Materials Science · Cross-listed from cs.CL
LLMs-Powered Accurate Extraction, Querying and Intelligent Management of Literature derived 2D Materials Data
Lijun Shang, Yadong Yu, Wenqiang Kang et al. (+7 more)
Two-dimensional (2D) materials have showed widespread applications in energy storage and conversion owning to their unique physicochemical, and electronic properties. Most of the valuable information for the materials, such as their properties and preparation methods, is included in the published research papers. However, due to the dispersion of synthe
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All authors Lijun Shang, Yadong Yu, Wenqiang Kang, Jian Zhou, Dongyue Gao, Pan Xiang, Zhe Liu, Mengyan Dai, Zhonglu Guo, Zhimei Sun
Strongly Correlated Electrons · Cross-listed from quant-ph
Doublon bound states in the continuum through giant atoms
Walter Rieck, Anton Frisk Kockum and Guangze Chen
Bound states in the continuum (BICs) are spatially localized modes embedded in the spectrum of extended states, typically stabilized by
symmetry or interference. While extensively studied in single-particle and linear systems, the many-body regime of BICs remains largely unexplored. Here, we demonstrate that
giant atoms,
quantum emitters coupled nonlocally to structured waveguides, can host robust doublon BICs, i.e., two-
photon bound states stabilized by destructive interference and interactions. We first analyze a driven two-
photon emission process and show how doublon BICs arise and mediate decoherence-free interaction between distant atoms. We then demonstrate that these many-body BICs also emerge under natural, undriven dynamics via a virtual two-
photon emission process in three-level
giant atoms. Our results reveal an interference-based mechanism for stabilizing many-body localization in open
quantum systems, with potential applications in
quantum simulation, non-ergodic dynamics, and protected
quantum information processing.
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Disordered Systems and Neural Networks · Cross-listed from physics.optics
Multi-port programmable silicon photonics using low-loss phase change material Sb$_2$Se$_3$
Thomas W. Radford, Idris A Ajia, Latif Rozaqi et al. (+7 more)
Reconfigurable photonic devices are rapidly emerging as a cornerstone of next generation optical technologies, with wide ranging applications in
quantum simulation, neuromorphic computing, and large-scale photonic processors. A central challenge in this field is identifying an optimal platform to enable compact, efficient, and scalable reconfigurability. Optical phase-change materials (PCMs) offer a compelling solution by enabling non-volatile, reversible tuning of optical properties, compatible with a wide range of device platforms and current CMOS technologies. In particular, antimony tri-selenide ($\text{Sb}_{2}\text{Se}_{3}$) stands out for its ultra low-loss characteristics at telecommunication wavelengths and its reversible switching. In this work, we present an experimental platform capable of encoding multi-port operations onto the transmission
matrix of a compact multimode interferometer architecture on standard 220~nm silicon photonics using in-silico designed digital patterns. The multi-port devices are clad with a thin film of $\text{Sb}_{2}\text{Se}_{3}$, which can be optically addressed using direct
laser writing to provide local perturbations to the refractive index. A range of multi-port geometries from 2$\times$2 up to 5$\times$5 couplers are demonstrated, achieving simultaneous control of up to 25
matrix elements with programming accuracy of 90% relative to simulated patterns. Patterned devices remain stable with consistent optical performance across the C-band wavelengths. Our work establishes a pathway towards the development of large scale PCM-based reconfigurable multi-port devices which will allow implementing
matrix operations on three orders of magnitude smaller areas than interferometer meshes.
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All authors Thomas W. Radford, Idris A Ajia, Latif Rozaqi, Priya Deoli, Xingzhao Yan, Mehdi Banakar, David J Thomson, Ioannis Zeimpekis, Alberto Politi, Otto L. Muskens
Materials Science
Engineering the Magnetocaloric Effect in Nd$T_4$B
Kyle W. Fruhling, Enrique O. González Delgado, Siddharth Nandanwar et al. (+4 more)
We present a comprehensive study of the magnetocaloric effect (MCE) in the Nd$T_4$B system where $T$ = Fe, Co, and Ni. These compounds are
ferromagnetic kagome materials with tunable ordering temperatures, transition width, and
magnetic moments depending on the choice of transition metal. Thus, they are good candidates for investigating the MCE. We characterize the MCE using standard metrics and construct ternary phase diagrams as functions of Fe, Co, and Ni concentrations. Using these phase diagrams, we engineer the composition NdFe$_{1.15}$Co$_{0.46}$Ni$_{2.39}$B to maximize the MCE. Interestingly, the Nd$T_4$B system shows a notable
entropy change over a wide temperature range ($\sim$10 to 650 K), and particular compositions have notable MCEs spanning hundreds of Kelvin, making this a suitable system to study for technologies used in a wide range of temperatures. In a few cases, we observe a two-peak MCE. These two transitions, releasing comparable
entropy, provide an interesting platform to study for applications in multi-stage cooling.
