Materials Science · Cross-listed from cs.ET
Full-Field Damage Monitoring in Architected Lattices Using In situ Electrical Impedance Tomography
Akash Deep, Andrea Samore, Alistair McEwan et al. (+2 more)
Electrical impedance
tomography (EIT) enables non-invasive, spatially continuous reconstruction of internal conductivity distributions, providing full field sensing beyond conventional point measurements. Here, we report the first in situ implementation of EIT within a tunable architected
lattice materials framework, enabling systematic exploration across a broad
lattice design space while achieving real time monitoring of damage
evolution, including early stage, prefracture events, in 3D printed multifunctional
lattice composites.
Lattices are designed via Voronoi based branch trunk branch motifs inspired by 2D wallpaper
symmetries and fabricated using CNT infused photocurable resins, with nanoscale filler dispersion confirmed by field emission scanning electron microscopy. Sixteen electrodes distributed along the
lattice periphery enable EIT measurements during quasi static tensile loading. Conductivity maps reconstructed using adjacent and across current injection schemes resolve sequential ligament fracture with high temporal resolution, with localised conductivity loss quantitatively coinciding with fracture sites, including regions remote from electrodes. Architectural tunability allows systematic control of EIT imaging sensitivity to early stage damage, while pronounced resistance discontinuities at failure further corroborate spatial localisation; global end to end resistance measurements complement macroscopic stress strain responses. Collectively, these results establish in situ EIT as a scalable, full field sensing modality for architected multifunctional materials, providing an experimentally validated pathway toward autonomous, intelligent materials and data rich material states that can inform digital twin frameworks for structural, biomedical, and energy related applications.
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All authors Akash Deep, Andrea Samore, Alistair McEwan, Andrew McBride, Shanmugam Kumar
Other Condensed Matter · Cross-listed from physics.chem-ph
Photoluminescent registration of fullerite C$_{60}$ derivatives during chemical interaction with H$_{2}$ and N$_{2}$ molecules
Victor Zoryansky, Peter Zinoviev and Yuri Semerenko
Single
crystals of C$_{60}$ saturated with molecular hydrogen and nitrogen were studied using the spectral-luminescent method of registration in the
quantum counting mode at a low temperature of 20 K. Previously, it was found that the temperature limit of the adsorption crossover (the transition from the
diffusion mechanism of intercalation - physisorption to chemical interaction - chemisorption) for fullerite C$_{60}$ in an H$_{2}$ atmosphere is about 525 K, and in an N$_{2}$ atmosphere 695 K, respectively. At saturation temperatures above those indicated, the process of chemical interaction of
impurity molecules and the fullerite
matrix occurs with the formation of new compounds. Therefore, saturation was carried out at temperatures of 570 K for hydrogen and 720 K for nitrogen under a pressure of 30 atm. For the first time, the results of registration of photoluminescent radiation at low temperatures from new substances based on fullerite C60 are presented. A mixture of weakly saturated fulleranes C$_{60}$H$_{X}$ was obtained by saturation of hydrogen from the gas phase at a temperature close to the sorption crossover temperature, and their low-temperature photoluminescence was identified for the first time. The analysis of the "blue" shift of the beginning of the spectrum of such radiation allowed us to more accurately attribute the obtained material to the initial segment of the fullerane series. The presence of radiation of the azafullerene dimer (biazafullerene) (C$_{59}$N)$_{2}$ in the spectra of the reaction products of C$_{60}$ with N$_{2}$ was also detected. It was shown that for polycrystalline samples of C$_{60}$ saturated in a nitrogen atmosphere, the characteristic luminescence of biazafullerene with a maximum at 1.53 eV determines the intensity and shape of the entire short-wave part of the emission spectrum of the complex of synthesized substances.
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Statistical Mechanics · Cross-listed from quant-ph
Relative Entropy Revivals Caused by Memory-Induced Loss of Divisibility in Classical Non-Markovian Dynamics
Koichi Nakagawa
Relative-
entropy revivals and negative
entropy-production rates are established signatures of
memory effects in non-Markovian dynamics. The present paper addresses a more specific question: what minimal dynamical mechanism produces
entropy overshoot in classical
stochastic relaxation? We define
entropy overshoot as a transient increase of the Kullback–Leibler divergence from a stationary distribution during a relaxation process that ultimately returns to
equilibrium. Starting from finite-state generalized master equations with
memory kernels, we analyze the effective time-local generator governing the observed dynamics. The standard monotonic decay of relative
entropy is recalled as a reference property of reversible Markov dynamics. We then show that
memory can destroy
stochastic divisibility by producing transiently negative effective rates. Once the
evolution ceases to be divisible into intermediate Markov steps, the usual relative-
entropy contraction argument no longer applies, and
entropy overshoot can occur. The contribution of the paper is therefore not the introduction of another witness of non-Markovianity, but the identification of a minimal structural mechanism and its phase structure. The mechanism is illustrated with two- and three-state
stochastic models, where the competition between the intrinsic relaxation time and the
memory time separates monotonic relaxation from overshoot. Numerical phase diagrams show that the overshoot region expands when
memory persists on the relaxation timescale. These results clarify the relation between classical information backflow, negative
entropy-rate behavior, and
memory-induced loss of divisibility. They also distinguish the present mechanism-based interpretation from previous work that used relative-
entropy revivals or
entropy-production rates primarily as indicators of non-Markovianity.
