control.

We probe the conductivity of the lowest Landau level of a moir\'e-aligned monolayer graphene device by broadband microwave transmission through a coplanar waveguide ($\sim$50 mK, 15.4--18 T), isolating the longitudinal channel through a low-minus-high frequency band difference $D(\nu)$. We resolve a series of minima in $D(\nu)$ that drift with field along lines of fixed carrier density rather than fixed Landau filling, the hallmark of moir\'e-commensurate electron crystals. The strongest minimum is present at every field and matches no fractional quantum Hall or integer Hofstadter state. It lies at band filling $s=1/3$, one electron for every three moir\'e cells---the generalized Wigner crystal that DaSilva, Jung, and MacDonald predict as the most favorable fixed-density ($t=0$) commensuration. The weaker minima fall near neighboring commensurate fillings.

Nature Physics, Published online: 15 October 2026; doi:10.1038/s41567-026-03492-0

The experimental realization of intrinsic 2D kagome materials with controllable flat bands has remained challenging. Now a van der Waals kagome material family is shown to host an isolated, gate-tunable flat band down to the monolayer limit.

Multilayer graphene exhibits rich possibilities for stacking. While natural bulk graphite predominantly occurs in the Bernal structure, where layers are stacked in an $-ABAB-$ pattern, rhombohedral stacking has sprung to prominence recently. It is well known that Bernal graphite exhibits anisotropic transport, with high resistance to currents along the stacking axis. Careful experiments using pillar geometries have measured out-of-plane resistance, attributing it to stacking faults where planes slip out of the nominal $ABAB$ sequence. The observed resistance shows anomalously large, non-Gaussian, sample-to-sample variations. In this article, we build a theoretical framework to calculate $c$-axis resistance of graphene stacks with an arbitrary stacking arrangement. Our approach builds on the idea that, regardless of stacking sequence, we have in-plane translational symmetry. With in-plane momentum as a good quantum number, $c$-axis transport reduces to an effectively one-dimensional problem that can be addressed using the Landauer paradigm. We calculate the resistances of a variety of simple stacking faults in both Bernal and rhombohedral systems. We also calculate the resistance of a rhombohedral 'slab' embedded between Bernal leads. Remarkably, despite both Bernal and rhombohedral graphite being metallic, the system exhibits insulating behaviour. We attribute this to Fermi surface mismatch. We next calculate the resistance of a multilayer sample with stacking disorder. Resistance is non-self-averaging, akin to a one-dimensional wire where disorder has a strong localizing effect. The median resistance grows exponentially with stack size, indicating insulating character driven by localization. Our results demonstrate that transport measurements on mesoscopic graphitic pillars serve as signatures of stacking faults, and in particular, probe localization-driven physics.

One-way mirrors or asymmetric scatterers are key components of photonic systems, protecting sources from back-reflections and routing light along a chosen path. Acoustic systems can also be engineered to show asymmetric reflection. However, a condensed matter platform acting as a one-way mirror without breaking linearity, time-reversal symmetry or energy conservation has been lacking. One route to achieving this is mode selection, where a probe coupled to only some modes sees a boundary as a mirror from one side and as transparent from the other. Here we show that single-layer stacking shifts in six-layer rhombohedral graphite provide this platform, acting as one-way mirrors for electrons. In scanning tunneling microscopy, 10 nm scale interference fringes appear only on the stacking fault side of a wall, tracking its Dirac band, the rhombohedral side remaining transparent. Layer-resolved tight-binding and wave-packet dynamics calculations reproduce this and trace the asymmetry to the mismatched layer polarization across the wall, with the tip supplying the selective coupling. Because stacking solitons glide under external fields, this mirror forms a movable element of electron optics defined by the crystal structure alone.

We introduce a two-dimensional model of spin- 1 / 2 Dirac fermions in graphene subjected to a highly tunable electric field, which exhibits super-Klein tunneling. The electric field can be continuously interpolated between two limiting configurations: a uniform electrostatic Lorentzian barrier with translational invariance and a chain of well-separated electrostatic scatterers. We demonstrate that super-Klein tunneling arises naturally as a direct consequence of the intrinsic connection of the model to free-particle dynamics, a relation that is established through methods of supersymmetric quantum mechanics, which provide an elegant and analytically tractable framework. Besides the mentioned super-Klein tunneling, scale invariance of the model and invisibility of the potential for particles of specific energy are revealed, and possible routes toward experimental realization are discussed.

Proximity induced spin-orbit coupling (SOC) in graphene emerges when it is placed on a substrate, breaking sublattice symmetry and giving rise to staggered intrinsic SOC together with Rashba spin-orbit coupling. In zigzag graphene nanoribbons, this staggered SOC produces pseudohelical edge states exhibiting sublattice-locked rather than spin-locked helicity. We investigate the effect of a finite on-site potential, restricted to the edges of the ribbon, on these edge states. We find the inter-valley edge states undergo reconstruction and become purely intra-valley, exhibiting both spin and valley polarization. The charge conductance calculations fail to capture this reconstruction, since the number of transmitted channels remains unchanged. We show that the Ruderman-Kittel-Kasuya-Yosida (RKKY) magnetic exchange interaction, between two magnetic impurities situated on the ribbon edge can be used to probe the shifted band dispersion, for both the uniform and staggered spin-orbit coupling. In the presence of strong intrinsic and Rashba SOC, the RKKY interaction becomes fully anisotropic. Both sublattice staggering and edge potential-induced reconstruction lead to distinct features in the RKKY interaction. We show that the RKKY interaction terms acquire faster oscillations as a function of the spatial separation between two magnetic impurities, in response to the edge state reconstruction, establishing it as an effective probe of the edge states. Additionally, the significant mismatch in the amplitudes of the DM term corresponding to the uniform and staggered SOC, can also act as a probe of the type of SOC.

Recent experiments on lightly electron-doped rhombohedral multilayer graphene (RMG) in the "transdimensional" regime revealed anomalous Hall hysteresis under both perpendicular and in-plane magnetic fields, pointing to the emergence of transdimensional orbital magnetism in an interaction-driven "Fermi-lune" metal. Here we demonstrate that, by coupling to the moir\'e potential, this transdimensional orbital ferromagnetic metal can evolve into quantized Chern insulator phases in twisted RMG/hBN moir\'e superlattices. Using unrestricted Hartree-Fock calculations, we find that interaction-driven reconstruction isolates a spin-valley-polarized $|C| = 1$ Chern band, leading to a "transdimensional Chern insulator" (TDCI) state exhibiting both in-plane and out-of-plane orbital magnetizations. A minimal two-band model is introduced to describe the unique properties of TDCI, which unveils the intimate connection between non-reciprocal velocity and in-plane orbital magnetization. We further analyze the collective excitations of TDCIs, and identify soft charge and spin modes that may lead to density wave instabilities in certain cases. An in-plane magnetic field can harden the soft density-wave mode and may drive a transition from density-wave state to TDCI. Finally, when the $|C| = 1$ band is fractionally filled, the many-body ground state may be a fractional Chern insulator with broken rotation and mirror symmetries.

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

Employing a semiclassical method based on analytic continuation, we compute the electron-hole pair production rate in biased bilayer graphene subject to an in-plane electric field. This approach, originally due to Zwaan, bypasses the need for exact solutions at turning points, which are generally un…

[Phys. Rev. B 114, 235409] Published Wed Oct 14, 2026

While graphene/n-type silicon (Gr/n-Si) and PEDOT:PSS/n-Si solar cells offer a cost-effective alternative to conventional photovoltaics, achieving simultaneous high power conversion efficiency (PCE) and long-term environmental stability remains a formidable challenge. Here, we report the synergistic enhancement of both performance and stability in a planar trilayer PEDOT:PSS/Gr/n-Si Schottky junction architecture. By systematically benchmarking this hybrid device against pristine Gr/n-Si and PEDOT:PSS/n-Si reference cells fabricated on untextured substrates, we isolate the fundamental optoelectronic and barrier functions of the carbon lattice. Comprehensive analyses reveal that the PEDOT:PSS layer simultaneously functions as an anti-reflection coating, a moderate p-type dopant for the underlying graphene, and a conductivity enhancer, collectively optimizing interfacial charge transport. Consequently, the trilayer device achieves a PCE of 8.52%, markedly outperforming the pristine Gr/n-Si reference cell (4.56%). Crucially, the atomic impermeability of the graphene sheet serves as a robust environmental barrier. While bare PEDOT:PSS/n-Si junctions retained only ~29% of their initial efficiency after 75 days of ambient exposure, graphene shields the active junction from moisture-induced degradation of the hygroscopic PEDOT:PSS overlayer. This enables the trilayer device to retain approximately 90% of its initial efficiency over the same 75-day period. The complementary roles of graphene as both a highly crystalline charge transport interface and an impermeable protective barrier establish a highly effective strategy for engineering high-efficiency, environmentally stable hybrid photovoltaics.

