Materials Science · Cross-listed from cond-mat.str-el
Pressure-Induced Chemical Bonding Effects on Lattice and Magnetic Instabilities in Antiferromagnetic Insulating CaMn$_2$Sb$_2$
Matt Boswell, Antonio M. dos Santos, Mingyu Xu et al. (+3 more)
Exotic
quantum phenomena often emerge near an electronic delocalization transition (EDT) from an
antiferromagnetic insulating phase to a strongly correlated metallic state under pressure. We report the pressure-induced structural and
magnetic evolution of the
antiferromagnetic insulator CaMn$_2$Sb$_2$. Single-
crystal X-ray diffraction reveals a first-order phase transition near 5.4 GPa from a trigonal P-3m1 structure to a monoclinic P2$_1$/m phase, accompanied by a ~7% volume collapse. Residual electron density analysis at intermediate pressures reveals charge localization along Mn-Sb chains, signaling electronic instability preceding the structural transition. Bonding analysis indicates anisotropic Mn-Sb orbital reconfiguration under pressure, driving a distorted square-pyramidal geometry.
Neutron scattering confirms the transition and identifies a pressure-induced incommensurate
magnetic order, distinct from the ambient
antiferromagnetic state. In the monoclinic phase, zigzag Mn chains exhibit
antiferromagnetic coupling along the ac-plane, enabled by enhanced orbital overlap. These results establish CaMn$_2$Sb$_2$ as a model system for studying the coupling of structural distortion, charge redistribution, and
magnetic order in layered Mn pnictides under pressure.
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All authors Matt Boswell, Antonio M. dos Santos, Mingyu Xu, Madalynn Marshall, Su-Yang Xu, Weiwei Xie
Materials Science
Observation of Iso-Symmetric Structural and Lifshitz Transitions in Quasi-one-dimensional CrNbSe$_5$
Mingyu Xu, Peng Cheng, Shuyuan Huyan et al. (+5 more)
Chalcogenides-rich transition metal compounds host a rich landscape of emergent
quantum phenomena that are intimately governed by their quasi-one-dimensional chemical-bonding frameworks and their response to external perturbations such as pressure. Here, we report a pressure-induced iso-symmetric structural transition in the quasi-one-dimensional compound CrNbSe$_5$, in which the electronic ground state is controlled not by
symmetry breaking but by a continuous reorganization of local bonding interactions. Applied pressure reversibly tunes CrNbSe$_5$ between semiconducting and semimetallic states, enabling access to low- and high-carrier electronic regimes through direct modulation of metal-chalcogen bonding. High-pressure single-
crystal X-ray diffraction directly resolves the
evolution of Cr-Se and Nb-Se bond distances, coordination polyhedra, and connectivity, revealing a fully reversible semimetal-
semiconductor-semimetal transition driven by gradual yet cooperative bond rearrangements within a preserved crystallographic
symmetry. In contrast to chemical substitution, which irreversibly alters composition and introduces disorder, pressure acts as a clean, continuous control parameter that reshapes the bonding landscape without disrupting structural
symmetry. These results establish CrNbSe$_5$ as a model system for electronically driven phase switching via tunable chemical bonding, highlighting iso-symmetric bond reorganization as a powerful design principle for pressure-controlled electronic and spintronic functionalities.
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All authors Mingyu Xu, Peng Cheng, Shuyuan Huyan, Wenli Bi, Su-Yang Xu, Sergey L. Bud'ko, Paul C. Canfield, Weiwei Xie
Materials Science
Raman relaxation in Yb(III) molecular qubits: non-trivial correlations between spin-phonon coupling and molecular structure
Giacomo Sansone, Lorenzo A. Mariano, Stefano Carretta et al. (+2 more)
The coordination complexes of Yb(III) exhibit some of the longest
spin coherence times among 4f compounds, making them a promising platform for molecular
quantum technologies. While
spin-
phonon relaxation remains a limiting factor for coherence times even at low temperature, its control through chemical design has the potential to push these
spin qubits prototypes beyond current limits. With the aim of providing insights on how to chemically control
spin-
phonon relaxation, we here present a full ab initio study of
spin-
phonon dynamics for three Yb(III) molecules exhibiting minimal chemical differences, yet quantitatively different
spin relaxation times. Results show that low-temperature relaxation is governed by Raman processes triggered by a small group of largely delocalized low-energy
phonons. The analysis of these contributions highlights that the modulation of
spin-
phonon coupling by molecular structure modifications beyond the first coordination shell are highly non-trivial in nature and hard to rationalize in simple chemical terms. These findings call for a conceptual step change from the attempt to use simple magneto-structural correlations to interpret the effect of molecular structural modifications on
spin-
phonon relaxation, and present predictive first-principles frameworks as a potential driving force of future chemical design strategies
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All authors Giacomo Sansone, Lorenzo A. Mariano, Stefano Carretta, Paolo Santini, Alessandro Lunghi
Materials Science
Irradiation-induced amplification of electric fields at oxide interfaces as revealed by correlative DPC-STEM and DFT
Elizabeth A. Peterson, Dongye Liu, Sean H. Mills et al. (+5 more)
Heterointerfaces are ubiquitous in modern devices, found in technologies ranging from microelectronics to structural components for energy applications. Many of these emerging technologies are found in applications such as satellites, batteries, and next generation
nuclear reactors, that are subject to harsh environments. In some scenarios, multiple extreme conditions, such as irradiation and corrosion, act on the material simultaneously. Extending the lifetime of these technologies is dependent on a detailed understanding of how their component materials platforms and interfaces respond in extreme environments, where irradiation and corrosion may couple in unique ways, distinct from corrosion under ambient conditions.
