CMP Journal 2026-11-09
Statistics
Nature Nanotechnology: 1
Nature Physics: 2
arXiv: 66
Research Square: 4
Nature Nanotechnology
Dynamic electrical control of on-chip second-harmonic generation with ferroelectric NbOBr2
Original Paper | Two-dimensional materials | 2026-11-08 19:00 EST
Xiangxin Gong, Ruihuan Duan, Wenjie Ming, Yuhui Yang, Jinpeng Huo, Sung-Gyu Lee, Shi Guo, Xin Guo, Jeremy Leong, Lalit Singh, Wenduo Chen, Qi Jie Wang, Wonkeun Chang, Yue Gong, Beng Kang Tay, Huijun Liu, Xiaoxu Zhao, Qingyun Wu, Lay Kee Ang, Chuanlai Ren, Hongseok Kim, Yunseok Kim, Han Yan, Hong Wang, Jia Xu Brian Sia, Nanxi Li, Cheng-Wei Qiu, Jiangyu Li, Zheng Liu, Sang Hoon Chae
Niobium oxide dihalide films show a second-harmonic generation (SHG) efficiency scaling with their thickness, owing to their weak interlayer electronic coupling, but their use in integrated nonlinear photonics has been limited by the lack of robust electrical tuneability. Here we integrate ferroelectric NbOBr2, of thicknesses ranging from 20 nm to 40 nm, with a silicon nitride microring resonator to realize electrically reconfigurable SHG on a photonic chip. NbOBr2 combines strong second-order susceptibility from intrinsic inversion-symmetry breaking with electrically switchable in-plane ferroelectric polarisation. By modulating the Schottky barrier at the NbOBr2-metal interface, ferroelectric switching controls carrier injection, free carrier absorption and dispersion, thereby tuning the cavity-enhanced nonlinear response. The device achieves an SHG conversion efficiency of 158% W-1 under continuous-wave excitation and a 53% electrical modulation depth. The polarisation states can also be programmed over multiple levels and retained after switching, enabling non-volatile control of the optical response. Using the fundamental and frequency-converted outputs as complementary channels, we further demonstrate dual-channel edge detection.
Two-dimensional materials, Nanophotonics and plasmonics, Nonlinear optics
Nature Physics
Bound states in the continuum through quantum interference in ultracold atomic collisions
Original Paper | Matter waves and particle beams | 2026-11-08 19:00 EST
Alexander Guthmann, Louisa Marie Kienesberger, Felix Lang, Eleonora Lippi, Artur Widera
Quantum-mechanical interaction potentials support localized bound states below the dissociation threshold or delocalized scattering states above it. Although bound states are energetically isolated, scattering states couple a quantum system to environmental modes, making dissipation and loss intrinsic to open systems. Bound states in the continuum are an exception, as destructive interference keeps them localized within the scattering continuum. Theory predicts that such states can arise through interference between two Feshbach resonances coupled to a common continuum. Here we form such an interference-stabilized state in ultracold collisions of 6Li atoms by coherently coupling two tunable Feshbach resonances using Floquet engineering. At a critical parameter point, elastic and inelastic coupling to the continuum vanish, producing a molecular state above the dissociation threshold. Consequently, resonant scattering features disappear and the colliding atoms become effectively transparent to one another. Full coupled-channel calculations and a minimal non-Hermitian model quantitatively reproduce our observations and identify the state as a Friedrich-Wintgen bound state in the continuum. These results show how quantum interference can control openness in quantum matter and enable the engineering of non-Hermitian Hamiltonians.
Matter waves and particle beams, Atomic and molecular collision processes
Active-flow-driven DNA remodelling generates millimetre-scale mechanical oscillations
Original Paper | Self-assembly | 2026-11-08 19:00 EST
Maya Levanon, Noa S. Goldberg, Dvir Cohen, Eran Bouchbinder, Ram M. Adar, Alexandra M. Tayar
DNA undergoes continuous and rhythmic mechanical remodelling through condensation, looping and disentangling to regulate gene expression, segregate chromosomes and guide morphogenesis. Here we demonstrate a purely mechanical route to rhythmic DNA reorganization in a minimal active composite of microtubules, kinesin motors and DNA. We embed DNA polymers in an active-turbulent microtubule-kinesin fluid, creating a self-morphing material. The active flows stretch and entangle the DNA, forming a self-organized viscoelastic network that resists active stresses and affects flow over large length scales. This mechanical feedback loop progressively amplifies velocity correlations and drives a sharp non-equilibrium transition tuned by DNA contour length: from disordered flow to synchronized, millimetre-scale oscillatory flow. We rationalize the sharp transition with an active-gel model that predicts a growing length scale and an oscillatory instability emerging from the interplay between activity, orientational order and self-generated viscoelasticity, rather than chemical signalling. The theoretical dependence of the oscillation frequency on system size and activity is in agreement with observations. Thus, flow-driven DNA remodelling provides a minimal physical route to autonomous, system-spanning oscillations in three dimensions and suggests design principles for programmable soft matter that coordinates, actuates and reshapes itself.
Self-assembly, Fluid dynamics, Phase transitions and critical phenomena, Biological physics
arXiv
Transformer-Based Characterization of Criticality in Directed Percolation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-11-09 20:00 EST
Directed percolation (DP) provides a canonical framework for studying nonequilibrium phase transitions into absorbing states, yet extracting critical behavior directly from high-dimensional spatiotemporal configurations remains challenging. Here, we investigate (1 + 1)- and (2 + 1)-dimensional bond DP using a supervised Transformer encoder. Supervised learning results demonstrate that the Transformer can distinguish between the active and absorbing phases of directed percolation with high accuracy. The critical point and critical exponents estimated from the model’s classification probabilities align closely with reference values from existing literature, indicating that the model not only achieves phase classification but also yields outputs containing information related to critical scaling behavior. To probe the model’s internal representation, we employ attention rollout and define an attention center that quantifies the temporal centroid of the cumulative attention distribution. The attention patterns and the attention center reorganize systematically near the critical region and exhibit pronounced finite-size dependence. Finally, we examined the model’s transferability between configurations generated from fully occupied initial states and those from single-seed initial states. The results indicate the presence of transferable information between the two types of data, though the transfer performance exhibits directional asymmetry. Furthermore, when using an equal amount of target-domain data, fine-tuning yielded only a marginal improvement in accuracy compared to training from scratch.
Statistical Mechanics (cond-mat.stat-mech), Computational Physics (physics.comp-ph)
Nonequilibrium Fluctuations and Intrinsic Stability of Nanostructured Solar Cells: Microscopic Derivation and Universal Laws
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-11-09 20:00 EST
Rivo Herivola Manjakamanana Ravelonjato, Ravo Tokiniaina Ranaivoson, Philipe Manjakasoa Randriantsoa, Raoelina Andriambololona, Wilfrid Chrysante Solofoarisina
We study nonequilibrium fluctuations of efficiency in nanostructured solar cells. Our contribution is threefold. First, we derive a microscopic stochastic model of efficiency from a two-state master equation describing absorption, radiative recombination, and extraction. This derivation establishes an explicit link between efficiency fluctuations and entropy production, and justifies the thermodynamic affinity through local detailed balance. Second, we review universal fluctuation laws established in the recent literature and apply them for the first time to the real parameters of nanostructured solar cells. We show that the total entropy production behaves as a submartingale, and that its negative exponential is a martingale. For a biased discrete random walk, the exact infimum law is verified numerically in the near-equilibrium regime, then applied to realistic solar cell configurations. Third, our simulations show that nanostructured solar cells operate in a strongly nonequilibrium regime, where negative entropy fluctuations, and hence efficiency fluctuations, are exponentially rare. Over all simulated trajectories, most configurations show no detectable negative fluctuation, consistent with the theoretical prediction. These results explain the intrinsic statistical stability of the devices and provide a conceptual and quantitative framework for understanding efficiency fluctuations around the mean values. They do not modify the mean efficiencies obtained previously, but clarify their statistical robustness in the strongly nonequilibrium regime.
Statistical Mechanics (cond-mat.stat-mech)
15 pages
Permutation order governs basin entropy in critical one-input Boolean networks
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-11-09 20:00 EST
Ruodan Liu, Ahana Ghosh, Sean Campbell, Venkata Sai Narayana Bavisetty, Matthew Wheeler, Claus Kadelka
Basin entropy measures uncertainty about a network’s long-term behavior. For every critical one-input synchronous Boolean network with $ m$ relevant nodes, we show that the permutation structure induced by its feedback loops determines basin entropy, up to a universal error. Although the loops oscillate independently, their relative phases can be offset, producing a deviation from additivity that can grow linearly in $ m$ . Yet at the ensemble level, a previously derived additive prediction is preserved through the first subleading term, with the discrepancy appearing at order $ \ln m\ln\ln m$ .
Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO), Molecular Networks (q-bio.MN)
14 pages, 3 figures
Experimental realization of twofold topological phase transition induced by long-range hoppings in one-dimensional chains
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
J. A. Franco-Medrano, B. Manjarrez-Montañez, E. Flores-Olmedo, G. Báez, A. M. Martínez-Argüello, Y. Betancur-Ocampo, R. A. Méndez-Sánchez
Long-range hoppings offer a powerful mechanism to engineer exotic topological phases beyond conventional tight-binding models. Here, we experimentally demonstrate a twofold topological phase transition driven by third-nearest-neighbor couplings in a one-dimensional phononic chain that emulates cis-polyacetylene. Tunable hopping parameters in highly structured aluminum plates allow us to observe the emergence of Dirac points, a valley pseudospin structure, and topological edge states. The experimental results are supported by non-equilibrium Green’s function transport calculations. Our findings confirm the predicted long-range phase diagram and establish phononic metamaterials as a versatile platform for exploring topological phenomena beyond the Su-Schrieffer-Heeger paradigm.
Materials Science (cond-mat.mtrl-sci)
Interacting particles crossing barriers: spatial statistics, choice of route taken and role of interactions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-11-09 20:00 EST
Gulzar Ahmad, Andrew J Archer, Sergey Savel’ev, Marco G Mazza
We consider the statistics of pairs of particles moving in a potential energy landscape exhibiting a choice of different pathways from a local minimum start point to the global energy minimum destination. We examine the impact of both attractive and repulsive interactions between the particles, treating these via either a soft Gaussian or a Lennard-Jones potential. We investigate the statistics of which particle arrives at the destination first, arrival-time distributions and where in the system the second particle is located when the first arrives. We find that the typical arrival time of the first particle can be significantly different to that of a single particle, sometimes being much longer and in other cases being shorter, depending on the nature of the particle interactions. In the case of soft Gaussian attractive interactions, which effectively bind the pair of particles together to form a single larger particle, the arrival time can be much longer, since bigger particles cross barriers more slowly. In contrast, the arrival time is shorter when there is a repulsive core interaction between the particles, due to excluded-area and particle-ordering effects. We investigate the probability distribution of particles’ positions through the Jensen–Shannon divergence which unveils the dependence of the spatial distribution of the particles within the confining potential on the parameters of the particle interaction potentials.
Statistical Mechanics (cond-mat.stat-mech)
15 pages, 9 figures
Physica A 704 (2026) 132183
Disentangling Multiple Scaling Dimensions via Operator Covariance in Critical Quantum Spin Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-11-09 20:00 EST
We present a general proof of different power-law decays versus distance of the eigenvalues of two-point covariance matrices in critical lattice quantum models, allowing extraction of multiple scaling dimensions. We demonstrate the practical utility of this method in the context of a spin-1/2 chain with critical ground state described by the SU(2)_1 Wess–Zumino–Witten field theory. Using quantum Monte Carlo simulations to compute covariance matrices in different symmetry sectors, we resolve the expected relevant and marginal primary operators as well as some descendants. The covariance method can be integrated into many existing numerical schemes and promises to significantly enhance computational studies of quantum criticality.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 3 figures, 1 table
Devitrification: crystal nucleation and growth mechanisms in glasses
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-11-09 20:00 EST
If a liquid is cooled rapidly, it may fall out of equilibrium before it can crystallize. It may, however, crystallize later from the nonequilibrium glassy state. Using the Random First-Order Transition (RFOT) theory of glasses, we discuss a variety of mechanisms of crystallization as a route to devitrification. Ordinary nucleation is sped up by the frozen in energy of the glass relative to the liquid. At sufficiently low temperatures, a mechanism of nanonucleation appears, producing nanometer scale crystal inclusions in the glass. Nanocrystallization depends strongly on the local fluctuations in stability, and the transition from classical nucleation and growth to nanocrystallization occurs dominantly through rare, less stable glassy regions that percolate through space, producing an additional dramatic speedup in the crystal nucleation and growth rates. Similar fluctuations in local stability also explain anomalies of crystal growth in deeply supercooled systems.