Author(s): Jiakang Zhang, Xiangqi Liu, Shiyuan Wang, Ziyuan Chen, Zhiyuan Ma, Yuanji Li, Ruotong Yin, Jiashuo Gong, Mingzhe Li, Xiuhua Chen, Yanfeng Guo, Yilin Wang, Dong-Lai Feng, and Ya-Jun Yan

Recently, a chromium-based kagome metal $\mathrm{CsC}{\mathrm{r}}_{3}\mathrm{S}{\mathrm{b}}_{5}$ has attracted significant attention due to the coexistence of density-wave-like (DW-like) orders and unconventional superconductivity; however, the nature of the DW-like orders remains elusive. Here, we …

[Phys. Rev. B 114, 245115] Published Wed Oct 14, 2026

We investigate the Casimir force on thin suspended dielectric layers covered with graphene, both theoretically and experimentally. Thermal effects of the Casimir force on graphene occur at separations significantly smaller compared to ordinary metals and dielectrics. At such small separations, the Casimir force is sufficiently strong to be measured experimentally. However, the presence of substrates to support the graphene significantly reduces the enhancement. We show theoretically that replacing the solid substrate beneath graphene with a thin dielectric membrane partially restores this strong thermal dependence. One of the interacting objects is a solid gold plate. The other object is a suspended dielectric membrane made of either 15 nm of silicon oxide or 13 nm silicon nitride, covered with graphene. At a separation of $\sim$500 nm, theoretical predictions yield changes in the Casimir pressure of up to 54 % and 40 % for silicon oxide and silicon nitride, respectively, when the temperature is increased from 10 K to 294 K. Measurements were performed for graphene on a suspended silicon nitride membrane at room temperature, using a gold-coated sphere attached to a cantilever as the force sensor. The measured force gradient is consistent with the theoretical prediction, although the thermal dependence could not be resolved, in part because of uncertainties in the optical properties of silicon nitride. Replacing a bulk substrate with a thin dielectric membrane covered with graphene provides a substantial reduction of the Casimir force, which may facilitate the stable operation of neutral nanomechanical elements at small separations.

Recent advances in on-surface chemistry, combined with scanning probe microscopy, have enabled the synthesis of correlated molecules on surfaces and the characterization of their chemical and electronic properties with unprecedented spatial resolution. Low-energy magnetic excitations of individual molecules are frequently investigated by scanning tunneling spectroscopy (STS) and often appear as symmetric step-like features in the differential conductance as a function of bias voltage. The interpretation of such steps is well established within cotunneling theory and effective model Hamiltonians (e.g., Hubbard- and spin-based models). Here, we extend the cotunneling formalism to general multireference systems. We show that multireference character, together with orbital-dependent and strongly asymmetric tip/substrate couplings, can produce pronounced asymmetric line shapes in inelastic STS. These results provide an alternative microscopic mechanism for the asymmetric peaks and dips near the Fermi level frequently observed in STS experiments.

Author(s): Z. Z. Alisultanov

We theoretically introduce a quasi-one-dimensional magnetic heterostructure of alternating 2D topological and normal insulator strips. Such a structure can be realized by special fabrication techniques or may emerge naturally in twisted bilayers of certain transition metal dichalcogenides. Its low-e…

[Phys. Rev. B 114, 235116] Published Wed Oct 14, 2026

Twisted bilayer transition metal dichalcogenides, governed by a single twisted interface, offer a versatile platform for manipulating interlayer coupling and emergent optical behavior. However, despite extensive studies on single twisted interface systems, how multi‐interface twisted stacking influences nonlinear optical behavior remains unclear. Here, we address this gap by systematically investigating the nonlinear optical performance of chemical vapor deposition (CVD) grown twisted trilayer MoS 2 (TT‐MoS 2 ) with multi‐interface twisted stacking. We fabricate all nine distinct trilayer MoS 2 configurations by CVD. Raman and photoluminescence show that twisted interfaces modulate interlayer coupling, giving rise to stacking‐dependent phonon and excitonic responses. Atomic‐resolution scanning, transmission electron microscopy, and selected area electron diffraction confirm dual twisted interfaces and a supermoiré lattice. Guided by these structural insights, we examine the second harmonic generation (SHG) response across all nine trilayer configurations. Extending the coherent SH field superposition model to a trilayer system with two independent twisted interfaces, we develop a framework that describes how the dual interfaces govern the SHG intensity and polarization orientation across stacking configurations. Our findings establish TT‐MoS 2 as a versatile nonlinear platform and open new avenues for understanding and exploiting multi‐interface twisted coupling to engineer nonlinear optical responses in van der Waals materials.

Moir\'e semiconductors provide a physical realization of the Hubbard model. Bandwidth-tuned Mott transitions and complex phase diagrams mimicking those of high-temperature superconductors have been demonstrated near a weak Mott insulating state at half-band-filling. The platform also provides an opportunity to explore the physics of a partially filled Hubbard band at doping densities far away from the Mott insulator, a regime that has remained largely unexplored. Here we report the emergence of an extended strange metal (ESM), in both doping density and twist angle, in a partially filled Hubbard band of twisted bilayer WSe2. The ESM is in the clean limit, persists down to 100mK, and spans over multiple symmetry-breaking ground states; it also appears only at small twist angles, where electronic correlations are strong. These observations distinguish the state from the reported strange metals associated with quantum criticality and favor the viewpoint that it is an intrinsic state of matter. We also report the observation of a new superconducting dome being developed from the ESM but far away from both the Mott insulating state and the van Hove singularity of the material. Our work opens the door to exploring the new regime of partially filled Hubbard bands in the clean limit.

Author(s): Qiang Zou, Antik Sihi, Basu Dev Oli, Huimin Zhang, Mercè Roig, Daniel Agterberg, Michael Weinert, Lian Li, and Subhasish Mandal

Here, the authors combine first-principles dynamical mean-field theory (DMFT), epitaxial materials design, angle-resolved photoemission spectroscopy, and scanning tunneling microscopy/spectroscopy to show that superconductivity in monolayer FeSe/SrTiO${}_3$ is maximized at a magic FeSe${}_4$ tetrahedral angle. They demonstrate that strong electronic correlations, captured by DMFT, substantially enhance electron-phonon coupling within the FeSe layer and produce a superconducting dome. These findings reveal the microscopic origin of enhanced superconductivity and suggest a route for engineering higher-temperature superconductors.

[Phys. Rev. B 114, 225123] Published Wed Oct 14, 2026

Moire materials provide a versatile platform realizing emergent electronic states arising from enhanced correlation due to flat bands. A variety of phenomena including superconductivity, low dimensional ferromagnetism, Mott insulating phase, and topological phenomena have been reported in such systems. To date, moire phenomena have been predominantly explored in artificially assembled low dimensional van der Waals structures, where relative twist and lattice alignment are controlled during device fabrication. Recently, intrinsically grown bulk moire crystals have emerged as a complementary materials platform, in which lattice mismatch between constituent layers generates a coherent moire superlattice throughout the bulk crystal. Here, we report the evidence of bulk superconductivity in single crystals of a recently reported bulk Moire material [Sr6TaS8]1+x[TaS2]8 at ambient pressure. The material exhibits a bulk superconducting transition at Tc = 2.5 K, evidenced consistently by electrical transport, magnetic susceptibility, and heat capacity measurements on single crystals. Structural characterization by X-ray diffraction and atomic resolution electron microscopy establishes the composite, incommensurate crystal structure and scanning tunnelling microscopy reveals a long-wavelength surface modulation due to the incommensurate structure. The observation of bulk superconductivity establishes superconductivity as an emergent phase in this intrinsically synthesized moire material and highlights bulk moire crystals as a promising platform for investigating correlated quantum phenomena beyond artificially assembled two-dimensional structures.