Oxides, which form readily over metal underlayers, can act as protective coatings; enhancing the robustness of
oxide overlayers to protect underlying metal
alloys is a potential avenue towards corrosion mitigation. Here we study the impact of irradiation-induced non-
equilibrium defects on charge segregation and electric fields at and near multi-phase
oxide heterointerfaces. We perform a detailed study of irradiated Fe2O3-Cr2O3 thin film
heterostructures using first-principles DFT electronic structure modeling paired with 4D-STEM DPC and EELS techniques to measure nanoscale changes in electric fields. Our results show clear evidence that irradiation drives substantial modulation of interfacial electric fields that can be tailored by controlling the atomistic chemical structure of the
oxide interface. We show that irradiation can selectively induce built-in electric fields, thereby altering their direction; this suggests a pathway to engineering protective
oxide heterostructure overlayers that can electrically control the spatial distribution of defects, with significant implications for the design of corrosion-resistant materials for extreme environments.
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All authors Elizabeth A. Peterson, Dongye Liu, Sean H. Mills, Tiffany C. Kaspar, Hyosim Kim, Yongqiang Wang, Blas P. Uberuaga, Andrew M. Minor
Materials Science
Tunable decoupling of coexisting magnetic orders in Co$_{1/3}$TaS$_2$
Yining Hu, Zili Feng, Takashi Kurumaji et al. (+3 more)
In multiferroics, new physical responses and functionalities emerge when
symmetry-distinct order parameters couple. This conventionally occurs when
lattice and
magnetic degrees of freedom order independently in a material. Here, we report an all-
magnetic analogue of multiferroic behavior in the antiferromagnet Co$_{1/3}$TaS$_2$, where topological scalar
spin chirality and nematicity coexist on the same
spin lattice. While the
chiral spin texture generates an anomalous
Hall effect (AHE), the nematic order breaks threefold rotational
symmetry and dominates longitudinal transport. Crucially, in zero field these
symmetry-distinct orders merely coexist yet
magnetic fields induce strong coupling between them, thus realizing a new type of multiferroic bebhavior via tuning of the coupling itself instead of direct manipulation of secondary orders. In sub-domain sized devices with achiral geometry, we demonstrate that nonreciprocal transport serves as a
symmetry-based probe of the global
spin chirality, co-aligned with the strong topological AHE of the system. In Co$_{1/3}$TaS$_2$ the topological
Hall state inherits a large resistance anomaly via
chiral-nematic coupling, thus our results showcase how hybrid
magnetic orders can achieve advanced functionalities by merging
symmetry-forbidden material responses.
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All authors Yining Hu, Zili Feng, Takashi Kurumaji, Linda Ye, Chunyu Mark Guo, Philip J. W. Moll
Materials Science
RASP: Reliability ab initio simulation package of MOSFETs based on all-state model
Xinjing Guo, Menglin Huang and Shiyou Chen
As transistors continue to scale down, device reliability has become a critical concern. In order to accurately simulate defect-induced reliability degradation in MOSFET based logic,
memory and power devices, we develop RASP (Reliability Ab initio Simulation Package), which implements the all-state model for reliability simulation. Unlike conventional two-state and four-state models that consider only two and four defect configurations respectively, the all-state model systematically considers all possible defect configurations in amorphous gate dielectrics and all nonradiative multiphonon (NMP) and thermal transition pathways among them. With defect parameters obtained from ab initio calculations as input, RASP enables accurate simulation of threshold voltage shifts caused by defects. Using RASP to simulate oxygen vacancies in a-SiO$_2$, we find that they are a non-negligible source of negative bias temperature instability (NBTI).
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Materials Science · Cross-listed from stat.ME
Bayesian Model Calibration with Integrated Discrepancy: Addressing Inexact Dislocation Dynamics Models
Liam Myhill, Enrique Martinez Saez and Sez Russcher
In this work, a novel approach to
Bayesian model calibration routines is developed which reinterprets the traditional definition of model discrepancy as defined by Kennedy and O'Hagan (KOH). The novelty lies in the integration of $\delta_\theta(x_i)$ GPs within the simulator, which is approximated as a GP surrogate model to ensure computational tractability. This approach assumes that the utilized simulator sufficiently predicts observed trends when calibrated with respect to the application domain, and that all model-form errors can be attributed to uncertainty in the input parameters. In contrast, the KOH method assumes discrepancy to be inherently decoupled from the simulator, acting as a 'catch-all' for various sources of model error. The new method is applied to Molecular Dynamics observations of the critical stress to drive dislocation dipoles, and equivalent predictions using a Discrete Dislocation Dynamics simulator whose coarse-grained physical interpretation of the underlying physical mechanisms requires calibration against MD observations. We present an overview of similar state-aware calibration routines; differentiate the provided approach through redefining the commonly used discrepancy Gaussian process and
benchmark against KOH. A philosophical argument as to when application of the proposed method is appropriate is provided, and future directions for expanding upon this methodology are proposed.