Soft Condensed Matter (cond-mat.soft)
Thirty years of 2D MIT
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-11-09 20:00 EST
Sergey V. Kravchenko, V. M. Pudalov, Alexander A. Shashkin
The zero-magnetic-field metal-insulator transition in strongly correlated two-dimensional electron systems was experimentally discovered three decades ago, thereby triggering extensive experimental and theoretical investigations. Prior to this discovery, the occurrence of such a transition — as well as the very existence of a metallic phase in two dimensions — was regarded as forbidden within the framework of the one-parameter scaling theory of localization. In this work, we provide a comprehensive review of the transport and thermodynamic properties of two-dimensional electron and hole systems in which carrier-carrier interactions constitute the dominant energy scale. We present and critically analyze both experimental observations and theoretical developments accumulated over the past thirty years.
Strongly Correlated Electrons (cond-mat.str-el)
Jackknife-conformal uncertainty for linear ACE potentials: calibrated forces and silicon properties compared with Bayesian and POPS baselines
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Machine-learned interatomic potentials are misspecified, so Bayesian posterior variances understate their errors. For linear atomic cluster expansion (ACE) potentials we derive calibrated uncertainties from one misspecification-robust parameter covariance, the delete-one-configuration jackknife. Scaled by one conformal quantile from a held-out part of the training set, it gives per-atom force uncertainties close to their target coverage on held-out silicon data and on cracks left out of the fit; screw dislocations left out are under-covered by the smaller of the two models. With one scale fitted to the forces of a held-out test split, the same parameter distribution is propagated to 21 properties of silicon, from elastic constants to defect and surface energies, by implicit differentiation through each relaxation and by committees, and is tested against density functional theory (DFT) without tuning on any property. For a smaller and a larger model the intervals cover most properties, and the larger model’s are about 4 times tighter. The Bayesian posterior with one calibrated scale has the wrong shape: it covers fewer properties and has far lower joint evidence. Pointwise optimal parameter sets (POPS), once their hypercube is numerically defined, performs comparably on the properties, but its per-atom force regions are not calibrated to a target (0.95 and 0.84 at a nominal 0.90). Where the jackknife fails is relaxed point defects, whose training cells are all hot snapshots: a bias that every configuration shares is invisible to a jackknife, but it can be measured from the training labels, and as a discrepancy term, devised after the property results were seen, it brings the coverage close to nominal.
Materials Science (cond-mat.mtrl-sci)
25 pages, 9 figures, 15 tables
Analytical mean-field model for electrochemical metallization memristors with a nanoporous matrix: application to Ag/anodic alumina/Al
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Lucy A. Valdez, Juan D. Ruiz Díaz, Rodolfo H. Romero, Víctor J. Toranzos
Memristors based on electrochemical metallization with many filaments are usually modeled by microscopic simulations with many parameters or by phenomenological laws whose parameters are hard to relate to physical quantities. We present an analytical mean-field model for a population of Ag filaments confined in the pores of a nanoporous matrix, built on Ohm’s law, Faraday’s law and a power-based rupture criterion. The filaments have a truncated normal distribution of cross-sections and rupture leaving lognormally distributed gaps whose median grows with the dissipated power. Gap closing shifts the distribution of squared gaps rigidly, and the model therefore admits closed-form expressions for the switching voltage, the read current, the rupture branch and the high-voltage current. We apply it to Ag/nanoporous anodic alumina/Al structures fabricated from industrial-grade aluminum, with a 2.4$ \mu$ m alumina layer, and measured under ambient conditions. The parameters were fitted to the bipolar sweeps, with the gap dispersion taken from the temporal shape of the read after a pulse. They reproduce the bipolar response, including voltage-controlled negative differential resistance, and predict without refitting the unipolar sweeps and the amplitude of the pulse response, where state memory appears. A second sample, with a larger contact deposited chemically, is described by the same model. In vacuum the devices neither switch nor show negative differential resistance, as expected if adsorbed water supplies the counter reaction; the residual high-voltage current follows ionic hopping conduction.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 6 figures
Ion Redistribution and Lattice-Distortion-Modulated d-Electron Correlation in Layered Multiferroic ABP$_2$S$_6$ Probed by X-ray Photoelectron Spectroscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Jing Tang, Ruiqi Lu, J. Anibal Boscoboinik, Xi Ling
Ferroelectric phase transitions are driven by ion displacement-induced symmetry breaking, yet their chemical signatures are rarely probed directly at the atomic level. Here, we establish temperature-dependent X-ray photoelectron spectroscopy (XPS) as a powerful and quantitative probe of ferroelectric phase transitions by tracking ion migration-induced changes in local chemical environments. Using van der Waals (vdW) layered ABP$ _2$ S$ _6$ materials as a model system, we systematically compare CuCrP$ _2$ S$ _6$ (CCPS), which undergoes a ferroelectric phase transition, with AgCrP$ _2$ S$ _6$ (ACPS), which remains paraelectric over the same temperature range. While ACPS exhibits only smooth trivial thermal broadening and shifts in core-level spectra, CCPS shows pronounced and enormously large temperature-dependent XPS anomalies across the ferroelectric transition, demonstrating that XPS is intrinsically sensitive to ferroelectric order. Detailed analysis of the Cu 2p spectra reveals that these anomalies originate from temperature-driven Cu$ ^+$ ion migration associated with polarization switching, whereas concurrent changes in the Cr core levels reflect secondary lattice squeezing and modulation of d-electron correlation induced by Cu displacement. Supported by a ferroelectric structural model, we further correlate XPS binding-energy shifts with the magnitude of Cu-ion migration, enabling a quantitative estimation of ionic displacement directly from spectroscopic observables. This work also highlights the rich information provided by temperature-dependent XPS for detecting and quantifying ferroelectric phase transitions and ion migration, offering a general chemical probe for ferroic materials and ion-displacement-driven phase transitions.
Materials Science (cond-mat.mtrl-sci)
Bichromatic light-induced electronic torques on the Néel vector in Rashba magnetic multipoles from $p$-wave magnets to $i$-wave altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Light can control magnetic order on ultrafast timescales, but for a two-dimensional magnet with an out-of-plane order parameter $ \boldsymbol N\parallel\hat z$ , the inverse Faraday field is collinear with $ \boldsymbol N$ and gives no transverse torque. Here we show that bichromatic $ (\omega,b\omega)$ light generates electronic torques perpendicular to $ \boldsymbol N$ in Rashba-coupled magnetic multipoles, from $ p$ -wave ($ n=1$ ) magnets to $ i$ -wave ($ n=6$ ) altermagnets. Beyond high-frequency effective fields, we evaluate the exact Floquet response and the generalized torque per occupied electron, for prescribed occupations. The momentum-dependent exchange terms dominate this Fermi-sea torque and remove the leading-order zeros (amplitude-ratio blindspots) of the momentum-independent field in the channels tested. For out-of-plane $ \boldsymbol N$ , rotational symmetry permits a transverse torque only if $ \gcd(n,b+1)=1$ for counter-rotating beams or $ \gcd(n,b-1)=1$ for co-rotating beams. For in-plane $ \boldsymbol N$ , the Fermi sea also gives a torque component along $ \hat z$ that the momentum-independent field cannot produce. We classify the active channels, with $ n=1,\dots,6$ and $ b=1,\dots,7$ , by frequency scaling and origin (cycle-averaged versus oscillating exchange). As a control, a Rashba ferromagnet ($ n=0$ ) has one symmetry-allowed out-of-plane channel and a weak in-plane response without a selection rule. Finite-momentum occupied-state physics is therefore essential for light-driven torques in unconventional magnets, and the exact Floquet calculation validates and extends the high-frequency description.
Materials Science (cond-mat.mtrl-sci)
25 pages, 7 figures, 6 tables
Growth and fabrication of advanced PbTe-Pb quantum devices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Zehao Yu, Wenyu Song, Lining Yang, Zeyu Yan, Yuhao Wang, Weizhao Wang, Xinchen He, Ruidong Li, Jiaye Xu, Shuai Yang, Zonglin Li, Shan Zhang, Xiao Feng, Tiantian Wang, Yunyi Zang, Lin Li, Runan Shang, Qi-Kun Xue, Ke He, Hao Zhang
We report recent progress in the growth and fabrication of advanced PbTe-Pb Majorana devices for three-terminal correlation experiments. A critical prerequisite for these devices is a continuous Pb film spanning from the PbTe nanowire to the substrate. In previous studies, PbTe nanowires were spatially separated from the substrate mask, making them unable to fulfill this requirement. To address this issue, we have developed a new growth and fabrication approach. Key fabrication steps are introduced between the PbTe growth and Pb deposition. The top facet of the PbTe nanowire is covered with a Te capping layer before breaking the ultra-high vacuum, enabling ex situ processing for subsequent steps. The mask is then removed, followed by the fabrication of shadow walls. After reloading the chip into the growth chamber, the Te protection layer is removed through thermal decomposition, and the Pb film is subsequently deposited. Notably, a pristine PbTe-Pb interface with an in-situ-equivalent quality can be achieved despite the ex-situ processing. Our technique facilitates the develop of advanced PbTe-Pb quantum devices with complex designs, paving the way toward the realization of topological qubits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Phys. Rev. Applied 26, 054018 (2026)
Conformationally frustrated epitaxy at heteromolecular interface
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Jakub Planer, Pavel Procházka, Tomáš Krajňák, Veronika Stará, Daniela Hrubá, Zdeněk Endstrasser, Tomáš Skála, Jan Čechal
Precise control of molecular heteroepitaxy offers a route to multilayer architectures with well-defined interfaces. However, the role of intramolecular flexibility in epitaxial matching remains insufficiently understood. Here, we investigate the heteroepitaxy of intact 1,3,5-tris(4-carboxyphenyl)benzene (BTB) on a molecular $ \delta$ -layer composed of fully deprotonated BTB molecules on Ag(111). Combining scanning tunneling microscopy, low-energy electron microscopy and diffraction, X-ray photoelectron spectroscopy, and density functional theory, we identify the key interactions controlling molecular packing and epitaxial growth. We show that intermolecular bonding motifs are preserved on the molecular template, but their lattice parameters and molecular conformations change as compared to a silver surface. Individual molecules exhibit distinct appearances in scanning tunneling microscopy, consistent with site-dependent conformational variations identified by theory. Our calculations reveal that the competition between molecule-substrate interactions and conformational energy produces different compromise geometries, resulting in conformational frustration at the epitaxial interface. Crucially, constraining BTB into a planar geometry changes the preferred lateral adsorption positions, demonstrating that molecular flexibility directly modifies the energetic preferences for epitaxial registry. Comparison with more rigid molecular overlayers further supports this interpretation. Our findings reveal that molecular flexibility contributes to epitaxial matching by allowing unfavorable molecule-substrate interactions to be compensated by energetically favorable conformations while preserving the intermolecular network.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft)
Magnetic-Field-Tuned Critical End Point and High-Field Phases in HoMn6Sn6
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Joanna Blawat, John Singleton, Junho Seo, Charles Mielke III, Tyler J. Slade, Paul C. Canfield, Philip J. W. Moll, Ross D. McDonald, Robert J. McQueeney
Topological Kagome RMn6Sn6 materials, where R is a rare-earth, exhibit a rich variety of magnetic phases which provide an opportunity to understand how different spin textures affect topological and transport properties through the application of magnetic field H. In this work, we report experiments on single-crystal HoMn6Sn6, made possible by pulsed magnetic fields of up to 60 T, that permit high-field features of the field-temperature phase diagram to be studied in detail using magnetometry. Complementary, sensitive transport experiments over the same field range employ focused-ion-beam fabrication of novel strain-relieved HoMn6Sn6 devices. In agreement with meanfield calculations, we find a metamagnetic transition at 45 T with H||c between canted phases that ends in a critical end point at about 90 K. As far as we are aware, this is the only critical endpoint that is observed within the RMn6Sn6 kagome metals, and its temperature and field far exceed those of analogous phenomena in other materials. In the low-temperature metamagnetic region, HoMn6Sn6 shows large magnetoresistance, reaching 900 % at 60 T, in concert with Shubnikov de Haas oscillations that suggest a slight Fermi-surface contraction as the metamagnetic transition is crossed. A phase analysis of the oscillations suggests non-trivial band topology, although a firmer attribution must await detailed bandstructure calculations. Near the critical end point, we find deviations from Fermi-liquid behavior in the temperature-dependent magnetoresistance. In the metamagnetic region, the anomalous Hall contribution is not proportional to magnetization, and peaks at about 40 K, suggesting the role of enhanced spin fluctuations near the critical point. At higher temperatures, the anomalous Hall effect reappears at low fields, showing that the magnetization provided by the Ho and Mn sublattices independently affect the conductivity.