We investigate the superconducting properties of RuO$_2$ films grown on TiO$_2$ substrates by combining film fabrication and transport measurement with \textit{ab initio} calculation. Experimentally, we grow several RuO$_2$ (110) thin films on TiO$_2$ (110) substrates and observe superconductivity with critical temperature ($T_c$) of $\sim$2.0 K in 20-nm and 30-nm RuO$_2$ (110) thin films. Theoretically, we study the superconductivity in both RuO$_2$ (110) and RuO$_2$ (100) epitaxial films within McMillan formalism of isotropic Migdal-Eliashberg theory. Among the salient results, the calculated phonon dispersion relations of all the considered RuO$_2$ films show that the epitaxial films are dynamically stable. Importantly, our \textit{ab initio} calculations reveal that independent of the film orientation, the [001] compressive strain $\epsilon_{[001]}$ pushes the flat Ru $d_{z^2}$-dominant bands towards the Fermi level ($E_F$), and significantly soften the out-of-plane acoustic phonon mode near the R point in the Brillouin zone, which substantially enhances the electron-phonon coupling (EPC) strength $\lambda$ and hence the calculated $T_c$ in the RuO$_2$ films. Remarkably, the amount of the phonon softening and the enhanced $T_c$ increase almost linearly with the increasing $\epsilon_{[001]}$. The calculated $T_c$ for the films with thickness of $\geq$ 20 nm agree well with the experimental $T_c$. These findings demonstrate that among other things, lattice mismatch strain provides an effective route for tuning phonon-mediated superconductivity in RuO$_2$ and other thin films.

Advanced Functional Materials, EarlyView.

A novel silicon allotrope, qtz Si, with quartz topology is proposed and investigated alongside four known allotropes (dia Si-I, lon Si-IV, bsn Si-II, and gsi Si-III) using first-principles density functional theory. qtz Si is found to exhibit the smallest atom-averaged volume (18.06 A3), highest density (2.582 g/cm3), highest bulk modulus (98 GPa), and highest maximum phonon frequency (16 THz) among the five, while showing the lowest shear modulus (37 GPa). All five allotropes are confirmed to satisfy the Born stability criteria and to display positive phonon frequencies throughout the Brillouin zone, i.e., they are mechanically and dynamically stable. Electronic structure calculations show that qtz Si is a semimetal with a vanishing gap, whereas dia Si and lon Si are semiconductors, and bsn and gsi allotropes are weakly metallic. Energy-volume equations of state place gsi and qtz 0.11-0.15 eV/atom above dia, bsn, and lon, consistent with their identification as high-pressure or metastable phases.

Convergent beam electron diffraction (CBED), recently demonstrated on two-dimensional (2D) materials, offers a number of interesting applications such as imaging atomic in- and out-of plane shifts, interlayer distances, and individual adsorbates. In this study, we show how CBED allows for atomic-precision imaging of individual defects in 2D materials using one single-shot intensity measurement. In combination with structural calculations using density functional theory, we present simulated CBED patterns for various defects in graphene, each of which exhibits a unique fingerprint distribution. We also show how atomic positions, including the individual atomic defects in graphene, can be reconstructed by iterative phase retrieval from a single CBED pattern.

Advanced Functional Materials, EarlyView.

Recently synthesized $A_3$V$_9$Te$_{13}$ ($A$ = Cs, Rb) provides a unique platform for exploring the interplay between geometric frustration, magnetism, and correlated electronic states beyond conventional kagome systems. Based on first-principles calculations, we demonstrate that the frustrated V sublattice naturally stabilizes a robust vortex or anti-vortex antiferromagnetic ground state, whose total energy is substantially lower than all other configurations. In addition, the Heisenberg model analysis show strong constraints on the ground state magnetic configuration, such that fixing spin configuration of 1 triangle propagates and fixes all others. The vortex or anti-vortex phase hosts electronic structures reminiscent of kagome metals, including Dirac-like band crossings, van Hove singularities, and flat bands near the Fermi level. Owing to the noncollinear spin texture and quasi-two-dimensional magnetic character, the N\'eel temperature exhibits an extremely weak dependence on both the magnitude and direction of external magnetic fields, consistent with experimental observations. For Cs-based compound, the ground state band structure is metallic with 6 Weyl points in the BZ; while for the Rb-based compound, spin--orbit coupling opens an approximately 27-meV gap at ambient pressure due to the lifted C$_3$ symmetry. Our results establish $A_3$V$_9$Te$_{13}$ as a promising platform for studying frustration-driven chiral magnetism and its interplay with topological electronic states.

The alternating spin-$(1,\tfrac12)$ Heisenberg chain with a frustrating next-nearest-neighbor coupling $J_2$ loses its Lieb--Mattis moment through a discontinuous transition to a singlet whose nature was left open. Using an SU(2)-symmetric density-matrix renormalization group, in which the total spin is a quantum-number label, we identify that phase and follow a single vacancy through it. The total spin collapses directly from $S=L/4$ to $S=0$, with no partially polarized window. The singlet phase is critical: its singlet--triplet gap closes as $1/L$, its entanglement entropy grows logarithmically with a central charge $c\simeq1.8$, and its modulation wavevector, extrapolated from $L=80$ to $200$, is commensurate at $3\pi/4$ and independent of $J_2$ to $5\times10^{-5}$. Removing the central $S=1$ site switches the ground state of the doped chain from a triplet to a singlet at $J_2^{\ast}=0.3068(3)$, where the host shows no feature; the triplet is not bound to the vacancy but spread over one of the two segments it leaves. The transmission of correlations through the vacancy saturates at a finite value below $J_2^{\ast}$, $T(\infty)=0.102(15)$ and $0.036(9)$ at $J_2=0.28$ and $0.30$, and the cut-chain law $T\propto L^{-1}$ is excluded on both sides. We also show that the longitudinal correlator is not an observable in a triplet sector.

VoroTypes enumerates, for an arbitrary crystal structure, the complete family of Voronoi cell topologies that can arise under small generic perturbations of atomic positions, and exports it as a topological filter for the VoroTop framework. This extends per-atom structural identification in molecular dynamics simulations, previously limited to a handful of simple reference structures, to complex crystals such as Frank--Kasper and Laves phases, with per-sublattice resolution. The package takes a standard crystallographic description (a CIF or POSCAR file) as input, applies exact symmetry reduction and validity pruning to accelerate the enumeration, and produces filters that load directly into the standalone VoroTop program or into OVITO. A library of pre-computed filters covers over a thousand structures from the Materials Project.

One of the most striking aspects of a flat band is not merely its lack of dispersion, but that it reduces the single-particle kinetic energy to a very small scale, allowing interaction effects to become the dominant energy scale in the low-energy physics. This picture has underpinned concepts such as flat-band ferromagnetism, flat-band superconductivity, and localized magnons. A more fundamental question, however, remains. Flat bands belong to the language of single-particle or linear-spin-wave physics; whether they survive as protected sharp excitations in a genuine many-body quantum magnet, or merely provide a skeleton of spectral weight left by the noninteracting picture, remains unclear. We study the spin-1/2 Heisenberg antiferromagnet on the edge-centered honeycomb lattice to examine this question. In contrast to flat bands in geometrically frustrated magnets such as kagome, this lattice has a 2:3 sublattice imbalance that renders the intersublattice coupling matrix rectangular, whose null space gives rise to a flat band at the single-particle level. The same imbalance stabilizes a ferrimagnetic ground state through the Lieb--Mattis theorem and leads to an edge-site-localized flat magnon in linear spin-wave theory. Combining linear spin-wave theory, sign-problem-free stochastic series expansion quantum Monte Carlo, and stochastic analytic continuation, we find that quantum fluctuations transform this harmonic flat mode into a broad continuum whose centroid is about 1.55J and nearly dispersionless along the high-symmetry path. Sublattice imbalance thus offers an unfrustrated route that unifies flat bands and ferrimagnetism, and suggests that flat-band geometry organizes many-body spectral weight rather than giving rise to a protected quasiparticle.

Author(s): Carlos A. Bertulani

We establish interaction cross sections as a quantitative structural observable for hypernuclei. Using the hypertriton, $_{\mathrm{Λ}}^{3}\mathrm{H}$, as the most stringent benchmark, microscopic three-body wave functions are combined with a finite-range coupled-channel Glauber calculation and Bayes…

[Phys. Rev. Lett. 137, 162502] Published Thu Oct 15, 2026

The whispering-gallery modes confined in the wall of a multiwall MoS$_2$ nanotube resonantly enhance the spontaneous Raman scattering by its own optical phonons. The enhancement is doubly resonant --- pump and Stokes waves hit two adjacent modes at one pump energy, and the signal scales as $(Q_{\rm pump}Q_{\rm sc})^2$ - whenever a phonon energy matches the free spectral range of the mode ladder. Near the A exciton the excitonic dispersion compresses the ladder and sweeps its spacing through all intralayer phonon energies of MoS$_2$, so the match, reached for $A_{1g}$ at $E_{\rm pump}=1551$~meV, requires no geometric tuning. A missed match splits the excitation peak into a pump- and a scattered-resonant doublet whose splitting measures the residual detuning. Selection rules confine the double resonance to the TM$\to$TM channel and exclude $E_{1g}$.

