Materials Science
Accurate Modeling of Gate Leakage Currents in SiC Power MOSFETs
Ang Feng, Alexander Karl, Dominic Waldhör et al. (+3 more)
Silicon carbide (SiC) metal-
oxide-
semiconductor field-effect-transistors (MOSFETs) enable high-voltage and high-temperature power conversion. Compared to Si devices, they suffer from pronounced gate leakage due to the reduced electron tunneling barrier at the interface between SiC and amorphous silicon dioxide (a-SiO$_2$). We develop a self-consistent, physics-based simulation framework that couples electrostatics,
quantum tunneling, carrier transport, impact ionization, and charge trapping for both electrons and holes. The model quantitatively reproduces measured gate-current-voltage characteristics of SiC MOS capacitors over a wide temperature (80-573 K) range and a wide bias range without empirical fitting. Simulations reveal that conduction electrons in a-SiO$_2$ can trigger impact ionization, which generates electron-hole pairs, and leads to capture of holes in the
oxide bulk, thereby enhancing gate leakage current. The framework captures these coupled processes across multiple orders of magnitude in time and field, providing predictive capability for
oxide reliability. Although demonstrated for SiC devices, the methodology also applies to Si technologies that uses the same gate dielectric.
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All authors Ang Feng, Alexander Karl, Dominic Waldhör, Marina Avramenko, Peter Moens, Tibor Grasser
Strongly Correlated Electrons
Ultrafast Stiffening of the Lattice Potential and Metastable State Formation in 1$T$-TiSe$_2$
Xue-Qing Ye, Hao Liu, Qi-Yi Wu et al. (+8 more)
We use ultrafast optical spectroscopy to investigate the electronic and
lattice dynamics of the charge-density wave (CDW) material 1$T$-TiSe$_2$ across various temperatures and pump fluences. We reveal a close relationship between the observed ultrafast dynamical processes and two characteristic temperatures: $T_{\rm CDW}$ ($\sim$202 K) and $T^*$ ($\sim$165 K). Two coherent
phonon modes are identified: a high-frequency $A_{1g}$ mode ($\omega_{1}$) and a lower-frequency $A_{1g}$ CDW amplitude mode ($\omega_{2}$). In stark contrast to thermal melting, where
phonons soften, the CDW amplitude mode exhibits anomalous hardening (frequency upshift) with increasing pump fluence. We establish this hardening as the direct signature of an ultrafast restoration of the bare
lattice potential. The photoexcited carrier
plasma screens the long-range electron-
phonon interactions that drive the Peierls-like instability, effectively “undressing" the soft
phonon and driving its frequency toward the stiffer value of the unrenormalized
lattice. Furthermore, an abrupt increase in the excited state buildup time above a critical pump fluence marks a sharp boundary to a photoinduced metastable metallic state. These findings demonstrate that the CDW order in 1$T$-TiSe$_2$ is governed by a fragile, fluence-tunable competition between excitonic correlations and
lattice dynamics.
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All authors Xue-Qing Ye, Hao Liu, Qi-Yi Wu, Chen Zhang, Xiao-Fang Tang, Bo Chen, Chuan-Cun Shu, Hai-Yun Liu, Yu-Xia Duan, Peter M. Oppeneer, Jian-Qiao Meng
Materials Science
Strengthening and toughening mechanisms in heterostructured laminates revealed by a phase field-enhanced crystal plasticity simulation
Yukai Xiong, Jianfeng Zhao, Jinling Liu et al. (+3 more)
Heterostructured (HS) materials exhibit excellent mechanical properties, combining high strength and significant ductility. Hetero-deformation-induced (HDI) hardening and strain de-localization are key to their strength-ductility synergy. However, existing models often fall short in addressing these aspects. In this work, a coupled framework integrating strain gradient
crystal plasticity and phase field damage models is developed. The interface dominated HDI hardening in HS laminates is handled by introducing a heterogeneity coefficient into the back stress. The phase field model accounts for defect energy-driven damage and accurately represents the materials ductile damage behavior by accounting for effects of microstructure on crack initiation and propagation. Simulation results on HS laminates align well with experimental results and reflect the distribution of geometrically necessary dislocations and back stresses at interfaces between regions with dissimilar microstructure. Crack initiation and propagation are accurately described, providing valuable insights into fracture behavior. The model can predict how strength and ductility change upon variations of the HS laminate microstructure, thus providing an essential tool for microstructure optimization. This work enhances the understanding of deformation mechanisms in HS laminates and provides valuable insights for design and optimization of this class of materials.
