Materials Science
Two-Dimensional Hexagonal BX3 (X = P, As) Monolayers as High-Capacity, Fast-Charging Anode Platforms for Lithium- and Sodium-Ion Batteries
Jakkapat Seeyangnok, Joongjai Panpranot and Udomsilp Pinsook
The rapid advancement of alkali-metal ion batteries demands robust anode platforms combining high specific capacities with rapid charge-discharge kinetics. Using first-principles density functional theory (DFT), we systematically evaluate two-dimensional (2D) hexagonal BX3 (X = P, As) monolayers as high-performance dual-use anodes for lithium-ion (LIBs) and sodium-ion batteries (SIBs). Both metallic host architectures display strong thermodynamic affinities for Li+ and Na+ adsorption, favoring the hollow H3 site through synergistic ionic charge transfer and orbital hybridization. Climbing image nudged elastic band (CI-NEB) calculations reveal low direct H3 -> H3
diffusion barriers: 0.40 eV (BP3) and 0.26 eV (BAs3) for Li+, and 0.26 eV (BP3) and 0.19 eV (BAs3) for Na+, confirming exceptional high-rate kinetics. Thermodynamic convex hulls establish maximum stable lithiation at Li3BX3, yielding low average operating potentials of 0.39 V (BP3) and 0.35 V (BAs3) alongside theoretical specific capacities of 775 mAh/g and 341 mAh/g, respectively, with BP3 doubling commercial graphite (372 mAh/g). For SIBs, multi-layer sodiation expands storage up to Na15BP3 and Na12BAs3, delivering ultrahigh capacities of 3875 mAh/g (BP3) and 1365 mAh/g (BAs3) at low voltages of 0.18 V and 0.15 V. Crucially, projected density of states (PDOS) analyses confirm that both frameworks preserve intrinsic metallic conductivity throughout all charging stages. These combined properties establish 2D BX3 monolayers as outstanding, structurally resilient anode candidates for next-generation LIB and SIB energy storage technologies.
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Materials Science
exa-PD: A scalable high-performance workflow for multi-element phase diagram construction
Zhuo Ye, Feng Zhang, Maxim Moraru et al. (+4 more)
Exa-PD is a highly parallelizable workflow designed for the construction of multi-element phase diagrams (PDs). It uses standard sampling techniques, molecular dynamics (MD) and Monte Carlo (MC) as implemented in the LAMMPS package, to simultaneously sample multiple phases over a fine temperature-composition mesh for free-energy calculations. Parsl serves as the global workflow engine, coordinating large ensembles of MD and MC tasks to achieve massive parallelization with strong scalability. The resulting free energies of
liquid and solid phases are then fed to CALPHAD modeling via the PyCalphad package to construct multi-element PDs.
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All authors Zhuo Ye, Feng Zhang, Maxim Moraru, Weiyi Xia, Ying Wai Li, Yongxin Yao, Cai-Zhuang Wang
Materials Science
Ab initio time-dependent GW approach for nonequilibrium exciton-phonon coupled dynamics across momentum space
Zhenfa Zheng, Benran Zhang, Jiawei Ruan et al. (+10 more)
The dynamics of optical excitations in materials generally involves intertwined electron-hole (e-h) and electron-
phonon (e-ph) interactions out of
equilibrium. However, a full theoretical description of such nonequilibrium dynamics requires a systematic treatment of the coherent excitonic excitations and
exciton-
phonon interactions across the entire
crystal momentum space in real time, which remains a major challenge and out of reach for first-principles approaches. Here, we present a new ab initio time-dependent adiabatic GW methodology that incorporates full finite-momentum e-h and e-ph couplings, enabling real-time simulations of the coherently coupled
exciton-
phonon dynamics. The excitonic excitations are naturally described by the equation of motion of the interacting single-particle density
matrix, whereas their couplings to
phonons are formulated within a linear-response framework, hence the simulations can be efficiently carried out within a primitive unit
cell. We demonstrate the capabilities of this new approach by investigating the direct-to-indirect
exciton transitions in monolayer WSe2 in a pump-probe setup of time-resolved and angle-resolved photoemission spectroscopy. Our results reveal that the
phonon-mediated ultrafast intervalley dynamics of
excitons of this system is within ~0.5 ps, manifested as in-gap photoemission intensity transfer from the K-valley to the Q-valley. This work establishes a comprehensive and practical nonequilibrium Green's function framework for accurately simulating nonequilibrium and coherent excitations involving coupled
excitons and
phonons from first principles.