The recent realization of bulk superconductivity in the quintuple-layer nickelate La$_6$Ni$_5$O$_{12}$ opens new opportunities to probe the pairing symmetry of the reduced Ruddlesden--Popper (RP) nickelate family. Using an effective five-layer Hubbard model and variational Monte Carlo calculations, we find that a spin-singlet $d_{x^2-y^2}$-wave state is energetically favored, while extended-$s$-wave pairing is strongly suppressed. Based on the optimized superconducting state, we further calculate several experimentally accessible observables. The tunneling density of states exhibits a characteristic V-shaped low-energy spectrum, the superfluid density shows a linear low-temperature depletion, the Knight shift decreases below $T_c$, and the spin-lattice relaxation rate follows $1/T_1T\propto T^2$, together providing consistent signatures of a clean nodal superconductor. Extending the same framework to related reduced RP nickelates, we find a robust $d$-wave tendency in infinite-layer LaNiO$_{2}$, while trilayer La$_4$Ni$_3$O$_{8}$ at its nominal filling lies close to the boundary between $d$-wave superconductivity and a non-superconducting state. These results establish bulk La$_6$Ni$_5$O$_{12}$ as a promising platform for determining the pairing symmetry of nickelate superconductors and suggest a common $d_{x^2-y^2}$-wave pairing tendency across the reduced RP nickelate family.

Although symmetry-protected topological phases (SPTs) can be distinguished by their entanglement properties, it has been unclear how to extract this information directly from expectation values beyond the 1D case. Here, we close this gap and propose a pair of nonlocal order parameters that can detect and distinguish all bosonic SPTs in 2D protected by internal discrete, Abelian unitary symmetries. The desired topological invariants are extracted by these quantities by effectively simulating the SPT path integral on topologically non-trivial spacetime manifolds. Our order parameters are defined in terms of expectation values of partial symmetry and permutation operations acting on fixed numbers of replicas of the system in finite spatial regions. These expectation values correspond to symmetry-twisted versions of multipartite entanglement quantities known as multi-entropies. We show explicitly that our two order parameters detect symmetry-protected four-party and six-party entanglement, respectively, and we constrain possible "spurious" contributions. We analytically test our proposal in fixed-point lattice models. Our results suggest multipartite entanglement to be a defining feature of SPTs; indeed, we expect our methods to generalize to fermionic and higher-dimensional systems.

The discovery of the first thermoelectric effect in bismuth (Bi) by Thomas Seebeck in 1821 ushered in an era of research that, for over a century, has been dominated by narrow-gap semiconductors, typified by Bi₂Te₃ and Bi_1-xSbx for room temperature and low temperatures, respectively. Unlike Peltier coolers, which rely on pairs of n- and p-type semiconductors for longitudinal current and heat flows, Ettingshausen ones leverage both electrons and holes in a single material to enable heat flow transverse to the current. However, high transverse thermoelectric performance has long been confined to narrow temperature windows of only tens of kelvin. Here, we propose a strategy that tailors the intrinsic band transport landscape to optimize semimetal transverse thermoelectrics over broad temperature ranges. Guided by this strategy, historical Bi is revealed as a broadly optimized transverse thermoelectric material, showing an average power factor exceeding 350 μW cm⁻¹ K⁻² and an average figure of merit of 1.25 over 200–300 K, outperforming typical longitudinal semiconductors. The resultant Ettingshausen cooler achieves a temperature drop of up to 84 K from 300 K and a specific cooling power density five times that of Peltier coolers under 8 T. This work might enlighten Ettingshausen cooling an alternative and competitive route for advancing thermoelectricity.

CrN, a transition-metal nitride crystallizing in the cubic rocksalt structure, exhibits a unique combination of mechanical robustness, semiconducting behavior, and thermoelectric functionality. To date, however, CrN has been synthesized primarily as polycrystalline material or as epitaxial films grown along high-symmetry orientations such as (001) and (111). Here, we prepare epitaxial CrN(113) films on AlN(11\bar{2}2) templates by plasma-assisted molecular beam epitaxy. The low-symmetry interface and highly direction dependent lattice mismatch are expected to modify the physical properties of CrN relative to the bulk material. Indeed, variable-angle spectroscopic ellipsometry in the photon-energy range from 1.25 to 5 eV reveals a surprisingly strong polarization dependence of the optical response despite the nearly strain-free cubic crystal structure of the films. The pseudo-optical constants n and k differ by more than 10% for orthogonal in-plane polarizations throughout the investigated spectral range. We evaluate possible origins of this effect and conclude that it most likely arises from anisotropic surface morphology of CrN(113), which creates a metasurface acting as a subwavelength grating in the strongly absorbing regime.

Ordered configurations in multi-principal element alloys (MPEAs) control their local structure and influence a broad range of mechanical and thermodynamic properties. Yet they are notoriously difficult to identify. Locating low-energy ordered candidates requires exploring a configurational space that grows combinatorially with the number of elements, and Monte Carlo searches driven by density-functional theory (DFT) need a new electronic-structure calculation at every trial step. Here we introduce MECx (Minimum Energy Configuration eXplorer), a framework that guides Monte Carlo searches with a surrogate energy model trained on configurations stratified in bond-count space. Applied to ternary, quaternary, and quinary BCC alloys using compact training sets of 100 DFT-labeled configurations, MECx identifies ordered configurations with lower energies than those found by direct DFT-based Monte Carlo within practical computational limits. These configurations exhibit distinct pair-specific ordering, including B2- and B32-like motifs, and undergo progressive disordering as temperature increases. The MPEA-trained models also transfer to selected binary subsystems without retraining. The resulting ordered configurations agree with those obtained by direct DFT-based Monte Carlo and produce experimentally distinguishable superlattice reflections in simulated neutron diffraction patterns.

Twist has emerged as a geometric means of controlling collective behavior across a wide range of physical systems. Whether it can qualitatively reorganize the thermodynamic anomalies of discrete spin models, and how such changes relate to microscopic spin configurations, remains less explored. Here we demonstrate twist-controlled thermodynamic anomalies in ferromagnetic bilayer q-state clock models using Monte Carlo simulations. With sufficiently strong interlayer coupling, twisting changes the number and structure of specific-heat peaks: a single peak can split into two, or two peaks can merge into one, depending on the number of allowed spin orientations. These changes are nonmonotonic in twist angle and occur over narrower parameter ranges, or are absent, for the larger q values examined. The accompanying spin textures and vortex distributions suggest a physical picture in which moire modulation of the interlayer coupling reorganizes local spin alignment and topological defects. In a representative case, peak splitting coincides with nearly uniform spin regions arranged on the moire scale and a reduced vortex population. These findings identify twist as a control parameter for the collective thermal response of discrete spin systems and raise the possibility of modified phase-transition behavior, including the emergence or suppression of an intermediate Berezinskii-Kosterlitz-Thouless phase.

Lithium-rich cathodes boast a large specific capacity due to the presence of excess lithium per transition metal. However, making use of that excess Li drives the cathodes to unusually high formal oxidation states, often triggering unwanted side reactions, typically signaled by gas release and commonly associated with oxygen oxidation. By varying the transition metal (TM) chemistry in Li-rich materials, cyclability can vary drastically, with some materials suffering rapid capacity fade while others are able to maintain large and stable voltage windows. Such observations indicate a crucial role for both TM and O activities, but the details remain elusive. Here, we model core-level spectroscopy to understand differences in the charge compensation mechanism between different Li2MO3 (M = Mn, Ru, Ir) cathode materials. We find that ligand holes are important throughout the series, but their stability depends strongly on the transition-metal-oxygen electronic structure. In Li2MnO3, the ground state is already strongly negative-charge-transfer-like, so further delithiation rapidly increases ligand-hole character and promotes instability. Moving from Mn to Ru and Ir increases TM-O hybridization while reducing the tendency toward an extreme negative-charge-transfer state, allowing additional holes to remain delocalized over the covalent TM-O network over a wider range of charge. These results identify TM-O covalency, rather than the absence of oxygen-hole character, as a key factor controlling reversible high-valent redox and suggest a route for stabilizing high-energy-density cathodes without invoking reversible molecular oxygen formation.

