Materials Science
A finite-element Delta-Sternheimer approach for computing accurate all-electron RPA correlation energies of polyatomic molecules
Hao Peng, Haochen Liu, Chuhao Li et al. (+2 more)
Attaining a reliable complete basis set (CBS) limit remains a significant challenge in ab initio correlated electronic-structure calculations. Building on our previous work for atoms and diatomic molecules, we present a finite-element (FE) Delta Sternheimer approach for numerically accurate random phase approximation (RPA) calculations applicable to general molecules. This approach seamlessly integrates atomic orbital basis sets with FE grids, enabling an arbitrary precision representation of first order wavefunctions. As a result, the density response function and RPA correlation energies can be computed with fully controlled numerical precision. The Delta Sternheimer approach thus provides direct access to RPA correlation energies at the CBS limit, eliminating reliance on conventional extrapolation schemes. We apply this approach to two problems: The energy hierarchy of 20 water-dimer configurations and the atomization energies of 50 molecules from the G2 set. For the water dimer, we examine the basis set dependence of the isomer energy ordering. For the G2 set, we investigate the residual numerical uncertainty in the conventional extrapolated CBS limit, both with and without correction for basis-set superposition error (BSSE).
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All authors Hao Peng, Haochen Liu, Chuhao Li, Hehu Xie, Xinguo Ren
Soft Condensed Matter
Fluctuation-Response Theory of Non-Equilibrium Complex Fluids
Ryota Takaki and Frank Jülicher
A fundamental challenge in soft matter physics is to describe materials, such as the living cytoplasm and tissues, that are simultaneously active, chemically driven, and exhibit long-lasting
memory of mechanical stresses. Here, we construct a generalized hydrodynamic framework at finite wavevectors and frequencies that is applicable to non-
equilibrium fluids with
memory. By leveraging stationary correlation identities, we derive a generalized linear response theory for non-
equilibrium steady states. This framework serves as a formal extension of Onsager's regression hypothesis beyond thermal
equilibrium. Our approach provides a direct pathway to derive transport coefficients from steady-state fluctuations without the traditional Mori-Zwanzig projection-operator formalism, generalizing the Green-Kubo relations to non-
equilibrium systems. As a corollary, we derive two model-free variants of the non-
equilibrium fluctuation-response relation for non-Markovian dynamics. These generalized relations explicitly capture the non-
equilibrium circulating currents–an out-of-
equilibrium signature that is invisible to conventional scalar formulations or frameworks that treat degrees of freedom independently. Applying our theory to chemically driven active fluids reveals the emergence of active viscoelastic
memory, wherein chemical reaction cycles dynamically renormalize the macroscopic viscous response. Strikingly, this active
memory can induce negative storage and loss
moduli at finite frequencies, a behavior absent in ordinary viscoelastic fluids. Our first-principles framework rigorously extends linear rheology to non-
equilibrium systems and provides a foundation for understanding non-Markovian dynamics across a broad range of biological and synthetic active matter.
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Superconductivity
Microwave surface resistance of Tl-1223 films in a dc magnetic field
Alessandro Magalotti, Andrea Alimenti, Emilio Bellingeri et al. (+8 more)
We present first preliminary surface impedance measurements on Tl-1223 films in dc
magnetic fields, in view of potential applications for the next generation Future Circular
Collider (FCC-hh) at CERN. The Tl-1223 samples were produced through
laser ablation, with nominal thickness of 1 {\mu}m and grown on a thick LaAl2O3 substrate. The presence of Tl-1212 phase identified by XRD and BSE microscopy, could be avoided by changing the oxygen partial pressure during heat treatment. The high-frequency transport properties of the samples were characterized using microwave resonant devices, at fixed frequencies of 14.9 GHz, 24.2 GHz and 26.7 GHz, in the temperature range 40 K to 140 K. An external applied static
magnetic field up to 12 T was applied. Samples from subsequent batches exhibited huge improvements in the microwave properties, confirming the progress in the deposition technique.
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All authors Alessandro Magalotti, Andrea Alimenti, Emilio Bellingeri, Cristina Bernini, Sergio Calatroni, Alessandro Leveratto, Enrico Silva, Kostiantyn Torokhtii, Ruggero Vaglio, Pablo Vidal García, Nicola Pompeo
Superconductivity
Growth and microwave properties of FeSe thin films and comparison with Fe(Se,Te)
Alessandro Magalotti, Andrea Alimenti, Valeria Braccini et al. (+10 more)
In this work, we have grown $\sim$100 nm thick pristine FeSe films by pulsed
laser deposition. The films were structurally characterized with X-ray diffraction and their surface morphology checked through atomic force microscopy. Microwave measurements, performed with a dielectric loaded resonator tuned at the frequency of 8 GHz, allowed the characterization of the samples surface resistance, in view of potential applications in microwave haloscopes for dark matter search. Here, we report the comparison of the microwave properties of FeSe with Fe(Se,Te) thin films, as the temperature is swept from 4 K to 20 K. By applying a constant static
magnetic field of 12 T, it was also possible to discern the
magnetic field resilience of the two samples. FeSe showed a larger critical temperature drift as the field is applied, while the Fe(Se,Te) response broadens remarkably less. A preliminary analysis of
vortex pinning shows margins for optimizing pinning in FeSe.