Materials Science (cond-mat.mtrl-sci)
Rotational Doppler Effect and Helimagnon Frequency Comb in Sliding Magnetic Spirals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Yang Liu, Jie Liu, Tianci Gong, Zhaozhuo Zeng, Xiaoping Gao, Kai Chang, Peng Yan
Collective spin motion can reshape magnon spectra by providing a dynamical magnetic background. Magnetic spirals offer a particularly clean setting, as they simultaneously host propagating helimagnons and a gapless Goldstone mode, i.e., the sliding of the spiral. Here, we show that once a helimagnon is excited and the spiral slides, the motion, which rotates the local spin frame, produces a thresholdless rotational Doppler shift of the helimagnon spectrum, with even winding for the linear mode and odd winding for its second harmonic. Stronger excitation generates one finite-momentum phason. Mixing of that phason with the helimagnon produces a helimagnon frequency comb only inside a finite driving window, spaced by the phason frequency fixed by the spiral length rather than by the sliding rate. These two scales are separable in a microwave experiment: the Doppler offset tracks the sliding velocity, whereas the comb spacing scales inversely with the length of the spiral.
Materials Science (cond-mat.mtrl-sci)
Limits of Lorenz number estimation from the temperature-dependent Seebeck coefficient
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Separating electronic and lattice thermal conductivity often relies on a Lorenz number estimated from the Seebeck coefficient using an assumed band and scattering model. We ask how much information about the Lorenz number comes from temperature-dependent Seebeck coefficients rather than the assumed model. We formulate compatible minimum and maximum Lorenz numbers as linear programs in a fixed finite spectral representation, assuming known chemical potentials and a common energy dependence across observation temperatures for each candidate spectrum. Reference Seebeck coefficients are generated by single-band and same-sign two-band models. Increasing the prescribed observations from one to five temperatures reduces the Lorenz interval widths by approximately 97.6% and 97.8%, respectively. Nevertheless, the single-band example retains an attained interval of approximately $ [1.46453,2.37037]\times10^{-8}$ W $ \Omega$ K$ ^{-2}$ at 400 K. Exact electrical conductivity values do not narrow these ranges when spectral amplitudes can vary independently with temperature. Thus, even exact Seebeck coefficients and electrical conductivities at all five temperatures need not uniquely determine electronic thermal conductivity at 400 K. For the same single-band example, known ratios of spectral amplitudes across temperatures allow electrical conductivity values to confine all compatible Lorenz numbers to an enclosing interval less than 1% as wide as the five-temperature free-amplitude interval. Temperature-dependent Seebeck data strongly narrow the compatible range, while conductivity provides further spectral constraints when the temperature dependence of spectral amplitudes is independently restricted.
Materials Science (cond-mat.mtrl-sci)
25 pages including Supplemental Material; 7 figures and 8 tables
A Real-Space Framework for the Bare and Interacting Longitudinal Susceptibility of Solids
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Rohit Pathak, Abhay Mishra, Mikhail I. Katsnelson, Anna Delin, Olle Eriksson, Vladislav Borisov
We present an implementation of the bare and interacting longitudinal susceptibility in a full-potential linear muffin-tin orbital code. The bare susceptibility is built in real space from Matsubara sums of Kohn-Sham Green’s functions and is resolved by site, spin and orbital degrees of freedom; the spin and charge susceptibilities follow from a Dyson equation, with an on-site exchange-correlation kernel. After testing the solver on the Stoner-like instability of bcc Fe, we apply it to four density-wave materials. The bare susceptibility peaks at H in bcc Cr, where the nonmagnetic state is close to a Stoner instability, and at the stripe vector M in FeSe. In LaTe3 the response of the Te nets peaks close to the observed charge-density-wave vector, at its image in the neighbouring Brillouin zone; which of the two equivalent vectors carries the response is set by the phases of the sites in the cell. In 2H-NbSe2 the response is weakly modulated, and the observed vector lies on the flank of a broad maximum, consistent with the known importance of electron-phonon coupling there. Antiferromagnetic order reduces the bare longitudinal response at the ordering vector by ~8% in Cr and about half in FeSe. The orbital decomposition of the bare susceptibility shows which orbitals contribute the most for the nearest-neighbor bonds.
Materials Science (cond-mat.mtrl-sci)
19 pages, 6 figures, plus 12 pages of Supplemental Material
A stochastic propagation method for large-scale phonon calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Wenyingdi He, Weiqing Zhou, Shengjun Yuan
Large-scale phonon calculations for structurally complex materials are limited by the cubic cost of full diagonalization. We extend the stochastic propagation method (sPM) from electronic systems to lattice dynamics for estimating phonon frequencies, constructing vibrational densities of states, and reconstructing selected phonon polarization vectors by propagating random initial vectors under the dynamical matrix. For finite-range interactions, the leading propagation cost scales linearly with atom number at fixed sampling and propagation parameters. Our error analysis shows that, for nondegenerate modes that are spectrally resolved and have nonzero frequency in the small-error regime, extending propagation yields faster asymptotic reduction of frequency-estimation errors than increasing the number of random initial states alone. Comparisons with direct diagonalization validate the spectral estimates and a selected polarization vector. Convergence tests support the predicted scaling of frequency errors for selected resolved modes.
Materials Science (cond-mat.mtrl-sci)
Mixed-dimensional topological charge compensation beyond Weyl-node pairing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Xiao-Jing Gao, Ke-Xin Pang, Yun-Yun Bai, Yanfeng Ge, Yan Gao
The Nielsen-Ninomiya no-go theorem requires the total topological charge ($ C$ ) in a periodic Brillouin zone to vanish, conventionally leading to opposite-chirality pairs of Weyl points (WPs). A charged nodal surface (NS) provides an alternative mechanism for compensating a same-chirality Weyl pair, yet the general symmetry constraints governing this configuration and its electronic realization remain unexplored. Here, by an exhaustive analysis of all 1651 magnetic space groups (MSGs), with and without spin-orbit coupling, we identify only 13 type-II MSGs that permit the realization of a minimal unpaired mixed-dimensional configuration comprising a single $ |C|=2$ NS and two same-chirality $ |C|=1$ WPs. Guided by this symmetry framework, we identify the chiral boron allotrope THC-B$ _{30}$ as the first electronic realization of this unconventional topology. First-principles calculations reveal only two WPs with $ C=-1$ and one NS with $ C=+2$ , satisfying global topological charge neutrality and exhibiting unconventional Fermi arcs connecting the WP and NS projections. Moreover, strain-induced topological phase transitions redistribute topological charge among distinct band-degeneracy manifolds. Our findings establish a symmetry-guided route to realizing same-chirality Weyl pairs through mixed-dimensional charge compensation beyond conventional Weyl-node pairing.
Materials Science (cond-mat.mtrl-sci)
6 figures
Evaporation-induced colloidal diffusiophoresis in electrolyte solutions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-11-09 20:00 EST
Dang Q. Duong, Jung Hyun Kim, Hanna Cho, Sangwoo Shin
Non-volatile solutes accumulate near a receding drying front, generating concentration gradients that can drive directional colloidal transport by diffusiophoresis. This dynamic spatial arrangement of colloidal particles could affect the microstructure and macroscopic properties of the dried film. Here, we combine experiments and theory to investigate polystyrene particles suspended in electrolyte solutions drying within a capillary tube. By varying the electrolyte composition and ambient relative humidity, we show that evaporation-induced ion gradients drive particles toward the liquid-gas interface and enhance interfacial accumulation, whereas slower drying at higher humidity weakens the gradient and particle migration. We use the heat balance integral method to predict the transient solute field for a receding interface and couple it to particle transport to capture the observed particle trajectories and accumulation trends. These results identify background electrolytes and drying rate as coupled controls on particle distribution and provide a predictive framework to optimize formulation and processing parameters for manufacturing slurry-based materials, such as battery electrodes and turbine coatings.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Native point defects in rock-salt and wurtzite MnSe: formation energies across the growth window and spin splitting in the A-type order
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Tomás Rojas Solorzano (1 and 2), Dale Igram (3) ((1) CICIMA, Universidad de Costa Rica, (2) Sede de Occidente, Universidad de Costa Rica, (3) University of Michigan)
Manganese selenide grows both as rock-salt $ \alpha$ -MnSe, a type-II antiferromagnet, and as metastable wurtzite w-MnSe, whose magnetic order has not been measured. We compute the neutral Mn and Se vacancies and the two antisites of both polymorphs with density functional theory plus a linear-response Hubbard $ U$ , between the Se-rich limit bounded by MnSe$ 2$ and the Mn-rich limit set by the measured formation enthalpy. In $ \alpha$ -MnSe the Mn vacancy is lowest over most of the window (0.92 eV under Se-rich conditions), consistent with its p-type conduction. In w-MnSe, the Se antisite is lowest under Se-rich conditions, narrowly in the A-type order and clearly in the stripe order, and the Se vacancy is lowest under Mn-rich conditions. The Se vacancy has nearly the same formation energy in both polymorphs, whereas defects that change the number of Mn atoms differ by 0.4-1.1 eV, although DFT+$ U$ places wurtzite below rock salt, contrary to experiment. A spin-degenerate stripe order lies 14 meV per formula unit below the altermagnetic A-type order of w-MnSe, and the formation energies shift between these orders by up to 0.24 eV, most for the Mn vacancy. Three of the four defects leave an uncompensated moment of 3-5 $ \mu\mathrm{B}$ . In the A-type order, band unfolding shows that the sign-reversing splitting of the most strongly split band, about 230 meV and 3 eV below the valence-band maximum, keeps its peak height within the 8% scatter of the analysis at 3% defects, while points on its shoulders move by up to about 70 meV. Band-edge states are not resolved.
Materials Science (cond-mat.mtrl-sci)
36 pages, 4 figures, 17 tables, including Supplementary Material
Symmetry-Gated Sliding: Decoupling Interlayer Translation from Polarization Reversal in Boron Nitride Ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Yinan Wang, Teruyasu Mizoguchi
Electric-field-driven polarization switching in sliding ferroelectrics depends on how local interlayer motion is accommodated by the surrounding structure. Yet the relationship between sliding, domain-wall (DW) propagation, and collective domain evolution under changing vector fields remains unclear. Here, we show that local symmetry governs the coupling between field-induced forces and interlayer sliding, while DW connectivity determines how local motion contributes to net domain conversion. These effects are examined across three structural scales, from monodomains and isolated DWs to reconstructed moire networks. We investigate bilayer hexagonal boron nitride (h-BN) using molecular dynamics with a machine-learning interatomic potential that incorporates field-dependent electric enthalpy. An initially monodomain bilayer switches through directional wrinkling and interlayer sliding, while the barrier along a constrained flat path remains finite. Pre-existing DWs propagate with velocities governed by their shear and tensile character, and an additional in-plane field tunes wall velocity and width according to its orientation. In reconstructed triangular moire networks, shared junctions and boundary curvature mediate domain evolution and recovery after field removal or reversal. Most strikingly, a rotating in-plane field translates the layers and displaces the moiré nodes by approximately 1 AA yet leaves the AB/BA domain-area ratio without detectable change, because threefold connectivity cancels the contributions of individual walls. We term this response polarization-silent sliding. These results distinguish local sliding, DW translation, and net domain conversion as different responses to electric fields and establish how local structural symmetry and DW connectivity shape their selective control.