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Materials Science
Revealing 3D orientation and strain heterogeneity in calcite generated by bio-cementation
Marilyn Sarkis, James A. D. Ball, Michela La Bella et al. (+5 more)
Bio-cementation uses bacterially induced calcite to bind sand grains, offering a low-carbon approach to soil stabilization. However, the 3D morphology, orientation texture, and internal strain states of individual calcite bonds remain insufficiently characterized. Here, we combine computed micro-
tomography, 3D X-ray Diffraction (3DXRD), and Dark-Field X-ray Microscopy (DFXM) to nondestructively characterize grain morphology, crystallographic orientation, and both type II (intergranular) and type III (intragranular) elastic strains in calcite formed at sand-sand contacts during bio-cementation.
Tomography establishes the sample morphology and the cemented contact architecture; 3DXRD provides grain-averaged orientation and strain states; and DFXM resolves sub-grain misorientations and localized strain concentrations generated during growth with 100 nm resolution. The combined results show that calcite precipitation through bio-cementation produces anisotropic internal strain and distinct sub-domain structures that can influence bond integrity and load transfer at the macroscopic scale.
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All authors Marilyn Sarkis, James A. D. Ball, Michela La Bella, Antoine Naillon, Christian Geindreau, Fabrice Emeriault, Carsten Detlefs, Can Yildirim
Materials Science
Depth-resolved magnetization dynamics in Fe thin films after ultrafast laser excitation
Valentin Chardonnet, Marcel Hennes, Romain Jarrier et al. (+12 more)
We performed time-resolved x-ray resonant
magnetic reflectivity measurements on a
laser-excited
ferromagnetic Fe thin film to simultaneously probe the transient
magnetic and structural depth profiles with nanometer spatial and femtosecond temporal resolution. Our results show that during the first picoseconds after optical excitation, the magnetization of the Fe layer is strongly inhomogeneous, especially in the vicinity of the buried interface. By comparing our experimental results to predictions based on the microscopic three-temperature model and simulations of
laser-induced
spin-currents, we demonstrate that local and non-local angular momentum transfer phenomena take place simultaneously. After a few picoseconds, the magnetization relaxes back to
equilibrium while the total thin film thickness starts oscillating periodically, with a maximum dilation of approximately 1.3% of the entire thin film thickness due to
laser-induced stresses.
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All authors Valentin Chardonnet, Marcel Hennes, Romain Jarrier, Renaud Delaunay, Nicolas Jaouen, Marion Kuhlmann, Cyril Leveillé, Clemens von Korff Schmising, Daniel Schick, Kelvin Yao, Xuan Liu, Gheorghe S. Chiuzbăian, Jan Lüning, Boris Vodungbo, Emmanuelle Jal
Materials Science
940-nm VCSELs grown by molecular beam epitaxy on Ge(001)
Karim Ben Saddik, Alexandre Arnoult, Pierre Gadras et al. (+5 more)
Vertical-cavity surface-emitting
laser (VCSEL) structures emitting near 940 nm were grown by solid source molecular beam epitaxy (MBE) on Ge(001) substrates. The VCSEL MBE-growth was realized upon a virtual substrate composed of GaAs on Ge grown by melatorganic vapour phase epitaxy (MOVPE). In situ monitoring during MBE growth employed multispectral reflectometry and magnification-inferred
curvature imaging for real-time growth analysis.
Curvature measurements revealed progressive compressive stress, while optical reflectivity data confirmed uniform layer growth and accurate stopband formation. Fabricated devices with mesa diameters of 35-40 $\mu$m, corresponding to
oxide apertures of approximately 11-16 $\mu$m, exhibited room-temperature lasing under continuous-wave bias with threshold currents below 3 mA. To the best of our knowledge, this is the first demonstration of monolithically integrated 940 nm VCSELs grown on Ge substrates by MBE. These results confirm the viability of MBE-grown VCSELs on Ge with in situ process control for scalable optoelectronic integration.
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All authors Karim Ben Saddik, Alexandre Arnoult, Pierre Gadras, Stéphane Calvez, Léo Bourdon, Richard Monflier, Wlodek Strupinski, Guilhem Almuneau
Materials Science
Symmetry-Driven Floquet Engineering in Multivalley SnS
Sotirios Fragkos, Benshu Fan, Umberto De Giovannini et al. (+5 more)
Coherent interactions between time-periodic electromagnetic fields and materials offer a powerful platform for engineering light-matter hybrid Floquet states with tailored functionalities. In particular, the ability to manipulate the wavefunction
symmetry of such Floquet states has recently emerged as a new frontier in the field of nonequilibrium control of
quantum materials. Here, we investigate
symmetry-driven Floquet engineering in bulk multivalley
semiconductor tin sulfide (SnS) using time-, polarization-, and angle-resolved extreme ultraviolet photoemission spectroscopy, group-theory analysis, and time-dependent density functional theory. We demonstrate that the material's inherent
symmetry gives rise to pronounced
symmetry-driven photoemission selection rules for both
equilibrium bands and light-induced Floquet states, which we probed through nonequilibrium linear dichroism in extreme ultraviolet photoemission. By leveraging the interplay between
crystal and driving-light
symmetry, we establish deterministic control over the parity of Floquet–Bloch states. Indeed, we show that the
symmetry of Floquet–Bloch states can be fully controlled by the relative
alignment between the drive polarization and the
crystal axes, enabling selective parity inversion with respect to the
equilibrium valence and conduction bands. Furthermore, we show that
symmetry-driven parity engineering allows for polarization- and valley-selective band renormalization. These findings advance the understanding of guiding principles for wavefunction
symmetry engineering, providing pathways for selectively controlling both the parity and renormalization of electronic states in
quantum materials using tailored electromagnetic fields.