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All authors Zhenfa Zheng, Benran Zhang, Jiawei Ruan, Chih-En Hsu, Zien Zhu, Supavit Pokawanvit, Felipe H. da Jornada, Hung-Chung Hsueh, Ting Cao, Mauro Del Ben, Yang-Hao Chan, Steven G. Louie, Zhenglu Li
Materials Science
Phase-Field Simulation of Dendrite Evolution in All-Solid-State Sodium Batteries during Cycling
Chengyin Wu, Wolfgang Windl, Jung-Hyun Kim et al. (+1 more)
Dendrite growth during cycling remains a critical challenge for all-solid-state batteries (SSBs), limiting the full realization of their inherent safety and high energy density. In particular, the mechanisms of continuous dendrite penetration during charge-discharge cycling remain poorly understood and are difficult to characterize experimentally. This study applies a phase-field model, informed by density functional theory calculations, to rationalize and visualize the dendrite penetration behaviors during cycling in sodium (Na) SSBs with pure Na or Na-Sb
alloy anodes and polycrystalline Na$_3$SbS$_4$ electrolyte. We show that dendrite stripping is intrinsically asymmetric with respect to plating due to grain boundary geometry, leading to the formation of isolated Na metal that persists between cycles. This residual Na metal becomes kinetically stabilized at grain-boundary junctions and is readily reactivated during subsequent plating, thereby accelerating and amplifying dendrite penetration. We further investigate the effects of applied voltage, solid-electrolyte microstructure, and anode chemistry on this phenomenon. These findings establish isolated Na metal as a key contributor for continued dendrite propagation in Na SSBs and provide design principles for stabilizing anode/electrolyte interfaces in Na SSBs.
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All authors Chengyin Wu, Wolfgang Windl, Jung-Hyun Kim, Yanzhou Ji
Materials Science · Cross-listed from cond-mat.str-el
Field-induced first order transitions and phase coexistence in the Kitaev quantum spin liquid candidate BaCo2(AsO4)2
Tanner J. Legvold, Bin Gao, Rong-Zhu Lin et al. (+9 more)
BaCo2(AsO4)2 (BCAO) is an insulating Kitaev
quantum spin liquid candidate with a rich low-temperature phase diagram. Below 5 K, it exhibits double-zigzag
magnetic order. Upon application of an in-plane
magnetic field, the
magnetic structure first transforms into an up-up-down (UUD) state near 0.12 T and then enters a fully
spin-polarized
ferromagnetic (FM) state near 0.5 T. In the narrow field regime close to the polarized phase, a finite residual thermal conductivity has been reported, suggesting a possible field-induced
quantum spin liquid phase. Using
neutron scattering, we show that the field-induced double-zigzag-to-UUD transition near 0.15 T is accompanied by the emergence of a cluster of localized UUD
spin excitations that coexist with conventional
spin waves. Upon further increasing field, BCAO undergoes a first-order UUD-to-FM transition with coexistence of UUD and FM phases, accompanied by a sharp response in the
spin Seebeck coefficient. These results do not support a
quantum spin liquid scenario near the UUD-to-FM critical field. Instead, modeling indicates that the broad excitations arise from bound
spin-flip pairs, while a low-lying dispersive branch near the FM phase boundary carries the same sign of magnetization as the FM order. These excitations naturally account for the observed sign of the
spin Seebeck response and are likely relevant to the thermal conductivity near the critical field.