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All authors Alessandro Magalotti, Andrea Alimenti, Valeria Braccini, Giuseppe Celentano, Matteo Cialone, Antonella Mancini, Andrea Masi, Nicola Pompeo, Enrico Silva, Giovanni Sotgiu, Kostiantyn Torokhtii, Pablo Vidal García, Angelo Vannozzi
Mesoscale and Nanoscale Physics
Emergent Topology in Kagome Ferromagnets
Seif Alwan and Jonas Fransson
We investigate the emergence of a topological
magnon phase in a two-dimensional kagome ferromagnet with Dzyaloshinskii-Moriya interaction (DMI) and scalar
spin chirality. By incorporating a
chiral interaction term proportional to the scalar triple product chi_ijk = S_i (S_j x S_k), we examine how the interplay between DMI and the topological orbital coupling kappa_TO gives rise to
geometric phase, nontrivial Berry
curvature, and quantized Chern numbers in the
magnon bands. Using a momentum-space representation and linear
spin-wave theory, we compute the orbital texture, its vorticity, and the Berry
curvature across the Brillouin zone. We show that noncoplanar
spin textures, driven by finite DMI, form momentum-space skyrmions that act as sources of
geometric curvature. Importantly, we demonstrate that DMI alone is insufficient to break time-reversal
symmetry; only the presence of finite scalar chirality terms allows the system to develop a nonzero Berry phase and topological transport signatures. We further explore the effect of a global plaquette rotation, showing that while the band structure remains invariant under this
unitary transformation, the Berry
curvature and Chern number are modulated, highlighting the
geometric sensitivity of the topological response. Our results establish a direct correspondence between the
lattice geometry, chirality, and
magnon topology, providing a route toward tunable topological phases in frustrated
magnetic systems.
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Materials Science
Facet Specific Electron Conduction in Pentavalent (W5+) WO3 Drives Superior Photocatalytic CO 2 Reduction in (002) Plane
Muhammad Rizwan Kamal, Mohammad Z. Rahman, Amil Aligayev et al. (+17 more)
This article reports a concept of heat-induced topological modifications of non-layered WO 3 followed by successful synthesis of oxygen-vacant more-porous nanosheets with exposed active (002) facet. Experimental measurements and Density Functional Theory (DFT) calculations have revealed that the photoexcited electrons are found to accumulate preferentially on (002) facet to yield enhanced electron conduction, and consequently, strengthen the reduction potential as active catalytic sites for photocatalytic CO2 reduction. Owing to these beneficial properties, the more-porous nanosheets of WO 3 with (002) facet have exhibited superior performance than that of less-porous nanosheets of WO3 with (220) facet and bulk WO3 with (205) facet. This study therefore provides a new understanding of regulating physical, optical, and electronic properties through intricate atomic structure modulation of WO3, and may find widespread application in optoelectronics, sensors, and energy conversion.
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All authors Muhammad Rizwan Kamal, Mohammad Z. Rahman, Amil Aligayev, Min Liu, Li Zhong, Pengfei Xia, Yueheng Li, Yue Ruan, Xia Xiang, Pir Muhammad Ismail, Qaisar Alam, Ahmed Ismail, Muhammad Zahid, Xiaoqiang Wu, Abdullah N. Alodhayb, Qing Huang, Raj Wali Khan, Fazal Raziq, Sharafat Ali, Liang Qiao
Superconductivity
Diode effect in Shapiro steps in an asymmetric SQUID with a superconducting nanobridge
Dmitrii S. Kalashnikov, Gleb S. Seleznev, Andrei Kudriashov et al. (+4 more)
We investigate the Josephson diode effect in an asymmetric SQUID consisting of a sinusoidal Josephson junction formed by a Bi$_2$Te$_2$Se flake and a superconducting Nb nanobridge with a linear and multivalued current-phase relation (CPR). Current-voltage characteristics were measured both in the absence (dc regime) and presence (ac regime) of external microwave irradiation. Our dc measurements reveal only weak critical current asymmetry (i.e. weak Josephson diode effect), while confirming the multivalued behavior of the SQUID. At the same time, the key finding of this work is the observation of strong Shapiro step asymmetry (concerning the dc current direction) in the ac regime at finite
magnetic flux. This peculiarity oscillates as a function of
magnetic field with the SQUID's periodicity and varies non-monotonically with the increase in microwave power. Our theoretical model shows that the pronounced Shapiro step asymmetry, despite the small diode effect in critical current, arises from the interplay between the sinusoidal and multivalued CPRs of the junctions.