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All authors Sotirios Fragkos, Benshu Fan, Umberto De Giovannini, Dominique Descamps, Stéphane Petit, Hannes Hübener, Angel Rubio, Samuel Beaulieu
Materials Science
Emergence of polar monoclinic phase in heterohalogen substituted CsGeX$_3$
Sourabh Vairat, Balachandra G. Hegde, Brajesh Tiwari et al. (+1 more)
The occurrence of ferroelectricity in inorganic germanium-based halide perovskites has provided an alternative to
oxide counterparts. Using first-principles methods, we have studied CsGeX$_3$ materials with heterohalogen substitution at the X site in a 2:1 configuration. Structurally, such variation alters the octahedral environment more strongly than in pristine materials, giving rise to a polar monoclinic phase at room temperature. The occurrence of the monoclinic phase is also confirmed through the energetics of structures generated by the displacements of atoms in accordance with soft mode eigenvectors of the dynamical
matrix along various directions. In the chemically tuned phase, the polarization is along [101] and increases by 10-15% compared to pristine ones. The electronic structure analysis reveals that
spin-splitting energy ranges from 25 to 250 meV in the valence band and from 9 to 80 meV in the conduction band in chemically tuned structures. In addition, these structures exhibit Rashba and persistent
spin textures, which are coupled to the polarization direction. The parameters of the
symmetry-dependent k.p
Hamiltonian provide insights into the strength of
spin-splitting and the nature of
spin-texture. The semiconducting and
spin-polarized nature of CsGeX$_3$ materials makes them strong candidates for Datta-Das
spin transistors.
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All authors Sourabh Vairat, Balachandra G. Hegde, Brajesh Tiwari, Ravi Kashikar
Materials Science
Origin and Propagation of Spin-orbit Torques in Pt/Co/Cu/NiFe/Capping Multilayers
Yuming Bai, Rulin Tian, Yue Zhang et al. (+1 more)
Spin-orbit torque (SOT) enables efficient current-driven control of magnetization, offering a promising pathway toward low-power spintronic devices. However, the origin and propagation of both damping-like (DL) and field-like (FL) SOTs in complex multilayers remain unclear. Here, we investigate NiFe thickness-dependent SOT efficiencies in Ta/Pt/Co/Cu/NiFe/Cu/Capping multilayers (x = 15 nm; Capping = Pt, Al, and SiO2). By employing a
spin rotation geometry, the perpendicularly magnetized Pt/Co/Cu stacks serve as a
spin source introducing unconventional
spin polarization orthogonal to the Oersted field, eliminating its contribution and enabling unambiguous separation of SOTs using planar
Hall and polar MOKE measurements. To distinguish bulk and interfacial contributions, we introduce a sample-area-normalized moment m = mNiFe/S, accounting for thickness-dependent magnetization and eliminating uncertainties arising from nominal thickness scaling and
magnetic dead layers. We find that DL-SOT follows nearly linear 1/m scaling, consistent with rapid
spin absorption at the Cu/NiFe interface but exhibits finite beta_SOT when 1/m approaches zero in both Pt- and Al-capped samples, indicating additional interfacial
spin-current contributions at Cu/Pt and Cu/Al interfaces. In contrast, SiO2-capped samples show negligible interfacial contributions. Furthermore, FL-SOT deviates markedly from 1/m scaling and exhibits a significantly longer
spin dephasing length (about 1.7 nm) compared to DL-SOT, implying extended propagation across NiFe. Comparative capping-layer studies further corroborate this behavior through interface-dependent
spin transport. Our findings clarify the origin and distinct propagation characteristics of DL and FL torques, providing guidelines for engineering interfacial
spin-orbit functionalities in ultrathin metallic
heterostructures.
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All authors Yuming Bai, Rulin Tian, Yue Zhang, Tao Wang
Materials Science · Cross-listed from cs.CV
A Decade of Generative Adversarial Networks for Porous Material Reconstruction
Ali Sadeghkhani, Brandon Bennett, Masoud Babaei et al. (+1 more)
Digital reconstruction of porous materials has become increasingly critical for applications ranging from geological reservoir characterization to tissue engineering and electrochemical device design. While traditional methods such as micro-computed
tomography and statistical reconstruction approaches have established foundations in this field, the emergence of deep learning techniques, particularly Generative
Adversarial Networks (GANs), has revolutionized porous media reconstruction capabilities. This review systematically analyzes 96 peer-reviewed articles published from 2017 to early 2026, examining the
evolution and applications of GAN-based approaches for porous material image reconstruction. We categorize GAN architectures into six distinct classes, namely Vanilla GANs, Multi-Scale GANs, Conditional GANs,
Attention-Enhanced GANs, Style-based GANs, and Hybrid Architecture GANs. Our analysis reveals substantial progress including improvements in porosity accuracy (within 1% of original samples), permeability prediction (up to 79% reduction in mean relative errors), and achievable reconstruction volumes (from initial $64^3$ to current $2{,}200^3$ voxels). Despite these advances, persistent challenges remain in computational efficiency,
memory constraints for large-scale reconstruction, and maintaining structural continuity in 2D-to-3D transformations. This systematic analysis provides a comprehensive framework for selecting appropriate GAN architectures based on specific application requirements.