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All authors Yukai Xiong, Jianfeng Zhao, Jinling Liu, Jie Wang, Michael Zaiser, Xu Zhang
Materials Science
Let Cyclic Electrochemical Data Speak for Your Energy Storage Material and Processing
Vinod Sarky, P. Laxman Mani Kanta, Shivangi Keshri et al. (+3 more)
Efforts to improve performance, like energy and power density of electrochemical energy storage devices (batteries, capacitors, and super-capacitors), are being made using a range of experimental and computational tools. The most common strategy involves exploring new material chemistries, developing advanced synthesis routes, and advanced ways to integrate these materials into device architectures. Although it is desirable to evaluate the performance of such efforts at a fixed
cell format, not all studies conduct testing across the same
cell formats. Specific performance normalized per mass of active material has been adopted as a universal indicator of performance, but it is not a reliable way to compare across
cell formats. We propose a new mass normalization, i.e., the mass of electrochemical participants, to calculate specific performance. This new specific performance makes it possible to efficiently compare the efficacy of materials, synthesis, and
cell assembly across different
cell formats. We developed a framework to comprehensively report materials, synthesis, and
cell assembly, and performance data, which facilitates succinctly reporting all performance indicators, including charge discharge curves over all cyclic stability assessments. The new specific performance and mass of the electrochemical participants per unit area of the electrode allows us to create a calculator to estimate performance at any commercial device-level
cell format from measured data at the laboratory-level
cell. The new specific performance also helps in optimizing the coating thickness and the loading of the active material. The framework can be adapted by journals to facilitate the reporting of data in a comprehensive way. Leveraging this framework, we have also compiled a database (hosted at https://power.tattvasar.com/) by extracting pertinent data from existing literature.
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All authors Vinod Sarky, P. Laxman Mani Kanta, Shivangi Keshri, Mannanvali Shaik, B. R. K. Nanda, Satyesh K. Yadav
Superconductivity
Intrinsic and Tunable Superconducting Diode Effect in Quantum Spin Hall Systems
Samuele Fracassi, Simone Traverso, Stefan Heun et al. (+3 more)
Nonreciprocal dissipationless transport has long been sought for applications in superconducting technologies. Recently, it has been implemented by the so called superconducting diode effect. Such effect arises from an imbalance in critical supercurrents flowing in opposite directions. In this work, we theoretically demonstrate how the superconducting diode effect emerges in the
quantum spin Hall phase when brought into full proximity with a
superconductor. We explore two regimes: large and narrow
quantum wells. In the former geometry, we show that the superconducting diode effect can be externally controlled using both
magnetic and electric fields, achieving unit efficiency. In the latter regime, where tunneling between opposite edges may occur, we propose a mechanism for an intrinsic superconducting diode effect driven by edge reconstruction, which does not require external
magnetic fields.
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All authors Samuele Fracassi, Simone Traverso, Stefan Heun, Maura Sassetti, Matteo Carrega, Niccolo Traverso Ziani
Soft Condensed Matter
Size control guidelines for chemically active droplets
Guido Kusters and David Zwicker
Biological
cells and synthetic analogues use
liquid-
liquid phase separation to dynamically compartmentalize their environment for various applications. In many cases, multiple droplets need to coexist, and their size needs to be controlled, which is challenging because large droplets tend to grow at the expense of smaller ones. Chemical reactions can, in principle, control droplet sizes, but there are no clear guidelines on how to robustly achieve size control. To provide guidelines, we consider a binary fluid model driven out of
equilibrium by chemical reactions. We reveal two different classes of size-controlled droplets, depending on the ratio of droplet radius to the reaction-
diffusion length. Moreover, we determine parameter regimes in which droplets become small. Taken together, our theory allows us to separately predict the chemical reactions necessary for maintaining droplets of a given class or size.