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All authors Dmitrii S. Kalashnikov, Gleb S. Seleznev, Andrei Kudriashov, Ian Babich, Denis Yu. Vodolazov, Yakov V. Fominov, Vasily S. Stolyarov
Mesoscale and Nanoscale Physics
Topological Magnetic Phases and Magnon-Phonon Hybridization in the Presence of Strong Dzyaloshinskii-Moriya Interaction
Weicen Dong, Haoxin Wang, Matteo Baggioli et al. (+1 more)
In recent years, the interplay between
quantum magnetism and
topology has attracted growing interest, both for its fundamental importance and its technological potential. Topological
magnons, quantized
spin excitations with nontrivial band
topology, hold particular promise for spintronics, offering routes to robust, low-dissipation devices for next-generation information processing and storage. While topological
magnons in honeycomb ferromagnets with weak next-nearest-neighbor Dzyaloshinskii-Moriya interactions (DMI) have been extensively investigated, the strong-DMI regime remains largely unexplored. In this work, we examine topological
magnetic phases and
magnon-
phonon hybridization in a two-dimensional
magnetic system with strong DMI. We show that strong DMI drives a transition from a
ferromagnetic ground state to a 120$^\circ$ noncollinear order. An additional Zeeman field further induces noncoplanar
spin textures, giving rise to a diverse set of topological phases. We demonstrate that these topological phases can be directly probed through the anomalous thermal
Hall effect. Finally, we find that the
spin-
spin interactions in the strong-$D$ phase enable
magnon-
phonon coupling that yields hybridized topological bands, whereas such coupling vanishes in the weak-$D$ phase.
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All authors Weicen Dong, Haoxin Wang, Matteo Baggioli, Yi Liu
Materials Science
CoNi-MOF laccase-like nanozymes prepared by dielectric barrier discharge plasma for treatment of antibiotic pollution
Chao Liu, Yi Cao, Qi Xia et al. (+2 more)
Laccase is a natural green catalyst and utilized in pollution treatment. Nevertheless, its practical application is constrained by limitations including high cost, poor stability, and difficulties in recovery. Herein, with inspiration from catalytic mechanism of natural laccase, we designed and prepared a bimetallic metal-organic framework, namely, CoNi-MOF, using low-temperature
plasma (LTP) technology. We employed dielectric barrier discharge (DBD)
plasma to prepare CoNi-MOF, and by precisely modulating the N2/O2 gas ratio, we could modulate the distribution concentration of oxygen vacancies in CoNi-MOF. Experimental investigations and density functional theory (DFT) calculations elucidated that the critical role of the oxygen vacancies in enhancing the laccase-like activity, which promoted the activation of molecular oxygen (O2) for generation of reactive oxygen species (ROS). Compared to natural laccase, CoNi-MOF exhibited superior catalytic performance in the degradation of antibiotic tetracycline (TC), along with enhanced resistance to harsh environmental conditions, improved stability, and low biotoxicity. Notably, aeration increased the dissolved oxygen (DO) content, further improving the TC degradation efficiency. As such, this study not only proposes a facile and efficient low-temperature
plasma technology for synthesizing high-performance laccase-like nanozymes but also provides a promising and environmentally friendly strategy for the remediation of antibiotic contamination in the environment.
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All authors Chao Liu, Yi Cao, Qi Xia, Amil Aligayev, Qing Huang
Materials Science
Synergistic modulation of band structure and phonon transport for higher thermoelectric performance of WSe2
Mazhar Hussain Danish, Amil Aligayev, Zahir Muhammad et al. (+8 more)
Tungsten diselenide (WSe2) emerges as a promising thermoelectric (TE) candidate due to its high thermopower (S), cost-effectiveness, and environmentally friendly characteristics. However, pristine WSe2 exhibits limited electrical conductivity (sigma), a low power factor (PF), and high
lattice thermal conductivity (k_L), which restrict its overall TE performance. Here, we show that through co-doping of Nb for W and Te for Se in WSe2, its power factor increases 17-fold, reaching 8.91 microW cm^-1 K^-2 at 850 K. Simultaneously, its
lattice thermal conductivity (k_L) decreases from 1.70 W m^-1 K^-1 to 0.48 W m^-1 K^-1. Experiments and density functional theory (DFT) analysis demonstrate that the enhancement of PF is linked to an increased density of states, higher effective mass (md*), improved mobility (mu), and elevated electrical conductivity (sigma) owing to the replacement of Se2- with Te2-; while the observed 72% reduction in k_L results primarily from
phonon scattering at Te-Se and Nb-W defects. As a result, a remarkable ZT_max ~ 1 is obtained at 850 K for the sample W0.95Nb0.05Se2-yTey with y = 0.3, which is about a 30-fold increase compared to WSe2, proving that Nb and Te co-doping in WSe2 can significantly boost its TE performance.
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All authors Mazhar Hussain Danish, Amil Aligayev, Zahir Muhammad, Tao Chen, Adil Mansoor, Zia Ur Rahman, F. J. Dominguez-Gutierrez, Di Li, Jian Zhang, Zhuang Hao Zheng, Xiaoying Qin
Mesoscale and Nanoscale Physics
Gate-tunable Josephson diodes in magic-angle twisted bilayer graphene
A. Rothstein, R. J. Dolleman, L. Klebl et al. (+8 more)
We report low-temperature measurements of two adjacent, gate-defined Josephson junctions (JJs) in magic-angle twisted
bilayer graphene (MATBG) at a moiré filling factor near $\nu = -2$. We show that both junctions exhibit a prominent, gate-tunable Josephson diode effect, which we explain by a combination of large kinetic inductance and non-uniform supercurrent distribution. Despite their proximity, the JJs display differences in their interference patterns and different diode behavior, underscoring that microscopic inhomogeneities such as twist angle variations shape the non-uniform supercurrent and drive the diode behavior. As a result, the nonreciprocal supercurrent can be tuned by gate voltage, enabling tuning of the diode efficiency and even reversing the polarity at fixed
magnetic fields. Our findings offer potential routes for tailoring Josephson diode performance in superconducting
quantum circuits.