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All authors Kyle W. Fruhling, Enrique O. González Delgado, Siddharth Nandanwar, Xiaohan Yao, Zafer Turgut, Michael A. Susner, Fazel Tafti
Materials Science
Trigonal Distortion Driven Ground States in VX3 (X = Br and I)
Chamini S. Pathiraja, Deniz Wong, Christian Schulz et al. (+3 more)
Transition-metal halides V$X_3$ ($X$ = Br and I) have emerged as promising candidates for two dimensional spintronic and
quantum applications due to their layer-dependent magnetism and tunable electronic states. However, experimental insights into their ground state electronic structures remain limited. Here, we present a comprehensive investigation of V$X_3$ using high resolution resonant inelastic x-ray scattering (RIXS) combined with ligand field multiplet calculations. The RIXS spectra reveal distinct $dd$ and charge-transfer excitations, allowing precise determination of electronic structure parameters, including the
crystal field splitting, trigonal distortion, and Racah parameters. The determined parameters showed clear variation, indicating an increase in covalency from Br to I. The trigonal distortion parameters $\Delta_{D_{3d}}$ were determined to be -0.096 eV in VBr$_3$ and 0.07 eV in VI$_3$, indicating a sign opposition between the two compounds, reflecting good agreement with experimental RIXS data. Cluster model calculations yield a high-
spin V$^{3+}$ $(S = 1)$ configuration, with an $e'^2_g$ ground state in VBr$_3$ and an $e'^1_ga^1_{1g}$ ground state in VI$_3$, consistent with trigonal elongation and compression, respectively. Our findings provide the most complete experimental determination of the low energy electronic structure in V$X_3$, offering valuable insights for designing 2D
magnetic and spintronic materials based on vanadium halides.
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All authors Chamini S. Pathiraja, Deniz Wong, Christian Schulz, Yi-De Chuang, Yu-Cheng Shao, Byron Freelon
Materials Science
Tuning Breakdown-to-Coercive Field Ratio in Ultra-Thin Al1-xScxN Films via Reactive Nitrogen Atmosphere
Yinuo Zhang, Walter J. Smith, Giovanni Esteves et al. (+3 more)
Al1-xScxN has attracted significant interest due to its large remnant polarization and low processing temperature when compared to other ferroelectric material systems. However, device dielectric failure before ferroelectric switching remains a critical limitation for AlScN-based
memory devices. With the continuing trend toward device miniaturization, expanding the operating window is essential for next-generation
memory development. In this work, we optimized the breakdown field (EBD) and coercive field (EC) in ultra-thin Al1-xScxN films by controlling defect density via adjustment of nitrogen gas flow during sputter deposition. The characteristic breakdown field, EBD, was evaluated using Weibull statistics, yielding optimal characteristic breakdown fields of 12.47 MV/cm (EBD+) and -12.63 MV/cm (EBD-) for samples deposited under 27.5 sccm N2 flow. The minimum EC was achieved at a nitrogen flow of 25 sccm and increased for higher gas flows, a trend that is opposite to previous reports in much thicker films. The highest EBD over EC ratio of 2.25 occurred at 27.5 sccm, effectively expanding the operational window. Using a combination of X-ray diffraction and photoluminescence spectroscopy to study changes in
crystal orientation and defects, device performance can be tuned by controlling the point defect concentration in the ultra-thin film via adjusting the sputtering N2 process gas flow rate.