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All authors Ali Sadeghkhani, Brandon Bennett, Masoud Babaei, Arash Rabbani
Materials Science
Cold source field-effect transistor with type-III band-aligned HfS$_2$/WTe$_2$ heterostructure
Shujin Guo, Qing Shi, Deping Guo et al. (+4 more)
The cold source field-effect transistor (CSFET) is promising for reducing power dissipation in integrated
circuits by engineering the density of states at the injecting source. Existing CSFET designs utilizing Dirac-source metals or p-Metal-n stacks are challenged by Schottky barriers at the metal-
semiconductor interface. In this work, a 2D WTe$_2$/HfS$_2$ heterojunction with type-III band
alignment is proposed to be an excellent design of cold source and CSFET. The architecture has a high band-to-band transport mechanism by removing the detrimental Schottky barrier issues. Importantly, the proposed CSFET has the same channel barrier modulation principle as conventional MOSFET to enable a high on-state current. Using first-principles-based
quantum transport modeling, we predict a very high $I_{\rm on}$/$I_{\rm off}$ ratio at $\sim$ 10$^{10}$, a low subthreshold swing below the thermal limit for a wide range of gate voltages, reaching as small as 41.3 mV/dec, at low source-drain bias $V_{DS}=0.3$ $\rm V$. These findings establish a design principles for next-generation low-power nanoelectronic switches leveraging 2D van der Waals
heterostructures.
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All authors Shujin Guo, Qing Shi, Deping Guo, Fei Liu, Xianghua Kong, Yonghong Zhao, Hong Guo
Materials Science
Phase Separation in Heritage Objects Made of Plasticised PVC: the Case of Joseph Beuys Multiples
Marwa Saad, Sonia Bujok, Aurora Cairoli et al. (+9 more)
This work addresses the advanced degradation of plasticised PVC boards, which constitute Joseph Beuys multiples Phosphorus-Cross Sled, focusing on the mechanisms responsible for the extensive exudation of a viscous
liquid. A multi-analytical approach combining chromatographic, spectroscopic, microscopic, and mechanical techniques was employed to characterise both the exuded surface layer and the
polymer bulk, and to evaluate the consequences of degradation for long-term mechanical behaviour. The experimental results are supported by density functional theory simulations, which indicate a thermodynamic driving force for plasticiser migration towards the PVC surface and its tendency to self-associate. These molecular-level insights provide a mechanistic explanation for the observed migration and exudation phenomena. Overall, the study outlines a coherent deterioration pathway for exudate-covered plasticised PVC. The application of NMR spectroscopy proved to be an efficient method for studying accelerated migration of the plasticiser in PVC, opening the path to the development of non-destructive, in situ preventive conservation tools, supporting the early identification of PVC artefacts or parts of a collection that are at risk of severe phase separation.
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All authors Marwa Saad, Sonia Bujok, Aurora Cairoli, Karol Górecki, Marek Bucki, Dorota Duraczyńska, Dominika Pawcenis, Dominika Anioł, Kosma Szutkowski, Artur Michalak, Krzysztof Kruczała, Łukasz Bratasz
Materials Science · Cross-listed from cond-mat.supr-con
Theoretical proposal of superconductivity in hole-doped reduced bilayer nickelate La3Ni2O6: a manifestation of orbital-space bilayer model with incipient bands
Shu Kamiyama, Reo Kohno, Yuto Hoshi et al. (+4 more)
A correspondence exists between the multi-orbital Hubbard model and the
bilayer Hubbard model, in which superconductivity is optimized in an incipient-band regime in both cases. In the multi-orbital system, the orbital level offset $\Delta E$ plays a role analogous to the interlayer hopping in
bilayer systems, and superconductivity is enhanced for large $\Delta E$. We refer to such a multi-orbital model as an orbital-space
bilayer model (OSBM). In this study, we theoretically propose that a reduced
bilayer nickelate La$_3$Ni$_2$O$_6$ can be a candidate for a
superconductor described by OSBM when an appropriate amount of holes is doped. By constructing a tight-binding model based on first-principles calculations, a large $\Delta E$ between the Ni $d_{x^2-y^2}$ and the other $d$ orbitals is obtained due to the absence of outer apical oxygens. Furthermore, our fluctuation exchange approximation calculations indicate the emergence of $s\pm$-wave superconductivity driven by interorbital interactions in an incipient-band situation, where the superconducting gap function changes its sign between the $d_{x^2-y^2}$ and other $d$ orbital bands. We also investigate the energetic and dynamical stability of the
crystal structure under atomic substitution and pressure. Although La$_3$Ni$_2$O$_7$ and La$_3$Ni$_2$O$_6$ share a similar chemical formula, our study shows that an entirely different pairing mechanism can take place in the latter.