Materials Science (cond-mat.mtrl-sci)
Coulomb screening of the orbital inverse Faraday effect in finite-size diffusive conductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
We study the effects of Coulomb screening on the second-order dc response in finite-size diffusive conductors. Starting from the Boltzmann equation supplemented by the self-consistent electrostatic field, we develop a kinetic theory of the inverse Faraday effect for a two-dimensional disk driven by a circularly polarized ac electric field. In this formulation, the first-order charge modulation and the induced electric field are coupled through the Coulomb interaction, and the self-consistent first-order solution determines the nonlinear source for the second-order dc circulating current responsible for the induced magnetic moment. The radial problem is solved numerically using an angular-harmonic expansion and the Chebyshev collocation method. It is shown that in the non-self-consistent approximation the frequency dependence of the second-order dc response has a maximum when the diffusion length associated with the radiation frequency becomes comparable to the sample radius. This behavior is found to be strongly modified by self-consistent screening. We demonstrate that Coulomb screening shifts the maximum of the dc response to a higher drive frequency and suppresses the peak amplitude. This behavior is observed consistently for the area-integrated circulating current and the induced magnetic moment. The obtained results clarify the limitations of the non-self-consistent description of the inverse Faraday effect and show that Coulomb self-consistency is crucial for quantitative predictions of optically induced dc magnetization in finite-size diffusive conductors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
24 pages, 6 figures
Strong phonon-coupled trion emission in Janus homobilayer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Tianyishan Sun, Dingkun Bi, Haonan Wang, Hiroto Ogura, Yanlin Gao, Mina Maruyama, Susumu Okada, Shiro Entani, Kenji Watanabe, Takashi Taniguchi, Kazunari Matsuda, Toshiaki Kato
Janus transition metal dichalcogenides with broken mirror symmetry provide a novel platform for exploring many-body effects mediated by spin-valley-phonon interactions. Strong electron-phonon coupling demands a precise match between a strong effective dipole moment and nanometer-scale charge confinement. Here, we report thermally robust and enhanced trion emission in a symmetric bilayer WSeS with an S/S stacking configuration. The inward-pointing antiparallel built-in electric fields induce a strong electron confinement effect at the interface, driving dominant trion emission at cryogenic temperatures. Furthermore, a massive electron-phonon coupling strength (3.9) resonant with the optical phonon A_1^2 energy (51 meV) contributes to the thermal stability of this trion emission at elevated temperatures. By tailoring the interfacial architecture in Janus WSeS homobilayers, this study overcomes the thermal decoherence limits inherent to traditional semiconductor systems, offering novel insights into room-temperature many-body interactions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
$\mathbb{Z}_2$ gauge and exact solution of the $\pm J$ Edwards-Anderson model in a transverse field
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-11-09 20:00 EST
Using the Majorana representation of spin-1/2 operators, we study the $ \pm J$ Edwards–Anderson model in a transverse field at $ T=0$ . We show that, in this representation, the quantity describing the coupling between neighboring spins commutes with the Hamiltonian and, unlike in the Kitaev model, is not subject to any Gauss law. The resulting $ \mathbb{Z}_2$ gauge freedom allows the disorder in the signs of the exchange integrals to be eliminated by an exact gauge transformation, so that the spectrum of the system coincides with that of the model with uniform couplings. The resulting theory is quadratic in the Majorana fields. Computing the local Green’s functions, we find that the Edwards–Anderson order parameter vanishes for $ \Delta>J\sqrt{Z}$ and equals $ 1/4$ for $ \Delta<J\sqrt{Z}$ , which signals a second-order transition from a paramagnetic phase to a spin-glass ground state that is degenerate over spin configurations and replica symmetric at $ T=0$ .
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
4 pages, 1 figure
Disentangling Spin and Orbital Contributions in the Search for Altermagnetic Terahertz Conversion in RuO2
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Jiahao Liu, Yuxiao Mo, Tongyang Guan, Wenhui Fang, Yongwei Cui, Wentao Qin, Zhe Yuan, Lishu Zhang, Zhensheng Tao, Yizheng Wu
Rutile RuO2 has emerged as a prominent candidate altermagnet, yet the microscopic origin of its reported charge-angular-momentum conversion remains unsettled. Recent theoretical and experimental advances have highlighted a potentially dominant role of orbital transport, raising a fundamental ambiguity between spin- and orbital-mediated conversion in RuO2. Here, we report the first experimental disentanglement of the spin- and orbital-to-charge conversion channels in RuO2 heterostructures using terahertz emission spectroscopy. We identify Fe as a predominantly spin-current injector, whereas Ni and permalloy predominantly inject orbital currents, revealing a substantial orbital contribution to ultrafast terahertz emission. Under controlled spin-current injection, we find no evidence for inverse altermagnetic spin-splitting effect. Instead, the observed anisotropy is consistent with an anisotropic inverse spin Hall response that is strongly conditioned by the near-interface environment. Under orbital-current injection, the anisotropy is markedly weaker, indicating that orbital-to-charge conversion is largely isotropic in RuO2. Our results establish orbital transport and interface-conditioned spin Hall conversion as key to terahertz emission from RuO2, underscoring the need to disentangle spin, orbital, and interfacial contributions before assigning anisotropy to altermagnetism.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Optics (physics.optics)
Spontaneous Formation of Lateral Defect-Density Gradient in CVD-Grown MoS2 Monolayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
M. Kostka, H.-S. Chen, C.-Y. Hsiao, Y.-R. Chu, J. Mach, M. Bartošík, J. Šťastný, T. Šikola, W.-C. Lin
Defect engineering in two-dimensional materials is a powerful strategy for tuning electronic, optical, and catalytic properties. While pristine molybdenum disulfide (MoS2) has been thoroughly studied, defective MoS2 remains poorly understood due to the complexity and inconsistency of controlled defect creation. Here, we report a defect-density gradient that forms spontaneously in MoS2 flakes during chemical vapor deposition (CVD) growth. Photoluminescence and Raman spectroscopy mapping reveal the lateral arrangement of this gradient across a single flake. Deconvolution of the excitonic photoluminescence emission identifies electron doping as the key factor governing the spatial variation in optical response. This doping likely originates from sulfur vacancies formed during CVD growth, as further supported by the observed Raman mode shifts. We propose that this gradient arises from precursor depletion near the nucleation center during growth, resulting in a gradual variation in defect density. This lateral defect structure provides a convenient platform for systematically characterizing defective MoS2 across a continuous range of defect densities within a single sample. The sulfur-vacancy-driven surface activation identified here can also be important for future catalytic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
15 pages, 5 figures
A Monte Carlo study of thermal conductivity in black phosphorene
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
L. O. Vilyaev, D. V. Zavyalov, V. I. Konchenkov
In this work the electronic thermal conductivity of black phosphorene is studied. Using the Monte Carlo method together with the Green-Kubo relations, a statistical modelling of the motion and scattering of electrons on acoustic and optical phonons is performed to estimate the electronic thermal conductivity. The scattering probability is expressed analytically. The obtained results show a pronounced anisotropy of the thermal conductivity: the thermal conductivity values along the armchair direction are an order of magnitude larger than those along the zigzag direction, in agreement with the experimental data for related materials. In addition, the modelling allowed a more rigorous justification of some results of previous theoretical works on the anisotropic thermal conductivity of black phosphorene.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
From local learning to global electronic properties in large-scale systems
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Yu Cheng, Zhichang Fu, Yechen Chen, Yonggang Li, Weiqing Zhou, Shengjun Yuan
Machine learning from local atomic environments offers an efficient route to electronic structure, but evaluating global electronic properties in large systems remains computationally demanding. Here we combine real space charge density learning with stochastic propagation using Kohn-Sham Hamiltonians constructed from the predicted densities. The framework avoids target system self-consistent iterations and explicit diagonalization, while hierarchical blocking enables dense grid inference within limited GPU memory. We demonstrate density of states calculations for one million Si atoms and optical and transport calculations for over one hundred thousand atoms, without training separate models for each property. This framework extends the practical scale of electronic structure calculations within Kohn-Sham DFT, opening opportunities to investigate how atomic structure governs electronic, optical and transport properties at length scales relevant to real materials and devices.
Materials Science (cond-mat.mtrl-sci)
Lefschetz-Thimble Method to the Sign Problem in the Sachdev-Ye-Kitaev Model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-11-09 20:00 EST
The sign problem in path integrals severely limits the application of quantum Monte Carlo methods to strongly correlated systems, whereas the Lefschetz-thimble method offers a rigorous framework to mitigate this issue. In this paper, we establish a numerical framework based on the Lefschetz thimbles for the Sachdev-Ye-Kitaev (SYK) model. By introducing continuous auxiliary fields via the Hubbard-Stratonovich transformation, the partition function is formulated as a high-dimensional complex integral. We employ the complex Langevin equation to explore the saddle-point distribution of the effective action in the complex plane. Monte Carlo integration is then performed to compute the partition function and Green functions. Our numerical results exhibit excellent agreement with high-temperature expansions, infrared-limit solutions, and determinantal quantum Monte Carlo (DQMC) simulations, confirming the validity of our framework. Furthermore, we demonstrate that our complex Langevin search successfully captures the relevant dominant saddle points governing the SYK model in the large-N limit. Our work deepens the understanding of the sign problem in the SYK model and provides a viable non-perturbative avenue for addressing sign problems in more complex strongly correlated systems.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages,6 figures
Pressure-induced symmetry breaking and polarity in the van der Waals magnet CrSBr
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Amit Pawbake, Sitaram Ramakrishnan, Kseniia Mosina, Aljoscha Soll, Zdenek Sofer, Pierre Rodiere, Rolf Heid, Gaston Garbarino, Pierre Bouvier, Clement Faugeras
The van der Waals magnet CrSBr has emerged as a fascinating platform for exploring coupled structural, magnetic, and electronic phenomena. Yet, the evolution of its crystal symmetry and electronic states under pressure and temperature remains unresolved. To elucidate this we employ low-temperature single-crystal X-ray diffraction, Raman scattering and photoluminescence measurements under hydrostatic pressures of up to 12 GPa, complemented by first-principles this http URL observe a cascade of pressure-induced structural transitions from the orthorhombic $ Pmmn$ to monoclinic $ P2_1/m$ phase at $ \approx$ 1.5 GPa, followed by the emergence of a polar orthorhombic $ Pmm$ 2 phase $ \approx$ 6.5 GPa. The change in symmetry is accompanied by phonon anomalies and a direct-to-indirect bandgap crossover. Our results demonstrate pressure as a knob to engineer structure, symmetry and electronic properties in CrSBr in a coupled manner.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
A Compact High-Repetition-Rate Intense THz Source for Atomic-Scale Materials Characterization
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Léo Guiramand (CORIA), Florant Exertier (GPM), Alexandre Fahy (CORIA), Anna Martinez, Matteo de Tullio (GPM), Saïd Idlahcen (CORIA), Jonathan Houard (GPM), Gerald da Costa (GPM), Thomas Godin (CORIA), Xavier Ropagnol (ÉTS), Domenico Paparo (ISASI), François Blanchard (ÉTS), Angela Vella (GPM), Ammar Hideur (CORIA)
High-intensity terahertz (THz) sources combining high repetition rates, strong field amplitudes, and long-term stability are key enabling technologies for next-generation ultrafast photonics. However, simultaneously achieving these characteristics in a compact and practical architecture remains a major challenge. Here, we report a high-performance tabletop THz source delivering intense single-cycle pulses at 100 kHz, generated by optical rectification in lithium niobate using an optimized echelon-based tilted-pulse-front scheme and driven by an industrial-grade ytterbium laser. The source achieves optical-to-THz conversion efficiencies exceeding 0.13% at room temperature, peak electric fields of several hundred kV/cm, and excellent long-term stability, establishing a robust platform for high-average-power strong-field THz applications. As a proof of concept, the source was integrated into an atom probe tomography (APT) instrument. APT reconstructs the three-dimensional chemical composition of materials through field-induced ion emission from a sharp nanotip. While THz-assisted ion emission has been shown to improve analytical performance by reducing thermal effects, previous demonstrations were limited to low-repetition-rate THz sources, restricting throughput and accessible analysis volumes. Using an aluminum nanotip, we demonstrate efficient THz-assisted APT at 100 kHz and benchmark its performance against conventional voltage- and laser-assisted operation. The high repetition rate enables rapid large-volume acquisition while improving mass resolving power, reducing thermal tailing, and preserving high-quality three-dimensional reconstructions. Beyond APT, this work establishes a compact and scalable high-repetition-rate THz platform for strong-field physics, nonlinear THz photonics, ultrafast spectroscopy, and material characterization at the nanoscale.
Materials Science (cond-mat.mtrl-sci)
ACS photonics, 2026, 13 (21), pp.6449-6459
Non-trivial topological spin-polarized surface states induced nonreciprocal transport in the hourglass semimetal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Zahir Muhammad, Ghulam Hussain, Zia ur Rehaman, Rajibul Islam, Igor Antoniazzi, Muhammad Ismail Khan, Carmine Autieri, Maciej R. Molas, Xiaoguang Li, Xiaoyang Lina Azizur Rahmana, Weisheng Zhaoa
Quantum materials such as topological semimetals have gained consummate interest due to their exotic band crossings and protected surface states. In particular, Ta$ _3$ GeTe$ _6$ has emerged as a prototypical hourglass Dirac semimetal, as confirmed by both experimental and theoretical analysis. The ARPES confirms the topological hourglass-type band dispersions and Rashba-type band, while Hall measurements reveal a high hole carrier concentration and nonreciprocal transport behavior. These findings are further supported by a phenomenological toy model, which predicts a nonreciprocal resistance, consistent with the observed direction-dependent magnetoresistance. Furthermore, the Raman spectroscopy uncovers two-fold and four-fold phonon symmetries drag of highly anisotropic phonons, which establishes symmetry-dependent resistance. DFT calculations reveal Dirac-like and hourglass Dirac band crossings near the Fermi level for the bulk, with Rashba-type spin splitting induced by the surface inversion-symmetry breaking, leading to spin-polarized surface states. The combined experimental and theoretical results demonstrate that Ta$ _3$ GeTe$ _6$ hosts a non-trivial electronic topology, with the inversion-symmetry breaking at the surface as the driver of this nonreciprocal transport behavior.