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Mesoscale and Nanoscale Physics
Hyperfine interaction of electrons and holes with nuclei probed by optical orientation in MAPbI$_3$ perovskite crystals
Mladen Kotur, Nataliia E. Kopteva, Dmitri R. Yakovlev et al. (+3 more)
Optical orientation of electron and hole
spins by circularly polarized light is investigated for MAPbI$_3$ single
crystals. The Hanle and polarization recovery effects measured in transverse and longitudinal
magnetic fields, respectively, evidence the hyperfine interaction with
nuclear spins as the main factor determining the
spin dynamics of charge carriers at cryogenic temperatures. The parameters of the
nuclear spin fluctuations within the carrier localization volume are evaluated. Dynamic polarization of the
nuclear spins is demonstrated by the Overhauser field reaching 5 mT for acting on the electrons and -30 mT for acting on the holes.
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All authors Mladen Kotur, Nataliia E. Kopteva, Dmitri R. Yakovlev, Bekir Turedi, Maksym V. Kovalenko, Manfred Bayer
Statistical Mechanics
Momentum-Driven Reversible Logic Accelerates Efficient Irreversible Universal Computation
Kuen Wai Tang, Kyle J. Ray and James P. Crutchfield
We present implementations of two physically-embedded computation-universal logical operations using a 2-bit logical unit composed of coupled
quantum flux parametrons – Josephson-junction superconducting
circuits. To illustrate universality, we investigate NAND gates built from these two distinct elementary operations. On the one hand, Controlled Erasure (CE) is designed using fixed-point analysis and assumes that information must be stored in locally-metastable distributions. On the other, Erasure-Flip (EF) leverages momentum as a computational resource and significantly outperforms the metastable approach, simultaneously achieving higher fidelity and faster computational speed without incurring any additional energetic cost. Notably, the momentum degree of freedom allows the EF to achieve universality by using both nontrivial reversible and irreversible logic simultaneously in different logical subspaces. These results not only provide a practical, high-performance protocol ripe for experimental realization but also underscore the broader potential of momentum-based computing paradigms.
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Quantum Gases
Direct Observation of the Three-Dimensional Anderson Transition with Ultracold Atoms in a Disordered Potential
Xudong Yu, Ke Xie, Hoa Mai Quach et al. (+7 more)
Anderson localization of particles – the complete halt of wave transport through multiple scattering and phase coherence – is a paradigmatic manifestation of
quantum interference in disordered media. In three dimensions, the scaling theory predicts a
quantum phase transition at a critical energy, the mobility edge, separating localized from diffusive states and underpinning metal-
insulator transitions in electronic systems. Despite decades of experimental efforts, a direct observation of this emblematic transition for matter waves has remained elusive. Previous attempts with ultracold atoms were hindered by strong and uncontrolled energy broadening, resulting in indirect, sometimes inaccurate, and model-dependent estimates of the mobility edge. Here we implement a novel energy-resolved scheme to prepare atomic matter waves with a narrow energy distribution and track their expansion dynamics over long timescales. This allows for a direct observation of the three-dimensional Anderson transition in a
laser-speckle disordered potential, and for a precise measurement of the mobility edge that is independent of any underlying theoretical modeling. Our measurements show excellent agreement with state-of-the-art numerical predictions over a wide range of disorder strengths, resolving long-standing discrepancies between prior experiments and theory. Beyond the three-dimensional Anderson transition, our approach opens new avenues for quantitative investigations of
quantum critical phenomena in spatially disordered systems, including the roles of dimensionality,
symmetry class, and interactions.
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All authors Xudong Yu, Ke Xie, Hoa Mai Quach, Yukun Guo, Myneni Niranjan, Sacha Barré, Jean-Philippe Banon, Alain Aspect, Nicolas Cherroret, Vincent Josse
Soft Condensed Matter
Yielding behaviour of glasses under shear deformation at constant pressure
Krishna K Tiwari and Srikanth Sastry
Computer simulations of yielding of glasses under shear have typically been performed under constant volume, strain controlled protocols. However, volumetric effects, such as the dilatancy associated with plastic rearrangements, and the observed reduction of density in shear bands, make it interesting to consider constant pressure shear protocols. We present a computational investigation on the nature of yielding of glasses under constant-pressure conditions, for different pressures. For uniform shear, the stress-strain curves at different pressures differ only by the stress scale. We find stable shear bands under cyclic shear whose steady-state width increases with an increase in external pressure, with density within shear bands being lower compared to the average values reached. Cyclically sheared well annealed glasses yield with a discontinuous dilation at the yield point, whereas the poorly annealed glasses undergo compaction before yielding accompanied by dilation. The external pressure influences the quantitative mechanical response of the glasses, but the qualitative behaviour is similar at different pressures, and remains the same as that of yielding at the constant-volume strain-controlled conditions. We discuss directions along with further investigations may be pursued, based on the results presented.