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Mesoscale and Nanoscale Physics
Tobias Rockinger, Bálint Szentpéteri, Szabolcs Csonka et al. (+10 more)
Recently, proximity-induced
spin-orbit coupling (SOC) has been observed in
heterostructures consisting of monolayer
graphene (ML-G) and transition metal dichalcogenides (TMDCs) such as WSe$_{2}$. Successful tuning of SOC in
graphene/WSe$_{2}$
heterostructures by applying mechanical pressure and electric fields was also demonstrated in previous studies. In addition, theoretical calculations predicted a strong dependence of the proximity-induced SOC on the twist angle between
graphene and TMDC. Here, we put these predictions to experimental test in ML-G/ML-WSe$_{2}$/hBN-
heterostructures, where the twist angle is determined by aligning fractured edges, and by crystallographic etching of
graphene. By performing weak anti-localization measurements, we determine the strength of the Rasbha-type SOC ($\lambda_\mathrm{R}$) and the valley-Zeeman-type SOC ($\lambda_\mathrm{VZ}$). Our experiments confirm a strong twist angle dependence of the proximity-induced SOC in agreement with theoretical predictions. Finally, we demonstrate the tunability of the SOC strength via mechanical pressure, which is in agreement with earlier findings.
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All authors Tobias Rockinger, Bálint Szentpéteri, Szabolcs Csonka, Marina Marocko, Julia Amann, Ziyang Gan, Antony George, Andrey Turchanin, Kenji Watanabe, Takashi Taniguchi, Dieter Weiss, Péter Makk, Jonathan Eroms
Statistical Mechanics
Mean First Passage Time of the Symmetric Noisy Voter Model with Arbitrary Initial and Boundary Conditions
Rytis Kazakevičius and Aleksejus Kononovicius
Models of imitation and herding behavior often underestimate the role of individualistic actions and assume symmetric boundary conditions. However, real-world systems (e.g., electoral processes) frequently involve asymmetric boundaries. In this study, we explore how arbitrarily placed boundary conditions influence the mean first passage time in the symmetric noisy voter model, and how individualistic behavior amplifies this asymmetry. We derive exact analytical expressions for mean first passage time that accommodate any initial condition and two types of boundary configurations: (i) both boundaries absorbing, and (ii) one absorbing and one reflective. In both scenarios, mean first passage time exhibits a clear asymmetry with respect to the initial condition, shaped by the boundary placement and the rate of independent transitions.
Symmetry in mean first passage time emerges only when absorbing boundaries are equidistant from the midpoint. Additionally, we show that Kramers' law holds in both configurations when the rate of independent transitions is large. Our analytical results are in excellent agreement with numerical simulations, reinforcing the robustness of our findings.
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Strongly Correlated Electrons
Thouless pumps and universal geometry-induced drift velocity in multi-sliding quasi-periodic lattices
Zixun Xu and Yuan Yao
Quantized Thouless pumps in periodic systems, set by Chern numbers or Wannier-center winding, is by now fairly well established, whereas its quasi-periodic extensions still require further clarification. Here, we develop a general quantitative paradigm for bulk Thouless pumps in continuous models with spacetime quasi-periodicity, applicable to arbitrary spatial dimensions. Within this framework, the bulk pumping turns out to be governed by an emergent long wave-length effective potential. Based on this mechanism, we obtain our main result a universal relation between topological drifting and the geometry of quasi Brillouin zone. Reduced to periodic systems, our result gives an explicit and compact formula which enables us to directly calculate Chern numbers by microscopic data. These proposals are corroborated by simulations of one- and two-dimensional continuous moiré-type spacetime quasi-periodic
lattices, which exhibit stable, localized, directional drift in excellent agreement with the theory.
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Strongly Correlated Electrons · Cross-listed from quant-ph
Improved Ising Meson Spectroscopy Simulation on a Noisy Digital Quantum Device
Hao-Ti Hung, Isabel Nha Minh Le, Johannes Knolle et al. (+1 more)
The transverse-field Ising model serves as a paradigm for studying confinement and excitation spectra, particularly the emergence of $E_8$
symmetry near criticality. However, experimentally resolving the Ising
meson spectroscopy required to verify these
symmetries is challenging on near-term
quantum hardware due to the depth of
circuits required for real-time
evolution. Here, we demonstrate improved spectroscopy of confined excitations using two distinct error-resilient
circuit construction techniques on the IBM Torino device: first-order Trotter decomposition utilizing native fractional gates, and a tensor-network-based
circuit compression via Riemannian optimization. By analyzing the
Fourier spectrum of error-mitigated time-series data, we successfully identify key signatures of $E_8$
symmetry despite hardware noise. These results validate the viability of both
circuit compression and hardware-efficient compilation for probing complex topological phenomena on NISQ devices.