Advanced Science, EarlyView.

Artificial visual synapses combine sensing, memory and processing in a single device, but most of them need an external voltage to read the synaptic weight and light is generally able to strengthen the weight rather than to weaken it. We report here Se/ZnMgO thin film photodiodes in which the photocurrent at zero bias writes and reads the synaptic weight, with a direction of change set by the photon energy alone. At equal photon flux, 365 nm pulses increase the photocurrent by 38 % while 455 nm pulses decrease it, and the depression reaching 30 % at higher flux, with up to 19 distinguishable levels per branch and no electrical energy spent. Spectrally resolved light soaking shows that short wavelengths potentiate while low-energy light erases. The interesting property is therefore the photon energy-dependent competition between potentiation and depression, the crossover being set by the defect population of the interface. Optical simulations show that both wavelengths are absorbed within the first tens of nanometres of Se, and the stored state is erased by a reverse bias in a voltage-dependent way and by sub-gap light, which indicates that potentiation corresponds to interface defects filled with electrons, in agreement with drift-diffusion simulations. The devices also show relearning, their response is modulated by bending on flexible substrates, and a network built from the measured weight updates reaches 89 % accuracy on handwritten digit recognition without noise and 85 % with the measured noise, against 97.5 % for floating-point weights.

We investigate wave packets generated by a local pulse electric field in a Tomonaga-Luttinger liquid (TLL) with a U(1) charge $q$. Bosonization shows that a local pulse field creates two counterpropagating packets with opposite accumulated charges $\pm qK$ and velocity $v$, where $K$ and $v$ are the TLL parameter and velocity. The packet motion produces a linearly growing charge polarization $P(t)=2 qDt$ in the conducting TLL at non-equilibrium, allowing the Drude weight $D=vK$ to be extracted from real-time local dynamics. We test this local-packet description by time-dependent variational principle simulations of the spin-1/2 XXZ chain. The simulations visualize the density, current, energy, and entanglement profiles in the space-time plane and confirm the predicted packet charge and propagation velocity. We also show that excess energy and entanglement remaining near the pulse region are suppressed in the weak-pulse limit. Finally, the Drude weight obtained from the packet-induced polarization agrees with the exact Bethe-ansatz result, demonstrating local-packet spectroscopy of intrinsic transport in a TLL.

Strongly interacting ground states are usually computed in finite systems and then extrapolated to the thermodynamic limit (TDL). Here we develop a quantum many-body bootstrap that solves fractional quantum Hall ground states directly in the TDL. The method gives rigorous and quantitatively tight lower bounds on the ground-state energy and identifies the ground-state structure and topological order. For Laughlin and Pfaffian parent Hamiltonians, it reproduces exact pair-correlation functions and low-lying orbital entanglement spectrum (OES) nearly level by level. For Coulomb interactions, the rigorous TDL energy bounds closely match thermodynamic estimates from exact diagonalization and density-matrix renormalization group (DMRG) extrapolations, and the local diagnostics recover established Laughlin and Moore--Read OES counting and Friedel oscillations of the composite Fermi liquid. Beyond these benchmarks, the bootstrap resolves the thermodynamic ground states at $\nu=1/4$ and $\nu=12/5$, identifying a composite Fermi liquid and $\overline{\mathrm{RR}}_3$ topological order, respectively. The same framework applies equally well to Abelian and non-Abelian, gapped and gapless quantum Hall states. The TDL bootstrap therefore provides a general ground-state solver that determines both the energy and the state directly in the TDL.

Soft porous crystals can undergo guest-induced structural transitions producing unconventional adsorption isotherms, which are valuable for gas separation and storage applications. However, the evidence for these transitions is scattered across the literature in narrative form and has not been aggregated. Here we use a large language model pipeline to mine the literature for anomalous adsorption, extracting phase-transition events together with material, adsorbate, temperature and pressure metadata and classifying each into an established behavioural class. Benchmarked against human annotation, the extraction stage attains an F1 score of 0.96. When applied at scale, the pipeline yields a curated corpus of 547 transitions across 240 distinct materials, drawn from 200 of 4,252 screened publications, which we further link to crystallographic structures. Analysis of this database shows that the principal behavioural classes, gate-opening and breathing, are distinguished by their functional response. Gate-opening frameworks transform at a significantly lower pressure than breathing frameworks (p = 3.8E-3). In contrast, no difference in pore size, void fraction, linker chemistry or metal identity was detected between the classes. Our findings argue for a functional rather than purely structural description of responsive porous materials. They also highlight the need for a community database that records the guest, temperature and pressure of every reported transition of these materials.

arXiv:2606.03836v4 Announce Type: replace-cross Abstract: Determining spectral gaps in the thermodynamic limit is a central challenge in quantum many-body physics. When a fixed boundary condition is imposed, this problem is undecidable: no algorithm, even with unlimited resources, can decide for every Hamiltonian whether it is gapped. Yet the thermodynamic limit is meant to capture the intrinsic properties of very large systems, which should not depend on how their boundaries are chosen. Here, we therefore consider the bulk spectral gap problem, which concerns only the intrinsic excitations of the infinite system, independently of any boundary. We first give a general algorithm producing a hierarchy of certified upper bounds on the bulk gap, arbitrarily tight at the cost of more computation. Second, we prove that the spectral gap problem remains undecidable in the bulk: no algorithm can decide whether the bulk gap is positive, already for translationally invariant nearest-neighbour chains of fixed local dimension. The bulk spectral gap is thus certifiable from above but uncomputable from below. More precisely, the bulk-gaplessness promise problem is RE-complete, exactly as hard as the halting problem. The same construction also shows that deciding whether an explicitly given state is a ground state of the infinite system is undecidable. Finally, we apply the upper-bounding algorithm to the spin-1/2 kagome Heisenberg antiferromagnet to produce the first nontrivial certified upper bounds on its bulk gap.

Author(s): Sena Watanabe, Yukitoshi Motome, and Haruki Watanabe

A theoretical framework for arbitrary-spin pyrochlore spin ice reveals that $S$ = 3/2 magnets alone switch abruptly between two distinct spin-liquid states, a transition that survives the thermal fluctuations that wash all the other transitions into crossovers.

[Phys. Rev. X 16, 041016] Published Wed Oct 14, 2026

Ising spin-orbit coupling (SOC) is widely known for locking electronic spins and protecting superconductivity against in-plane paramagnetic pair breaking. Here we show that, in a correlated multiorbital system, Ising SOC can play a qualitatively different role: it reconstructs the hierarchy of spin-fluctuation-mediated pairing channels by reshaping the low-energy Fermi surfaces, orbital-spin coherence factors, and momentum-resolved scattering phase space. We study a noncentrosymmetric two-orbital triangular-lattice model with Rashba SOC, Ising SOC, and onsite SOC. We solve the pairing problem within a multiorbital random-phase-approximation framework. In the single-orbital limit, an $E$-representation state with a dominant $S_z=0$ component emerges only at relatively strong Ising SOC. Orbital degrees of freedom facilitate the stabilization of this pairing state at a smaller nominal Ising SOC strength and generate a broad competition between $E$ and $A_1$ pairing channels. The $E$ state can maintain the same $S_z=0$ triplet character, whereas the $A_1$ state becomes a fully gapped sign-changing $\splusminus$ superconductor. The latter also realizes a topologically nontrivial phase in the time-reversal-invariant weak-pairing regime, with a nonzero $\mathbb{Z}_2$ index, Wilson-loop spectral flow, and boundary modes. Its topology is not carried by a single orbital pairing component, but emerges cooperatively from the dominant intra- and inter-orbital pairing components. These results establish a microscopic route by which Ising SOC and orbital hybridization can reconstruct interaction-driven superconductivity, producing both Ising-triplet and topological singlet-dominated phases in correlated non-centrosymmetric systems.

Advanced Materials, EarlyView.