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All authors Tanner J. Legvold, Bin Gao, Rong-Zhu Lin, Violet Williams, Tong Chen, Dehong Yu, Chien-Lung Huang, Gage Eichman, Renjie Lui, Benedetta Flebus, Pengcheng Dai, Douglas Natelson
Materials Science
Spontaneous Nanopatterning and Strain Relaxation in SiGe Layers Grown by Oxidative Solid Phase Epitaxy
Sophie E. Bierer, Trevor R. Smith, Arezoo Mafi et al. (+5 more)
The wafer-scale monolithic integration of III-V materials on Si would lead to revolutionary optoelectronic hardware for data, computing and other applications. However, heteroepitaxy of III-Vs on Si requires overcoming the large
lattice and thermal mismatches between the materials and reducing threading dislocations densities. In this work, we explore the oxidative solid phase epitaxy (SPE) of Ge+ implanted Si(111) to form ultra-thin strain-relieving SiGe metamorphic buffer layers for heteroepitaxy on Si. The SPE process is shown to result in a nanopatterning of the Ge concentration variation across the sample surface, visible by scanning and transmission electron microscopy (SEM and TEM). The concentration patterning is the result of a hexagonal network of Shockley partial dislocations at the SiGe/Si interface. Analyzing the pattern spacing observed by SEM is demonstrated as an easy, non-destructive method for obtaining the local strain state of SiGe layers. This work is important for engineering ultra-thin SiGe metamorphic buffer layers for III-V optoelectronics heteroepitaxy on the silicon platform.
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All authors Sophie E. Bierer, Trevor R. Smith, Arezoo Mafi, Sunzhuoran Wang, Chengqian Liao, Vatsalkumar Patel, Andrew P. Knights, Ryan B. Lewis
Materials Science · Cross-listed from quant-ph
Coulomb blockade in microscopic material defects as a source of decoherence and noise in solid-state quantum circuits
R. Banerjee, L. P. Lindoy, M. Hegedus et al. (+9 more)
A critical limitation of solid-state
quantum devices arises from the materials from which they are fabricated: uncontrolled surfaces, interfaces, and structural imperfections introduce numerous sources of loss and decoherence. Despite extensive efforts, linking these decoherence mechanisms to their microscopic material origins – essential for developing effective mitigation strategies – remains an outstanding challenge that has slowed coherence improvements. Here, using scanning gate microscopy on live superconducting
circuits we identify a previously unrecognised decoherence mechanism originating from Coulomb blockade and microwave-driven charge tunnelling in metallic grains. Such grains are ubiquitous in thin-film devices fabricated by standard lithography processes. By characterising multiple defects across different devices, we find such defects to be as common and as debilitating to device performance as two-level system (TLS) defects, while originating from a fundamentally different physical mechanism. Importantly, conventional characterisation techniques would misattribute this loss to other, microwave power-independent processes. Our observations thus reveal a widespread source of decoherence in superconducting
circuits, challenging the prevailing paradigm that coherence lifetimes are primarily limited by TLS defects. Eliminating metallic grains during fabrication provides a clear and practical route to suppress this mechanism, offering a pathway towards improved coherence and reduced noise in microwave-based solid-state
quantum devices.
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All authors R. Banerjee, L. P. Lindoy, M. Hegedus, A. Hutcheson, T. Hawkins, E. Daghigh-Ahmadi, S. Samaddar, T. Barker, J. P. Goff, A. Ya. Tzalenchuk, I. Rungger, S. E. de Graaf
Materials Science · Cross-listed from cond-mat.supr-con
High-Q superconducting microwave resonators using MBE titanium nitride
Anand Ithepalli, Haoran Lu, Eegene Clara Chung et al. (+9 more)
Using molecular beam epitaxy, we have realized thin films of titanium nitride (TiN) on c-plane sapphire that exhibit the lowest observed full-width at half maximum X-ray rocking curve width of 18 arcsec. Though the (111) oriented TiN exhibits an abrupt and crystalline interface with sapphire, for the first time we observe sub-surface defects in the sapphire substrate, which nucleate structural defects in the epitaxial TiN layer. Using quarter-wavelength coplanar waveguide (CPW) resonators in a 3 \textmu m/6 \textmu m/3 \textmu m gap/strip/gap lines in a hanger geometry, we find the internal quality factor of the TiN resonators to be $>10^{6}$ in the single-
photon $\langle n \rangle \sim 1$ limit at 5.8 GHz and 10 mK, rising to $>20 \times 10^{6}$ at $\langle n \rangle \sim 10^{6}$. The results are of high interest for applications of superconducting TiN in several areas, and provide a path towards epitaxial Josephson junctions with crystalline barriers in the future for high coherence
qubits.