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All authors Shu Kamiyama, Reo Kohno, Yuto Hoshi, Kensei Ushio, Daiki Nakaoka, Hirofumi Sakakibara, Kazuhiko Kuroki
Materials Science
First-principles insights into the optoelectronic and thermoelectric properties of X3NbY4(X= Cu, Ag, Au; Y=S, Se, Te) sulvanite compounds for energy applications
Sadeya Sabnam Emo, Md. Sharear Aman, Md. Abdur Rashid et al. (+1 more)
The structural, electronic, optical and transport properties of X3NbY4(X= Cu, Ag, Au; Y=S, Se, Te) sulvanite chalcogenides materials have been investigated using the Full Potential Linear Augmented Plane wave (FP-LAPW) within the density functional theory (DFT). The calculated structural information of X3NbY4 compounds is consistent with reported results of the same family compounds. The electronic band diagram exhibit indirect type band structures with bandgap value in the range of Eg 1.65- 0.50 eV using PBE-GGA functional and 1.80 eV-1.18 eV using TB-mBJ functional which indicates that these are
semiconductor materials. The density of states (DOS) shows that the amount of bandgap decreases owing to move of valence band maximum (VBM) to the high energy level whereas the conduction band minimum (CBM) to the low energy level owing to the replacement of S-S-Te and Cu-Ag-Au atoms. The hybridized orbital by X-d, Nb-d and Y-p atomic orbitals dominate the VBM while hybridized by Nb-d and Y-p atomic orbitals mainly contribute the CBM. The elastic calculations exhibit that Cu-based materials have brittleness nature whereas Ag- and Au-based compounds are ductile nature. Furthermore, the
phonon dispersion curves probes that these X3NbY4 compounds are dynamically stable. However, the calculated optical properties: dielectric function, absorption coefficient, refractive index, and energy loss function; specifically, the higher value of absorption coefficient (105 cm-1) indicates that these materials are attractive candidates in optoelectronics applications. Finally, thermoelectric parameters such as Seebeck coefficient, thermal conductivity, electrical conductivity, power factor (P.F) and ZT value of these compounds have also been investigated. Overall, the finding explores that these materials are potential candidates for the applications in optoelectronic and thermoelectric devices.
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All authors Sadeya Sabnam Emo, Md. Sharear Aman, Md. Abdur Rashid, Jaker Hossain
Materials Science
Melting of thin silicon films: a molecular dynamics study with two machine learning potentials
Yu. D. Fomin, E. N. Tsiok and V. N. Ryzhov
Thermal stability of silicene and thin silicon films is studied by molecular dynamics using two machine-learning potentials, SNAP and GAP. For SNAP potential, systems ranging from a single silicene layer to films of 36 layers are considered. Silicene is found to lose its structure at 500 K. The decomposition temperature increases with film thikness and reaches saturation at about 28 layers, corresponding to the bulk melting point of the SNAP model (1380 K). Thin films up to 8 layers exibit two-phase coexistence upon decomposition, while thicker films undergo surface melting followed by complete collapse into the
liquid state. The GAP potential, although more accurate for bulk silicon, fails to describe the gas phase: silicene modelled with GAP decomposes into a set of small clusters. The results are compared with earlier data for the Stillinger-Weber potential.
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Materials Science · Cross-listed from cs.CV
PolyCrysDiff: Controllable Generation of Three-Dimensional Computable Polycrystalline Material Structures
Chi Chen, Tianle Jiang, Xiaodong Wei et al. (+1 more)
The three-dimensional (3D) microstructures of polycrystalline materials exert a critical influence on their mechanical and physical properties. Realistic, controllable construction of these microstructures is a key step toward elucidating structure-property relationships, yet remains a formidable challenge. Herein, we propose PolyCrysDiff, a framework based on conditional latent
diffusion that enables the end-to-end generation of computable 3D polycrystalline microstructures. Comprehensive qualitative and quantitative evaluations demonstrate that PolyCrysDiff faithfully reproduces target grain morphologies, orientation distributions, and 3D spatial correlations, while achieving an $R^2$ over 0.972 on grain attributes (e.g., size and sphericity) control, thereby outperforming mainstream approaches such as Markov random field (MRF)- and convolutional neural network (CNN)-based methods. The computability and physical validity of the generated microstructures are verified through a series of
crystal plasticity finite element method (CPFEM) simulations. Leveraging PolyCrysDiff's controllable generative capability, we systematically elucidate how grain-level microstructural characteristics affect the mechanical properties of polycrystalline materials. This development is expected to pave a key step toward accelerated, data-driven optimization and design of polycrystalline materials.
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All authors Chi Chen, Tianle Jiang, Xiaodong Wei, Yanming Wang
Materials Science
Shear-Coupled Grain Growth Statistics
Caihao Qiu, David J. Srolovitz, Gregory S. Rohrer et al. (+2 more)
Grain growth (GG), driven by grain boundary (GB) migration, is a fundamental mechanism of microstructural
evolution in polycrystalline materials. GB migration is frequently accompanied by a relative shear displacement of grains meeting at GBs, a phenomenon known as shear coupling. This coupling induces internal stresses within the microstructure, which recent studies have shown to play a decisive role in dictating the
evolution of microstructure and GG pathways. This work provides a detailed characterization of the statistical features of two-dimensional GG in the presence of GB shear coupling through continuum modeling of GB migration that incorporates fundamental microscopic mechanisms and diffuse-interface simulations. We demonstrate that incorporating shear coupling produces a more heterogeneous, less equiaxed microstructure than conventional
curvature-driven GG, while yielding topological and
geometric properties consistent with experimental and atomistic observations. We further demonstrate that as grain grows, internal stress relaxes. Highly stressed grains shrink faster, and lightly stressed grains grow faster than other grains. These findings demonstrate that internal stress, an intrinsic feature of GG, profoundly changes essential features of GG microstructure and kinetics, consistent with experiments and atomic-scale simulations.
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All authors Caihao Qiu, David J. Srolovitz, Gregory S. Rohrer, Jian Han, Marco Salvalaglio
Materials Science
Rainbow Scattering from Graphene
Carolin Frank, Kevin Vomschee, Radek Holeňák et al. (+3 more)
We report the experimental observation of atomic rainbow scattering of 40 keV Xe$^+$ ions transmitted through self-supporting single-layer
graphene using time-of-flight medium energy ion scattering. Supported by molecular dynamics and binary collision approximation simulations, we show that the rainbow pattern of
graphene consists of a small hexagonal inner rainbow, arising from projectiles with characteristic trajectories interacting with multiple carbon atoms, and a larger circular outer rainbow, arising from close binary collisions between projectiles and individual carbon atoms.