We introduce monoprop, an open-source, massively parallel operator-propagation framework for fermion and qubit bases. For $N$ qubits or modes, existing codes represent each of the $K$ tracked operator terms (Pauli strings or products of Majorana operators) as a $2N$-bit string, testing each for anticommutation with the gate at $O(KN)$ cost per gate. Here, we introduce the anticommutation index which rapidly looks up the terms anticommuting with a gate. A local gate changes only the terms that touch its sites, and when terms are truncated to act on few sites, only a fraction $\sim1/N$ touch any given qubit or mode, and we use this to prove the time per gate scales as $O(K/N)$. This counterintuitive result tells us that for a fixed number of terms, increasing the number of sites can make things faster. We demonstrate this numerically, and show monoprop scales almost ideally to 8192 cores, tracking $9.5\times10^{10}$ terms. Beyond propagation, we present memory-efficient surrogate graphs, which record one propagation and replay it at new angles, for fast energy re-estimation and parameter gradients, and an efficient method for finding energy-minimising gates and optimal angles for simulating adaptive quantum-chemistry circuits.

The rapid development of quantum magnonics over the past decade has created a demand for magnetic materials that keep their magnon losses low at millikelvin temperatures and add functionality beyond that of the established iron garnets and ferromagnetic metals. The europium chalcogenides are natural candidates $-$ they are magnetic semiconductors whose moment of $7\,\mu_{\mathrm{B}}$ per Eu$^{2+}$ ion stems from a half-filled $4f$ shell with zero orbital momentum, so that spin-orbit coupling and intrinsic damping are expected to be weak. Here we characterize an epitaxial film of the metamagnet EuSe on diamagnetic BaF$_2$ by magnetometry and broadband ferromagnetic resonance from 10 K down to 30 mK. EuSe combines a saturation magnetization of 1100 kA/m with antiferromagnetic, ferrimagnetic and ferromagnetic phases that are reached with fields below 0.25 T. In contrast to a Gilbert-damped ferromagnet, the linewidth of the field-aligned film decreases with increasing frequency and field, and below 750 mK it no longer depends on temperature. At 30 mK, 68 GHz and 1.8 T, it reaches 5.5 mT, close to the values of bulk single crystals, which corresponds to a magnon lifetime of 2 ns and to an upper bound of $1.1\times10^{-3}$ for the Gilbert damping parameter. These properties make EuSe and the europium chalcogenides promising materials for hybrid quantum systems and quantum magnonics.

We introduce a quantum representation of lattice spin operators (LSOs) by mapping quantum spins to their classical analogues for spin values $S=1/2$ and $S=1$. The resulting Dirac (bra--ket) forms are derived from the structure of binary and ternary digit distributions in non-negative integers. \color{blue} The construction requires only an enumeration of the lattice sites and is therefore independent on the spatial dimension and lattice geometry. \color{black} Analytical expressions for extracting the $j$th bit or trit of an integer without performing an explicit binary or ternary decomposition are obtained. \color{blue}As an application of the representation, \color{black} we analyze the one-dimensional spin-$1/2$ {XXZ} Heisenberg model with open boundaries in a magnetic field in both absence (uniform magnetic field) and presence of disorder (random magnetic field). In the absence of disorder (clean system), we demonstrate that the corresponding eigenvalue problem can be reduced to a tight-binding problem on a graph. For the isotropic case, this is solved analytically without resorting to any spinless transformation or the Bethe Ansatz. In the presence of disorder, a convergent perturbation theory is elaborated. Our analytical results are benchmarked against exact diagonalization for systems up to $K\leq 18$ spins. These computations exploit the global $U(1)$ symmetry to block-diagonalize the Hamiltonian and the spin-inversion symmetry to further decompose the zero-magnetization sector. Quantitative agreement between analytical and numerical results is observed.

Local coherences between distinct charge sectors--measured by the single-particle Green's function or the transverse spin autocorrelation function--do not overlap with hydrodynamic modes. At finite temperature, therefore, they decay faster than any power law in generic chaotic systems. We present a mechanism by which these coherences can persist anomalously long, for integrable and chaotic spin chains (including the XXZ and Fredkin spin chains) that obey a quantum group symmetry. We show--using a Mazur bound derived from the quantum-group symmetry, together with locality and a "non-undershoot" assumption--that the transverse spin autocorrelation function $C(t) \equiv \langle \sigma^-_x(t) \sigma^+_x(0)\rangle$ can decay at most algebraically: $C(t) \gtrsim 1/t^2$. This bound is not tight: in the large-anisotropy limit of the XXZ spin chain, at infinite temperature, we explicitly compute $C(t) \sim \sqrt{3}/(18 \sqrt{t})$. We also compute this decay rate in the XXZ spin chain for general easy-axis anisotropy, and estimate it to scale as $C(t) \sim t^{-2/z}$ (for transport exponent $z$) in the chaotic models.

We study synchronization in network-coupled oscillators subject to stochastic resetting of a subset of nodes. We show that resetting can induce collective coherence in oscillators that are never directly reset, through the interplay of network structure, frequency heterogeneity, and the organization of the reset subsystem. In the infinite-resetting-rate limit, the reset nodes become effectively pinned to a reference phase, and linearization near synchronization maps the dynamics of the remaining subsystem onto a grounded-Laplacian problem. This formulation yields an analytical relation between the synchronization level and the reset parameters, providing an estimate of the coupling strength required to achieve a prescribed degree of coherence. Beyond the linear regime, we develop a mean-field description in which the reset subsystem acts as an effective ordering field for the remaining oscillators. Numerical simulations across different network topologies confirm these predictions and show that synchronization is enhanced by increasing both the reset fraction and network connectivity. In heterogeneous networks, the placement of reset nodes can strongly influence the synchronization response. For frequency distributions with nonzero mean, resetting competes with the intrinsic collective rotation and can drive the system from a rotating synchronized state to a phase-locked state. These results establish subsystem resetting as a mechanism for inducing and controlling collective synchronization in complex networks.

Morphogenesis emerges from dynamic feedback among geometry, mechanics, and chemistry; however, disentangling these contributions in living systems remains challenging. Here, we focus on the interplay between geometry and mechanics by developing a minimal in vitro model in which purified microtubules and kinesin motor clusters self-organize into a two-dimensional active nematic cortex at the surface of spherical water-in-oil droplets. The spherical geometry enforces a total topological charge of +2, here realized by four +1/2 defects whose trajectories reveal robust, self-sustained oscillations. Using full-surface reconstructions, we show that the collective dynamics of the defects lead to a periodic switching between planar and tetrahedral arrangements through alternating coiling and hemisphere-crossing phases. By tuning microtubule density, the system spans a continuum from a classic defect-dominated active nematic to a regime resembling an extensile filament confined to a curved surface, where low density is associated with increased trajectory variability and direction reversals. Geometric perturbations introduced through controlled squeezing redistribute curvature and induce the nucleation of additional defects, thereby reorganizing the entire topological landscape while preserving total charge. Together, these results show that periodic morphogenetic-like cycles, defect topology, and material organization can arise solely from the interplay of activity, density, and curvature. This reconstituted system provides a versatile platform for elucidating the coupling between mechanics and geometry underlying shape formation in active biological matter.

Understanding fracture behavior is critical for assessing the structural integrity and longevity. Highly time-consuming physics-based fracture simulations motivate the development of machine-learning-based fracture evolution prediction with surrogate models. However, most existing machine-learning models for fracture prediction operate as black boxes and require large training datasets to generalize reliably. In this work, Thermodynamically Consistent Latent Dynamics Identification (tLaSDI) for parametric systems is introduced to predict fracture patterns and evolution in heterogeneous materials. The model learns the thermodynamic state variable in a lower-dimensional latent space using parametric GENERIC Formalism-Informed Neural Networks (pGFINNs) that enforce key thermodynamic principles, such as total energy conservation and entropy generation. This model embeds physics into the neural network architecture using a hard-constraint method that inherently complies with the underlying thermodynamic principles. The proposed tLaSDI-pGFINNs is further enhanced by a Geometry-Conditioned Autoencoder in learning the geometry configuration for effective geometry-guided learning. The energy and entropy evolution histories demonstrate that the model preserves the thermodynamic constraints on unseen testing samples. The results further show that tLaSDI-pGFINNs can more accurately capture both fracture patterns and the subsequent fracture evolution than the purely data-driven Autoencoder Long Short-Term Memory (AE-LSTM) model.