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All authors Hao-Ti Hung, Isabel Nha Minh Le, Johannes Knolle, Ying-Jer Kao
Materials Science
Low-temperature thermal conductivity of the substrate material YAlO3 and its unconventional sister compound YbAlO3
Parisa Mokhtari, Ulrike Stockert, Stanislav E. Nikitin et al. (+3 more)
We present thermal conductivity data on single
crystals of YAlO3 and YbAlO3 for temperatures between 2 K and 300 K and the heat current along b and c. Both materials are very good thermal conductors in the investigated temperature range. The thermal conductivity in these electrical
insulators is due to
phonons. The effect of Y-Yb exchange is found to be rather small despite the considerable difference in density and average atomic mass. For YAlO3 we find a moderate thermal conductivity anisotropy with weak temperature dependence and a ratio of c to b direction between at most 1 and 2.2. It is discussed with regard to the velocities of sound and relevant scattering processes. For YbAlO3 the small
crystal size limits the precision of absolute thermal conductivity values and does not allow drawing conclusions on the anisotropy. Our results on YAlO3 confirm that the material is suitable for applications requiring a good thermal conductivity at temperatures down to
liquid helium, such as
lasers, substrates, and detectors.
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All authors Parisa Mokhtari, Ulrike Stockert, Stanislav E. Nikitin, Leonid Vasylechko, Manuel Brando, Elena Hassinger
Strongly Correlated Electrons
Emergent Chiral Spin Crystal Phase in (111) SrRuO3 Thin Films
Zhaoqing Ding, Yongjie Xie, Xuejiao Chen et al. (+13 more)
Perovskite ruthenates are fascinating playgrounds for exploring topological
spin textures, but generally rely on extrinsic mechanisms to trigger the noncoplanar states. Here we report the discovery of an emergent
chiral spin crystal phase in (111) SrRuO3 epitaxial films, characterized by a significant topological
Hall effect and noncoplanar
spin arrangements with different propagation vectors along two orthogonal directions. Instead of driven by the enhanced Dzyaloshinskii-Moriya interaction due to broken inversion
symmetry at heterointerfaces, this emergent state arises intrinsically from the interplay of dipolar interactions and
magnetic frustration, leading to the stabilization of topological phases in much thicker films. These findings open a new pathway for creating and controlling the topological
spin states in perovskites, with broad implications for spintronic device design.
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All authors Zhaoqing Ding, Yongjie Xie, Xuejiao Chen, Sheng Wang, Zhen Wang, Zeguo Lin, Enling Wang, Xiaofeng Wu, Mingyu Yang, Yuelong Xiong, Meng Meng, Fang Yang, Jiandi Zhang, Xianggang Qiu, XIaoran Liu, Jiandong Guo
Strongly Correlated Electrons
Quasi-steady electron-excitonic complexes coupling in a two-dimensional semiconductor
Shangkun Mo, Hao Zhong, Keming Zhao et al. (+10 more)
Excitons and their complexes govern optical-related behaviors in
semiconductors. Here, using angle-resolved photoemission spectroscopy (ARPES), we have elucidated the light-matter interaction mediated by quasi-steady excitonic complexes within a monolayer of the prototypical two-dimensional (2D)
semiconductor WSe2. Under continuous incident light, we have observed the generation of quasi-steady
excitons and their complexes, encompassing ground and excited state
excitons, trions, as well as their intricate interplay. We further show spectral evidence of electronic excitation states within the background of quasi-steady excitonic complexes, characterized by valence band (VB) effective mass renormalization, the enhanced
spin-orbit coupling (SOC), the formation of an excitonic gap near the
Fermi level (EF ) of the conduction band (CB), and intervalley excitonic band folding. Our findings not only unveil a quasi-steady excitonic complex background for the creation of diverse electronic excitations in 2D
semiconductors but also offer new insights into the role of
excitons in the charge density wave (CDW) formation mechanism and facilitate the advancement of correlated electronic state engineering based on the coupling between electrons and excitonic complexes in a quasi-
equilibrium state.