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All authors Carolin Frank, Kevin Vomschee, Radek Holeňák, Yossarian Liebsch, Marika Schleberger, Daniel Primetzhofer
Materials Science
Unlocking nanoscale microstructural detail in aluminium alloys through differential phase contrast segmentation in STEM
Matheus A. Tunes, Martin Hasenburger, Rostislav Daniel et al. (+5 more)
Differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM) maps projected electric fields through the phase sensitivity of segmented low-angle detectors. Although typically applied to atomic-resolution imaging at low beam currents, STEM-DPC is here demonstrated as a rapid micro- and nanoscale image-
segmentation tool for materials characterization in advanced aluminium
alloys. Decomposition of false-colour DPC micrographs in hue-saturation-value space enables simultaneous identification and quantification of nanoclusters, GP zones, intermediate precipitate phases, dislocation cores, and associated strain fields within a single field of view. The method is demonstrated across multiple
alloy systems, including clustering and strain-field mapping in a deformed AlMgZn(Cu) crossover
alloy, precipitate identification in a paint-baked automotive sheet
alloy, phase-variant
segmentation in overaged AA7075-T7, and nanopore and nanoparticle detection in an anodic coating on AA2024-T3. Coupling DPC with neural-network
segmentation further enables automated grain-boundary delineation and quantification in nanocrystalline aluminium thin films. Combined with STEM-EDX, DPC-based
segmentation enables correlative microstructural analysis, establishing DPC as a rapid complement to techniques such as SPED and 4D-STEM.
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All authors Matheus A. Tunes, Martin Hasenburger, Rostislav Daniel, Oscar M. Prada-Ramirez, Philip Aster, Sebastian Samberger, Thomas M. Kremmer, Johannes A. Österreicher
Materials Science
High-fidelity level-set modeling of polycrystalline grain growth
Tianchi Li and Marc Bernacki
Accurate modeling of polycrystalline microstructure
evolution under strong crystallographic heterogeneities remains a major challenge for full-field numerical methods at the mesoscopic scale. In this work, we present a high-fidelity level-set framework for capillarity-driven grain growth in polycrystals with highly-heterogeneous, disorientation-dependent grain boundary energies. The novel framework represents a polycrystalline extension of our level-set formulation, previously developed and validated using a single triple junction
benchmark case. In-depth comparisons with three established level-set models demonstrate that the proposed method yields the most energetically-consistent
evolution of grain statistics, disorientation distribution function, and triple junction dihedral angles. Accuracy and robustness are maintained across the entire heterogeneity spectrum. To the best of our knowledge, this approach delivers the highest-fidelity front-capturing level-set modeling of grain growth based on Mullins' mean
curvature flow theory, paving the way for state-of-the-art digital twins for annealing applications.
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Materials Science
High-pressure phase stability and superconductivity in La-Zr-H hydrides
Ijaz shahid, Maxim A. Grebeniuk, Jinbin Zhao et al. (+8 more)
Hydrogen-rich ternary hydrides are promising candidates for high-Tc superconductivity at megabar pressures, yet their chemical space is vast and largely unexplored. Combining evolutionary structure searches with first-principles calculations, we comprehensively investigate the La-Zr-H ternary system in the 150-300 GPa pressure range. Zero-point energy-corrected convex hull analysis identifies multiple stable superconducting phases, including R3m-Zr2H17 at 300 GPa and P6/mmm-LaZr2H24 at 200 GPa, both of which are thermodynamically and dynamically stable and exhibit strong electron-
phonon coupling. Solution of the Eliashberg equations predicts high superconducting transition temperatures of Tc = 209 K for R3m-Zr2H17 at 300 GPa and Tc = 202 K for P6/mmm-LaZr2H24 at 200 GPa. In addition to these stable phases, we identify a high-
symmetry metastable compound, P6m2-LaZrH18, which lies just 0.027 eV/atom above the convex hull yet remains dynamically stable and exhibits a high predicted Tc of 206 K at 300 GPa. We find that, across all phases, the elevated Tc correlates with the high-
symmetry structure with dense hydrogen cages, favorable electron counts per hydrogen, and a large hydrogen-derived density of states at the
Fermi level. Finally, a random- forest machine learning model, trained on diverse hydrides superconductivity data, reproduces these structure-property trends across predicted structures, enabling to identify potential hydrides with high predicted Tc for targeted follow-up calculations and future high-pressure experiments.
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All authors Ijaz shahid, Maxim A. Grebeniuk, Jinbin Zhao, Ergen Bao, Tianye Yu, Xiangyang Liu, Yi-Chi Zhang, Artem R. Oganov, Yan Sun, Peitao Liu, Xing-Qiu Chen
Materials Science · Cross-listed from physics.optics
Quantitative 3D imaging of highly distorted micro-crystals using Bragg ptychography
Peng Li, David Yang, Christoph Rau et al. (+3 more)
Bragg coherent diffraction imaging (BCDI) fails to reliably retrieve phases in micro-
crystals exhibiting strong strain inhomogeneities, which restricts its applicability. Here we show that three-dimensional Bragg ptychography (3DBP) overcomes this limitation by enabling stable inversion for large
lattice distortions. Using a combination of experimental measurements and numerical tests, we compare the performance limits of the two approaches and demonstrate that 3DBP tolerates
lattice distortions more than six times larger than BCDI. We also establish the sensitivity of both methods on a weakly distorted
crystal, for which 3DBP yields smoother amplitude and phase fields with reduced short-length-scale artifacts. 3DBP thus provides a reliable route for imaging micro-
crystals with large
lattice distortions, expanding the scope of coherent X-ray Bragg microscopy to strongly deformed systems.