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All authors Anand Ithepalli, Haoran Lu, Eegene Clara Chung, Xiangqin Wang, Amit Rohan Rajapurohita, Keun-Yeol Park, Celesta S. Chang, Peter McMahon, Huili Grace Xing, David Muller, Valla Fatemi, Debdeep Jena
Materials Science · Cross-listed from cond-mat.supr-con
Magnetic Order in bilayer Ruddlesden-Popper Nickelates
Yiming Wang, Guijing Duan, Zhiguang Liao et al. (+3 more)
The recent discovery of high-temperature superconductivity in the
bilayer nickelate La$_3$Ni$_2$O$_7$ has led to extensive interest in the correlation physics of its normal state. Given that the superconducitivity develops near a density wave order in the phase diagram, it is important to elucidate the nature of this order. Based on the accumulated experimental evidence for a bad metal state in proximity to an orbital-selective Mott phase, here we describe
magnetic correlations of the system in a conceptually new way – in terms of effective local moments experiencing a combination of RKKY and superexchange interactions. This gives rise to a
magnetic order with a wavevector that is close to $\mathbf{Q}=(\pi/2,\pi/2)$ and, at the same time, yields a clear understanding of the associated
spin dynamics. Our results are consistent with the rapidly emerging experiments about the
magnetic correlations in the density wave order of the
bilayer nickelate. Implications for unconventional superconductivity in this and related multiorbital systems are discussed.
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All authors Yiming Wang, Guijing Duan, Zhiguang Liao, Kuan-Sen Lin, Rong Yu, Qimiao Si
Materials Science
Hyperfine driven spin relaxation of charge carriers in metal-halide perovskites
Guillaume Lague, Frédérick Bernardot, Mauricio Calvo et al. (+6 more)
Spin relaxation of localized charge carriers in
semiconductors is primarily governed by hyperfine interaction with the surrounding
nuclear spin bath. While this mechanism is well-established in III-V bulk materials and
quantum dots, its critical role in metal halide perovskites (MHPs) has only recently emerged. Their inverted band structure induces an unusual hierarchy of hyperfine couplings, with hole interactions dominating electron interactions, particurlaly in Pb-based perovskites. Here, we adapt a
spin relaxation model - originally developed for
muon spin spectroscopy - to provide an exact description of longitudinal
spin relaxation for localized carriers across arbitrary hyperfine correlation times. This approach is motivated by recent experimental evidence in MAPbI3, which places carrier
spins in an intermediate correlation regime, where conventional mono-exponential approximations fail. Our analysis reveals distinct hyperfine relaxation channels: electrons couple primarily to halogen
nuclei, whereas holes are governed by metal
nuclei. This leads to a key prediction - perovskites with lighter halogens and metal cations exhibit significantly extended
spin lifetimes. Applied to time-resolved Faraday rotation data obtained from two perovskite samples, our model extracts key microscopic parameters - including the carrier localization volume and hyperfine correlation time - demonstrating the necessity of the exact dynamical solution over a single-exponential approximation. These findings provide microscopic insight into hyperfine-driven
spin relaxation in MHPs and establish a robust framework for characterizing carrier localization and
spin dynamics.
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All authors Guillaume Lague, Frédérick Bernardot, Mauricio Calvo, Olfa Selmi, Sofia Masi, Christophe Testelin, Hernan Miguez, Ivan Mora-Sero, Maria Chamarro
Materials Science
Emergent d-wave altermagnetism in chlorine-adsorbed FeSe monolayer
Zi-Hao Ding, Ze-Feng Gao, Kai Liu et al. (+2 more)
The recent emergence of altermagnetism has opened new frontiers in condensed matter physics, yet material platforms capable of hosting both intrinsic altermagnetic order and superconductivity remain exceedingly rare. Here, based on
symmetry analysis and first-principles calculations, we propose a realistic route to engineer robust altermagnetism in monolayer FeSe, a prototypical iron-based
superconductor. By designing a stoichiometric Fe2Se2Cl structure through single-side Cl adsorption and introducing gate-tunable hole doping, we achieve a highly stable altermagnetic ground state. Our calculations reveal a synergistic mechanism: hole doping firmly stabilizes the checkerboard
magnetic order, while the asymmetric ligand environment intrinsically breaks the outof-plane spatial inversion
symmetry. Consequently, this interplay induces a
giant altermagnetic
spin splitting of up to 620 meV. Crucially, we demonstrate that this altermagnetic state and its
giant spin splitting are highly resilient, persisting even in a 10-layer slab model that accurately simulates the bulk limit. By introducing altermagnetism into the well-established FeSe-based superconducting family, our findings identify Fe2Se2Cl as a promising platform for spintronic applications and motivate future studies of the possible interplay between altermagnetism and superconductivity.
