Materials Science · Cross-listed from cond-mat.stat-mech
On first-order thermodynamic equilibrium conditions for fluid-fluid and solid-phase interfaces
Nicodemo Di Pasquale and Thomas Hudson
Starting from the constrained variational formulation of Larché and Cahn for solids in contact with fluids, a unified thermodynamic framework for such systems is developed. Both bulk and interfacial
equilibrium conditions arise as stationarity conditions of a single thermodynamic functional. While earlier theory neglects a full treatment of interfacial contributions and therefore cannot describe systems in which surface effects are significant, the present formulation incorporates interfacial thermodynamics directly into the variational principle. The framework is introduced first for fluid-fluid systems to establish the underlying mathematical structure, and is then extended to solid-fluid interfaces. Within this setting, classical
equilibrium relations for heterogeneous systems emerge naturally from different classes of admissible variations, providing a common theoretical basis for bulk, interfacial, and configurational thermodynamics.
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Materials Science
Helimagnetism from competing intra- and interchain interactions in CrBr$_2$ and CrI$_2$
John A. Schneeloch, Matthew B. Stone, Zachary Morgan et al. (+1 more)
CrBr$_2$ and CrI$_2$ are promising platforms for studying the effect of dimensionality on
magnetic order, having been isolated in a 3-, 2-, and 1-dimensional form as bulk
crystals, monolayers, and individual chains encapsulated in carbon nanotubes. However, the interactions that give rise to their helimagnetic order are unknown. Via inelastic
neutron scattering on single
crystals, we have determined the exchange interactions of these compounds from the
spin wave dispersions, finding that the helimagnetic order arises primarily from competing antiferromagnetic interactions between intrachain and interchain nearest-neighbors. Single-ion anisotropy is substantial, modulating the helical
spin rotation and gapping the inelastic intensity at points of branch crossings. As temperature increases, long-range order vanishes but intralayer correlations remain detectable up to at least 50 K.
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All authors John A. Schneeloch, Matthew B. Stone, Zachary Morgan, Despina Louca
Materials Science
Balanced electron and phonon heat transport in metallic $\varepsilon$-TaN
Sungyeb Jung, Hongze Li, Yudan Li et al. (+6 more)
Most materials with high thermal conductivity belong to one of two classes: metals, where heat is carried predominantly by electrons, and
insulators, where heat transport is dominated by the
phonon contribution. Materials that combine substantial electronic thermal conductivity and
lattice thermal conductivity are rare, because the mechanisms that favor electron transport typically suppress
phonon transport, and vice versa. Here, we report the theoretical prediction and experimental realization of such a material, metallic $\varepsilon$-TaN. Our calculations predict a total thermal conductivity at room-temperature of 273$\pm$5Wm$^{-1}$K$^{-1}$ in single
crystals and 145$\pm$5Wm$^{-1}$K$^{-1}$ in polycrystals with 0.5$\mu$m grains, with an unusually large
lattice contribution (79%) for a metal. The latter value is in agreement with our local transient thermoreflectance measurements on polycrystalline samples yielding $\sim$130Wm$^{-1}$K$^{-1}$. We show that the balanced electronic and
lattice thermal conductivities of $\varepsilon$-TaN originate from a combination of large Fermi velocity and small Fermi density of states on the electron side, and large speed of sound and wide
phonon gap on the
lattice side.
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All authors Sungyeb Jung, Hongze Li, Yudan Li, Noah Rossignol, Woongchul Choi, Yaguo Wang, Jianshi Zhou, Li Shi, Feliciano Giustino
Materials Science
Revealing the Atomic Structure of NiO/Ga$_{2}$O$_{3}$ Interfaces
Michelle A. Smeaton, Krishna Acharya, Anna Sacchi et al. (+5 more)
NiO/Ga$_{2}$O$_{3}$ heterojunctions have garnered significant
attention for use in power electronics due to the ultrawide bandgap and wafer-scale availability of Ga$_{2}$O$_{3}$ and the controllable p-type doping of NiO. However, the structure of NiO/Ga$_{2}$O$_{3}$ interfaces remains underexplored, largely due to the complexity of the junction between their dissimilar cubic and monoclinic
crystal structures. Here we investigate the atomistic structure of the NiO/Ga$_{2}$O$_{3}$ interface for (100), (-201), and (001) oriented Ga$_{2}$O$_{3}$ substrates using aberration-corrected scanning transmission electron microscopy (STEM) in combination with interface modeling and image simulations. We evaluate the abruptness and consistency of the interfaces and compare them to calculated interface models, proposing precise atomic structures and assessing potential structural variation arising from complexity of the monoclinic Ga$_{2}$O$_{3}$
crystal structure. Our interface analysis supports increased focus on (100) oriented Ga$_{2}$O$_{3}$ as a candidate for fabricating high quality, low defect density NiO/Ga$_{2}$O$_{3}$ heterojunction devices. Importantly, we consider the effects of specimen thickness and 3D-to-2D projection during the STEM imaging process to differentiate such effects from real
crystal variations. This work provides insight into the effect of substrate orientation on NiO film and interface quality, creating a pathway to improving heterojunction properties. It further highlights important considerations for interpretation of stability and interlayer phase formation in these interfaces, which is crucial for their integration into reliable and robust power electronic devices.