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All authors Shangkun Mo, Hao Zhong, Keming Zhao, Yunfei Bai, Dingkun Qin, Chunlong Wu, Qiang Wan, Renzhe Li, Cao Peng, Xingzhe Wang, Enting Li, Sheng Meng, Nan Xu
Superconductivity
Translational symmetry breaking in the electronic nematic phase of BaFe2As2
K. Koshiishi, L. Liu, K. Okazaki et al. (+13 more)
The microscopic origin of the nematicity, namely, four-fold rotational
symmetry breaking in iron-based
superconductors has been controversial since its discovery. In particular, its relationship with the stripe-type
spin-density-wave order and the orthorhombic
lattice distortion in the
antiferromagnetic orthorhombic (AFO) phase, which exists at temperatures below the electronic nematic phase, has been highly debated. Here, we report on the temperature
evolution of angle-resolved photoemission spectra of the parent compound BaFe2As2, ranging from the AFO to nematic to paramagnetic phases. The Dirac cone feature, which is formed in the AFO phase, is found to persist in the nematic phase, suggesting that an antiferroic order of the same periodicity as the AFO phase persists in the nematic phase. Considering the relatively shallow d_xy orbital in BaFe2As2, we propose that an antiferro-orbital order involving the d_xy and other orbitals takes place in the nematic phase.
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All authors K. Koshiishi, L. Liu, K. Okazaki, H. Suzuki, J. Xu, M. Horio, H. Kumigashira, K. Ono, M. Nakajima, S. Ishida, K. Kihou, C. H. Lee, A. Iyo, H. Eisaki, S. Uchida, A. Fujimori
Quantum Gases
Orbital-resolved three-body recombination across a p-wave Feshbach resonance in ultracold $^6$Li
Shaokun Liu, Zhekang Xu, Shuai Peng et al. (+4 more)
We report precision, orbital-resolved measurements of three-body recombination near the 159~G $p$-wave Feshbach resonance in an ultracold gas of $^{6}$Li atoms prepared in their lowest hyperfine state. Using a
radio-frequency gated protocol that suppresses
magnetic-field transients below the milligauss level, we resolve loss features associated with the $|m_\ell|=1$ and $m_\ell=0$ orbital projections. The measured three-body loss coefficient $L_3$ is well captured by a thermally averaged cascade-recombination model, enabling extraction of the resonance splitting $\delta B$ and effective-range parameter $k_e$. At the lowest temperature, we obtain $\delta B = 7.6(3)$~mG and $k_e = 0.151(6)\,a_0^{-1}$, both in quantitative agreement with coupled-channel theory. These results establish orbital-resolved three-body spectroscopy as a precision probe of $p$-wave scattering and provide a
benchmark for microscopic models of resonant few-body loss.
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All authors Shaokun Liu, Zhekang Xu, Shuai Peng, Sijia Peng, Tangqian Shu, Jiaming Li, Le Luo
Mesoscale and Nanoscale Physics
Su-Schrieffer-Heeger model driven by sequences of two unitaries: periodic, quasiperiodic, aperiodic, and random protocols
Maitri Ganguli and Diptiman Sen
We study the effect of driving the Su-Schrieffer-Heeger model using two
unitary operators $U_1$ and $U_2$ in different combinations; the
unitaries differ in the values of the inter-
cell hopping amplitudes. Specifically, we study the cases where the
unitaries are applied periodically, quasiperiodically, aperiodically and randomly. For a periodic protocol, when $U_1 = e^{-i H_1 T/2}$ and $U_2 = e^{-i H_2 T/2}$ are applied alternately, we find that end modes may appear, but the number of end modes does not always agree with the winding number which is a $Z$-valued topological invariant. We then study the Loschmidt amplitude ($LA$) starting with a initial state which is an end mode of $H_1$. We find that the $LA$ exhibits pronounced oscillations whose
Fourier transform has a peak at a frequency which is equal to the quasienergy of an end mode of $U$. Next, when $U_1$ and $U_2$ are applied in a quasiperiodic or aperiodic way (we consider the Fibonacci and Thue-Morse protocols as examples), we study the Loschmidt echo ($LE$) starting with an initial state which is an end mode of the
Hamiltonian $H_1$. When the inter-
cell hoppings differ by a small amount denoted by $\epsilon$, and the time period $T$ of each
unitary is also small, the distance between the
unitaries is found to be proportional to $\epsilon T$. We then find that the $LE$ oscillates around a particular value for a very long time before decaying to zero. The deviation of the value of the $LE$ from 1 scales as $\epsilon^2$ for a fixed value of $T$, while the time after which the $LE$ starts decaying to zero has an interesting dependence on $\epsilon$ and $T$. Finally, when $U_1$ and $U_2$ are applied in a random order, the $LE$ rapidly decays to zero with increasing time. We have presented a qualitative understanding of the above results.