Materials Science (cond-mat.mtrl-sci)
21 pages, 4 figures + SI
Momentum-space engineering in van der Waals heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Xiao Li, Astrid Weston, James G. McHugh, Michael D. Thompson, Matthew Watson, Yunze Gao, Nicholas Clark, Laxman Nagi Reddy, Samuel Magorrian, Wendong Wang, Zhiyuan Wang, Sofia Konyzheva, Francisco Selles, Amy Carl, Katarzyna J. Salamon, Alex Summerfield, Nicholas Hine, Andre K. Geim, Neil R. Wilson, Jonathan R. Prance, Andrey V. Kretinin, Vladimir I. Falko, Roman Gorbachev
Twenty years of graphene research have established Dirac fermions as a versatile platform for exploring quantum topological phenomena. Yet control over graphene’s low-energy spectrum mostly follows the route of miniband engineering using real-space superlattices. Here we introduce a complementary approach based on momentum-space ‘Umklapp’ band engineering. This is realised by matching reciprocal space positions of band edges of two adjacent highly incommensurate 2D crystals to coincide upon a boost from their Bragg vectors, creating resonant interlayer hybridisation that qualitatively reconstructs their spectra. To demonstrate this approach experimentally, we use monolayer graphene on MoS$ _2$ , twisted such that MoS$ _2$ Q-valley states are brought by Umklapp into energy-momentum resonance with graphene’s Dirac cones. The ensuing hybridization results in the formation of a clear additional Dirac-like spectral feature, identified by a distinct Landau-level fan and Shubnikov-de Haas oscillations characteristic to Berry phase $ \pi$ electrons. These new topological spectral features create a spin-valley locked Ising system which is robust against small twist-angle variations that can be further tuned by an external displacement field. More broadly, Umklapp band engineering offers a practical strategy for tailoring the electronic structure in van der Waals heterostructures, expanding the design space of quantum materials beyond moiré superlattices and weak proximity effects.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
18 pages 4 figures
Thermalization of coarse-grained variables in the Toda lattice: a numerical study
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-11-09 20:00 EST
Martina Giachello, Cesare Vianello, Giacomo Gradenigo
We present here a numerical study of the Toda lattice Hamiltonian dynamics showing how, despite model integrability, it is possible to find many macroscopic observables which display standard equilibrium behavior. In particular, we study numerically the energy time correlation of certain coarse-grained variables, showing that it decays with either exponential or stretched exponential behaviour, thus indicating good thermalization properties. The spirit of our observation is complementary to that of standard Fermi-Pasta-Ulam-Tsingou-like numerical experiments, in which the breaking of integrability is regarded as the key ingredient for relaxation to thermal equilibrium. The present communication corroborates, on the contrary, the view that integrability is not an obstacle to thermalization, provided that a sufficiently weak definition of the latter is accepted. In the Toda lattice we have introduced several kinds of coarse-grained variables, constructed with the purpose to maintain a thermodynamic relevance also for large system sizes, which all show good thermalization properties.
Statistical Mechanics (cond-mat.stat-mech)
26 pages, 8 figures
Thermodynamic Phase Diagrams in $λ$-(BETS)$_2$GaBr$x$Cl${4-x}$ under Physical and Chemical Pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2026-11-09 20:00 EST
Aulia Anisa Firdaus, Arifa Diana Agustin, Fathan Muyassar Santana, Taiyo Oka, Shuhei Fukuoka, Atsushi Kawamoto, Dita Puspita Sari, Yasuyuki Ishii
The evolution of electron correlation in the superconducting state of the mixed-crystal series $ \lambda$ -(BETS)$ 2$ GaBr$ x$ Cl$ {4-x}$ was investigated by magnetic and transport measurements. Br concentrations evaluated by electron-probe microanalysis agree well with single-crystal X-ray diffraction refinement. Demagnetization-corrected susceptibility and magnetization of crystals with $ x{c(rf)}$ = 0.22, 0.24, 0.42, and 0.63 all show a diamagnetic superconducting transition. The lower critical field $ H{c1}$ , determined from the deviation from the Meissner response, shows a dome-like maximum at $ x{c(rf)}$ = 0.24. The upper critical field $ H_{c2}$ , obtained from the first high-field magnetoresistance measurements in this system, decreases with increasing Br concentration up to $ x_{c(rf)}$ = 0.42, establishing the high-field superconducting boundary on the chemical-pressure side. Combining these results with reported transport data under chemical and physical pressure, we propose a pressure-temperature phase diagram for $ \lambda$ -(BETS)$ _2$ GaCl$ _4$ . Its double-dome-like structure has a local minimum near x = 0, where a quantum-critical point was proposed at P $ \approx$ 0.13 GPa, separating a low-pressure regime of superconductivity coexisting with magnetism and an unconventional metallic state from a higher-pressure regime with conventional metallic behavior. A low-temperature resistivity upturn, previously reported only under physical pressure, is also found under chemical pressure, suggesting that spin-density-wave fluctuations may extend continuously across both pressure axes. The phase diagram overlaps with that of $ \lambda$ -(STF)$ _2$ GaCl$ _4$ under physical pressure, indicating that chemical substitution, external pressure, and molecular substitution can be unified in a single bandwidth-controlled phase diagram for $ \lambda$ -type molecular superconductors.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
20 pages, 10 figures, 6 tables. Submitted to Superconductor Science and Technology
Physics Informed Priors for Machine Learning Interatomic Potentials with Uncertainty Quantification
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
George I. Simmons, Thomas D. Swinburne, Thomas Hudson, James R. Kermode
Standard uncertainty quantification methods for machine learning interatomic potentials often fail to quantify the effects of model misspecification despite its prominence as a source of error. To combat this, misspecification-aware uncertainty schemes have been gaining attention, pointwise optimal parameter set regression (POPS-Regression) among them. However, no guarantees on the physicality of the posterior distribution are given and uncertainty estimates can be conservative compared to the true error. To combat this, we present a model misspecification aware scheme that builds on POPS-Regression by allowing users to specify physical priors that are enforced across the obtained ensemble of models. This allows the user to incorporate misspecification-aware uncertainties without compromising on physical properties. The scheme is applicable to any physical quantity that can be represented by a convex set of parameters and so is robust for a wide variety of static properties which can help inform dynamical simulations. Here, we demonstrate the scheme for phononic vibrations and elastic properties. The scheme is also applied to both linear and message-passing neural network potentials by exploiting the linearity available in both architectures; for neural network potentials we approximate the readout layer as a linear model based on fixed non-linear features. The versatility of the method provides an alternative to hand-crafted or active learning approaches to data-set construction to correct physical failures by adding data thus reducing the computational overhead for designing potentials for specific applications.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Motion-Induced Polaron Resonance beyond the Orthogonality Catastrophe
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-11-09 20:00 EST
We investigate the spectroscopic response of a repulsively interacting, infinitely heavy impurity moving at constant velocity $ v$ through a one-dimensional ideal Fermi gas. Using an exact functional-determinant approach, we calculate the Ramsey response and spectral function, fully accounting for many-body particle-hole excitations. We uncover a strongly nonmonotonic dependence on impurity velocity: decoherence is enhanced around the Fermi velocity, whereas sufficiently rapid motion restores a narrow, long-lived polaron resonance. A long-time wave-packet analysis yields analytical expressions for the polaron energy and decay rate over the full velocity range and quantitatively captures the numerical results. At high velocity, the polaron energy approaches the mean-field value, the decay rate vanishes as $ 1/v$ , and the spectral weight approaches unity. Thus, rapid prescribed motion provides a dynamical route to suppressing the orthogonality catastrophe and restoring polaron coherence even for an infinitely heavy impurity, where recoil is entirely absent.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Mathematical analysis of the Markovian Mpemba effect
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2026-11-09 20:00 EST
Umashankar Pardhi, Syed Abbas, Moupriya Das
The Mpemba effect is a counterintuitive phenomenon in which two equilibrium systems at different temperatures, say hot and warm systems, when quenched at the same bath temperature, for some pair of hot and warm temperatures, the hot system comes to bath temperature faster than the warm system. In recent years, studies on the Mpemba effect for Markovian systems under external potential, which are continuous-time, continuous-state-space Markov processes, have been carried out theoretically and experimentally by resorting to pseudo-distance measures which are not true distance metrics. Moreover, maximum crossover time is given for the Mpemba effect for all monotone distance measures or functions (which include true distance metrics and pseudo-distance measures). However, no mathematical analysis is carried out for the mere possibility of the presence of the Mpemba effect for Markovian systems under an external potential with a true distance metric. In this paper, by using a true distance metric which arises naturally from the weighted Hilbert space in which the adjoint of the generator of the Markov process is a Hermitian operator, we have shown the mathematical analysis of the possibility of the presence of the Mpemba effect by using Poincaré inequality and the geometry of Hilbert space.
Statistical Mechanics (cond-mat.stat-mech)
12 pages, 3 figures
Helical magnetism from sliding Luttinger liquids in hole-doped twisted bilayer WTe$_2$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Yung-Yeh Chang, Chen-Hsuan Hsu
We investigate carrier-mediated helical magnetism in hole-doped twisted bilayer WTe$ _2$ coupled to localized moments. The itinerant carriers are described by a valleyless two-flavor sliding Luttinger liquid. Via the feedback mechanism of the helical order formed within individual channels, we show that the interchannel spin susceptibility mediates a Ruderman-Kittel-Kasuya-Yosida interaction between localized moments that can stabilize a coherent helical magnetic texture across the coupled-wire array. A spin-wave analysis of the ordered state allows us to estimate the magnon energies and helix-ordering scale. The magnon energies depend on the carrier interactions with representative values falling in the microwave regime, suggesting possible detection by magnetic-resonance techniques. The helical order partially gaps the carrier spectrum and renormalizes the spin-correlation and relaxation exponents. These results identify twisted bilayer WTe$ _2$ as a tunable low-dimensional platform for realizing and probing carrier-mediated helical magnetism.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 2 figures. Accepted for publication in JPS Conference Proceedings (SCES2026)
Coexistence of antiferromagnetism and topological $s+d+id$ superconductivity in twisted cuprate bilayers
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-11-09 20:00 EST
Javier Castro Luaces, Manuel Fernández López, Jorge Bravo-Abad, Jaime Merino
We investigate the interplay between antiferromagnetism and topological superconductivity in twisted cuprate bilayers. We demonstrate how topological $ s+d+id$ superconductivity is induced by a twist of $ \theta \sim 45^\circ$ in a microscopic $ t$ -$ J$ type model of cuprate bilayers, where it robustly coexists with antiferromagnetic order at low hole doping. This novel pairing state becomes physically accessible at realistic interlayer couplings in the overdoped regime. Crucially, it displays a characteristic $ 2$ -fold rotational symmetry in angle-resolved photoemission spectroscopy (ARPES) not observed in the competing time-reversal symmetry breaking $ d+id$ or $ s+id$ states previously found. A finite Josephson effect at $ 45^\circ$ twist together with signatures in scanning tunneling spectroscopy of its two Majorana edge modes identifies this topological $ s+d+id$ state unambiguously.
Strongly Correlated Electrons (cond-mat.str-el)
19 pages, 13 figures
Stacking, symmetry and exciton fine structure in boron nitride bilayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Mehdi Arfaoui (1 and 2), Sylvain Latil (1), Lorenzo Sponza (2) ((1) Université Paris-Saclay, CEA, CNRS, SPEC, Gif-sur-Yvette, France. (2) Université Paris-Saclay, ONERA, CNRS, Laboratoire d’étude des microstructures, Châtillon Cedex, France.)
Engineering of two-dimensional material heterostructures offers a broad range of degrees of freedom through the selection of type and number of layers and their relative stacking configurations. In these compound materials, the stacking sequence plays a central role in determining electronic, mechanical, and optical properties. Here, we present a theoretical study of its signature on the excitons of hexagonal boron nitride bilayers based on first-principle calculations within the GW approximation and the Bethe-Salpeter equation. We explain how stacking-dependent symmetry variations lead to distinct electronic structures, particularly near the band edge around the K high-symmetry point, and consequently to markedly different excitonic landscapes. Indeed, we analyze the symmetry-governed character of the low-lying excitonic states, identifying their bright or dark nature for each stacking configuration and performing a systematic comparison. Our results clarify how van der Waals interlayer coupling reshapes excitons in hexagonal boron nitride bilayers and outline prospects for twist-controlled exciton engineering in this material.