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Superconductivity
Effect of metal encapsulation on bulk superconducting properties of niobium thin films used in qubits
Amlan Datta, Kamal R. Joshi, Sunil Ghimire et al. (+18 more)
Niobium metal occupies nearly 100% of the volume of a typical 2D transmon device. While the aluminum Josephson junction is of utmost importance, maintaining
quantum coherence across the entire device means that pair-breaking in Nb leads, capacitive pads, and readout resonators can be a major source of decoherence. The established contributors are surface
oxides and hydroxides, as well as absorbed hydrogen and oxygen. Metal encapsulation of freshly grown surfaces with non-oxidizing metals, preferably without breaking the
vacuum, is a successful strategy to mitigate these issues. While the positive effects of encapsulation are undeniable, it is important to understand its impact on the macroscopic behavior of niobium films. We present a comprehensive study of the bulk superconducting properties of Nb thin films encapsulated with gold and palladium/gold, and compare them to those of bare Nb films. Magneto-optical imaging, magnetization, resistivity, and London and Campbell penetration depth measurements reveal significant differences in encapsulated samples. Both sputtered, and epitaxial Au-capped films exhibit the highest residual resistivity ratio and superconducting transition temperature, as well as the lowest upper critical field, London penetration depth, and critical current. These results are in good agreement with the microscopic theory of anisotropic normal and superconducting states of Nb. We conclude that pair-breaking in the bulk of niobium films, driven by disorder throughout the film rather than just at the surface, is a significant source of
quantum decoherence in transmons. We also conclude that gold capping not only passivates the surface but also affects the properties of the entire film, significantly reducing the scattering rate due to defects likely induced by surface
diffusion if the film is not protected immediately after fabrication.
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All authors Amlan Datta, Kamal R. Joshi, Sunil Ghimire, Bicky S. Moirangthem, Makariy A. Tanatar, Mustafa Bal, Zuhawn Sung, Sabrina Garattoni, Francesco Crisa, Akshay Murthy, David A. Garcia-Wetten, Dominic P. Goronzy, Mark C. Hersam, Michael J. Bedzyk, Shaojiang Zhu, David Olaya, Peter Hopkins, Matthew J. Kramer, Alexander Romanenko, Anna Grassellino, Ruslan Prozorov
Superconductivity
Topological and Planar Hall Effect in Monoclinic van der Waals Ferromagnet NbFeTe$_2$
Suchanda Mondal, Shubhankar Roy, Poulami Manna et al. (+1 more)
Two-dimensional (2D) van der Waals (vdW) ferromagnets have emerged as a critical class of
quantum materials for next-generation, low-dimensional spintronic devices. In this study, we report a comprehensive study of the transport properties of the layered soft ferromagnet $\text{NbFeTe}_2$. We report the first observation of the topological
Hall effect (THE) and the planar
Hall effect (PHE) in metallic $\text{NbFeTe}_2$. THE signatures persist up to 45 K, while PHE remains evident well above Curie temperature ($T_C$). The observed negative longitudinal magnetoresistance, along with the PHE, provides strong evidence for a nontrivial electronic band structure. The coexistence of perpendicular
magnetic anisotropy and a substantial THE: two key properties that are highly desirable for future spintronics applications, makes monoclinic vdW
ferromagnetic $\text{NbFeTe}_2$ a promising platform to advance spintronics applications.
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All authors Suchanda Mondal, Shubhankar Roy, Poulami Manna, Ravi Prakash Singh
Materials Science
Acoustic wave scattering by spatio-temporal interfaces
J. Galiana, J. Redondo, R. Picó et al. (+1 more)
Space-time materials are obtained by modulating a physical medium with a traveling-wave perturbation of one or several of its constitutive parameters, such as the density or the bulk modulus in the case of acoustic materials. When this modulation has the form of a moving and abrupt (subwavelength) transition between two parameter values, we refer to a spatio-temporal interface, which may be considered as a building block for more complex space-time materials. This work considers the problem interaction and scattering of acoustic waves with a single spatio-temporal interface, and a sequence of two interfaces forming a slab. Several regimes defined by the relation between the sound propagation velocities and the interface velocity (namely subsonic, intersonic, and supersonic regimes) are discussed. Analytical expressions for the frequency conversions and scattering coefficients are obtained, and compared with numerical simulations based on an equivalent FTFD squeme.