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All authors Yinuo Zhang, Walter J. Smith, Giovanni Esteves, Eric A. Stach, Thomas E. Beechem, Roy H. Olsson III
Mesoscale and Nanoscale Physics
Effect of two-dimensional nonlocal screening on mobility of electrons in transition-metal dichalcogenide monolayers
Aram Manaselyan, Vram Mughnetsyan, Anna Asatryan et al. (+1 more)
A new mechanism for charge carrier scattering in transition-metal dichalcogenide monolayers is proposed on the basis of the theory of two-dimensional nonlocal screening developed for the dielectric function of thin-layer insulating materials (P. Cudazzo et al. PRB 84, 085406 (2011)). The expressions for the transport relaxation time and for the electron mobility are obtained for electrons scattering on Coulomb
impurity centers in monolayers of transition-metal dichalcogenide on various substrates. It is found that taking nonlocal screening into account increases the mobility of electrons by several times. Although the value of the mobility decreases with increasing temperature, the relative enhancement due to nonlocal screening grows 6-9 times at room temperature, in the case of SiO$_2$ substrate.
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All authors Aram Manaselyan, Vram Mughnetsyan, Anna Asatryan, Albert Kirakosyan
Mesoscale and Nanoscale Physics
Interface-engineered voltage-driven magnetic tunnel junctions with ultra-low-energy magnetization switching
Yu Zhang, Meng Xu, Bowei Zhou et al. (+9 more)
Electric-field control of
spin states offers a promising route to ultra-low-power, ultra-fast magnetization switching in spintronic devices such as
magnetic tunnel junctions (MTJs). Recent progress in modulating
spin-orbit interactions at the interfaces between 3d transition-metal ferromagnets and dielectric layers has underscored the role of atomic-scale heavy-metal doping in optimizing device performance. Here, we experimentally demonstrate highly energy-efficient, voltage-driven magnetization switching in MTJs exhibiting large tunnel magnetoresistance (TMR), enabled by a remote doping technique that precisely controls the iridium (Ir) concentration near the MgO-CoFeB interface in the free layer. Our devices achieve a switching energy of only 3.5 fJ per bit for nanoscale MTJs operating in the sub-nanosecond regime, while maintaining a TMR ratio up to 160 percent after 400 C post-annealing. These findings establish a viable pathway toward scalable, ultra-low-power nonvolatile
memory, positioning voltage-driven MTJs as strong contenders for next-generation magnetoresistive random-access
memory (MRAM) and other emerging spintronic applications.
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All authors Yu Zhang, Meng Xu, Bowei Zhou, Carter Eckel, Supriya Ghosh, Hwanhui Yun, Ali Habiboglu, Deyuan Lyu, Daniel B Gopman, Jian-Ping Wang, K. Andre Mkhoyan, Weigang Wang
Statistical Mechanics
Spectral mechanism and nearly reducible transfer matrices for pseudotransitions in one-dimensional systems
Onofre Rojas
While true phase transitions are forbidden in one-dimensional systems with short-range interactions, several models have recently been shown to exhibit sharp yet analytic thermodynamic anomalies that mimic thermal phase transitions. We show that this behavior arises from transfer
matrices that are mathematically irreducible but possess a nearly block-diagonal structure due to the weak contribution of off-diagonal Boltzmann weights in the low-temperature regime. This results in weakly coupled competing sectors whose
eigenvalue competition produces abrupt crossovers without nonanalyticity, a mechanism we term nearly block-diagonal irreducible. A key thermodynamic signature of such pseudotransitions is that the residual
entropy at the interface remains bounded between the residual
entropies of the competing sectors. We develop a general spectral framework to describe this behavior and apply it to two representative models: the Ising chain with internal degeneracy (Doniach model) and a hexagonal nanowire chain with mixed
spin-1/2 and
spin-1 components. In the first case, we derive exact expressions for the pseudo-critical temperature and residual
entropy. In the second, we reduce the full $1458\times1458$ transfer
matrix via
symmetry decomposition and construct a low-rank effective
matrix that accurately captures the crossover between quasi-
ferromagnetic and quasi-core-
ferromagnetic regimes. Our results demonstrate that pseudotransitions can be understood as spectral phenomena emerging from irreducible but functionally decoupled structures within the transfer
matrix.