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All authors A. Rothstein, R. J. Dolleman, L. Klebl, A. Achtermann, F. Volmer, K. Watanabe, T. Taniguchi, F. Hassler, L. Banszerus, B. Beschoten, C. Stampfer
Strongly Correlated Electrons · Cross-listed from hep-lat
The Truncated Hankel Correlator Method
Johann Ostmeyer and Carsten Urbach
We introduce a new method to approximate Euclidean correlation functions by exponential sums. The Truncated Hankel Correlator (THC) method builds a Hankel
matrix from the full correlator data available and truncates the eigenspectrum of said Hankel
matrix. It proceeds by applying the Prony generalised
eigenvalue method to the thus obtained low-rank approximation. A large number of algebraic correlator analysis methods including (block) Prony (and equivalently (block) Lanczos) and the generalised
eigenvalue problem (GEVP) can be reproduced as sub-optimal special cases of the THC method. Weights, for instance inverse square errors, can be included in the analysis, so that the result has a close to optimal $\chi^2$-value. This makes the THC method very similar in spirit to a closed form solution to multi-state fits, naturally including the case of
matrix-valued correlators. We show that, in general, finding approximations better than those provided by the THC method is exponentially hard in the number of exponentials. Moreover, the THC method is robust against noise and requires comparably little human oversight. Finally, when applied to symmetric data, the obtained energy spectrum is guaranteed to be symmetric up to machine precision.
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Quantum Gases
Fractional Quantum Hall Wedding Cakes
Chloé Van Bastelaere, Felix A. Palm, Botao Wang et al. (+2 more)
This work investigates the coexistence of distinct topologically ordered phases within a single setup. We demonstrate this concept through tensor network simulations of the Hofstadter-Bose-Hubbard model under a spatially modulated chemical potential. Focusing on cylindrical geometries, we realize regions exhibiting the Laughlin-1/2 phase and its particle-hole conjugate, and confirm their topological character via the local Středa's response and Laughlin's flux insertion protocol. Our approach offers a new pathway for experimentally and numerically charting entire phase diagrams within a single system, possibly eliminating the need for independent parameter scans.
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All authors Chloé Van Bastelaere, Felix A. Palm, Botao Wang, Nathan Goldman, Laurens Vanderstraeten
Materials Science
Antiphase boundaries in Ni-Mn-Ga single crystal - experiment and model
O. Heczko, F. Maca, V. Drchal et al. (+3 more)
Thermally induced antiphase boundaries (APBs) in
ferromagnetic, ordered Ni-Mn-Ga single
crystal exhibit complex, irregular shapes and closed loops without any
lattice plane preferences. The APBs were visualized on polished (100) surface using
magnetic force microscopy (MFM) at the same location in parent cubic austenite and monoclinic martensite with uniaxial
magnetic anisotropy. Based on ab-initio calculation we suggest that one APB curve with dark and light contrast consists of a pair of APB interfaces with narrow, only one-layer thick, core with structural partial B2' order in contrast to full L21 order of bulk. Calculated
magnetic contrast using magnetostatic continuum simulations agrees well with MFM observation.
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All authors O. Heczko, F. Maca, V. Drchal, L. Fekete, L. Straka, J. Zemen
Soft Condensed Matter
Confinement-Induced Delay in Chiral Active Brownian Particles
Hrithik Barman
We investigate the interplay between chirality and confinement in harmonically trapped active particles. The circular character of
chiral motion combines with the radial
symmetry of the potential to create distinctive non-
equilibrium behavior. Chirality induces oscillatory cross-correlations between positional components that vanish in the absence of torque while the harmonic potential generates a finite delay between orientation and velocity - a signature of time-reversal
symmetry breaking distinct from inertial delay mechanisms. The delay function exhibits characteristic temporal
evolution with depth and persistence controlled by trap strength and rotational noise. The stationary probability distribution displays strongly non-Maxwellian characteristics, transitioning from broad annuli to compact localized peaks as confinement increases with the distribution radius governed by the competition between
chiral propulsion and trap strength. These features emerge from the interplay between
chiral swimming and the restoring force of the trap, revealing how confinement and activity jointly shape particle dynamics and transport properties in nonequilibrium steady states.