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Other Condensed Matter · Cross-listed from physics.atom-ph
Demonstration of magic dressing of $^3$He
Raymond Tat
A common concern in high-precision
neutron electric dipole moment (nEDM) experiments is that of
magnetic field stability. For static fields, this problem can be mitigated through the use of a superconducting holding field coil, which when operated in persistent current mode serves to stabilize the
magnetic field. However, such a solution is not viable when time-varying
magnetic fields are present, as is the case for the
spin dressing mode of the proposed nEDMSF (nEDM super-fluid) experiment. This experiment features an oscillating
magnetic field to dress the gyromagnetic ratios of $^3$He and
neutrons to the same value, a condition known as critical dressing. Fluctuations in the dressing field amplitude have the potential to disrupt this condition. Here, we investigate a modification to
spin dressing, termed “magic dressing,” which renders the system insensitive to small variations in dressing field amplitude. We further demonstrate the utility of this method for the single
spin-species case using a sample of polarized $^3$He. We find a dramatic increase in transverse relaxation time in the presence of
magnetic field gradients.
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Materials Science
Harnessing Multifractality to Enhance Thermal Stability in Mixed-Phase Vanadium Oxide Thin Films
Abhijeet Das, Ram Pratap Yadav, Rashmi Roy Karmakar et al. (+2 more)
Vanadium
oxide thin films exhibit temperature-driven electronic transitions desirable for sensing and microelectronic applications, yet their performance is often limited by thermal hysteresis. This study demonstrates that electronic stability is governed not simply by roughness or crystallinity but by a unique combination of surface morphological complexity and thermal hysteresis, revealed across films deposited with varying working pressure using Direct Current/
Radio Frequency magnetron sputtering. Specifically, the film grown at 15 mTorr shows a distinct convergence of highest morphological vertical complexity and lowest thermal hysteresis, exhibiting nearly reversible transport with activation energies ranging from 0.26 to 0.28 eV and negative temperature coefficients of resistance between -0.0337 and -0.035 K-1. While conventional roughness metrics and mono-fractal parameters do not capture this behavior, multifractal detrended fluctuation analysis uncovers a pronounced peak in multifractality strength, which correlates inversely with thermal hysteresis. This highlights multifractality strength as a predictive descriptor of electronic stability, identifying a multiscale structural signature that enhances stress accommodation during thermal cycling. These results define an optimal deposition window and provide a morphology-guided pathway for developing thermally robust mixed-phase vanadium
oxide films.
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All authors Abhijeet Das, Ram Pratap Yadav, Rashmi Roy Karmakar, Jyoti Jaiswal, Sanjeev Kumar
Superconductivity
Simulation-Based Inference of Ginzburg–Landau Parameters in Type–1.5 Superconductors
Jung-Shen Kao
Inferring microscopic couplings in multi-component
superconductors directly from
vortex configurations is a challenging inverse problem. In Type-1.5 systems, Time-Dependent Ginzburg-Landau (TDGL) dynamics generate complex, glassy
vortex patterns with high metastability. We explicitly quantify this intractability by analyzing the Hessian spectrum of the energy landscape, revealing a proliferation of soft modes that hinders traditional sampling. We address this challenge by combining a differentiable TDGL solver with Simulation-Based Inference (SBI). Our approach treats the solver as a
stochastic forward model mapping physical parameters ({\theta} = ({\eta}, B, {\nu})) to
vortex density fields. Using Neural Ratio Estimation (NRE), we train a classifier to approximate the likelihood-to-evidence ratio and perform
Bayesian inference for the interband Josephson coupling from
vortex density fields. On synthetic data, the proposed method reliably recovers the coupling with calibrated uncertainty.