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Soft Condensed Matter
Scale-Rich Network-Based Metamaterials
Csaba Both, Andrew Yen-Jong Chen, Ting-Ting Gao et al. (+4 more)
Materials, at their essence, are networks defined by homogeneity: uniform bonds, fixed thicknesses, and discrete length scales. Mechanical metamaterials, while representing structurally more diverse microstructures, remain defined by the homogeneity of their unit
cells, pore sizes, or repeating features. In contrast, as network science has revealed, real-world and biological systems – from the Internet to the
brain – derive their function from broad, multiscale variability in connectivity and link length. Here, we introduce Scale-Rich (SR) metamaterials, a design framework that embeds network heterogeneity into mechanical metamaterials, achieving order-of-magnitude heterogeneity in ligament lengths, thicknesses, and connectivity. Governed by only two parameters, SR networks span orders of magnitude in structural features, overcoming prior constraints in metamaterial design. Translating these network models into physically realizable materials, we use simulations and experiments to show that SR metamaterials exhibit properties inaccessible to traditional single-scale systems, including highly tunable elastic anisotropy, delocalized nonlinear deformation with high energy absorption, and programmable acoustic wave control. This network-science-based paradigm establishes a minimal yet universal framework for engineering multifunctional materials whose mechanical and acoustic behavior emerge directly from scale diversity itself.
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All authors Csaba Both, Andrew Yen-Jong Chen, Ting-Ting Gao, Niek Mooij, Mohammad Charara, Carlos M. Portela, Albert-László Barabási
Quantum Gases
Proposals for realizing a Josephson diode in Atomtronic circuits
Nalinikanta Pradhan, Rina Kanamoto, M. Bhattacharya et al. (+1 more)
The Josephson diode, a non-reciprocal
quantum element analogous to the familiar
semiconductor p-n junction diode, has been realized in solid-state systems but remains unexplored in tunable atomtronic
circuits. In this work, we propose and numerically demonstrate the realization of the Josephson diode effect in an atomtronic
circuit consisting of a ring-shaped Bose-Einstein condensate and with optical barriers serving as Josephson junctions. Our implementation of this macroscopic non-reciprocal
quantum phenomenon is based on realizing the required inversion
symmetry breaking through asymmetric barrier placement and an asymmetric alternating current (AC) drive, enabling position- and drive-tunable diode effects with efficiencies up to 15% and 91%, respectively. While standard time-of-flight absorption imaging can readily observe these effects, we employ cavity optomechanics for in situ, real-time, and non-destructive measurements of the relevant condensate dynamics. Our results establish a highly tunable platform for nonreciprocal Josephson transport, opening avenues for diode-based neutral-atom technologies in future
quantum circuits.
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All authors Nalinikanta Pradhan, Rina Kanamoto, M. Bhattacharya, Pankaj Kumar Mishra
Soft Condensed Matter
Active motility and wetting cooperatively regulate liquid-liquid phase separation
Dixi Yang, Anheng Wang, Chunming Wang et al. (+2 more)
Liquid–
liquid phase separation in aqueous two-phase systems is widespread in physical and biological settings, yet how motile
agents regulate its morphology and kinetics remains poorly understood. Combining experiments on Pseudomonas aeruginosa in a dextran–polyethylene glycol mixture with hydrodynamic simulations, we show that interfacial wetting couples bacterial motility to phase-separation dynamics. At high dextran fraction, bacteria-driven rotational flows shear inter-droplet gaps and hinder
liquid-bridge formation, thereby suppressing coalescence and coarsening. As the dextran fraction decreases, wetting-driven bridging becomes increasingly important, producing an intermediate chain-like state and, ultimately, branched bacterial clusters in which activity instead accelerates capture and aggregation. A biofilm-associated
protein provides an independent wetting component that similarly promotes bacterial clustering. These results reveal a composition-controlled crossover between activity-induced suppression of coalescence and wetting-dominated bridging.