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All authors J. Galiana, J. Redondo, R. Picó, V. J. Sánchez-Morcillo
Materials Science
Thermal Stability and Phase Transformation of Conductive $\alpha$-$(\mathrm{Al}_{x}\mathrm{Ga}_{1-x})_{2}\mathrm{O}_{3}/\mathrm{Ga}_{2}\mathrm{O}_{3}$ Heterostructures on Sapphire Substrates
Botong Li, Shisong Luo, Jaeheon Jung et al. (+10 more)
Thermal stability and phase transformation of conductive $\alpha$-$(\mathrm{Al}_{0.16}\mathrm{Ga}_{0.84})_{2}\mathrm{O}_{3}/\mathrm{Ga}_{2}\mathrm{O}_{3}$
heterostructures on sapphire substrates were investigated using in situ high-temperature X-ray diffraction (HT-XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Conductive $\alpha$-$(\mathrm{Al}_{0.16}\mathrm{Ga}_{0.84})_{2}\mathrm{O}_{3}/\mathrm{Ga}_{2}\mathrm{O}_{3}$
heterostructures with fluorine (F) doping were grown by mist chemical vapor deposition on sapphire substrates, achieving a
Hall mobility of $28~\mathrm{cm^{2}\,V^{-1}\,s^{-1}}$ and an electron concentration of $1.4\times10^{20}~\mathrm{cm^{-3}}$. The
heterostructures exhibited thermal stability up to approximately $550$–$
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All authors Botong Li, Shisong Luo, Jaeheon Jung, Bobby G. Duersch, Cheng Chang, Lucas Lau, Zonghao Zhang, Jianhua Li, Hunter Ellis, Imteaz Rahaman, Roy Byung Kyu Chung, Kai Fu, Yuji Zhao
Superconductivity
Turning non-superconducting elements into superconductors by quantum confinement and proximity
Giovanni A. Ummarino and Alessio Zaccone
Elemental good metals, including noble metals (Cu, Ag, Au) and several $s$-block elements, do not exhibit superconductivity in bulk at ambient pressure, mainly due to weak electron-
phonon coupling that cannot overcome Coulomb repulsion.
Quantum confinement in ultra-thin films reshapes the electronic spectrum and the density of states near the
Fermi level, producing strong, often non-monotonic, thickness dependencies of the critical temperature in established
superconductors. Here, we examine whether confinement alone, or combined with proximity effects, can induce superconductivity in metals that are non-superconducting in bulk form. We review recent theoretical progress and introduce a unified framework based on a confinement-generalized, isotropic one-band Eliashberg theory, where the normal density of states becomes energy dependent and key parameters ($E_F$, $\lambda$, $\mu^$) acquire explicit thickness dependence. By numerically solving the Eliashberg equations using ab initio or experimentally determined electron-
phonon spectral functions $\alpha^2F(\Omega)$ and Coulomb pseudopotentials $\mu^$, and without adjustable parameters, we compute the critical temperature $T_c$ as a function of film thickness for representative noble, alkali, and alkaline-earth metals. The results predict that superconductivity emerges only in selected cases and within extremely narrow thickness windows, typically at sub-nanometer scales ($L \sim 0.4-0.6$ nm), indicating strong fine-tuning requirements for confinement-induced superconductivity in good metals. We also consider layered
superconductor/normal-metal systems where confinement and proximity effects coexist. In these
heterostructures, a substantial enhancement of the critical temperature is predicted, even when the constituent materials are non-superconducting or weak
superconductors in bulk form.
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Statistical Mechanics
Capturing the Topological Phase Transition and Thermodynamics of the 2D XY Model via Manifold-Aware Score-Based Generative Modeling
Pratyush Jha
The application of generative modeling to many-body physics offers a promising pathway for analyzing high-dimensional state spaces of
spin systems. However, unlike computer
vision tasks where visual fidelity suffices, physical systems require the rigorous reproduction of higher-order statistical moments and thermodynamic quantities. While Score-Based Generative Models (SGMs) have emerged as a powerful tool, their standard formulation on Euclidean
embedding space is ill-suited for continuous
spin systems, where variables inherently reside on a
manifold. In this work, we demonstrate that training on the Euclidean space compromises the model's ability to learn the target distribution as it prioritizes to learn the
manifold constraints. We address this limitation by proposing the use of
Manifold-Aware Score-Based Generative Modeling framework applied to the 64x64 2D XY model (a 4096-dimensional
torus). We show that our method estimates the theoretical Boltzmann score with superior precision compared to standard
diffusion models. Consequently, we successfully capture the Berezinskii-Kosterlitz Thouless (BKT) phase transition and accurately reproduce second-moment quantities, such as heat capacity without explicit feature engineering. Furthermore, we demonstrate zero-shot generalization to unseen
lattice sizes, accurately recovering the physics of variable system scales without retraining. Since this approach bypasses domain-specific feature engineering, it remains intrinsically generalizable to other continuous
spin systems.