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Mesoscale and Nanoscale Physics
Quantum Coulomb drag signatures of Majorana bound states
Zi-Wei Li, Jiaojiao Chen, Wei Xiong et al. (+2 more)
Majorana bound states (MBSs), with their non-Abelian statistics and topological protection, are key candidates for fault-tolerant
quantum computation. However, their unambiguous identification in solid-state systems remains a fundamental challenge. Here, we present a theoretical study demonstrating that drag transport in a capacitively coupled double
quantum dot system offers a robust and nonlocal probe of weakly coupled MBSs. Using the master equation approach, we investigate both steady-state and transient dynamics and uncover a distinctive signature of MBSs, namely the emergence of pronounced split peaks in the drag transconductance, directly linked to inter-MBS coupling. We further show that the dynamics of
quantum coherence is correlated with the emergence and enhancement of MBS-induced split peaks in the drag transconductance. A comparative analysis with trivial subgap states reveals key differences, that is, MBS-induced transconductance peaks are symmetric and exhibit characteristic splitting, while trivial-state features are generally asymmetric and lack such robust splitting behavior. These findings establish experimentally accessible criteria for distinguishing MBSs from trivial subgap states and provide a practical framework for probing Majorana physics through nonlocal transport.
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All authors Zi-Wei Li, Jiaojiao Chen, Wei Xiong, Xiao Xue, Zeng-Zhao Li
Materials Science
Coupled plastic strain- and stress-induced phase transformations and microstructure evolution in Fe-7%Mn alloy in a dynamic rotational diamond anvil cell
Sorb Yesudhas, Mrinmay Sahu, Valery I. Levitas et al. (+3 more)
Studies of severe plastic deformation (SPD), microstructure
evolution, and plastic strain-induced phase transformations (PTs) are crucial for various fundamental and applied disciplines and phenomena. However, they are performed either quasi-statically or at low strain rates and pressures. Here, in situ experiments in a dynamic rotational diamond anvil
cell (dRDAC) on SPD and BCC<->HCP PTs at pressures up to 27.6 GPa, rotation rates up to 1,500 RPM, and strain rates up to 2,299/s are performed, considering Fe-7%Mn
alloy as an example. Strong plastic straining leads to a unique mechanism and kinetics with simultaneous direct and reverse PTs, which has not been studied for any material. For quasi-static loading, we determine the kinetic parameters for strain-induced direct-reverse PTs and the stationary volume fraction $c$ versus pressure. During torsion at 1,000 and 1,500 RPM, $c$ does not change. After torsion stops, 51 minutes later, it increases by 31% at 1,000 RPM and $c$->0, 7 minutes later at 1,500 RPM. These findings contradict the general wisdom that strain-induced PTs occur only during straining and are governed by strain, independent of time; they reveal an alternative mechanism. It is revealed that the crystallite size of ~28(6) nm, microstrain ~0.0035(8), and dislocation density ~1.3(6)x$10^{15}$/$m^2$ in the HCP phase are steady during static compression and dynamic torsion, during and after the PT, and after torsion. These parameters are independent of pressure, plastic strain tensor, its path, strain rates, and $c$. The results obtained open fundamental research on combined strain- and stress-induced PTs and microstructure
evolution under dynamic SPD and high pressure, with various important applications.
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All authors Sorb Yesudhas, Mrinmay Sahu, Valery I. Levitas, Dean Smith, Aniket Singh, Jeffrey T. Lloyd
Strongly Correlated Electrons
Self-Consistent Random Phase Approximation from Projective Truncation Approximation Formalism
Yue-Hong Wu, Xinguo Ren and Ning-Hua Tong
We derive the self-consistent random phase approximations (sc-RPA) from the projective truncation approximation (PTA) for the equation of motion of two-time Green's function. The obtained sc-RPA applies to arbitrary temperature and recovers the Rowe's formalism at zero temperature. The PTA formalism not only rationalize Rowe's formula, but also provides a general framework to extend sc-RPA. We implement the sc-RPA calculation for the one-dimensional spinless
fermion model in the parameter regime of disordered ground state, with the N-representability constraints enforced. The obtained ground state energy, correlation function, and density spectral function agree well with existing results. The features of the Luttinger
liquid ground state and the continuum/bound state in the spectral function are well captured. We discuss several issues concerning the approximations made in RPAs, difficulties of RPA for symmetric state, and the static component problem of PTA.