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All authors Dixi Yang, Anheng Wang, Chunming Wang, Hajime Tanaka, Jiaxing Yuan
Materials Science
Hydrogen diffusion in TiCr$_2$H$_x$ Laves phases: A combined ab initio and machine-learning-potential study
Pranav Kumar, Fritz Körmann, Kaveh Edalati et al. (+2 more)
The kinetics of hydrogen
diffusion in C15 cubic and C14 hexagonal TiCr$_2$H$_x$ (0 < $x$ <= 4) Laves-phase hydrogen storage
alloys is investigated with density functional theory (DFT) and machine learning interatomic potentials (MLIPs). Generalized solid-state nudged elastic band calculations are conducted based on DFT for all symmetrically inequivalent paths between the first-nearest-neighbor face-sharing interstitial sites. The hydrogen migration barriers are substantially higher for the paths that require breaking a Ti-H bond than for those that require breaking a Cr-H bond. Molecular dynamics (MD) simulations with the MLIPs also demonstrate that hydrogen migration occurs more frequently within the hexagonal rings made of the A$_2$B$_2$ interstitial paths, each requiring the breaking of Cr-H bonds, than along the inter-ring paths. The
diffusion coefficients of hydrogen obtained from the MD simulations reveal a non-monotonic dependence on hydrogen concentration, which is more pronounced at lower temperatures. Time-averaged radial distribution functions of hydrogen further show that hydrogen avoids face-sharing positions during
diffusion and that the hydrogen occupancy at the second-nearest-neighbor edge-sharing positions increases with increasing hydrogen concentration. The
diffusion coefficients of hydrogen within 400-1000 K follow an Arrhenius relationship, with activation barriers consistent with most experimental values. One-order of magnitude overestimation of
diffusion coefficients compared with some experiments suggests a substantial impact of hydrogen trapping by defects such as Cr vacancies and Ti anti-sites in non-stoichiometric TiCr$_2$ in experiments.
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All authors Pranav Kumar, Fritz Körmann, Kaveh Edalati, Blazej Grabowski, Yuji Ikeda
Strongly Correlated Electrons
Many-body electronic structure in pyrochlore superconductor CsBi2 and spin liquid Pr2Ir2O7
Wei Song, Guowei Liu, Hanbin Deng et al. (+26 more)
The pyrochlore
lattice materials can exhibit geometrical frustration, while the related many-body electronic states remain elusive. In this work, we performed scanning tunneling microscopy measurements on the pyrochlore
superconductor CsBi2 and
spin liquid Pr2Ir2O7 at 0.3 K. For the first time, we obtained atomically resolved images of their (111) surfaces, revealing a hexagonal
lattice or a kagome
lattice. Tunneling spectroscopy in CsBi2 reveals a nearly fully opened superconductivity gap. The ratio of 2{\Delta}/kBTC = 4.7 suggests relatively strong coupling superconductivity, as compared with that in kagome
superconductors AV3Sb5 (A = K, Rb, Cs). In contrast to the previous study categorizing CsBi2 as a type-I
superconductor, the applied
magnetic field induces a hexagonal
vortex lattice in which each
vortex core exhibits an intriguing three-fold
symmetry state. In Pr2Ir2O7, we observed a spatially homogeneous Kondo-
lattice resonance, which is compared with that in the kagome Kondo-
lattice material CsCr6Sb6. We further discover that the Kondo resonance exhibits a spatial modulation with three-fold
symmetry, and the applied
magnetic field induces a Zeeman splitting of the Kondo resonance with intriguing atomic site dependence. We discuss the relations of these many-body electronic phenomena with the pyrochlore
lattice geometry and its charge or
spin frustration. Our systematic observations offer atomic-scale insights into the many-body electronic structures of the geometrically frustrated pyrochlore
superconductors and
spin liquids.
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All authors Wei Song, Guowei Liu, Hanbin Deng, Tianyu Yang, Yongkai Li, Xiao-Yu Yan, Ruoxing Liao, Qianming Wang, Jiayu Xu, Chao Yan, Yuanyuan Zhao, Hailang Qin, Da Wang, Wenchuan Jing, Dawei Shen, Kosuke Nakayama, Takafumi Sato, Chandan Setty, Desheng Wu, Boqing Song, Tianping Ying, Zhaoming Tian, Akito Sakai, Satoru Nakatsuji, Harish Kumar, Christine A. Kuntscher, Zhiwei Wang, Qi-Kun Xue, Jia-Xin Yin
Mesoscale and Nanoscale Physics
Minimizing energy dissipation during programming of resistive switching memory devices using their dynamical attractor states
Valeriy A. Slipko, Alon Ascoli, Fernando Corinto et al. (+1 more)
Under certain conditions, applying a sequence of voltage pulses of alternating polarities across a resistive switching
memory device induces a finite number of fixed-point attractors in its time-averaged dynamics, known as dynamical attractors. Remarkably, dynamical attractors can be used to program analog values into the device state without supervision. Because different pulse sequences can produce the same trajectory solution for the state in the phase space, there is strong potential for optimization, particularly regarding the energy cost of the programming phase, which this study addresses. The proposed theory-based energy minimization strategy is applied to the voltage threshold adaptive memristor (VTEAM) model, which is known for its predictive capability and adaptability in fitting a large number of resistive switching
memory devices. The optimization design crafts ad-hoc pulse sequences that minimize the energy required to program the device into a desired dynamical attractor. The theoretical approach is also extended to cover situations where a fast programming scheme should be adopted to serve time-critical electronics applications.