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Materials Science · Cross-listed from cs.AI
MSP-LLM: A Structured Large Language Model Framework for Inorganic Material Synthesis Planning
Heewoong Noh, Gyoung S. Na, Namkyeong Lee et al. (+1 more)
Material synthesis planning (MSP) remains a fundamental and underexplored bottleneck in AI-driven materials discovery, as it requires not only identifying suitable precursor materials but also designing coherent sequences of synthesis operations to realize a target material. Although several AI-based approaches have been proposed to address isolated subtasks of MSP, a methodology for solving the entire MSP task has yet to be established. We propose MSP-LLM, a structured LLM-based framework that formulates MSP as a two-stage process composed of two constituent subproblems: precursor prediction (PP) and synthesis operation prediction (SOP). Our approach introduces a discrete material class as an intermediate decision variable that organizes both tasks into a chemically consistent decision chain. For SOP, we further incorporate hierarchical precursor types as synthesis-relevant inductive biases and employ precursor constraint factorization that preserves precursor-related information in the autoregressive decoding state. Extensive experiments show that MSP-LLM consistently outperforms existing methods on both PP and SOP, as well as on the MSP task, demonstrating an effective and scalable framework with practical potential for autonomous MSP.
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All authors Heewoong Noh, Gyoung S. Na, Namkyeong Lee, Chanyoung Park
Materials Science
Positron annihilation lifetime and Doppler broadening spectral calculations of oxygen-doped 3C-SiC
Yi Zhao, Hongtao Zhang, Qiang Li et al. (+2 more)
Based on density functional theory (DFT), the formation energies of intrinsic vacancy defects (VC, VSi, and VSi+C) and oxygen-related defects (OC, OSi, OCVSi, and OSiVC) in 3C-SiC are systematically investigated. The results indicate that all defects considered, except for OC, possess neutral or negative charge states, thereby making them suitable for detection by positron annihilation spectroscopy (PAS). Furthermore, the electron and positron density distributions and positron annihilation lifetimes for the perfect 3C-SiC supercell and various defective configurations are computed. It is found that the OSi and OSiVC complexes act as effective positron trapping centers, leading to the formation of positron trapped states and a notable increase in annihilation lifetimes at the corresponding defect sites. In addition, coincidence Doppler broadening (CDB) spectra, along with the S and W parameters, are calculated for both intrinsic and oxygen-doped point defects (OC, OSi, OCVSi, and OSiVC). The analysis reveals that electron screening effects dominate the annihilation characteristics of the OSi defect, whereas positron localization induced by the vacancy is the predominant contributor in the case of OSiVC. This distinction results in clearly different momentum distributions of these two oxygen-related defects for different charge states. Overall, the PAS is demonstrated to be a powerful technique for distinguishing intrinsic vacancy-type defects and oxygen-doped composites in 3C-SiC. Combining the analysis of electron and positron density distributions, the electron localization and positron trapping behavior in defect systems with different charge states can be comprehensively understood. These first-principles results provide a solid theoretical foundation for identifying and characterizing the defects in oxygen-doped 3C-SiC by using PAS.
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All authors Yi Zhao, Hongtao Zhang, Qiang Li, Xian Tang, Guodong Cheng
Mesoscale and Nanoscale Physics · Cross-listed from cs.AI
GraphAgents: Knowledge Graph-Guided Agentic AI for Cross-Domain Materials Design
Isabella A. Stewart, Tarjei Paule Hage, Yu-Chuan Hsu et al. (+1 more)
Large
Language Models (LLMs) promise to accelerate discovery by
reasoning across the expanding scientific landscape. Yet, the challenge is no longer access to information but connecting it in meaningful, domain-spanning ways. In materials science, where innovation demands integrating concepts from molecular chemistry to mechanical performance, this is especially acute. Neither humans nor single-
agent LLMs can fully contend with this torrent of information, with the latter often prone to
hallucinations. To address this bottleneck, we introduce a multi-
agent framework guided by large-scale knowledge graphs to find sustainable substitutes for per- and polyfluoroalkyl substances (PFAS)-chemicals currently under intense regulatory scrutiny.
Agents in the framework specialize in problem decomposition, evidence
retrieval, design parameter extraction, and graph traversal, uncovering latent connections across distinct knowledge pockets to support hypothesis generation. Ablation studies show that the full multi-
agent pipeline outperforms single-shot prompting, underscoring the value of distributed specialization and relational
reasoning. We demonstrate that by tailoring graph traversal strategies, the system alternates between exploitative searches focusing on domain-critical outcomes and exploratory searches surfacing emergent cross-connections. Illustrated through the exemplar of biomedical tubing, the framework generates sustainable PFAS-free alternatives that balance tribological performance, thermal stability, chemical resistance, and biocompatibility. This work establishes a framework combining knowledge graphs with multi-
agent reasoning to expand the materials design space, showcasing several initial design candidates to demonstrate the approach.