Materials Science (cond-mat.mtrl-sci)
15 pages, 11 figures
Interplay of Ni Order and Local Moments in Intercalated NixNbS2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Gaurav Pransu, Naveen Singh Dhami, Wojciech Sas, Yuki Utsumi Boucher, Bruno Gudac, Ana Smontara, Davor Tolj, Victor Balédent, Mario Novak, Neven Barišić, Ivo Batistić, Mirta Herak, Petar Popčević
Magnetic ions intercalated into the van der Waals gaps of layered transition metal dichalcogenides provide a system where local moments interact strongly with a metallic host. How the order of the intercalant sublattice affects their magnetism is important but rarely addressed, although disorder is hard to avoid, in particular in thin films and heterostructures. Here this question is examined in single crystals of Ni$ x$ NbS$ 2$ with $ 0.10 \leq x \leq 0.57$ , whose composition and Ni order were determined by energy-dispersive x-ray spectroscopy and synchrotron x-ray diffraction. Anisotropic magnetic susceptibility measurements reveal three regimes. Long-range antiferromagnetic order appears only for $ 0.25 \leq x \leq 0.33$ , where the Ni ions form the $ 2 \times 2$ and $ \sqrt{3} \times \sqrt{3}$ R$ 30^\circ$ superstructures, and $ T\mathrm{N}$ reaches 96 K at $ x = 1/3$ . In this range the effective moment, $ \approx 2.5 \mu\mathrm{B}$ per Ni, agrees with DFT+$ U$ calculations, in which the Ni spin is partly delocalized onto the surrounding S ligands. For $ x \leq 0.18$ the dilute, randomly distributed Ni ions remain paramagnetic down to 2 K with a reduced moment. For $ x \geq 0.37$ , where Ni-Ni contacts are unavoidable, long-range order gives way to a short-range ordered state below 10-15 K with a further reduced moment. As calculations for ordered Ni arrangements find the Ni state nearly independent of $ x$ , even at $ x = 1/2$ , the reduction of the moment is attributed to a disorder-enabled reduction of the charge transfer from Ni to the NbS$ _2$ layers. The magnetism of Ni$ _x$ NbS$ _2$ is thus governed by the (dis)order of the Ni sublattice rather than by the Ni concentration alone.
Materials Science (cond-mat.mtrl-sci)
21 pages, 7 figures, 2 tables
Driving Atomic Spins through Their Substrate Electrons
New Submission | Superconductivity (cond-mat.supr-con) | 2026-11-09 20:00 EST
Coherent control of single spins on surfaces has relied on decoupling them from the substrate with insulating films, which protects the spin but also removes any electronic means of addressing it. Here we show that a local electric potential can drive an adatom spin through the substrate electrons themselves. An exact reciprocity relation fixes the torque, which equals the change of the local electron density when the moment rotates; the drive map is thus a ground-state property that can be measured independently. The relation also implies sharp selection rules, since point-contact spins, spin-$ 1/2$ and the central transition of half-integer spins remain dark. On a normal metal the hybridization responsible for the drive also destroys coherence, but on a superconductor the drive survives while substrate damping is confined to subgap transitions. For atomically sharp tips we find Rabi frequencies of several MHz at RF amplitudes of tens of mV, with substrate-limited linewidths below $ 0.1$ ~MHz, so that strong hybridization, usually the enemy of spin coherence, becomes an asset.
Superconductivity (cond-mat.supr-con)
High-Volume Wurtzite MnSe in MnSe/CdSe Superlattices: Structure, Magnetism and Optical Response
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Michał J. Grzybowski, Katarzyna Gas, Jaroslaw Z. Domagala, Serhii Kryvyi, Łukasz Gondek, Soumik Das, Jan Suffczyński, Oleksii Liubchenko, Anna Kaleta, Sławomir Kret, Maciej Sawicki, Wojciech Pacuski
Polymorphism in Mn-based chalcogenides offers access to magnetic semiconductors with distinct crystal symmetries, polar structures, and different magnetic orders. In particular, wurtzite MnSe exhibits an appealing interplay of electric polarization and several competing magnetic phases including altermagnetic order. However, stabilizing metastable polymorphs, such as wurtzite MnSe, in experimentally useful volumes remains challenging. Here, we show that a nanoscale-period MnSe/CdSe superlattice stabilizes wurtzite MnSe over micrometer-scale total thickness while suppressing the formation of the thermodynamically favored rock-salt phase. The increased magnetic volume enables bulk-sensitive characterization of this polar polymorph. The room-temperature lattice parameters of wurtzite MnSe are studied by independent experimental techniques and determined to be $ a = (4.18 \pm 0.03),\mathring{A}$ and $ c = (6.78 \pm 0.03), \mathring{A}$ . SQUID magnetometry reveals antiferromagnetic ordering with $ T_N = 62,\text{K}$ , which is accompanied by an anomaly of the MnSe lattice parameter, as oberved by temperature-dependent X-ray diffraction. Optical measurements reveal excitonic transitions pointing to the band gap at around 3.4 eV. These results highlight the utility and importance of heterostructure engineering for detailed studies of metastable phases of magnetic semiconductors, in particular wurtzite MnSe.
Materials Science (cond-mat.mtrl-sci)
Superconducting Fluctuation Driven Quantum Transport in Bi$_2$Sr$_2$CaCu$2$O${8+δ}$ Thin Films
New Submission | Superconductivity (cond-mat.supr-con) | 2026-11-09 20:00 EST
Sohini Guin, Naresh Shyaga, Jagadish Rajendran, Aryaman Das, Subhransu Kumar Negi, Saisab Bhowmik, Pankaj Bhardwaj, Chandni Usha, Dhavala Suri
Superconducting fluctuations (SF), arising from Cooper-pair-driven interactions and electron-electron interactions within the transition regime, can dominate the magnetoconductance (MC) of superconducting thin films near their transition temperature. In some systems, this fluctuation-dominated regime is preceded by a narrow window in which quantum interference effects are manifested as weak antilocalization (WAL) or weak localization (WL). Here, we report magnetotransport measurements on thin films of the high-temperature superconductor Bi$ _2$ Sr$ _2$ CaCu$ _2$ O$ {8+\delta}$ (BSCCO) that establish SF as the dominant mechanism governing MC across the transition regime. In the narrow temperature window well above $ T_c$ where SF does not exist, a cusp in MC can be attributed to WAL-like signature well described by the Hikami–Larkin–Nagaoka (HLN) framework. Closer to the transition ($ T{BKT}$ ), we observe signatures consistent with Berezinskii–Kosterlitz–Thouless (BKT) correlations, underscoring that the dominant physics is set by collective, pairing-driven behavior rather than single-particle quantum interference. Measurements on non-superconducting control samples show no WAL-like features, indicating that the WAL over narrow temperature window, emerges only in conjunction with superconducting fluctuations. Hall measurements further reveal a concomitant sign reversal of the dominant carrier response, pointing to a substantial reorganization of transverse transport coincident with the onset of superconductivity. Together, these observations establish that magnetotransport in BSCCO thin film.
Superconductivity (cond-mat.supr-con)
The Central Inferences and Figures of the paper have changed significantly compared to v1 of arXiv: 2511.00803
Graph representations of dislocation networks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Gaurav Lathiya, Markus Stricker
The mechanical response of a crystal is governed by the evolving network of dislocations it contains, yet quantitatively linking the `state of that network’ to its yield stress remains challenging. Here we represent the dislocation networks obtained from discrete dislocation dynamic simulation as graphs, using five distinct graph representations, characterize each network through a compact set of topological properties, and predict the yield stress from these graph properties and the applied strain rate using a standard random forest model evaluated with strain rate stratified cross-validation. The model predicts the yield stress with $ R^2\approx0.86-0.90$ across all box sizes and $ R^2\approx0.91-0.94$ for larger box sizes, and this accuracy is consistent across all five representations, indicating that the topology-stress relationship is a robust feature of the graph properties rather than an artefact of any single graph representation. We propose graph topology as a compact and robust route for connecting the microstructural state of a dislocation network to its mechanical response in addition to established variables.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
28 pages, 15 figures
Josephson current along the domain walls in Weyl fully compensated ferrimagnet Ti$_2$MnAl
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
V.D. Esin, N.N. Orlova, A.R. Banschikova, Yu.S. Barash, D.N. Borisenko, N.N. Kolesnikov, E.V. Deviatov
We experimentally investigate Josephson current in planar Nb-Ti$ _2$ MnAl-Nb proximity devices, which are formed as junctions between superconducting niobium leads and single crystal flakes of the Weyl fully compensated ferrimagnet Ti$ _2$ MnAl. We demonstrate well developed Josephson effect for 2~$ \mu$ m distance between the niobium contacts on the Ti$ _2$ MnAl surface. The measured critical current dependence on the magnetic field $ I_c(B)$ shows strong anisotropy for two magnetic field orientations in respect to the Nb-Ti$ _2$ MnAl-Nb junction plane. For the parallel magnetic field, one can see standard Fraunhofer-like $ I_c(B)$ suppression pattern. In contrast, $ I_c(B)$ is qualitatively different in normal magnetic field, indicating non-trivial distribution of the Josephson current within the junction plane. From this anisotropy, long-range supercurrent and fast aperiodic fluctuations in $ I_c(B)$ we conclude that Josephson current is transferred by the chiral surface states, which emerge along the domain walls in topological compensated ferrimagnet Ti$ _2$ MnAl. The conclusion on the domain walls is supported by magnetization data for small Ti$ _2$ MnAl flakes.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Inverse design of superconductors and semiconductors with differentiable foundation models
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Cristóbal Méndez, Justin Tahmassebpur, Tomás A. Arias
Designing a crystal for a target property requires choosing its elements, stoichiometry, and atomic structure together, yet gradients exist only for the continuous structural variables. We introduce differentiable Equiformer fast effective-atom theory (DEFEAT), which lets a pretrained EquiformerV3 foundation model accept continuous species weights and site occupancies without retraining on fractional data, thereby enabling gradient-based materials optimization. Gradients from fine-tuned property models and a machine-learned energy penalty then guide updates to composition, atom count, atomic positions, and lattice vectors in a single optimization. In a search for phonon-mediated superconductors, density-functional perturbation theory on 45 structurally novel designs gives isotropic Allen-Dynes critical temperatures above 10 K for 39; the highest is 24.0 K for ZrTiNb2CN3, and H4LiPd3 (23.2 K) lies on the static DFT hull. In searches for photovoltaic absorbers, SCAN calculations confirm ten novel crystal structures with band gaps within 20% of a 1.34 eV target on their respective raw or empirically corrected scales, all within 70 meV/atom of the DFT hull, and show that the systematic gap error of the training functional propagates into the designs unless the objective corrects for it. Quasiharmonic free energies from machine-learned potentials further show that finite-temperature competition with solid phases can reorder candidates relative to the static hull.
Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
Quantum Interference Control of Coupled Atomic Spins
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Sergio Santiago Gomez, Gustavo Mauricio Meneses Ancalle, Daniel Domínguez, María José Sánchez, Alejandro Ferrón
We propose a protocol for the non-resonant electric control of quantum states in atomic-scale spin systems using Landau-Zener-Stückelberg-Majorana (LZSM) interferometry. We focus on a Ti-Ti-Fe trimer on a thin MgO layer, a platform that has recently emerged as a promising candidate for qubit realization using electron spin resonance combined with scanning tunneling microscopy (ESR-STM). We first analyze a Ti dimer in the absence of the Fe atom and show, through a detailed spectroscopic study, that avoided level crossings can be engineered by combining the in-plane component of the external magnetic field, the tip magnetic field, and the applied bias voltage, which allows the system to be tuned electrically through these crossings. Based on this, we develop LZSM protocols for coherent state control in the dimer using non-resonant LZSM-STM. We then consider the full trimer, where the Fe atom generates a local magnetic field at the remote Ti atom, enabling non-local spin control. We show that this remote and non-resonant manipulation reduces unwanted effects associated with tunneling electrons and enables quantum operations on short timescales. Our results show that quantum interference can be used as a resource for electrically driven, non-resonant, and non-local spin control in atomic-scale systems. This approach enables fast quantum operations while mitigating decoherence, offering a promising route toward scalable atom-based qubit architectures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 6 figures, 1 appendix
Scanning Probe Control, Quantum Dynamics, and Dispersive Readout of Suspended Carbon Nanotube Resonators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Suspended carbon nanotubes (CNTs) offer promising opportunities for quantum nanomechanics owing to their small effective mass, strong electrostatic tunability, and mechanical nonlinearity. We develop a unified theoretical framework for coherent control and readout of a suspended CNT driven by an atomic force microscope (AFM) tip and capacitively coupled to a Cooper-pair box (CPB). We first derive the linear and nonlinear Duffing response of the CNT and quantify the effects of AFM force gradients, tip-position fluctuations, and voltage noise on mechanical stability, dephasing, and heating. These results establish operating conditions for coherent actuation with limited backaction. We then quantize the Duffing oscillator, derive its Kerr anharmonicity, and identify the requirements for selective control of individual vibrational transitions. Estimates of thermal occupation and active cooling illustrate the constraints for CNT modes spanning frequencies from 54 MHz to 5.37 GHz. Finally, we derive the CNT–CPB interaction and its dispersive limit, showing how phonon number and parity can be mapped onto the CPB through Ramsey interferometry and detected using quantum-capacitance readout. The resulting framework identifies the conditions under which localized AFM actuation, nonlinear quantum dynamics, and superconducting state-resolved detection can operate within a single CNT device.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph), Quantum Physics (quant-ph)
21 pages, 4 figures
Quantum-walk measurements with sequential imaging of the same atomic sample
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-11-09 20:00 EST
Ryuta Yamamoto, Takeshi Fukuhara
We demonstrate sequential single-atom-resolved imaging of the same ultracold atomic sample and apply this technique to quantum-walk measurements in an optical lattice. In quantum gas microscope experiments, fluorescence imaging provides microscopic information on atomic distributions but induces motional heating through photon scattering, making it difficult to reuse the same sample for subsequent quantum dynamics. To overcome this limitation, we apply Raman sideband cooling with parameters optimized for post-imaging cooling, enabling sequential single-atom-resolved measurements of the same sample. By optimizing the cooling parameters with machine learning, we achieve high fidelity over multiple imaging cycles. To demonstrate the capability of this technique, we measure one-dimensional quantum walks of single atoms in an optical lattice. By determining the initial atomic positions from fluorescence images, we extract quantum-walk transition probabilities without requiring deterministic preparation of the initial atomic positions. The observed dynamics agree with numerical simulations of quantum walks of single atoms. Our method provides a route toward reducing experimental overhead in quantum gas microscope studies requiring repeated acquisition of spatially resolved correlation data.