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All authors Valeriy A. Slipko, Alon Ascoli, Fernando Corinto, Yuriy V. Pershin
Quantum Gases
Effective action approach to quantum and thermal effects: from one particle to Bose-Einstein condensates
Luca Salasnich
We present a detailed derivation of the
quantum and
quantum-thermal effective action for non-relativistic systems, starting from the single particle case and extending to the Gross-Pitaevskii (GP) field theory for weakly interacting
bosons. In the single-particle framework, we introduce the one-particle irreducible 1PI effective action formalism taking explicitly into account the choice of the initial
quantum state, its saddle-point plus Gaussian fluctuation approximation, and its finite temperature extension via Matsubara summation. This yields a clear physical interpretation in terms of zero-point and thermal contributions to the Helmholtz free energy. The formalism is then applied to the GP action producing the 1PI effective potential at zero and finite temperature including beyond-mean-field Lee-Huang-Yang and thermal corrections. We discuss the gapless and gapped Bogoliubov spectra, their relevance to
equilibrium and nonequilibrium regimes, and the role of regularization. Applications include the inclusion of an external potential within the local density approximation, the derivation of finite-temperature Josephson equations, and the extension to D dimensional systems. This unified approach provides a transparent connection between microscopic
quantum fluctuations and effective macroscopic equations of motion for Bose-Einstein condensates.
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Soft Condensed Matter
Deformation and organization of droplet-encapsulated soft beads
Shunsuke Saita, Finn Bastian Molzahn, Clara Delahousse et al. (+2 more)
Many biological, culinary, and engineering processes lead to the co-encapsulation of several soft particles within a
liquid interface. In these situations the particles are bound together by the capillary forces that deform them and influence their biological or rheological properties. Here, we introduce an experimental approach to encapsulate a controlled number of soft beads within aqueous droplets in oil. These droplet-encapsulated gels are manipulated in a deformable microfluidic device to merge them and modify the
liquid fraction. In the dry limit the contact surface between the hydrogels is found to be determined by the elastocapillary number $E_c$, with the contact radius following a $E_c^{1/3}$ dependence, indicating that the deformation increases for soft or small particles. When multiple beads are co-encapsulated within a single droplet they can be arranged into linear or three-dimensional aggregates that remain at a local energy minimum.
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All authors Shunsuke Saita, Finn Bastian Molzahn, Clara Delahousse, Julien Husson, Charles N. Baroud
Materials Science
PyAPX: Python toolkit for atomic configuration pattern exploration
Akira Kusaba, Tetsuji Kuboyama, Karol Kawka et al. (+2 more)
In materials discovery, the integration of first-principles calculations with machine learning techniques has been actively studied for two key tasks:
crystal structure prediction, which searches for stable structures given a chemical composition, and elemental substitution, which explores chemical compositions that yield desirable properties in a given
crystal structure. However, even when both the
crystal structure and chemical composition are fixed, material properties can still vary depending on the atomic arrangements (configurations) at crystallographic sites. To support detailed material design, we present PyAPX, a Python toolkit that performs
Bayesian searches of stable atomic configurations. A distinctive feature of this initial release is the introduction of encoding methods suitable for configuration search, and we evaluate their performance using the h-BCN system. As a result, they were confirmed to yield superior convergence compared to commonly used one-hot encoding. PyAPX is broadly applicable to crystalline materials and is expected to further advance materials discovery.
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All authors Akira Kusaba, Tetsuji Kuboyama, Karol Kawka, Pawel Kempisty, Yoshihiro Kangawa
Materials Science
Density functional theory for core-level X-ray absorption
Seokkyu An and Taisuke Ozaki
We establish a rigorous density functional theory (DFT) framework for core-level X-ray absorption spectroscopy (XAS) by formulating a constrained search for core-excited states based on the Gunnarsson-Lundqvist
theorem. Within this framework, the explicit-core Delta SCF scheme enables shift-free absolute edge
alignment and a consistent treatment of L/M edges with
spin-orbit-resolved projectors. In addition, by exploiting dipole selection rules, we recast the evaluation of the dipole
matrix elements, which otherwise requires many independent Slater determinant calculations, into a compact single determinant form. This reduces the computational scaling from $\mathcal{O}(N^4)$ to $\mathcal{O}(N^3)$, where $N$ is the number of electrons, without introducing additional approximations. Across representative C, B, O, and Li K-edge
benchmarks in molecules and solids, the method reproduces line shapes, polarization anisotropies, and absolute onsets without empirical shifts, providing a robust and scalable route to quantitatively reliable XAS simulations within DFT.