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All authors Isabella A. Stewart, Tarjei Paule Hage, Yu-Chuan Hsu, Markus J. Buehler
Superconductivity
Complete electronic phase diagram and enhanced superconductivity in fluorine-doped PrFeAsO1-xFx
Priya Singh, Konrad Kwatek, Tatiana Zajarniuk et al. (+4 more)
Establishing a complete electronic phase diagram for REFeAsO (RE = rare earth, RE1111) ironbased
superconductors has remained experimentally challenging. Here, we report a systematic investigation of PrFeAsO1-xFx over the full nominal fluorine-doping range 0 to 1 and construct the first comprehensive electronic phase diagram for this system. The
evolution from the nonsuperconducting parent compound to the fluorine-rich limit reveals a broad dome shaped superconducting region. Structural refinement demonstrates a systematic
lattice contraction with increasing fluorine content (x), corroborated by Raman spectroscopy through softening of the Pr(A1g)
phonon mode and hardening of the Fe(B1g) mode, confirming effective fluorine incorporation at the oxygen sites. The maximum superconducting transition temperature (Tc) reaches up to 52.3 K, approximately 5 K higher than previous reports for Pr1111. Magnetotransport measurements yield large upper critical fields Hc2(0) exceeding 100 T, while analysis of resistive transition broadening reveals thermally activated flux flow with a crossover from single-
vortex to collective pinning regimes. Specific-heat measurements exhibit a reduced jump deltaC/{\gamma}Tc < 1.43, reflecting strong superconducting fluctuations and multiband pairing. These results establish clear structure property correlations and provide a unified description of superconductivity across the entire doping range of the Pr1111 system.
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All authors Priya Singh, Konrad Kwatek, Tatiana Zajarniuk, Taras Palasyuk, Cezariusz Jastrzębski, A. Szewczyk, Shiv J. Singh
Materials Science
Benchmarking the plasmon-pole and multipole approximations in the Yambo Code using the GW100 dataset
M. Bonacci, D. A. Leon, N. Spallanzani et al. (+4 more)
Verification and validation of electronic structure codes are essential to ensure reliable and reproducible results in computational materials science. While density functional theory has been extensively benchmarked, systematic assessments of many-body perturbation theory methods such as the GW approximation have only recently emerged, most notably through the GW100
dataset. In this work, we assess the numerical accuracy and convergence behavior of the GW implementation in the yambo code using both the Godby-Needs plasmon-pole model and the recently introduced multipole approximation. Quasiparticle energies are compared against GW100 reference data to evaluate the performance, numerical stability, and consistency of these approaches.
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All authors M. Bonacci, D. A. Leon, N. Spallanzani, E. Molinari, D. Varsano, A. Ferretti, C. Cardoso
Materials Science
Spontaneous Symmetry Breaking and Collective Higgs-Goldstone Dynamics in Solid-State Phononic Frequency Combs
Murtaza Rangwala and Adarsh Ganesan
We investigate the generation of phononic frequency combs arising from nonlinear coupling between
Higgs-like and Goldstone-like
phonon modes in hexagonal InMnO3. The
Higgs-like mode, an infrared-active optical
phonon, is resonantly driven by a short, high-electric field terahertz pulse, while the optically inactive Goldstone-like mode is indirectly excited through intrinsic nonlinear mode coupling. Using a nonlinear phononics model, we numerically solve the coupled equations of motion governing the
lattice dynamics and analyze the resulting time- and frequency-domain responses. By systematically varying key drive and material parameters-including electric field amplitude, pulse width, driving frequency, and mode damping-we identify the conditions under which stable phononic frequency combs emerge. Our results reveal clear threshold behaviors for comb formation, tunability of comb spacing and spectral bandwidth through external control parameters, and a breakdown of coherent comb structure at high drive strengths or weak damping. These findings demonstrate how nonlinear
Higgs-Goldstone interactions enable controllable phononic frequency comb generation and provide insight into ultrafast
lattice dynamics in
symmetry-broken materials.