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Statistical Mechanics · Cross-listed from hep-th
Quantum Corrections in the Low-Temperature Fluid/Gravity Correspondence
Jun Nian, Leopoldo A. Pando Zayas and Cong-Yuan Yue
Attempts to construct a low-temperature version of the fluid/
gravity correspondence have faced obstacles manifested in the form of logarithmic terms in the frequency, $\log(\omega)$, leading to non-local in time constitutive relations for the stress tensor and the charge current. These difficulties can be broadly presented as a breakdown of the hydrodynamic description due to additional infrared modes. We employ new
quantum insights into the physics of near-extremal black holes, brought about in the context of Jackiw-Teitelboim
gravity, as an effective description of
quantum fluctuations in the throat, to revisit the fluid/
gravity correspondence at very low temperatures. The
quantum corrections naturally include a new length scale, $C$, and an effective action that parametrizes the breaking of near-horizon
symmetries. We show that with an appropriate choice of order of limits in the derivative expansion within the low-temperature regime, the $\log(\omega)$ infrared divergence can be resolved. By
quantum averaging the infrared Schwarzian modes as an effective extra contribution to the long-wavelength fluid modes, the resulting low-temperature effective fluid description is consistent. We present the dispersion relations for all the relevant hydrodynamic modes. We also revisit the shear viscosity to
entropy density ratio and find that at very low temperatures the universal $\frac{1}{4\pi}$ bound is violated due to
quantum correction.
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Statistical Mechanics
Coarsening kinetics in spin systems with long-range interactions: from voter to Ising
Federico Corberi, Eugenio Lippiello, Paolo Politi et al. (+1 more)
In this paper, we start reviewing the main features of the one-dimensional Ising model with long-range interactions, where the
spin-
spin coupling decays as a power law, $J(r) \propto r^{-\alpha}$. We then discuss the key properties of the one-dimensional voter model, in which two
agents (
spins) at distance $r$ interact with a power-law probability with the same form of $J(r)$. The two models are compared, and the so-called $p$-voter model is presented, which provides a framework to interpolate between them. Specifically, the $p$-voter model reduces to the voter model for $p = 1$ and $p = 2$, while for $p \ge 3$ it falls into the universality class of the Ising model.
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All authors Federico Corberi, Eugenio Lippiello, Paolo Politi, Luca Smaldone
Materials Science
Unravelling the Catalytic Activity of Dual-Metal Doped N6-Graphene for Sulfur Reduction via Machine Learning-Accelerated First-Principles Calculations
Sahil Kumar, Adithya Maurya K R and Mudit Dixit
Understanding and optimizing polysulfide adsorption and conversion processes are critical to mitigating shuttle effects and sluggish redox kinetics in lithium-sulfur batteries (LSBs). Here, we introduce a machine-learning-accelerated framework, Precise and Accurate Configuration Evaluation (PACE), that integrates Machine Learning Interatomic Potentials (MLIPs) with Density Functional Theory (DFT) to systematically explore adsorption configurations and energetics of a series of N6-coordinated dual-atom catalysts (DACs). Our results demonstrate that, compared with single-atom catalysts, DACs exhibit improved LiPS adsorption and redox conversion through cooperative metal-sulfur interactions and electronic coupling between adjacent metal centers. Among all DACs, Fe-Ni and Fe-Pt show optimal catalytic performance, due to their optimal adsorption energies (-1.0 to -2.3 eV), low free-energy barriers (<=0.4 eV) for the Li2S2 to Li2S conversion, and facile Li2S decomposition barriers (<=1.0 eV). To accelerate catalyst screening, we further developed a machine learning (ML) regression model trained on DFT-calculated data to predict the Gibbs free energy (\Delta G) of Li2Sn adsorption using physically interpretable descriptors. The Gradient Boosting Regression (GBR) model yields an R^2 of 0.85 and an MAE of 0.26 eV, enabling the rapid prediction of \Delta G for unexplored DACs. Electronic-structure analyses reveal that the superior performance originates from the optimal d-band
alignment and S-S bond polarization induced by the cooperative effect of dual metal centres. This dual ML-DFT framework demonstrates a generalizable, data-driven design strategy for the rational discovery of efficient catalysts for next-generation LSBs.
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Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Nonunitary Quantum Criticality Driven by a General Boundary Condition: Exact Solution
Yao Zhou and Peng Ye
Nonunitary
quantum critical phenomena remain largely unexplored, hindered by the scarcity of exactly solvable models and the numerical challenges in non-Hermitian systems. Here we demonstrate that a general boundary condition drives fundamentally new nonunitary boundary
quantum criticality in an exactly solvable
lattice model. The exact solution yields a closed-form expression for the boundary-induced equal-time correlation function. The algebraic long-distance behavior of the boundary-induced correlation is governed by the single-particle reflection amplitude at the
Fermi level, whose anomalous amplification is forbidden in
unitary scattering and therefore provides a direct scattering signature of the nonunitary boundary-critical regime. We use the biorthogonal
entanglement entropy as a many-body probe of this boundary-critical behavior and find that it retains logarithmic scaling, while the associated effective central charge, continuously tunable by the boundary parameters, changes from real to complex. The real branch admits a
unitary defect conformal field theory (CFT) description, whereas the complex branch lies beyond analytic continuation from the
unitary theory. These results establish minimal boundary engineering as an exactly solvable platform for nonunitary boundary
quantum criticality and provide a
benchmark for broader studies of nonunitary critical phenomena.