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All authors Zi-Hao Ding, Ze-Feng Gao, Kai Liu, Peng-Jie Guo, Zhong-Yi Lu
Materials Science · Cross-listed from cond-mat.str-el
Driven-dissipative superconductivity in moiré heterostructure without attraction
Tsung-Sheng Huang, Atac Imamoglu, Mohammad Hafezi et al. (+1 more)
Dissipative preparation of
quantum order offers a route to superconductivity that does not rely on enhancing attractive interactions. Here we propose a driven-dissipative protocol to prepare superconductivity as a stationary state of a two-dimensional moiré
heterostructure. The key ingredient is a
bilayer moiré platform in which the layer degree of freedom acts as a pseudospin, allowing the pseudospin structure required for pairing to be implemented through optically induced spatial operations. This preparation scheme requires local dissipation, which we show to arises naturally from weakly dispersive bosonic modes in the
heterostructure. In contrast, in the opposite regime of collective dissipation, the same platform exhibits an early-time superradiant burst. Our results establish driven-dissipative moiré
heterostructures as a promising platform for preparing superconductivity, while also revealing a connection between steady-state pairing and transient superradiance.
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All authors Tsung-Sheng Huang, Atac Imamoglu, Mohammad Hafezi, Sebastian Diehl
Materials Science
Growth-controlled suppression of electrically active defects in CrSBr
Sara R. Tulchinsky, Sergii Grytsiuk, Shen van Hassel et al. (+7 more)
In CrSBr, as in many crystalline materials, the type and density of defects are expected to strongly influence material behavior. Identifying the underlying atomic defect configurations and controlling their populations during growth are therefore important steps toward understanding and ultimately tailoring its rich magneto-electrical properties. However, systematic control of defects in CrSBr during chemical vapor transport (CVT) growth has not yet been established. Here, we correlate CVT growth conditions with defect concentrations measured using conductive atomic force microscopy (CAFM). We focus on a characteristic defect with a strong electronic fingerprint, labeled D*, and decrease its concentration by up to an order of magnitude through optimized growth conditions. We show that defect densities can be tuned by adjusting precursor stoichiometry, where sulfur- and bromine-rich conditions suppress defect formation, and by lowering the absolute growth temperatures while maintaining the same temperature gradient. Thermodynamic modeling and density functional theory calculations suggest that D* is most consistent with a sulfur-related vacancy complex rather than an isolated point defect. These results provide practical strategies for growing high-quality CrSBr with controlled defect densities.
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All authors Sara R. Tulchinsky, Sergii Grytsiuk, Shen van Hassel, Iva Plutnarová, Rami Dana, David Sedmidubský, Zdenek Sofer, Malte Rösner, Frances M. Ross, Julian Klein
Materials Science
Local magnetic correlations and light-sensitive centers in the Cr2AlC MAX phase
Malgorzata Wierzbowska, Anna Basa, Kazuhiro Marumoto et al. (+6 more)
Cr2AlC MAX phase is synthesized by high-pressure solid-state annealing and investigated as a candidate platform for optically responsive magnetism. Structural characterization confirms the formation of the Cr2AlC phase, while
magnetic and optical-
magnetic properties are examined by superconducting
quantum interference device (SQUID) magnetometry, electron
spin resonance (ESR), and first principles calculations. SQUID magnetometry identifies Cr 2AlC as a weak, field-linear metallic paramagnet dominated by Pauli-like susceptibility of itinerant Cr-derived states. Its non-monotonic temperature dependence is described by an additional contribution from antiferromagnetically coupled Cr-Cr dimers, whereas the low-temperature Curie-like upturn originates from only a trace population of localized Cr centers. Under red-light illumination, SQUID magnetometry does not reveal an intrinsic macroscopic optomagnetic response. In contrast, ESR at 4 K shows a reversible light-induced reduction of a local
magnetic signal, but the optically modified
spin population corresponds only to several tens of ppm of the Cr sublattice. Ab initio Bethe-Salpeter equation (ai-BSE) calculations combined with the maximally localized Wannier function analysis suggest that optical excitation can redistribute
spin polarization between neighboring Cr sites with the opposite local moments. The combined experiment-theory approach therefore establishes the hierarchy of
magnetic contributions in Cr 2AlC and identifies the microscopic origin of its local optical sensitivity. This provides a reference for designing MAX phases and related MXenes in which defects, surface terminations or reduced dimensionality may enhance optically active
magnetic states.