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Mesoscale and Nanoscale Physics
Theory of Integer Quantum Hall Effect in Irrational Magnetic Field
Zhao-Wen Miao, Chen Zhao, Jin-Hua Gao et al. (+1 more)
The conventional theory of the integer
quantum Hall effect (IQHE) fails for irrational
magnetic fields owing to the breakdown of
magnetic translational
symmetry. Here, based on the recently proposed incommensurate energy band (IEB) theory, we present a universal IQHE theory that does not rely on
magnetic translation
symmetry and is applicable to both rational and irrational
magnetic fluxes. Using the square
lattice as a paradigmatic example, we first show that the IEB framework provides a superior description of its energy spectrum in a
magnetic field, as it explicitly reveals the momentum-space distribution of eigenstates. Key to our IQHE theory is that each gap in the IEB spectrum is intrinsically labeled by an integer pair (m,g), defined by the corresponding Bragg planes. When the
Fermi energy lies within such a gap, the occupied electron states $N_{\text{occ}}$ is determined by the k-space volume enclosed by these Bragg planes, leading to the fundamental relation $N_{\text{occ}}/N_0 = m(\phi/\phi_0) + g$. Through Středa formula, this leads directly to the quantized
Hall conductance $\sigma_{xy} = m e^2/h$ under arbitrary
magnetic fields. Our work resolves the long-standing problem of IQHE under irrational flux, and establishes a new paradigm for IQHE.
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All authors Zhao-Wen Miao, Chen Zhao, Jin-Hua Gao, X. C. Xie
Disordered Systems and Neural Networks
Insensitive nonreciprocal edge breathers
Bertin Many Manda and Vassos Achilleos
We uncover subtle and previously unexplored phenomena arising from the interplay of nonlinearity and nonreciprocity in topological mechanical metamaterials. We study a nonreciprocal topological Klein-Gordon chain of asymmetrically coupled nonlinear oscillators, which serves as a minimal mass-spring model capturing the features of several active nonreciprocal metamaterials across mechanical, electronic, and acoustic platforms. We demonstrate that continuous families of nonreciprocal edge breathers (NEBs), namely boundary-localized, time-periodic waves, emerge from the linear edge mode as its amplitude increases. Remarkably, despite the absence of
chiral or sublattice
symmetries, we identify insensitive NEBs whose nonlinear frequency remains fixed to that of the linear edge mode with increasing nonlinearity. Our analysis reveals that the mechanism underlying this insensitivity stems from a competition between mode nonorthogonality and nonlinear interactions, yielding an exponential decay of the NEB nonlinear frequency shift with system size. Crucially, these insensitive NEBs also persist in the strongly nonlinear regime. Our work establishes a novel pathway toward realizing robust nonlinear topological waves in mechanical metamaterials without relying on
symmetry-protected nonlinearities.
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Quantum Gases · Cross-listed from quant-ph
Non-Markovianity in a dressed qubit with local dephasing
Saima Bashir, Muzaffar Qadir Lone and Prince A Ganai
We study the dynamics of a dressed
qubit implemented by a spinless
fermion hopping between two
lattice sites with each site strongly coupled to a bath of
phonons. We employ Lang-Firsov transformation to make the problem tractable perturbatively. Applying time-convolutionless master equation within the polaron frame, we investigate decoherence dynamics of the dressed
qubit within the singlet-triplet basis of the system for a wide range of bath spectral densities. It is shown that the coherence persists for longer time scales for large coupling values and shows non-monotonic behaviour reflecting the presence of non-Markovianity in the dynamics. Non-Markovianity, characterized by coherence revivals and non-monotonic decay patterns, emerges distinctly depending on the bath spectrum and coupling strengths. Systems coupled to sub-Ohmic baths, whether both or in combination with another type, display pronounced
memory effects at relatively small values of couplings. In contrast, combinations involving Ohmic and super-Ohmic baths exhibit noticeable non-Markovianity only at higher couplings.
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Materials Science
First-principles study on the high-$T_\text{c}$ superconductivity of Mg-Ti-H ternary hydrides up to the liquid-nitrogen temperature range under high pressures
Pan Min, Wang Yujie, Hu Kaige et al. (+1 more)
Ternary hydrides have emerged as the primary focus of the new wave of research into superconducting hydrides. In this work, Mg-Ti-H ternary hydrides are explored under high pressures up to 300 GPa using the prediction method of the particle swarm optimization
algorithm combined with first-principles calculations. Two new structures, $P4/nmm$-MgTiH$_6$ and $Pmm2$-Mg$_3$TiH$_6$, are identified to be thermodynamically stable at both 200 GPa and 300 GPa. Thermodynamically stable structures of Mg$_3$TiH$_{12}$ are also identified, whose space groups are $R3/m$ at 200 GPa and $Pm\bar{3}m$ at 300 GPa, respectively. Among these Mg-Ti-H structures, $P4/nmm$-MgTiH$_6$ achieves a record-high $T_\text{c}$ of 81.9 K at 170 GPa, exceeding the boiling point of
liquid nitrogen. Such a high $T_\text{c}$ is primarily attributed to strong electron-
phonon coupling (EPC) driven by low-frequency acoustic
phonon modes, with the EPC strength reaching a large value of 1.54. The $T_\text{c}$ of $Pm\bar{3}m$-Mg$_3$TiH$_{12}$ is predicted to be 40 K at 300 GPa. Furthermore, element substitution of Zr(Hf) for Ti achieves considerable enhancement of superconducting properties in our predicted hydrogen-rich and high-symmetric
crystal structures, i.e., $P4/nmm$-MgTiH$_6$ and $Pm\bar{3}m$-Mg$_3$TiH$_{12}$. The high pressure required for dynamical stability is lowered to 100 GPa in both $Pm\bar{3}m$-Mg$_3$ZrH$_{12}$ and $Pm\bar{3}m$-Mg$_3$HfH$_{12}$, and to 90 GPa and 120 GPa for $P4/nmm$-MgZrH$_6$ and $P4/nmm$-MgHfH$_6$, respectively. Particularly, the electronic structure near the
Fermi level is significantly modified in the $P4/nmm$-MgHfH$_6$ phase, and pronounced softening of low-frequency acoustic
phonon modes occurs. As a result, the EPC strength is enhanced to 1.72, leading to a higher $T_\text{c}$ of 86 K.