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All authors Peng Li, David Yang, Christoph Rau, Marc Allain, Felix Hofmann, Virginie Chamard
Materials Science · Cross-listed from physics.app-ph
Metasurface Tape for Efficient Millimeter-Wave Power Transfer via Surface-Wave Propagation
Phuc Toan Dang, Kota Suzuki, Yoshiki Ashikaga et al. (+3 more)
Millimeter-wave technologies are essential for future high-speed wireless communications. However, a fundamental challenge remains in the form of severe free-space path loss, where the power density decreases inversely with the square of the distance r (i.e., proportional to r^{-2}) as a spherical dependence. To overcome this limitation, we propose a flexible metasurface tape that is designed to guide electromagnetic energy as surface waves. Unlike conventional free-space propagation, this engineered metasurface confines the field to a subwavelength interface, thereby altering the power decay law to a circular dependence (i.e., proportional to r^{-1}). We numerically and experimentally, for the first time, demonstrate this concept using a periodic grounded-patch array fabricated on a flexible substrate and operated at approximately 100 GHz. The measurement results show that the metasurface tape significantly increases the transmitted power, yielding an average rate of improvement of approximately 40 per meter in received power relative to the free-space baseline in our measurement geometry (e.g., 29-dB increase at 2 m). This increase is realized over a broad bandwidth from 95 GHz to 105 GHz (i.e., approximately 10 %), accommodating wideband modulation schemes required for high-data-rate applications. The flexible, lightweight nature of the tape allows it to be easily installed on diverse surfaces. Our demonstration indicates that the metasurface tape is a promising platform for extending the effective range of millimeter-wave systems, thus offering a robust solution to the path-loss bottleneck in next-generation wireless networks.
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All authors Phuc Toan Dang, Kota Suzuki, Yoshiki Ashikaga, Yasushi Tsuchiya, Sendy Phang, Hiroki Wakatsuchi
Materials Science · Cross-listed from cond-mat.str-el
Suppression of local magnetic moment formation and paramagnetic exchange interactions in monolayer Fe$_3$GeTe$_2$
A. A. Katanin, A. N. Rudenko, D. I. Badrtdinov et al. (+1 more)
We study the electronic and
magnetic properties of monolayer Fe$_3$GeTe$_2$ within the DFT+DMFT approach in the paramagnetic phase. We argue that this compound is sufficiently far from the local
magnetic moment limit, demonstrating non-linear temperature dependencies of the partial inverse local and uniform
magnetic susceptibilities in a broad temperature range. We find that in the regime of moderate Coulomb interactions ($U=3-4$ eV), the iron atoms located above and below the Ge plane carry a substantial local
magnetic moment ($\mu \gtrsim 4.5 \mu_B$), while the iron atom located within the Ge plane does not exhibit any pronounced
magnetic moment. At the same time, the RKKY-type exchange interactions between these two
symmetry-nonequivalent types of atoms turn out to be crucial for stabilizing long-range
ferromagnetic order in Fe$_3$GeTe$_2$. The estimated
spin-wave stiffness and Curie temperature are in good agreement with the experimental data, indicating that a dynamical treatment of electron correlations in Fe$_3$GeTe$_2$ is essential to properly describe its partially itinerant
magnetic behavior.
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All authors A. A. Katanin, A. N. Rudenko, D. I. Badrtdinov, M. I. Katsnelson
Materials Science
Imaging antiferromagnetic domains in LiCoPO$_4$ via the optical magnetoelectric effect
B. Tóth, V. Kocsis, Y. Tokunaga et al. (+3 more)
Antiferromagnetic (AFM) materials are considered as promising building blocks of novel data storage devices, still, detecting and manipulating AFM domains have remained challenging. Here, we demonstrate that the two antiphase domains of the magnetoelectric antiferromagnet LiCoPO$_4$ can be distinguished by their light absorption difference. Using visible and infrared spectroscopy, we observed spontaneous non-reciprocal absorption, also termed as directional dichroism, at the
crystal field excitations of Co$^{2+}$ ions coordinated by distorted oxygen octahedra. This absorption contrast is particularly pronounced near the telecommunication wavelength of 1550 nm. These findings allowed us to image the AFM domains in LiCoPO$_4$ using a simple transmission light microscopy setup. Our findings suggest that optical magnetoelectric effects offer promising routes for probing the AFM order parameter in non-centrosymmetric transition metal compounds.
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All authors B. Tóth, V. Kocsis, Y. Tokunaga, Y. Taguchi, Y. Tokura, S. Bordács
Materials Science
Why ice is so slippery
Sigbjørn Løland Bore, B.N.J. Persson and Henrik Andersen Sveinsson
We simulate nanoscale ice–glass friction from first principles and upscale it by modelling frictional heating. Nanoscale simulations alone overestimate friction and miss its velocity dependence. Frictional heating warms the contact toward the melting point, thickening the premelting film tenfold and cutting its viscosity a hundredfold; friction drops with velocity, matching experiment. Premelting forms the film without sliding or heating, but its slipperiness hinges on frictional heating, as Bowden and Hughes proposed in 1939, without melting. Snow, other materials and coatings remain open.
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