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All authors Michelle A. Smeaton, Krishna Acharya, Anna Sacchi, Renae N. Gannon, M. Brooks Tellekamp, Andriy Zakutayev, Vladan Stevanovic, Steven R. Spurgeon
Materials Science
Light Polarization Sensitive Transistor Action in the van der Waals ferroelectric 4H-SnS2
Abhishek Bajgain, Rabindra Basnet, Subhashree Chatterjee et al. (+2 more)
Van der Waals (vdW) ferroelectric
semiconductors provide a unique platform for exploring the interplay between spontaneous polarization, electronic transport, ion migration, and photocarrier generation at the nanoscale. Here, we establish a room-temperature ferroelectric state in SnS2 and its sensitivity to structural polytype by directly contrasting the centrosymmetric 2H-phase with the polar 4H-phase. Raman spectroscopy distinguishes the 2H and 4H polymorphs of SnS2 through their characteristic
phonon fingerprints. Piezoresponse force microscopy confirms room-temperature ferroelectricity in the 4H phase, while the 2H phase exhibits no ferroelectric response. The built-in polarization in a three-terminal transistor device of the 4H-SnS2 is modulated significantly by electrostatic gating and on exposure to linear and circularly polarized light. This device reveals polarization-controlled output characteristics with distinct gate-voltage induced hysteretic response and thermally activated carrier transport, confirming p-type semiconducting behavior strongly coupled to ferroelectric polarization. The photoresponse likewise exhibits polarization-assisted carrier separation, sublinear power-law scaling, a nonmonotonic temperature response correlated with the characteristic Raman modes, ferroelectric hysteresis, and a pronounced dependence on the circular and linear polarization states of the incident
laser beam. These results establish 4H-SnS2 as a promising material system for polarization-driven electronic and optoelectronic technologies, including nonvolatile
memory and photoferroelectric functionalities.
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All authors Abhishek Bajgain, Rabindra Basnet, Subhashree Chatterjee, Alexander Samokhvalov, Ramesh C. Budhani
Materials Science · Cross-listed from physics.optics
Practical Evaluation of FFT-Based Thickness Extraction for Thick-Film Reflectometry
Zimu Zhou, Enrique A. Lopez-Guerra, Michael Kwan et al. (+1 more)
Fast
Fourier transform (FFT) is widely used for thick-film reflectometry because of its simplicity and computational efficiency. However, its performance under practical thick-film measurement conditions has received limited experimental evaluation. In this work, FFT, Linearized Reflectance Zero-Crossing (LRZ), and optical model fitting were compared using reflectometry measurements from a nominal 52 {\mu}m dielectric film acquired on a production wafer, with White-Light Interferometry (WLI) serving as an independent reference. Although FFT exhibited excellent repeatability, it showed systematic deviation from WLI (RMSE = 0.62 {\mu}m), whereas LRZ significantly improved accuracy (RMSE = 0.20 {\mu}m). Simulations and theoretical analysis indicate that the observed systematic deviation is consistent with spectral leakage caused by finite measurement windows and non-integer fringe periodicity. These results demonstrate that excellent repeatability does not necessarily imply high accuracy and highlight the advantages of zero-crossing-based approaches for thick-film thickness metrology.