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All authors Pan Min, Wang Yujie, Hu Kaige, Deng Huiqiu
Materials Science
Efficient and Robust p-type Transistor based on Ultra-wide-bandgap Semiconductor
Kaijian Xing, Zherui Yang, Weiyao Zhao et al. (+17 more)
The p-type transistor is an indispensable component of
semiconductor technology, enabling complementary operation with n-channel transistors for computation, storage, and communication. Achieving both high robustness and high efficiency is highly desirable but challenging for p-type transistors due to limited
semiconductors with reliable hole transport and their high activation energies. Here, we achieved a robust yet efficient p-type transistor by heterogeneously integrating an ultra-wide-bandgap
semiconductor and a high-k dielectric layer through van der Waals integration. The p-type transistor employs a two-dimensional hole channel on hydrogenated diamond (bandgap 5.6 eV) combined with a high-k (30.5) SrTiO3 perovskite membrane. At room temperature, the transistor exhibits stable operation with a high on-current (~200 mA/mm), low subthreshold swing (70 mV/dec), high hole mobility (566 cm^2/Vs to 572 cm^2/Vs) and high on-off ratio (~10^9). Furthermore, tuning annealing temperature allows operation in either enhancement or depletion mode. The robust p-type transistor with high efficiency holds great potential for future power electronics, UV optoelectronics, and harsh-environment electronic applications.
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All authors Kaijian Xing, Zherui Yang, Weiyao Zhao, Yuefeng Yin, Huiping Han, Shanhu Wang, Shifan Wang, James Bullock, Alastair Stacey, James A. Belcourt, Sergey Rubanov, Hang Yin, David A. Broadway, Jean-Philippe Tetienne, Xinmao Yin, Liang Wu, Dong-Chen Qi, Michael S. Fuhrer, Qingdong Ou, Xiao Renshaw Wang
Disordered Systems and Neural Networks
Continuum model for the terahertz dielectric response of glasses
Tatsuya Mori, Hideyuki Mizuno, Yuzuki Motokawa et al. (+6 more)
Boson peak dynamics in glasses produce a robust crossover in the terahertz (THz) dielectric response that standard Debye or Lorentz models do not capture. We develop a continuum description of this THz response, coupling an infrared-effective charge fluctuation spectrum to a frequency-dependent shear modulus, and apply it to glycerol glass. The model reproduces the measured complex dielectric function and the nearly linear infrared light-vibration coupling around the
boson peak, and it highlights the dominant role of transverse shear dynamics.
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All authors Tatsuya Mori, Hideyuki Mizuno, Yuzuki Motokawa, Dan Kyotani, Soo Han Oh, Yasuhiro Fujii, Akitoshi Koreeda, Shinji Kohara, Seiji Kojima
Statistical Mechanics
Berezinskii-Kosterlitz-Thouless phase transitions of the antiferromagnetic Ising model with ferromagnetic next-nearest-neighbor interactions on the kagome lattice
Yutaka Okabe and Hiromi Otsuka
We investigate the six-state clock universality of the Ising model on the kagome
lattice, considering
antiferromagnetic nearest-neighbor (NN) and
ferromagnetic next-nearest-neighbor (NNN) interactions. Our comprehensive study employs three approaches: the level-spectroscopy method, Monte Carlo simulations, and a machine-learning phase classification technique. In this system, we observe two Berezinskii-Kosterlitz-Thouless (BKT) transitions. We present a phase diagram consisting of three phases: the low-temperature ordered phase with sublattice magnetizations, the intermediate BKT phase, and the high-temperature disordered phase, as a function of the ratio of the NNN interaction to the NN interaction. We verify the six-state clock universality through the machine-learning study, which uses data from the six-state clock model on the kagome
lattice for training.
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