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Soft Condensed Matter
Friction-controlled reentrant aging and fluidization in granular materials
Ye Yuan, Walter Kob and Hajime Tanaka
Granular materials densify under repeated mechanical perturbations, a nonequilibrium dynamics that underlies many natural and industrial processes. Because granular relaxation is governed by frictional contacts and energy dissipation, this aging behavior fundamentally differs from that of thermal glasses despite their apparent similarities. Here, we uncover how friction controls the compaction dynamics of granular packings subjected to cyclic shear. Using discrete element simulations, we construct a dynamic state diagram as a function of strain amplitude and friction, revealing a rich interplay between jamming marginality, stabilization, and fluidization. We identify a friction-dependent crossover strain that separates aging and fluidized regimes, showing reentrant, non-monotonic behavior: Increasing friction first suppresses fluidization, then promotes it through smooth, creep-like rearrangements. This transition is marked by a shift from intermittent, avalanche-like rearrangements to continuous, diffusive motion. Our findings demonstrate that friction exerts a dual role in granular aging – both stabilizing and fluidizing – thereby uncovering the fundamental nonequilibrium mechanisms that govern compaction, rheology, and aging in athermal disordered systems. More broadly, our results reveal a general principle for how friction governs metastability and flow in athermal matter – from granular and frictional colloids to soils and seismic faults – linking microscopic contact mechanics to macroscopic dynamics.
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Materials Science
Dielectric Deposition Enhanced Crystallization in Atomic-Layer-Deposited Indium Oxide Transistors Achieving High Gated-Hall Mobility Exceeding 100 cm2/Vs at Room Temperature
Chen Wang, Kai Jiang, Jinxiu Zhao et al. (+4 more)
In this work, we report high-performance atomic-layer-deposited indium
oxide (In2O3) transistors with high gated-
Hall mobility ({\mu}H) exceeding 100 cm2/Vs at room temperature (RT). It is found that the deposition of top hafnium
oxide (HfO2) above the In2O3 channel significantly enhances its crystallization, leading to an average grain size of 97.2 nm in a 4.2-nm In2O3 channel. The ALD of In2O3 exhibits an epitaxy-like growth behavior, with its (222) planes aligning parallel to the (111) planes of both the top and bottom HfO2 dielectrics. As a result, bottom-gate In2O3 transistors with a high {\mu}H of 100.9 cm2/Vs and a decent subthreshold swing (SS) of 94 mV/dec are achieved by gated-
Hall measurement at RT. Furthermore, the devices maintain excellent performance at low temperatures, achieving a {\mu}H of 162.2 cm2/Vs at 100 K. Our study reveals the critical role of dielectric deposition induced crystallization in enhancing carrier transport and offers a scalable pathway toward high-mobility devices.
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All authors Chen Wang, Kai Jiang, Jinxiu Zhao, Ziheng Wang, Guilei Wang, Chao Zhao, Mengwei Si
Mesoscale and Nanoscale Physics
Altermagnetism induced surface Chern insulator
Xuance Jiang, Sayed Ali Akbar Ghorashi, Deyu Lu et al. (+1 more)
We propose a new pathway to the quantized anomalous
Hall effect (QAHE) by coupling an altermagnet to a topological crystalline
insulator (TCI). The former gaps the topological surface states of the TCI, thereby realizing the QAHE in a robust and switchable platform with near- vanishing magnetization. We demonstrate the feasibility of this approach by studying a slab of the TCI SnTe coupled to an altermagnetic RuO2 layer. Our first-principles calculations reveal that the d-wave altermagnetism in RuO2 induces a 7 meV gap to the Dirac surface states on the (110) surface of SnTe, producing a finite anomalous
Hall effect. Our approach generalizes to broader classes of altermagnetic materials and TCIs, thereby providing a family of topological altermagnetic
heterostructures with small or vanishing magnetization that support nontrivial Chern numbers. Our results highlight a promising new topological platform with great tunability and applications to spintronics.
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All authors Xuance Jiang, Sayed Ali Akbar Ghorashi, Deyu Lu, Jennifer Cano
Materials Science
Ab-initio study of structural, vibrational and non-linear optical properties of (TiO2)-(Tl2O)-(TeO2) glasses
Raghvender Raghvender, Assil Bouzid, Evgenii M. Roginskii et al. (+4 more)
This paper reports on a systematic first-principles molecular dynamics investigation of binary (TlO$_{0.5}$)$_{y}$-(TeO$_2$)$_{1-y}$ and ternary $(TiO$_{2}$)$_{x}$-(TlO$_{0.5}$)$_{y}$-(TeO$_2$)_{1-x-y}$ tellurite glasses. The obtained structural models are validated against available measured X-ray pair distribution functions. In the binary system, increasing TlO$_{0.5}$ content induces network depolymerization through the reduction of Te coordination number, the substitution of Te-O-Te linkages with Te=O$^{-}$...Tl$^{+}$ units, and the proliferation of non-bridging oxygens. In addition, rings analysis demonstrates a loss of the network connectivity via the opening of small n-membered rings. In contrast, TiO$_2$ acts as a network former in ternary glasses, preserving Te coordination number, and promoting a high fraction of bridging oxygens. Ti atoms induces a network repolymerization that manifests through the formation of smaller Ti-containing n-membered rings thereby balancing the strong effect of Tl$_2$O modifier. Beside the structural analysis, we also computed Raman spectra and non-linear optical properties on the obtained large periodic models. Our results reproduce experimental trends in Raman band shifts with composition, while nonlinear optical calculations show that <$\chi^{(3)}$> remains stable with TlO$_{0.5}$ addition in binary glasses, consistent with experiment. In the case of ternary systems, we find that the inclusion of a small fraction of TiO$_2$ preserves the high optical nonlinearity of the TeO$_2$ network while maintaining the overall network connectivity. These results establish a predictive framework for tailoring the atomic structure and nonlinear optical response of tellurite glasses through the controlled interplay of modifiers nature and concentration.