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Materials Science
2D-RIXS: Resonant inelastic x-ray scattering microscopy with high energy and spatial resolutions
Kohei Yamamoto, Hakuto Suzuki and Jun Miyawaki
A two-dimensional resonant inelastic x-ray scattering (2D-RIXS) microscopy system has been developed at the beamline BL02U of NanoTerasu. The instrument combines a Wolter type-I mirror for spatial imaging with a varied-line-spacing grating spectrometer, simultaneously achieving micrometer-scale spatial resolution and ultrahigh energy resolution in the soft x-ray regime. Test chart measurements confirm a vertical spatial resolution of 1.0 um near the field-of-view center, and the horizontal resolution determined by the incident beam footprint is 0.8 um. RIXS imaging capabilities have been demonstrated by the measurements of a patterned NanoTerasu logo and exfoliated NiPS${}_3$ nanoflakes, highlighting its efficiency in locating specific microscale regions within inhomogeneous samples. These results establish 2D-RIXS microscopy as a position-sensitive probe of elementary excitations in
quantum materials and functional devices.
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Disordered Systems and Neural Networks · Cross-listed from quant-ph
Brute-force positivization of $J_1-J_2$ model ground states
P. A. Bannykh, O. M. Sotnikov and V. V. Mazurenko
Exploring sign structures of
quantum wave functions attracts considerable
attention due to the potential for advances in modeling complex phases of matter. This stimulates developing different optimization procedures for imitating and manipulating sign structures of
quantum states. In this work, utilizing a brute force approach based on a set of single-
qubit transformations we evaluate protocols enabling positivization of the one-dimensional $J_1 -J_2$ model ground states in the regime of strong frustration. Based on the obtained positivization results, we show the difference between the cases of periodic and open boundary conditions, and also establish the dependence of the sign structure on parity of the simulated
spin chains.
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Materials Science
Hexagonal polymorphism induced structural disorder and dielectric anomalies of Ca/Mn modified BaTiO3
P. Maneesha, Dilip Sasmal, Rakhi Saha et al. (+7 more)
This work involves the local structural investigation of the samples using Extended X-ray Absorption Spectra (EXAFS) analysis to investigate structural changes due to the Ca and Mn-modified BaTiO3. TEM investigation of the
crystal structure reveals the coexistence of the tetragonal and hexagonal phases of BaTiO3. Band gap modification and Urbach tail variation in UV-DRS measurements reveal a reduction of band gap from UV to Visible range (3.2 eV to 2 eV). This band gap change is correlated with the valence band modification observed in PES measurements due to localised defects in the material, and supported by theoretical Density of States calculations. The electron localisation function calculation is used to analyse the changes in the localised electron density near the dopant atoms. It reveals the local expansion and contraction of the
lattice surrounding the dopant atom. All these structural modifications lead to variations in the dielectric properties and diffusive nature of the phase transition. The defect-induced structural modifications, multiple phase coexistence, band gap variations and dielectric properties are explored and correlated.