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All authors Malgorzata Wierzbowska, Anna Basa, Kazuhiro Marumoto, Jiaxi Wang, Katarzyna Gas, Maciej Sawicki, Kacper Sierakowski, Karel Carva, Michal Bockowski
Materials Science · Cross-listed from physics.chem-ph
Interaction energies of H$_2$ and CO on transition-metal surfaces computed by a range-separated hybrid van der Waals density functional
Per Hyldgaard
Dissociative chemisorption (DC) of H$_2$ on the Cu(111) surface is a prototypical problem for understanding elements of heterogeneous catalysis [Science 326, 832 (2009)]. The challenge lies in modeling the reaction dynamics that in turn reflects a classical potential for atomic deformations, friction, and inelastic scattering. Here, I test the use of a set of range-separated hybrid (RSH) van der Waals density functionals (vdW-DFs) [JPCM 37, 211501 (2025)] on their ability to describe the classical barrier for dynamics in this H$_2$+Cu(111) DC problem. I furthermore document use of a variant for fast accurate predictions of the molecular quasi-particles (QPs), finding excellent performance across a set of small molecules that are often studied in catalysis. Finally, I suggest and implement a way to use that QP focus to identify what I consider a best-possible non-empirical (yet adsorbate specific) RSH vdW-DF version, denoted AHBR($\gamma^*$) for H$_2$ DC modeling, navigating what are partly conflicting requirements on the molecule and metal sides. I find that the AHBR($\gamma^*$) can determine the classical H$_2$+Cu(111) DC barrier height close to chemical accuracy. I suggest that DC modeling can test broader relevance of the physics underpinning these RSH vdW-DFs.
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Materials Science · Cross-listed from cs.CE
Neural operators solve inverse problems for constitutive model discovery
Moritz Flaschel, Burigede Liu and Ellen Kuhl
Characterizing the mechanical response of materials traditionally requires solving optimization problems in which model parameters are calibrated or trained to minimize the discrepancy between model predictions and experimental data. This process can be computationally expensive and time-consuming. To overcome this limitation, we propose two neural operator architectures that directly map experimentally measured data to the constitutive functions governing the mechanical response of the material: Physics-Augmented Neural Operators (PANO) and Constitutive Artificial Neural Operators (CANO). The proposed neural operators approximate the mapping between the infinite-dimensional input space of full-field displacement measurements and net reaction forces, and the infinite-dimensional output space of hyperelastic strain-energy density functions. The displacement fields are encoded through
Laplacian eigenfunctions to obtain discretization-independent and noise-robust predictions. Our framework constrains the output space to physically admissible material models that satisfy fundamental physical requirements by design. The neural operators are trained on simulated data tuples of displacement fields and reaction forces for a range of material models. Once trained, the neural operators enable near-instantaneous material characterization and require only a single forward pass to infer the strain-energy density function from a given experimental
dataset. We test the predictive power of the neural operators for unseen data, noisy data, data with missing information, data from different spatial discretizations, and data from geometries of different sizes.