Quantum Gases (cond-mat.quant-gas)
Local Correlations Determine the Dephasing Threshold of $\mathbb{Z}_2$ Topology
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Rishith Reddy V, Ashutosh Dubey, Partha Sarathi, Ankur Das
In this work, we try to understand the question of how to address the survival of band topology in the presence of dephasing. We investigate this question in the Kane-Mele $ \mathbb{Z}_2$ topological insulator. To determine the stability of the topological invariant we construct a single particle Hamiltonian that also provides identical correlation at the single particle level. The phase transition from topological to trivial is determined by the gap closing of this correlation Hamiltonian. This gap closing is related to purity gap. As a diagnostics we calculated the invariant directly and as a complementary diagnostic, coherent two-terminal transport through the auxiliary correlation Hamiltonian exhibits quantized conductance in the nontrivial region. This does not establish physical conductance under dephasing. Our results identify a predictive local criterion for the survival of single-particle topological structure under a specified noise channel.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
10 pages, 5 figures
Inversion symmetry breaking by interlayer hybridization in a tetralayer van der Waals heterostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Juan C. Arias-Muñoz, Cuiju Yu, Nianze Shang, Christopher P. Edwards, Zixuan Ning, Farzaneh Bouzari, Rodolfo Canet-Albiach, Seyed Hossein Hosseini-Shokouh, Ruihuan Fang, Hanlin Fang, Sanshui Xiao, Jose L. Lado, Zhipei Sun
Inversion symmetry breaking unlocks a broad range of physical phenomena fundamental for modern technologies, motivating efforts to engineer noncentrosymmetric materials. In this context, monolayer transition metal dichalcogenides, which naturally lack inversion symmetry, have emerged as a versatile platform for valley physics, strong excitonic effects, and nonlinear optics. However, in their hexagonal stacking phase, inversion symmetry is restored in even-layer stacks and bulk form, suppressing these effects and limiting applications. In this work, inversion symmetry breaking is demonstrated in a vertically stacked tetralayer heterostructure assembled from two intrinsically centrosymmetric bilayer flakes, as evidenced by second harmonic generation measurements with an intensity comparable to that of their constituent monolayer. Spectroscopic measurements and theoretical estimations indicate that effective symmetry breaking in the tetralayer heterostructure is driven by interlayer hybridization, giving rise to pronounced electronic and phononic signatures. This symmetry breaking further induces polar anisotropy, with an intensity ratio reaching 2.36. We propose that asymmetric contributions from excitons to the second harmonic optical dipole may influence this behavior. These findings establish interlayer coupling as a critical mechanism for introducing inversion symmetry breaking and tuning the optical response of van der Waals heterostructures, providing a powerful strategy for photonics and optoelectronics in two-dimensional materials.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Optics (physics.optics)
19 pages, 5 figures
Experimental Evaluation of High-Throughput Structure Predictions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
Gabriele D. Di Gianluca, James Grossmann, Jackson Niedel, Juan Esquivel, Molly Crossman, Tyler Miniati, Melchior Jean, Zhongwei Li, Pawan Prakash, Andrew Valentini, Jung Soo Kim, Benjamin Geisler, Richard G. Hennig, Peter J. Hirschfeld, Gregory R. Stewart, James J. Hamlin
High throughput computational databases such as Materials Project, the Open Quantum Materials Database, and Alexandria now each list on the order of 10^5 predicted stable compounds. However, the overall reliability of these predictions in terms of actual experimental synthesizability remains poorly understood. In this work we attempt to synthesize, via arc melting, 34 different predicted ternary compounds. The majority of these materials did not form in the predicted structure, instead resulting in disordered variants or multiphase mixtures. Four formed ordered structures not reported before, one of them at a composition reported earlier without a structure. We discuss both the failures and the successes, and identify simple filtering criteria that can help researchers avoid hypothetical materials that are unlikely to form.
Materials Science (cond-mat.mtrl-sci)
12 pages, 2 figures, 1 table
Influenza A Virus as a Multivalent Active Particle: Statistical Mechanics of Binding, Motility, and Antiviral Design
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-11-09 20:00 EST
Sumati Bhatia, Andreas Herrmann, Thomas Kolbe, Lalan Kumar, Daniel Lauster, Susanne Liese, Bortolo Matteo Mognetti
In this contribution, we review existing multivalent models of Influenza A Virus (IAV) systems to study virion dynamics and design of multivalent entry blockers. We review existing biochemical estimations of the dissociation constants and catalytic activities of the two virion ligands [hemagglutinin (HA) and neuraminidase (NA)], which can be used to develop quantitative theories and experiments. Multivalent models are statistical mechanics frameworks for studying the simultaneous interaction of multiple reversible ligand-receptor bonds. They quantify the effects of both combinatorial entropy terms and single-molecule ligand-receptor affinities. Multivalent frameworks led to the rationale of superselectivity, the ability of probes to sense specific concentrations of conjugated receptors. Multivalent models guided the design of antiviral nanomedicines constituted by polymeric scaffolds conjugated with small molecules such as sialic acid receptors targeting the ligands on the surface of the virion. Importantly, neuraminidase is an enzyme that limits the number of host-guest bonds through receptor desialylation. Like active particles, neuraminidase activity enhances virion motility in the extracellular medium. Modeling the dynamics of Influenza A virions requires developing out-of-equilibrium multivalent models.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Review article. Authors listed in alphabetical order
Theory of Optical and Magneto-Optical Properties of [111]-Oriented Site-Controlled Quantum Dots
New Submission | Materials Science (cond-mat.mtrl-sci) | 2026-11-09 20:00 EST
N. D. O’Connor, G. Juska, E. Pelucchi, S. Schulz
Site-controlled [111]-oriented quantum dots (QDs) are promising sources of non-classical light, yet their optical spectra exhibit apparently conflicting symmetry signatures. At zero magnetic field, excitonic spectra are commonly interpreted as $ C_{2v}$ -like, whereas measurements in Faraday geometry display selection rules characteristic of $ C_{3v}$ -like symmetry. Here, we show that both regimes can be described consistently without invoking any change in the underlying structural symmetry. Combining 8-band $ \mathbf{k}\cdot\mathbf{p}$ theory, a self-consistent Hartree-informed configuration interaction scheme, and group theoretical analysis, we introduce a controlled symmetry reducing perturbation that lowers the QD symmetry to $ C_s$ . At zero field, the optical response remains predominantly $ C_{2v}$ -like because the additional low-symmetry transitions carry only weak oscillator strengths. In Faraday geometry, the same reduced-symmetry structure produces four dominant, nearly circularly polarised trion transitions, reproducing the experimentally observed $ C_{3v}$ -like response. By contrast, an exact $ C_{2v}$ description inferred from the zero-field spectrum permits only two such trion transitions and therefore fails at finite field. Our results thus provide a unified description of the zero and finite magnetic field optical response without any restoration or enhancement of the underlying structural symmetry. More generally, we demonstrate that a higher-symmetry-like optical spectrum does not uniquely identify the exact symmetry of a QD, therefore also providing useful guidance for other QD and nanostructure systems that lie beyond the ones studied here.
Materials Science (cond-mat.mtrl-sci)
15 pages, 8 figures, 13 pages supplemental information
Cavity-enhanced second harmonic generation from Rydberg excitons in Cu$_2$O
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Horatio Q. X Wong, Krzysztof Sawicki, Madeleine Fisher, Stephen A. Lynch, Wolfgang Langbein, Sai Kiran Rajendran, Hamid Ohadi, Matthew P. A. Jones, Liam A. P. Gallagher
Rydberg excitons in Cu$ _2$ O provide a solid-state setting for creating giant optical nonlinearities. Here, we use second-harmonic generation (SHG) to study Rydberg excitons in a doubly resonant optical microcavity designed to enhance both the pump and second-harmonic fields. We observe even-parity exciton states in an optical cavity and extend cavity-based measurements of Rydberg excitons up to $ n=10$ . The SHG intensity depends strongly on pump cavity detuning, showing the dominant role of the microcavity is the enhancement of the intra-cavity pump field. Analysis reveals an additional enhancement from the resonant second-harmonic cavity giving an overall SHG enhancement factor of $ 21 \pm 2$ inside the microcavity. These results establish cavity-enhanced SHG spectroscopy as a valuable tool for studying Rydberg excitons in microcavities and provide a pathway towards exploiting optical nonlinearities in Rydberg exciton polariton systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
8 pages, 3 figures
Exciton design via topological spin textures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Karim Rezouali, Selcuk Sözeri, Samir Lounis
Excitons carry energy and information through a semiconductor without carrying charge. This makes them attractive for optoelectronics, but also hard to guide. Magnetic skyrmions, on the other hand, are moved by small electrical currents. Here we develop a theory of excitons interacting with a skyrmion in which the electron and the hole are treated as distinct constituents, each with its own spin–orbit coupling. We find that the topology of the skyrmion is transferred to the exciton only when the exchange coupling exceeds the relevant spin–orbit splitting. The exciton then experiences a full flux quantum, with opposite signs in the two valleys. The quantum metric of the spin texture creates a ring-shaped barrier that traps excitons, whereas the topological charge fixes the angular momentum of the trapped states and hence their optical selection rules. Because the trap moves with the skyrmion, excitons can be transported by current pulses, and small skyrmions accommodate a single exciton, which opens the door for potential hybrid applications in future information technology intertwining topological magnetic bits with optical excitations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Reversible Interchain Associations Dominate Plateau Elasticity in Conjugated Polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2026-11-09 20:00 EST
Juncheng Zheng, Xiaobing Zuo, Xiaodan Gu, Shiwang Cheng
The modulus plateau is widely regarded as a hallmark of topological entanglement in homopolymer melts and has been used to identify entanglement in semiflexible conjugated polymers. Using regiorandom poly(3-alkylthiophenes) as a model system, we show that their plateau elasticity relaxes through an Arrhenius process decoupled from segmental and terminal dynamics, reorganizes persistently under mechanical perturbation, and varies systematically with side-chain length. These behaviors are hard to reconcile with a purely topological-entanglement picture and instead support a transient network dominated by reversible interchain associations, consistent with {\pi}-{\pi} interactions between conjugated backbone segments. The results thus demonstrate that plateau elasticity alone does not uniquely identify topological entanglement in conjugated polymers. More broadly, they identify the strength and lifetime of interchain association as molecular design parameters linking backbone packing to stress relaxation, viscoelastic properties, and processability in conjugated polymers, complementing their established role in electronic structure and charge transport.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
32 Pages, 5 Figures
Microscopic theory of exciton polarons in transition metal dichalcogenides
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Carlos Maciel-Escudero, Giuseppe Meneghini, Jamie M. Fitzgerald, Ermin Malic
Polarons are composite quasiparticles formed when charge carriers strongly couple to lattice vibrations, manifesting as carriers dressed by a surrounding cloud of phonons. Although this dressing fundamentally renormalizes the effective mass and mobility of carriers, its impact on electrically neutral exciton polarons in 2D semiconductors has received limited attention. In particular, despite the growing interest in polaronic effects in atomically thin semiconductors, only a few theoretical studies have addressed spectral signatures and renormalized properties of exciton polarons in these materials. Here, we develop a microscopic model to describe exciton polarons in transition metal dichalcogenides. Applying this model to $ 1s$ acoustic polarons in an MoSe$ _2$ monolayer, we reveal a distinct kink in the polaron dispersion, accompanied by a pronounced broadening of its spectral function. These spectral signatures mark a critical transition from a regime of well-defined bound exciton polarons, characterized by a renormalized energy, reduced group velocity, and enhanced effective mass, to a regime dominated by exciton-phonon scattering. Furthermore, by incorporating intervalley exciton-phonon interaction, we demonstrate that the energetic position of momentum-dark excitons strongly modifies the exciton-polaron lifetime. Overall, our work provides a microscopic framework for determining renormalized properties of exciton polarons and establishes experimentally accessible polaron signatures in 2D semiconductors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Raman anyon-Hubbard model in a 1D Bose lattice gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2026-11-09 20:00 EST