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All authors Raghvender Raghvender, Assil Bouzid, Evgenii M. Roginskii, David Hamani, Olivier Noguera, Philippe Thomas, Olivier Masson
Strongly Correlated Electrons
Magnetic fluctuations and anisotropy in UTe2: a multi-orbital study based on GGA+U and RPA
Makoto Shimizu and Youichi Yanase
Pressure-induced changes in the
magnetic and superconducting properties of a
spin-triplet
superconductor candidate UTe$_2$ have attracted considerable interest, underscoring the need for microscopic theoretical insight. In this paper, we investigate
magnetic fluctuations and their anisotropy at ambient pressure and under pressure using density functional theory (DFT) combined with the random phase approximation (RPA). For each pressure, we perform DFT+$U$ calculations for several values of the Coulomb interaction $U$, construct a 72-orbital periodic Anderson model, and calculate
magnetic susceptibilities with use of the RPA. For $U = 2\mathrm{\;eV}$, the
Fermi surface has a quasi-two-dimensional shape,
antiferromagnetic fluctuations develop with the wave vector along the $\boldsymbol{a}^*$ axis, and the
magnetic anisotropy follows $\chi^b > \chi^a > \chi^c$. The
antiferromagnetic fluctuations are suppressed under pressure because of a reduced density of states at the
Fermi level, while the
magnetic anisotropy is weakened. In contrast, for $U = 1\mathrm{\;eV}$, where the
Fermi surface is more three-dimensional,
antiferromagnetic fluctuations with $\boldsymbol{Q}_2 = 0.22\,\boldsymbol{b}^*$ appear, accompanied by anisotropy $\chi^a > \chi^c > \chi^b$, consistent with experiments. Under pressure,
antiferromagnetic fluctuations around $\boldsymbol{Q}_2$ are enhanced, the
magnetic wave vector tilts slightly toward the $\boldsymbol{a}^*$ direction due to
Fermi-surface distortion, and the
magnetic anisotropy is suppressed. These results demonstrate that the pressure
evolution of magnetism in UTe$_2$ is governed by the momentum-space distribution of U $5f$ states and the density of states at the
Fermi level, providing a microscopic basis for understanding the
magnetic and superconducting properties of UTe$_2$.
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Superconductivity · Cross-listed from quant-ph
Investigating the performance of RPM JTWPAs by optimizing LC-resonator elements
M.A. Gali Labarias, T. Yamada, Y. Nakashima et al. (+2 more)
Resonant phase-matched Josephson traveling-wave parametric amplifiers (RPM JTWPAs) play a key role in
quantum computing and
quantum information applications due to their low-noise, broadband amplification, and quadrature squeezing capabilities. This research focuses on optimizing RPM JTWPAs through numerical optimization of parametrized resonator elements to maximize gain, bandwidth and quadrature squeezing. Our results show that optimized resonators can increase the maximum gain and squeezing by more than 5 dB in the ideal noiseless case. However, introducing the effects of loss through a lumped-element model reveals that gain saturates with increasing loss, while squeezing modes degrade rapidly, regardless of resonator optimization. These results highlight the potential of resonator design to significantly improve amplifier performance, as well as the challenges posed by current fabrication technologies and inherent losses.
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All authors M.A. Gali Labarias, T. Yamada, Y. Nakashima, Y. Urade, K. Inomata
Mesoscale and Nanoscale Physics
Does Moire Matter? Critical Moire Dependence with Quantum Fluctuations in Graphene Based Integer and Fractional Chern Insulators
Zihao Huo, Wenxuan Wang, Jian Xie et al. (+11 more)
Rhombohedral multilayer
graphene has emerged as a powerful platform for investigating flat-band-driven correlated phenomena, yet most aspects remain not understood. In this work, we systematically study the moire-dependent band
topology in rhombohedral hexalayer
graphene. For the first time we demonstrate that the moire twist angle plays a crucial role in the formation of the moire Chern
insulators in rhombohedral hexalayer
graphene/hexagonal boron nitride (RHG/hBN) moire superlattices. In the moire-distant regime at filling factor v = 1, only systems with a twist angle {\theta} < 1.1{\deg} exhibit an integer moire Chern
insulator, while the fractional Chern
insulator at v = 2/3 requires smaller twist angle to be stabilized. Our theoretical modelling, which includes
quantum fluctuations and exact diagonalization results, suggests that mean-field theory, which has been widely adopted, does not explain the twist-angle dependence of the v = 1 phase diagram, and that correlation effects are crucial. Moreover, we realize two distinct stacking configurations ( /Xi=0 and /Xi=1) between
graphene and hBN, and find that both cases can yield a Chern
insulator at v = 1. Our experimental work upends the current mean-field paradigm, illuminates how
quantum fluctuations and moiré effects shape the RHG/hBN phase diagram, and paves the way for future understanding and engineering of topological correlated states in rhombohedral
graphene moire systems.