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All authors Zimu Zhou, Enrique A. Lopez-Guerra, Michael Kwan, Chester Chien
Materials Science
MXene with Janus Structure at Transition metal site -A route to Emergent Properties
Rajdeep Biswas and Tanusri Saha Dasgupta
Motivated by the discovery of bimetallic MXene compounds with Janus metal sites, we investigate Janus MXenes TiM"CO2, where M" = Mo, W. Our computational analysis reveals that broken inversion
symmetry in the Janus structure, coupled with strong
spin-orbit coupling at M", generates diverse and remarkable functionalities. These include pronounced Rashba
spin splitting, non-trivial Z2
topology, Berry-
curvature-dipole-driven nonlinear anomalous Hall effect, and strain control of the Berry
curvature dipole. Notably, the 4d transition-metal-based TiMoCO2 and 5d transition-metal-based TiWCO2, with M" elements from the same column of the periodic table, display markedly different behaviors. While TiMoCO2 is a Z2 topological
insulator, TiWCO2 is a trivial semimetal. Both compounds, however, exhibit compelling
quantum properties. TiWCO2 shows a robust Rashba effect with a large Rashba coefficient of 1.35 eV. Angstrom and a large nonlinear anomalous Hall conductivity of 120 x 0.0001 G0. TiMoCO2, a Z2 narrow-gap
semiconductor with weaker Rashba splitting and moderate nonlinear anomalous Hall conductivity, exhibits a strain-driven transition from
semiconductor to semimetal. This transition modulates both the sign and magnitude of the Berry
curvature dipole, yielding a sizable nonlinear anomalous Hall conductivity of 17 X 0.0001 G0 under 2% tensile strain. Our findings underscore the potential of MXenes as a platform for investigating and tailoring multifunctional
quantum phenomena.
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Materials Science
Solver-Agnostic Implementation of Atom-Informed Thermal Conductivity Fields in Continuum Heat-Flow Simulations
W. Downs, C. Ugwumadu, M. Ali et al. (+1 more)
A recent work introduced the Simulator Collection for Atomic-to-Continuum Scales (SCACS) toolkit, a framework for improving finite element predictions of heat flow by mapping atom-resolved thermal conductivity into the stiffness
matrix of the Galerkin finite element formulation [Ugwumadu et al., Phys. Rev. Materials 10, 053804 (2026)]. Here, we demonstrate that SCACS-derived conductivity fields are solver-independent and can be transferred to existing continuum simulation platforms. As a proof of concept, we map SCACS-derived conductivity fields from complex silicon structures onto finite element meshes in Abaqus and compare the resulting heat-flow solutions with that obtained using conventional uniform-conductivity assignment within Abaqus. Comparison of the two implementations shows that atom-informed conductivity fields can be incorporated into existing finite element workflows and improve realistic prediction and the accuracy of its solution. This work supports broader efforts to improve the predictive capability of continuum simulations for efficient materials design and property prediction.
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All authors W. Downs, C. Ugwumadu, M. Ali, R. M. Tutchton
Materials Science
Cell Natural Orbitals in Quantum Materials
Harshitra Mahalingam, Nishchhal Verma, Daniel Muñoz-Segovia et al. (+1 more)
Understanding correlated
quantum matter starts with an accurate model of the single-particle states that interact at low energies: their dispersion, band geometry, orbital content and charge density. In many cases, notably the topological bands of moire materials, it is not straightforward to find a real-space description with a few local orbitals that accomplishes this task. Here we provide a systematic way to identify the local degrees of freedom that best capture the band geometry and charge density of any chosen set of bands. We use the unit-
cell one-particle reduced density
matrix (UC-1pRDM), obtained by restricting the projector onto the target bands to a single unit
cell. Its eigenstates, which we call
cell natural orbitals (CNOs), form a local, symmetric basis uniquely determined by the Bloch wavefunctions and the choice of real-space partition. Their
eigenvalues measure the occupation of each CNO in the target bands, quantifying
entanglement across unit-
cell boundaries and the importance of multi-orbital character. A set of CNOs that maximizes total spectral weight and reproduces the target band
symmetries provides optimal trial states for Wannierization. We exemplify this by constructing a
lattice model for twisted bilayer WSe$_2$ that tracks the orbital content across twist angles.