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Materials Science
Effective Mass of a Migrating Interface
Xinyuan Song and Chuang Deng
Interfaces are ubiquitous in materials and play a central role in microstructural
evolution and material properties. Although interface migration has been studied for more than a century and remains an active field, several foundational assumptions of interface kinetics remain largely untested. In particular, interfaces are commonly treated as massless objects governed by overdamped dynamics. In this study, we show that grain boundaries exhibit measurable inertial behavior under high-frequency oscillatory driving. We introduce a quantitative method to extract an effective interface mass from the phase lag between the applied force and the interface velocity, and find that this mass scales with the atoms participating in boundary migration. Using this framework, we identify regimes in which inertial effects significantly modify interfacial kinetics, especially at frequencies relevant to thermal fluctuations. These results challenge the conventional overdamped description and establish effective interface mass as a key ingredient in a physically complete theory of interface migration.
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Strongly Correlated Electrons
Fast Dipolar Charge-Polarization Fluctuations: Toward a Unified Pairing Mechanism in Bad Metals
M. A. Zeb
The dynamics of a
quantum system at low energies is strongly influenced by effective interactions generated by states at higher energies. In effective models of correlated electron systems, contributions from the high-energy bands to the two-particle scattering vertex, beyond dielectric screening, are typically limited to virtual hopping-induced purely kinetic corrections. Considering a mixed kinetic-potential process involving the Coulomb interaction between particles and hopping-induced fast dipolar charge-polarization fluctuations, we obtain an analytical expression for the effective interaction between particles at low energies. Applied to cuprates (doped Mott
insulators) and iron-based systems (Hund's metals), the interaction yields the observed $d_{x^2-y^2}$ and $s^{+-}$ gap
symmetries, raising the prospect of a unified pairing mechanism across bad metals.
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Mesoscale and Nanoscale Physics
Anharmonic interaction as random field for thermal transport in FPU-$\beta$ lattice
Li Wan
We present an open
quantum theory for the thermal transport in the
Fermi-Pasta-Ulam-$\beta$(FPU-$\beta$)
lattice. In the theory, local
bosons(LBs) are introduced as carriers for the transport. The LBs are stimulated by individual atoms in the
lattice, which are different from the
phonons that are collective motions of the atoms. The LBs move in the FPU chain and are governed by a set of
stochastic differential equations(SDEs). The anharmonic interaction between the atoms in the
lattice is transformed to a random field by the Hubbard-Stratonovich transformation, and has been implemented in the set of SDEs. By solving the set of SDEs at the steady state, we study the influence of the anharmonic interaction on the thermal transport. Results show that the anharmonic interaction decreases the thermal current by trapping the LBs on the
lattice sites, as well as increase the thermal current by enhancing the amount of the LBs for the transport. The competition between these two mechanisms makes the thermal conductivity of the
lattice dependent on the anharmonic interaction non-monotonically. The finite size effect of the thermal conductivity has also been captured by the theory.
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Materials Science
An experimentally validated end-to-end framework for operando modeling of intrinsically complex metallosilicates
Jong Hyun Jung, Tom Schächtel, Yongliang Ou et al. (+5 more)
Structurally and chemically complex materials such as amorphous metallosilicates underpin major catalytic and separation technologies, yet their intrinsic complexity challenges reliable atomistic modeling under realistic conditions. Consequently, simulations that connect composition to material properties remain largely inaccessible for these materials. Here, we enable quantitative operando atomistic modeling of intrinsically complex materials through an experimentally validated end-to-end computational framework. The approach combines separation of simulation domains, lightweight machine-learning potentials trained on high-fidelity data, and large-scale de novo in silico synthesis that mimics experimental procedures. We apply the framework to realistic mesoporous SiO$_2$(Al$_2$O$_3$)$_{x/2}$ (0 $\leq x \leq$ 0.4) and validate the results experimentally. Simulations quantitatively reproduce multiple experimental observables, including bulk densities, pair distribution functions, infrared spectra, and hydroxyl densities. Beyond prediction, the framework enables analysis of acid sites and vibrations for catalytic and adsorption processes. By integrating simulation and experiment within a unified workflow, we advance the realism and reliability of atomistic modeling for intrinsically complex materials.
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All authors Jong Hyun Jung, Tom Schächtel, Yongliang Ou, Selina Itzigehl, Marc Högler, Niels Hansen, Johanna R. Bruckner, Blazej Grabowski