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All authors Zihao Huo, Wenxuan Wang, Jian Xie, Yves H. Kwan, Jonah Herzog-Arbeitman, Zaizhe Zhang, Qiu Yang, Min Wu, Kenji Watanabe, Takashi Taniguchi, Kaihui Liu, Nicolas Regnault, B. Andrei Bernevig, Xiaobo Lu
Disordered Systems and Neural Networks · Cross-listed from cs.LG
Identifying internal patterns in (1+1)-dimensional directed percolation using neural networks
Danil Parkhomenko, Pavel Ovchinnikov, Konstantin Soldatov et al. (+2 more)
In this paper we present a neural network-based method for the automatic detection of phase transitions and classification of hidden percolation patterns in a (1+1)-dimensional replication process. The proposed network model is based on the combination of CNN, TCN and GRU networks, which are trained directly on raw configurations without any manual feature extraction. The network reproduces the phase diagram and assigns phase labels to configurations. It shows that deep architectures are capable of extracting hierarchical structures from the raw data of numerical experiments.
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All authors Danil Parkhomenko, Pavel Ovchinnikov, Konstantin Soldatov, Vitalii Kapitan, Gennady Y. Chitov
Materials Science
Enhanced magnetic, electrical, and magnetostrictive properties of La-doped SrCoO3 synthesized by microwave heating
L.A. Longchar, M. Manikandan and R. Mahendiran
We report microwave-assisted synthesis and physical properties of La-doped SrCoO3-{\delta}. The Sr0.8La0.2CoO3-{\delta} synthesized via microwave heating (MWH) exhibits superior physical properties compared to a nominally identical composition obtained by conventional heating (CH) in an electrical furnace. The MWH sample exhibits an enhanced
ferromagnetic Curie temperature (158 K in CH and 176 K in MWH samples) and higher saturation magnetization but smaller coercive field and magnetoresistance at 10 K compared to the CH sample. While the dc resistivity increases substantially below 120 K in the CH sample, it is metallic from 350 to 10 K in the MWH sample. Further, the longitudinal magnetostriction of the MWH sample ({\lambda}par = 247 ppm for H = 50 kOe) at 10 K is also higher than that of the CH sample ({\lambda}par = 128 ppm). The observed enhanced properties of the MWH sample can not be attributed to grain size and grain boundaries but are likely to arise from lesser oxygen defects and partial oxidation of Co3+ into Co4+, however, the exact mechanism is not fully understood at present.
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Statistical Mechanics
Finite-frequency fluctuation-response inequality
Andreas Dechant
We derive an inequality relating the finite-frequency linear response and fluctuations of an observable in a physical system. The relation holds for arbitrary observables and perturbations in general Markovian dynamics, including over- and underdamped Langevin systems and jump processes, both in and out of
equilibrium. As a consequence, we obtain a universal upper bound on the broad-band signal-to-noise ratio of noisy dynamics, which only depends on the damping constant and temperature. We further show that the inequality reduces to an equality for appropriately chosen observables or perturbations in linear systems, both overdamped and underdamped and both in and out of
equilibrium.
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Materials Science · Cross-listed from physics.chem-ph
High-entropy perovskites as new photocatalysts for cocatalyst-free water splitting
Ho Truong Nam Hai, Makoto Arita and Kaveh Edalati
The photocatalytic water-splitting process is thermodynamically challenging and requires catalysts with suitable band structures, as well as the presence of supporting cocatalysts. By considering the unique charge carrier mobility in perovskites, this study introduces three new ABO3-type high-
entropy perovskites (Ba1/2Sr1/2)(Ti1/3Zr1/3Hf1/3)O3, (Ba1/2Sr1/2)(Ga1/3In1/3Sn1/3)O3 and (Ba1/2Sr1/2)(Ti1/3Zr1/3Sn1/3)O3 for cocatalyst-free photocatalysis. The three catalysts, having a single-phase cubic structure, are designed by considering configurational
entropy, tolerance factor, octahedral factor, ionic radius deviation and valence deviation of >1.5R (R: gas constant), 0.9-1.0, 0.4-0.8, >0.3 and >0.3, respectively. The perovskites exhibit similar valence band tops, while their bandgaps vary slightly depending on the composition at the B-site (slightly lower bandgap by including d10 cations). Additionally, all three materials demonstrate effective hydrogen generation without the need for added cocatalysts. This investigation confirms that high-
entropy oxide perovskites can offer significant potential for cocatalyst-free photocatalytic reactions.
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