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Materials Science
Recent progress on liquid transport growth of quantum materials
Jiaqiang Yan and Brenden Ortiz
Liquid transport growth (LTG) is a horizontal flux growth technique that is closely analogous to chemical vapor transport, with the key distinction that a molten flux rather than a vapor serves as the transport
agent. Unlike conventional flux growth, LTG spatially separates charge dissolution and
crystal precipitation and couples them through continuous solute transport under a deliberately imposed temperature gradient. This enables
crystal growth to begin before the charge is completely dissolved, removes the
equilibrium solubility constraint on the starting charge/flux ratio, and allows large yields of single
crystals to be obtained from a single growth. Recent studies have further shown that by spatially separating dissolution and crystallization and maintaining crystallization at a nearly constant temperature, LTG is particularly effective for two classes of materials: compounds that crystallize only within a narrow temperature and/or composition window, and compounds whose stoichiometry, defect concentration, and thus physical properties are sensitive to the crystallization temperature. In this review, we discuss representative examples including Fe$_3$Sn$_2$, CrTe$_3$, YFe$_2$Ge$_2$, UTe$_2$, CeRh$_2$As$_2$, MoTe$_2$, WTe$_2$, and LuNb$_6$Sn$_6$ to illustrate the unique capabilities of LTG for producing high quality single
crystals of diverse
quantum materials. We also summarize practical considerations for LTG experimental design, including furnace selection, growth time, melt stability, and ampoule geometry, and discuss future opportunities for transforming LTG from an empirical growth method into a more predictive
crystal growth technique.
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Materials Science
Ridge-Spin-Layer Coupling and Emergent Ridgetronics in 2D Altermagnets
Mu Tian, Run-Wu Zhang, Chaoxi Cui et al. (+2 more)
Extending valleytronics from discrete points to continuous lines in momentum space transforms dispersionless bands into a controllable degree of freedom. Here we introduce ridge–
spin–layer coupling (RSLC) in two-dimensional (2D) altermagnets, where a one-dimensional continuous line of dispersionless electronic states (a ridge) in momentum space locks to both
spin polarization and atomic sublayer. This ridge-induced quenching of kinetic energy mimics flat-band physics, yet crucially, RSLC grants external control, allowing for layer-selective switching of ridge orientation in reciprocal space,
spin-filtered transport in real space, and a distinct electric
Hall response. Guided by collinear
spin layer group
symmetry, we identify three 2D candidate materials, namely Mg$_2$Mo$_2$(PO$_5$)$_2$, Ca(FeP)$_2$, and Mg$_2$V$_2$(SO$_5$)$_2$, each featuring a crossed-ridge structure with two ridges, one per
spin channel and sublayer. Our work establishes ridgetronics as a controllable platform for direction-discriminating currents, bridging dispersionless bands with multifunctional device operation.
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All authors Mu Tian, Run-Wu Zhang, Chaoxi Cui, Zhi-Ming Yu, Yugui Yao
Materials Science · Cross-listed from cond-mat.soft
Plug Flow and Cavitation in Rough Lubricated Contacts: Molecular Dynamics of Single- vs. Two-Component Fluids
Shubham Agarwal and Martin H. Müser
We present non-
equilibrium molecular dynamics simulations of lubricated sliding between rough, deformable surfaces under conditions representative of mixed lubrication. One aim is to reduce the gap between highly idealized simulations of smooth interfaces and real, rough, load-bearing contacts. Another aim is to determine whether favorable tribological properties of two-fluid lubrication reported for solvated hydrophilic-hydrophobic
polymer-brush interfaces can also be realized in rough contacts without brushes. To this end, we compare aqueous (water), hydrocarbon (n-dodecane), and immiscible two-fluid lubrication under identical
geometric conditions representing randomly rough surfaces. For the single-component lubricants, the simulations reproduce established trends: water shows stronger speed dependence but reduced load-bearing capacity than n-dodecane, despite their similar ambient viscosities. Beyond this expected behavior, the simulations reveal that the combination of strong confinement and large height gradients can cause plug flow and thereby cavitation after asperity collisions. For a high-surface-tension
liquid like water, cavitation leads to an abrupt shear-stress release on scales much exceeding the size of the cavity. Since plug motion only weakens with single-component lubricants at low speeds, the two-fluid lubricant can only leverage its potential advantages at low sliding velocities. It is also the only system in which folding lips form, occasionally developing into transient, detached clusters at high speeds.