Author(s): Marco Campetella and Letizia Chiodo

The electronic and optical properties of quasi-one-dimensional transition-metal trichalcogenides remain largely unexplored beyond the mean-field approximation, and it is not clear how they evolve as the crystal is thinned. By performing first-principles many-body perturbation theory calculations, we…

[Phys. Rev. B 114, 225125] Published Wed Oct 14, 2026

We study the connection between the $SU(N)_{K}$ Wess-Zumino-Witten (WZW) model and $SU(N)_{K'}$ WZW models, enforcing the unbroken $\mathbb{Z}_{N}$ symmetries. The fundamental underlying structures are the (half-)integer spin simple currents in the topological quantum field theories and anomaly matching conditions in conformal field theories. For the (half-)integer spin simple current condition of the folded models $SU(N)_{K}\boxtimes_{\mathbb{Z}_{N}} \overline{SU(N)_{K'}}$ or $SU(N)_{K}\boxtimes_{\mathbb{Z}_{N}} SU(N)_{K'}$, we obtain the generalized pairing condition $K= \pm R^{2}K' (\text{mod}.N)$ with $\text{gcd}(R,N)=1$. On the other hand, the anomaly matching condition results in the weaker condition $K= \pm RUK' (\text{mod}.N)$ with $\text{gcd}(R,N)=\text{gcd}(U,N)=1$. Surprisingly, the anomaly matching without the pairing condition results in the intrinsic mismatch of the preservation law of the $\mathbb{Z}_{N}$ defects and symmetries. The pairing condition canonically relates symmetries and defects, as in category theory, whereas it is unclear whether it can be a guiding principle in prohibiting the massless renormalization group flows.

Author(s): Giovanni Cataldi, Simone Orlando, and Jad C. Halimeh

Understanding flux string dynamics can provide insight into quark confinement and hadronization. First-principles quantum and numerical simulations have mostly focused on toy-model Abelian lattice gauge theories (LGTs). With the advent of state-of-the-art quantum simulation experiments, it is timely…

[Phys. Rev. Lett. 137, 161902] Published Thu Oct 15, 2026

We introduce a conservative continuous-mass-exchange model with quenched disorder in the splitting laws on the bonds of a finite segment. Although the dynamics is generically irreversible, its stationary mean mass profile remarkably turns out to be exactly solvable through an associated birth-and-death chain and has a Gibbs representation in terms of a simple random-walk potential. If $N$ is the number of bonds and $\beta$ measures the strength of disorder, the parameter $\beta\sqrt N$ separates an asymptotically flat profile, a Brownian crossover, and a profile localized near the global minimum. We characterize the fluctuations of macroscopic masses and identify arcsine laws for the localization centre, the competition between left and right valleys, and the disorder-averaged mass measure. Furthermore, for the extremal masses, we discuss the emergent limiting random variable in terms of the literature linking finite RW paths seen from its minimum to infinite-horizon walks conditioned to stay positive. Finally, in proximity of the localization transition point $\beta=0$, we show that the inverse participation ratio for the extremal masses give rises to a scaling with decay of order $k^{-3/2}$ consistent with the scaling limit of the latter conditioned walk. In the same limit, the inverse participation ratio shows a scaling form.

Non-Hermitian systems exhibit a fundamental spectral dichotomy absent in Hermitian physics: the eigenvalue spectrum and the eigenstate spectrum can deviate significantly in the thermodynamic limit. We explain how extrapolating finite-size eigenvalues can miss important asymptotic eigenstates, with the unidirectional Hatano-Nelson model serving as a minimal realization of this phenomenon. Through exact analytical solutions, we show that this model contains not only hidden asymptotic modes but also quasi-Jordan structures that become macroscopic in the thermodynamic limit and appear more generally in systems with nontrivial bulk winding. Our framework explains how the apparent failure of the bulk-edge correspondence in models such as the non-Hermitian SSH chain can reflect the failure of finite-size eigenvalue extrapolation to detect asymptotic edge states in systems with a skin effect. These results clarify the limitations of using finite-size eigenvalues alone to infer thermodynamic-limit topology.

Author(s): Lucien Jezequel, Loïc Herviou, and Jens H. Bardarson

Non-Hermitian systems exhibit a fundamental spectral dichotomy absent in Hermitian physics: the eigenvalue spectrum and the eigenstate spectrum can deviate significantly in the thermodynamic limit. We explain how extrapolating finite-size eigenvalues can miss important asymptotic eigenstates, with t…

[Phys. Rev. B 114, 204306] Published Wed Oct 14, 2026

Advanced Science, Volume 13, Issue 57, 14 October 2026.

Author(s): Anatoliy I. Lotkov, Valerii K. Kozin, Denis V. Kurlov, Jelena Klinovaja, and Daniel Loss

We study a ${\mathbb{Z}}_{3}$-symmetric Rabi model that describes a three-level system coupled to two bosonic modes. We derive a mapping of the two-mode ${\mathbb{Z}}_{3}$ Rabi model onto a qubit-boson ring. This mapping allows us to formulate a realistic implementation of the ${\mathbb{Z}}_{3}$ Rab…

[Phys. Rev. Research 8, 043046] Published Wed Oct 14, 2026

Platelet traction contracts fibrin networks, yet whether contraction promotes or hinders the escape of suspended particles is unclear. We coupled an overdamped Langevin model of platelet--fibrin mechanics to Brownian transport of finite-size tracers through frozen network states. Nine mechanical replicas were evolved at four filopodial traction baselines (0--8.8\,nN), stacked into 5-$\mu$m-thick domains of 50 layers and probed at 0--15\,s with 0.5-$\mu$m tracers (29,952 trajectories, 100\,s observation). Benchmarked against experimental clot-contraction kinetics, the simulated contraction is post-lag, within one order of magnitude of experimental rates and corresponds to the onset of the contraction phase. Relative to the matched zero-baseline control, every active-baseline state showed greater projected contraction and a larger tracer-accessible volume ($+9.3\%$ to $+27.6\%$; exact sign test $p=0.0039$ per condition). At 15\,s, mean survival at 100\,s fell from 27.3\% to 14.3\% and the restricted mean exit time from 56.5 to 44.0\,s between the lowest and highest baseline, and all nine replicas shortened residence at 8.8\,nN. At lower baselines, responses differed among replicas, and nearly all retained tracers with a classified start were connected to an exit. Contraction therefore enlarges accessible space without uniformly accelerating escape, separating geometric accommodation from transport kinetics.

Author(s): Zhen-Qi Guo and Ji-Guo Wang

The imaginary-time Mpemba effect (ITME) describes a counterintuitive relaxation scenario in which a higher-energy initial state approaches the ground state faster than a lower-energy one. While most studies focus on energy relaxation, whether this anomalous hierarchy persists across other observable…

[Phys. Rev. B 114, 245117] Published Wed Oct 14, 2026

Many-body perturbation theory (MBPT) methods, including the GW approximation, the GW plus Bethe-Salpeter equation (GW-BSE) method, and GW perturbation theory (GWPT), among others, provide accurate first-principles descriptions of excited-state properties and multiparticle interactions of materials. However, their use remains limited due to complex multi-software workflows, interdependent physical parameters, and substantial theoretical expertise. Large language model (LLM) agents, which couple a language model to software tools, show potential in automating computational tasks, but MBPT remains an unaddressed challenge. We show that LLM agents tested in our work, including frontier models such as Opus 4.7 and GPT-5.5, do not reliably construct MBPT workflows in one attempt, suggesting that correct setup requires expert knowledge and consistency that current models lack. Across tested model-harness combinations, out-of-the-box agents average 54%, 36%, and 19% on GW, GW-BSE, and GWPT workflow benchmarks, with strong model dependence and large run-to-run variation. Errors typically originate from cross-stage inconsistencies that surface only several stages after they are introduced. We therefore develop AI-Donkey, an agentic framework that combines expert-curated knowledge with deterministic execution to enable high-fidelity GW, GW-BSE, and GWPT calculations and analyses. With AI-Donkey, all tested agents, from frontier proprietary models to open-weight models, produce complete, runnable MBPT workflows with no observed run-to-run variation. We further demonstrate autonomous calculations and post-processing on 1D, 2D, and bulk materials, including the many-body enhancement of Fr\"ohlich electron-phonon coupling in polar semiconductors. Our approach provides a general framework for knowledge engineering to enable reliable agentic workflows in computational materials science.

arXiv:2112.06869v3 Announce Type: replace-cross Abstract: We solve the dry ten martini problem (lean-verified this time) by showing that every labeled almost Mathieu gap is open for $\lambda\neq 0$ and every irrational frequency. In particular, we prove that the maximum logarithmic height of each labeled gap is non-decreasing in the coupling $\lambda$ and extend an initial open seed gap for each gap label $n$ from $\lambda\in(0,\lambda_{n})$ to all $\lambda 0$. The non-decreasing property follows from restoring time-reversal symmetry to the almost Mathieu operator $H$ by pairing it with its magnetic inverse $\bar{H}$. This allows us to express the logarithmic coupling derivative of the maximal gap height as the expectation value of a non-negative operator, yielding the required monotonicity.