Josep Cabedo, Claudio Iacovelli, Leticia Tarruell, Alessio Celi
The anyon-Hubbard model is the paradigmatic lattice model of one-dimensional (1D) anyons, in which chiral interactions make bosons equivalent to particles with fractional statistics. Its continuum limit, the chiral BF theory, emerges as the low-energy description of a Raman-coupled Bose gas with imbalanced interactions. Here, we show that loading such a gas into a 1D optical lattice realizes the lattice counterpart of this theory, which we name the Raman anyon-Hubbard model. The Raman-dressed bosons acquire density-dependent Peierls phases when tunneling through occupied sites. For a small statistical phase, the model reduces to the anyon-Hubbard model, while beyond this limit it defines a distinct lattice anyon model with unbounded rather than periodic statistical interactions. Numerically, we show that the dressed gas displays the defining properties of 1D anyons, namely a density-dependent asymmetry of the ground-state momentum distribution, interaction-induced asymmetric transport and chiral bound states. Remarkably, these features are readily accessible with Raman-coupled $ ^{39}$ K atoms, opening up the experimental exploration of 1D anyons beyond the few-particle regime.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
10 pages + appendix, 5 figures, 1 table
Energy- and momentum-resolved Cooper-pair emission from a cuprate superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2026-11-09 20:00 EST
Henry Amir, Jack Zwettler, Ka Ho Wong, Genda Gu, Rafael M. Fernandes, Jorge Noronha, Dirk K. Morr, Fahad Mahmood
Superconductivity arises from Cooper pairing, but conventional photoemission probes electrons individually rather than as pairs. Here we report the observation of Cooper-pair emission from an optimally doped cuprate superconductor using two-electron angle-resolved photoemission (2e-ARPES). Below the superconducting transition, we observe a distinct two-electron emission peak at zero pair binding energy and zero pair momentum that disappears in the normal state, revealing the characteristic fingerprint of a Cooper pair. Unexpectedly, the joint energy distribution broadens markedly along the relative-energy axis as temperature decreases, while the total energy width remains nearly unchanged. This anomalous behavior cannot be explained by instrumental resolution, static disorder or thermal broadening, and instead points to scattering processes involving collective excitations of the superconductor. Our results establish 2e-ARPES as a probe of both Cooper-pair emission and the many-body dynamics of the superconducting state.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Trajectory-Dependent Decoherence and Leakage During Shuttling of Multi-Spin Qubits
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2026-11-09 20:00 EST
Yu-Ning Zhang, Aleksandr S. Mokeev, Maximilian Rimbach-Russ, David P. DiVincenzo, Viatcheslav V. Dobrovitski
Logical qubits encoded in collective states of multiple spins are promising building blocks for large-scale semiconductor quantum processors. As novel fault-tolerant architectures increasingly rely on qubit shuttling, understanding decoherence of the shuttled multi-spin qubits becomes crucial. We analyze fidelity and leakage of the logical qubits dephased by the spatio-temporally correlated $ 1/f$ noise, considering two-, three-, and four-spin encodings. We study different shuttling protocols and establish that for all encodings generally, parallel shuttling provides the best protection against decoherence at short distances, whereas sequential shuttling outperforms others for long-range transport (although the exact boundaries depend on the specific device parameters). We explain this common behavior in terms of the dephasing factors of pairs of the shuttled spins; we provide explicit expressions for fidelities and leakage, thus enabling experimentalists to predict performance of the multi-spin qubits from only several independently measured pairwise dephasing factors. Our results establish a connection between shuttling trajectories, noise correlations, and qubit decoherence, and provide guidance for achieving noise-resilient shuttling in scalable semiconductor quantum processors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
22 pages, 12 figures (including Appendices A–E and the references)
Unraveling square and kagome lattice frustrated magnetism by scalable tensor networks
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2026-11-09 20:00 EST
Xing-Yu Zhang, Jutho Haegeman, Yuchi He
We extend the scalability of variational infinite two-dimensional tensor network methods with application to investigate frustrated magnetism of the square-lattice $ J_1$ -$ J_2$ model and kagome-lattice Heisenberg model. In the sign-problem-free limit of the square-lattice model, we achieve high ground-state energy precision comparable to quantum Monte Carlo methods. With no obstruction beyond this limit, our method obtains direct estimates of order parameters. For the square-lattice $ J_1$ -$ J_2$ model, we determine isotropic plaquette order in the valence-bond solid region. For the model near $ J_2/J_1=0.5$ , and the kagome lattice Heisenberg model, our data indicate linear-dispersion gapless states. To probe the candidate spin-liquid nature of the highly frustrated cases, we go beyond inferring the absence of symmetry-breaking orders and analyze susceptibilities that characterize gapless spin liquids. By estimating scaling dimensions, our data indicate a stable gapless spin liquid on the kagome lattice, and competing scenarios for the intermediate regime of the square-lattice model. Our developments include parallelization and randomized low-rank methods and largely expand the frontier of high-precision variational numerics for quantum phases of matter.
Strongly Correlated Electrons (cond-mat.str-el)
5+3+12 pages
Research Square
THz Calorimetry of Electrolyte Solutions Links Water’s H-Bond Network to Macroscopic Properties
Article | Chemical physics | 2026-11-08 19:00 EST
Gerhard Schwaab, Chun Ma, Simone Pezzotti, Martina Havenith
Understanding the macroscopic properties of aqueous electrolyte solutions over their full solubility range requires a detailed microscopic picture of water-ion interactions. We combine THz calorimetry and dimensionality-reduction tech- niques to demonstrate that two to four spectroscopic markers are sufficient to describe ion-specific variations in mixing entropies and enthalpies, viscos- ity, and limiting conductivity across 19 electrolytes. Those markers allow us to classify electrolytes as ‘strong’ or ‘weak’ and report on changes in the water’s H-bond network. As concentration increases, spectroscopic nonlinearities due to ion aggregation appear that, based on a multipole expansion model for activi- ties, are correlated with density changes. For CsI and LiCl, as prototypes of weak and strong electrolytes, respectively, the multipole expansion model accurately describes their conductivities, viscosities, and surface tensions. THz spectroscopy in combination with an activity coefficient model directly correlates macroscopic solution properties with changes in the H-bond network, paving the way towards efficient machine-learning approaches.
Research Square:rs-11463600 (2026)
Posted on Research Square and Under Review at Nature Portfolio
Physical sciences/Chemistry/Physical chemistry/Chemical physics, Physical sciences/Chemistry/Physical chemistry/Thermodynamics, Physical sciences/Chemistry/Chemical engineering, Physical sciences/Physics/Statistical physics, thermodynamics and nonlinear dynamics/Thermodynamics, Physical sciences/Physics/Techniques and instrumentation/Characterization and analytical techniques
Unlocking electron transfer across carbon overlayers via single-atom engineered built-in electric field for industrial water purification
Article | Pollution remediation | 2026-11-08 19:00 EST
Yafei Zhao, Tianran Sheng, Xing-En Lin, Gang Zhao, Ruoyan Wei, Xiangyu Shu, Cheng Qian, Zhen Zhang, Liangquan Sheng, Yude Su
Precisely regulating active-sites structures and charge transfer kinetics is crucial for developing high-performance catalysts, yet achieving their synergy remains challenging. Herein, we anchor atomically dispersed cobalt electronic coupling nodes into ultrathin N-doped carbon overlayers (4-5 atomic layers thick) with metallic nanoparticles inside (M@Co1, M = Co2P, Co, Ni or Cu). As revealed by characterization and theoretical calculations, the isolated Co sites mediate interlayer electron transfer between the confined nanoparticles and outermost catalytic interfaces. The extended d-orbital states of single-cobalt atoms establish a built-in electric field and enable work-function matching in hybrid nanostructures. Efficient electron mobility facilitates product desorption and decreases the charge-transfer resistance toward reactants to 19.8% of that in the Co₁-deficient counterpart. Accordingly, Co2P@Co1 exhibits excellent industrial water purification ability via peroxymonosulfate activation, achieving ≥99% phenol removal in 90 s at a low catalyst dosage. It also shows environmental tolerance in real matrices, such as residual organic solvents and inorganic ions.
Research Square:rs-11520806 (2026)
Posted on Research Square and Under Review at Nature Portfolio
Earth and environmental sciences/Environmental sciences/Environmental chemistry/Pollution remediation, Physical sciences/Materials science/Nanoscale materials/Nanoparticles
Precoordination-directed synthesis of high-entropy perovskite colloidal nanocrystals
Article | Synthesis and processing | 2026-11-08 19:00 EST
Yu Hou, Wenbo Tan, Xinyi Liu, Guocan Chen, Xing Wang, Yu Peng, Da Liu, Kuan Xue, Jialu Yu, Yilin Xu, Haiyang Yuan, Shuang Yang, Huagui Yang
Perovskite nanocrystals (PNCs) are solution-processable quantum materials with defect tolerance, tunable electronic structures and strong light-matter interactions, enabling applications in optoelectronics and photocatalysis. Integrating high-entropy configurations into PNCs unlocks a vast chemical space for multicomponent synergy and functional expansion beyond conventional stoichiometry. However, their synthesis has been fundamentally constrained by mismatched multi-precursor kinetics and a trade-off between entropic stabilization and enthalpic phase segregation. Here we report a precoordination-directed strategy for the colloidal synthesis of high-entropy vacancy-ordered double perovskite nanocrystals with high phase purity, near-equimolar stoichiometry and elemental homogeneity. We show that the participation of excess chloride energetically encourages the formation of well-defined metal-halide octahedral units in the precursor, thereby promoting the topological conversion to a high-entropy double-perovskite phase after hot-injection. The elemental synergy of high-entropy PNCs renders them versatile catalysts, delivering ~ 14-fold improvement in photocatalytic coupling of benzyl alcohol to hydrobenzoin, ~ 17-fold in oxidative coupling of methane to ethane, and ~ 35-fold in oxidation of toluene to benzaldehyde, relative to their low-entropy analogues.
Research Square:rs-11348610 (2026)
Posted on Research Square and Under Review at Nature Portfolio
Physical sciences/Materials science/Nanoscale materials/Synthesis and processing, Physical sciences/Materials science/Materials for energy and catalysis/Photocatalysis
Structural and Thermodynamic Decoupling in 5 nm Transverse Orbitronic MRAM for Century-Scale Enterprise Non-Volatile Caches
Article | Electronic and spintronic devices | 2026-11-08 19:00 EST
Malik Adam
Ultra-scaled spin-transfer torque (STT) and conventional spin-orbit torque (SOT) magnetoresistive random-access memory (MRAM) cells face an existential physics bottleneck at 5 nm node: the severe coupling of read and write paths within Two-Terminal layouts. Operating at sub-nanosecond precessional limits forces massive transient current spikes through thin oxide layers, driving catastrophic dielectric breakdown and severe thermal burnout. Here, we present a complete engineering framework for an ultra-scaled 5 nm decoupled Three-Terminal transverse orbitronic MRAM architecture that resolves these scaling trade-offs. By routing the write current horizontally through a monolayer polar 2D Cu2WSe4 (Wtrack = 6 nm, Ltrack = 12 nm), the vertical oxide barrier is structurally isolated from write stress, dropping the operational junction voltage drop to exactly Vops = 0.0 V. Combined with an integrated synthetic antiferromagnet (SAF) storage assembly and an adaptive +12% electrical current boost, this transverse design completely neutralizes adjacent magnetostatic and thermal cross-talk. Numerical modeling via stochastic Heun integration demonstrates a ballistic stable switching threshold at a target pulse width 74.5 ps, an operational temperature envelope extended up to 412.5 K (139.35°C), and a reduction in error correction code (ECC) requirements to ≲ 2 bits/block at the 85°C industrial limit. This multi-axial co-optimization expands the manufacturing tolerance window and establishes a concrete roadmap for a zero-degradation 100-year century enterprise non-volatile cache lifetime.
Research Square:rs-11640133 (2026)
Posted on Research Square
Physical sciences/Physics/Electronics, photonics and device physics/Electronic and spintronic devices, Physical sciences/Engineering/Electrical and electronic engineering