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All authors P. Maneesha, Dilip Sasmal, Rakhi Saha, Kiran Baraik, Soma Banik, R. Mittal, Mayanak K. Gupta, Abdelkrim Mekki, Khalil Harrabi, Somaditya Sen
Soft Condensed Matter
Dynamic Slowdown and Spatial Correlations in Viscous Silica Melt: Perspectives from Dynamic Disorder
Shubham Kumar, Zhiye Tang and Shinji Saito
The dynamic slowdown in glass-forming
liquids remains a central topic in condensed matter science. Here, we report a theoretical investigation of the microscopic origin of the slowdown in amorphous silica, a prototypical strong glass former with a tetrahedral network structure. Using molecular dynamics simulations, we analyze atomic jump dynamics, the elementary structural change processes underlying relaxation. We find that the jump statistics deviate from Poisson behavior with decreasing temperature, reflecting the emergence of dynamic disorder in which slowly evolving variables modulate the jump motion. The slowdown is species-dependent: for silicon, the primary constraint arises from the fourth-nearest oxygen neighbor, while at lower temperatures, the fourth-nearest silicon also becomes relevant; for oxygen, the dominant influence comes from the second-nearest silicon neighbors. As the system is cooled, the jump dynamics become increasingly slow and intermittent, proceeding in a higher-dimensional space of multiple slow variables that reflect cooperative rearrangements of the network. Species-resolved point-to-set correlations further reveal that the spatial extent of cooperative relaxation grows differently for silicon and oxygen, directly linking their relaxation asymmetry to the extent of collective motion. Together, these results provide a microscopic framework linking dynamic disorder, species-dependent constraints, and cooperative correlations, offering deeper insight into the slowdown of strong glass-forming networks.
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Materials Science
Appraising the absolute limits of nanotubes and nanospheres to preserve high-pressure materials
Yin L. Xu, Guang F. Yang, Yi Sun et al. (+5 more)
Matter under high pressure often exhibits attractive properties, which, unfortunately, are typically irretrievable when released to ambient conditions. Intuitively, nanostructure engineering might provide a promising route to contain high-pressure phase of materials because of the exceptional mechanical strength at nanoscale. However, there is no available theoretical model that can analyze this possibility, not to mention to quantitatively evaluate the pressure-bearing capability of nano-cavities. Here, a physical model is proposed to appraise the absolute theoretical limit of various nanotubes/nanospheres to preserve high-pressure materials to ambient conditions. By incorporating with first-principles calculations, we screen and select four types of representative nanomaterials:
graphene, hexagonal boron nitride (h-BN), biphenylene, and {\gamma}-graphyne, and perform systematic investigations. The results indicate that nanotube/nanosphere of
graphene exhibits the best pressure-bearing capability, followed by h-BN, biphenylene and {\gamma}-graphyne. Our model reveals that the structure with the largest average binding energy per bond and the highest density of bonds will have the highest absolute limit to contain pressure materials, while electron/hole doping and interlayer interactions have minor effects. Our finding suggests that one can utilize nanotube/nanosphere with multiple layers to retrieve compressed material with higher pressures. For example, a single layer
graphene sphere can retrieve compressed LaH10 with a volume size of 26 nm3 that corresponding to a pressure of 170 GPa and with a near room temperature
superconductor transition of Tc=250 K. Similarly, in order to retrieve the metastable atomic hydrogen or molecular metallic hydrogen at about 250 GPa, it requires only three layers of a nanosphere to contain a volume size of 173 nm^3.
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All authors Yin L. Xu, Guang F. Yang, Yi Sun, Hong X. Song, Yu S. Huang, Hao Wang, Xiao Z. Yan, Hua Y. Geng
Mesoscale and Nanoscale Physics · Cross-listed from physics.app-ph
Validation of the copper equation of state via shock loading experiments of loosely associated powders
Yufeng Wang, Long Hao, Lixin Liu et al. (+5 more)
High-fidelity shock experiments were performed on copper powders with controlled porosity via improved target fabrication and assembly. Optical velocimetry and multi-channel pyrometry were used to obtain Hugoniot data, isentropic release paths, and interface temperature histories. The results validate a modified two-phase equation of state (EOS) for copper based on the framework of Greeff et al. The measured Hugoniot shows good agreement with the present model but exhibits significant softening above ~156 GPa relative to the original Greeff EOS, indicating that reduction in
lattice specific heat becomes essential when shock temperatures exceed three times the melting point (T > 3Tm). Unloading behavior matches hydrodynamic simulations incorporating the recalibrated EOS, confirming its accuracy for off-Hugoniot states. Theoretical analysis of temperature release profiles suggests that the thermal conductivity of shocked copper powders may be considerably higher than first-principles predictions. Crucially, despite heterogeneity in shock heating, the macroscopic dynamic response of copper powders with a porosity of ~1.7 is well captured by an average-density EOS model, supporting the use of porous material experiments for EOS validation under extreme conditions.
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All authors Yufeng Wang, Long Hao, Lixin Liu, Fengchao Wu, Shijia Ye, Yuanchao Gan, Yi Sun, Hua Y. Geng