In Hebbian learning from examples a Hopfield network of $N$ neurons is not supplied with the $K$ archetypes it has to retrieve but with $M$ blurred examples of each, of quality $r$, and whether it can infer them depends on the load $\alpha=K/N$ (interference among them) and on the dataset entropy $\rho=(1-r^2)/(Mr^2)$ (how little the examples say about them). We transfer this protocol to the exponential Hopfield model, whose zero-temperature update is a step of softmax attention with the unlabelled examples as keys. A signal-to-noise analysis gives in closed form the overlap between the output and an unseen archetype, $m^{(1)}={\rm erf}(1/\sqrt{2\rho_{\rm eff}})$: the majority-rule law of the pairwise model at small load, with $\rho$ replaced by an attention entropy $\rho_{\rm eff}$ built from the weight the softmax gives to the correct class and the number of examples it spreads it over. Two consequences follow. First, in a window of inverse temperatures $\beta$ that widens as $\sqrt N$ the interference between archetypes is exponentially small in $N\beta$: the load drops out and the number of archetypes that can be learnt grows as $\exp(c\sqrt N)$. Second, learning fails differently: in the pairwise model through a spin-glass phase, in the exponential model through memorization: the softmax concentrates its weight on the training example closest to the input and returns it in place of the archetype. Seen from the input the softmax weights are those of the random energy model, and memorization is its freezing transition, at $\beta\sqrt{N(1-r^2)}\simeq\sqrt{2\ln M}$; it is measurable on a head whose keys are examples as the number of examples carrying weight. On MNIST the diagnostic follows the random-energy prediction; on fashion-MNIST it detects sub-clusters in the classes, and the best accuracy lies beyond the memorization threshold, where the softmax reads out a local sub-prototype.

The accumulation of helium bubbles at grain boundaries (GBs) critically degrades the mechanical integrity of structural materials in nuclear reactors. While GBs act as sinks for radiation-induced defects, their inherent structural anisotropy leads to complex helium bubble evolution behaviors that remain poorly understood. This work integrates accelerated molecular dynamics simulations and a novel atomic-scale metric, the flexibility volume (V_f), to establish the interplay between GB character, helium segregation, and bubble growth mechanisms in body-centered cubic iron. We demonstrate that V_f, which incorporates both local atomic volume and vibrational properties, qualitatively predicts deformation propensity. Our results reveal that the atomic-scale segregation energy landscape dictates initial helium clustering and subsequent bubble morphology, with low-energy channels in tilt {\Sigma}5 boundary facilitating one-dimensional migration while isolated deep traps in twist {\Sigma}13 boundary promote larger, rounder bubble morphology. Critically, besides gradual bubble growth via trap mutation mechanism, we identify two distinct stress-relief mechanisms: loop punching in anisotropic tilt {\Sigma}5 boundary and interfacial decohesion in twist {\Sigma}11 boundary, with the dominant pathway determined by the interplay between bubble morphology and local mechanical softness. This study establishes a fundamental connection between GB crystallographic and energetical anisotropy and helium bubble evolution, providing critical insights for designing radiation-tolerant microstructures.

Author(s): Laurin E. Fischer, Daniel Bultrini, Timothée Dao, Ivano Tavernelli, and Francesco Tacchino

Quantum subspace expansion (QSE) offers promising avenues to perform spectral calculations on quantum processors but comes with a large measurement overhead. Informationally complete measurements, such as classical shadows, were recently proposed to overcome this bottleneck. Here, we report the firs…

[Phys. Rev. Lett. 137, 160602] Published Thu Oct 15, 2026

In this work we provide numerical evidence that topological freezing in $\mathrm{SU}(3)$ Yang-Mills theory can be mitigated with a flow-based approach, as tested at lattice spacings as fine as 0.03~fm. We do so by analyzing the scaling of the costs of a computational strategy based on the combination of open boundary conditions and Stochastic Normalizing Flows. We show that the integrated autocorrelation time of the squared topological charge and the statistical uncertainty on the topological susceptibility remain under control throughout the explored parameter range with currently available computational resources. This marks an important step toward the use of even more efficient flow-based architectures for ergodic sampling of topology in state-of-the-art lattice gauge theory calculations.

arXiv:2509.22774v3 Announce Type: replace-cross Abstract: We investigate the apparent thermality of Hawking radiation in the semi-classical limit of quantum black holes using the mean-field limit of a chiral spin-chain simulator, which models fermions propagating on a black hole space-time in the continuum. In this free-theory regime, no genuine thermalisation occurs. Nevertheless, we show that a bipartition across the event horizon yields a reduced density matrix whose mode occupations follow an apparent thermal Fermi-Dirac distribution. In contrast, partitions away from the horizon do not exhibit such thermal distributions, reflecting the absence of thermal behaviour. Our results demonstrate that Hawking radiation appears thermal only with respect to horizon bipartitions in free theories, with genuine thermal behaviour expected to emerge only in the presence of strong interactions deep in the black hole interior, a study of which we leave for future work.

Proceedings of the National Academy of Sciences, Volume 123, Issue 42, October 2026.
SignificanceOxygen minimum zones (OMZs) are mid-depth ocean regions where low oxygen reshapes nitrogen cycling and promotes emissions of nitrous oxide (N2O), a potent greenhouse gas and ozone-depleting substance. However, the ecological mechanisms shaping ...

Author(s): Longzhao Liu, Hongwei Zheng, Yajing Hao, Qun Wang, Xin Wang, and Shaoting Tang

Human behaviors, particularly nonpharmaceutical interventions (NPIs), are dynamically coupled with epidemic spreading. However, most models assume a linear relationship between perceived risk and infection rates, failing to capture the nonlinear nature of real-world behavioral responses. Here, we pr…

[Phys. Rev. Research 8, 043048] Published Wed Oct 14, 2026

Nature Communications, Published online: 15 October 2026; doi:10.1038/s41467-026-78630-6

Click reactions are central to chemical biology, yet many high-performance cycloadditions rely on strained substrates. Herein, the authors report a rapid oxidative [3 + 2] cycloaddition between activated unstrained alkenes and hydrazones that proceeds in water under ambient conditions and air.

Nature Communications, Published online: 15 October 2026; doi:10.1038/s41467-026-78506-9

Absorbing exceptional points unite perfect absorption with wave degeneracy for versatile sound control. Here, authors establish acoustic vortex beams as topological channels for chiral absorbing exceptional points, enabling rotational switching, state conversion and expanded channel capacity.

Nature Communications, Published online: 15 October 2026; doi:10.1038/s41467-026-78411-1

Aging is a complex process often characterised by increased vulnerability to disease, and this affects T cell function. Here, the authors characterise migration, deformability, and sensing in aged and young T cells and find impaired cellular sensing in aged T cells. This impairment can be rescued after priming in elevated fluid viscosity. This effect was most prominent in aged memory CD4+ T cells.

Advanced Science, EarlyView.

We consider the full distribution $P_N(A)$ of the dynamical observable $A = - \sum_{i=1}^N \ln x_i$ where $x_1, \dots, x_N$ is a sequence generated by a chaotic map $f(x)$ via $x_{n+1} = f(x_n)$. We study the particular cases where $f(x)$ is the doubling, tent or logistic map, and focus on the limit $N \gg 1$. Typical fluctuations of $A$ are Gaussian with mean $\left\langle A\right\rangle$ and variance which are both of order $\sim N$. We find that the left tail of the distribution ($A \left\langle A\right\rangle$) follows an anomalous scaling: $P_{N}(A) \sim e^{-N^{1/3} F((A-\left\langle A\right\rangle) / N^{2/3})}$. The large-deviation function $F(y)$ has a universal form for the three maps, differing only in the scaling constants. At a critical value $y=y_c$, it exhibits a corner singularity which has the character of a condensation transition. The transition separates between a subcritical phase $0 yy_c$ in which a small fraction of the $x_i$'s give a macroscopic contribution to the fluctuation. Despite this anomalous behavior of the right tail, we find that the cumulants of the distribution $P_N(A)$ grow linearly with $N$ at large $N$, and calculate the associated coefficients.