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Materials Science
Modeling the Fatigue Behavior of Amorphous Polymers
Valeriy V. Ginzburg, Oleg V. Gendelman and Alessio Zaccone
Prediction of material durability is both very important and very difficult. In many cases, material durability is measured by subjecting a sample to repeating oscillatory cycles (in shear or tension-compression) until it fails in either ductile or brittle fashion. Typically, the stress amplitude is denoted S, and the number of cycles N, so the resulting dependence is known as the SN-curve. For many materials, SN curve has been shown to obey the empirical Basquin's law, N = AS^(-m), where the prefactor A was a function of the temperature, load frequency, and sample history, and the power law m was a real number, usually between 3 and 12. Here, we derive the Basquin's law using a linearized version of the Long's plasticity model and demonstrate that within this framework, m = 3. We also derive the expression for the prefactor A. Finally, we show that our theory successfully describes experimental data for three amorphous
polymers, PS, PMMA, and PVC.
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Materials Science
Scalable Fabrication of Diamond-on-Silica Heterostructures via High-Selectivity Deep ICP-RIE and Room-Temperature Bonding
R. Chembra Vasudevan, A. Hammouti, J. Le Pouliquen et al. (+4 more)
Single-
crystal diamond is a leading material platform for high-power electronics and solid-state
quantum technologies, yet many device architectures require micrometer-scale membranes with deeply etched features, patterned from commercially available substrates. In this work, we demonstrate a complete through-etch of a 16 {\mu}m -thick NV-doped single-
crystal diamond membrane using a single-layer SiO2 hard mask combined with a multi-step oxygen-based ICPRIE process. With a diamond-to-SiO2 selectivity of 15:1, this non-metallic mask strategy can achieve etch depths of few tens of {\mu}m with well-defined sidewalls, conserved surface roughness and negligible micromasking. Furthermore, we use the
oxide layer that remains after etching to serve as the bonding surface in a subsequent integration step. The etched microstructures are transferred onto SiO2 substrates and bonded at room temperature using O2
plasma surface activation and a sodium silicate interlayer. The resulting siloxane film is optically transparent across the visible spectrum and introduces no detectable parasitic photoluminescence, preserving the optical readout of the embedded NV centers. Together, this deep-etch and room-temperature bonding process provides a scalable and contaminationfree route from bulk diamond membranes to diamond-on-silica
heterostructures for integrated
quantum photonics and sensing applications.
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All authors R. Chembra Vasudevan, A. Hammouti, J. Le Pouliquen, T. Batte, P. Pirasteh, Y. Dumeige, P. Huillery
Materials Science
Synergistic Effects of Phosphorus Doping and Oxygen Vacancies on Formaldehyde Oxidation over CeO$_2$(111): A First Principles Investigation
Tarek Ayadi, Mourad Debbichi, Michael Badawi et al. (+3 more)
Using a combination of static and dynamic density functional theory simulations, we systematically investigated how phosphorus doping and oxygen vacancies on the CeO$_2$(111) surface influence the oxidation mechanisms of formaldehyde (HCHO). Our results reveal that P cations (P$^{5+}$) substitutionally replace Ce$^{4+}$ in the
lattice, forming Ce$-$O$-$P bonds that reduce the band gap (from 2.26 eV to 2.09 eV) and generate localized Ce$^{3+}$ states through charge redistribution. This synergistic effect of P doping combined with oxygen vacancy strengthens HCHO adsorption by decreasing the adsorption energy from -0.62 eV on pristine CeO$_2$(111) to -2.65 eV on the defective P-doped surface. Importantly, P doping lowers the C$-$H bond cleavage barrier by 0.84 eV relative to pristine CeO$_2$(111), accelerating formaldehyde oxidation on the defective surface. In addition, the rapid desorption of CO$_2$ and H$_2$O ($\tau \sim 0.59 s$ at 300 K) indicates weak product-surface interactions, which favor efficient catalyst regeneration during continuous operation. These findings highlight P-doped CeO$_2$(111) as a promising system for low-temperature HCHO oxidation and provide insights into the design of ceria-based catalytic materials.
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All authors Tarek Ayadi, Mourad Debbichi, Michael Badawi, Fabien Pascale, Adel Mesbah, Sébastien Lebègue