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All authors Harshitra Mahalingam, Nishchhal Verma, Daniel Muñoz-Segovia, Raquel Queiroz
Materials Science
Numerical modeling of microstructure evolution in nanocrystalline alloys - grain boundary segregation, solute drag and mechanics
Prakarsh Pandey and Shiva Rudraraju
Nanocrystalline (NC)
alloys hold much promise as structural
alloys due to their superior mechanical properties over traditional coarser grained microcrystalline
alloys. Strength of metallic
alloys is related to the underlying grain size - as represented by the classical Hall-Petch relation. Generally, a metals strength increases with decreasing mean grain size from the micrometer scale to the nanometer scale, until about a mean size of 20 nm. Any further decrease of grain size results in decreasing strength. Thus, there is an optimal range of mean grain size for most metals about which maximum material strength can be obtained. In the context of NC
alloys, stabilization of the grain size in this optimal range is one of the primary synthesis challenges. Since nm-scale mean grain sizes are desired, phenomena like GB solute segregation and solute precipitation are utilized during
alloy synthesis to mitigate grain growth. Numerical modeling the phenomena of GB-solute interactions and the
evolution of these stabilized GBs under mechanical load are of immense interest to the NC
alloy community. To enrich the numerical modeling formulations available in this space, we present here a phase-field method based numerical framework to model GB segregation, solute precipitation and effect of external loading on NC
alloys. While some of these effects have been modeled in isolation, a unified treatment of the solute and GB segregation with mechanics interactions has not be considered in the literature. We present a 3D FEM finite-strain phase-field formulation for modeling grain
evolution and microstructure stabilization. Beyond the formulation, various case studies demonstrate the applicability of this framework. Further, thermodynamic and kinetic arguments are provided based on the
evolution of GB energy to explain the effects of solute drag, GB pinning and mechanical deformation.
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Materials Science · Cross-listed from cond-mat.str-el
Cell Natural Orbitals in Interacting Topological Bands
Nishchhal Verma, Harshitra Mahalingam, Daniel Muñoz-Segovia et al. (+1 more)
Topological bands exhibit obstruction to exponentially localized and symmetric Wannier functions, challenging the standard paradigm of representing projected interactions in terms of local orbitals with finite range. To faithfully capture the form factors and
quantum geometry of topological bands we introduce a singular-value decomposition of the band-projected density form factors, enabling a geometry-based truncation scheme of the
Hilbert space, exposing an intrinsic hierarchy on band-projected interactions that is determined by the underlying wavefunctions. This decomposition is most naturally described in terms of
Cell Natural Orbitals (CNOs), as the eigenstates of the unit-
cell reduced one-particle density
matrix, whose occupation provide a measure of the minimal orbital complexity required to faithfully represent the band wavefunctions overlaps. The CNO decomposition identifies systematically the minimal number of local orbitals needed to reproduce short-ranged interactions while resolving the hierarchy of interaction strengths across CNO channels. Applied to magic-angle twisted bilayer
graphene in the chiral limit, we find that the dominant CNO is centered at the AA site, resembling the $f$-
fermion of the heavy-
fermion model. The subdominant CNO channels carry progressively weaker interaction
matrix elements, allowing them to be treated at the static mean-field level, while the dominant channel requires a dynamical self-energy. The formalism illustrates how variations of charge density within the unit
cell generate momentum dependence in the CNO envelope function and, consequently, dispersion in the single-particle spectral function. More broadly, our results establish CNOs as a geometry-informed bridge between band
topology and real-space correlations, providing a systematic framework for analyzing interactions and emergent phases in
quantum materials.
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All authors Nishchhal Verma, Harshitra Mahalingam, Daniel Muñoz-Segovia, Raquel Queiroz
Materials Science
AES-Debye: an Accurate, Efficient, and Scalable Engine for Debye Scattering Calculations
Navid Panchi, Sebastian Kuckuk, Markus Wittmann et al. (+2 more)
Total scattering models are essential for characterizing the structure and disorder of nanoscale materials. The Debye scattering equation (DSE) provides a rigorous route to elastic total scattering, but its direct evaluation is computationally demanding because pairwise contributions must be accumulated at every scattering vector, whereas common acceleration strategies based on binned pair-distance distributions or gridded fast
Fourier transforms can introduce discretization and aliasing artifacts that compromise diffuse-scattering accuracy. Here, we present AES-Debye, an accuracy-preserving DSE framework that aggregates pair distances into a pair distribution function (PDF) using corrected bin centers and numerically robust accumulation to suppress discretization and summation errors. A data-locality-aware parallel design enables efficient execution on CPUs and GPUs. We demonstrate strong scalability by computing a high-resolution total scattering profile for a system of 90 million atoms, $(0.1,\mu\mathrm{m})^{3}$, in minutes on a distributed-
memory CPU platform. These capabilities extend accurate elastic total scattering calculations to large, complex systems while simultaneously providing high-resolution PDFs for downstream structural analysis.
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All authors Navid Panchi, Sebastian Kuckuk, Markus Wittmann, Michael Engel, Alberto Leonardi
Materials Science
Substrate-dependent thermally driven morphological evolution of Pt$_{0.9}$Ni$_{0.1}$ thin films on sapphire and langasite
M. Awais Fiaz, M. Greenslit, R. J. Lad et al. (+3 more)
We examine the thermal
evolution of 100-nm-thick Pt$_{0.9}$Ni$_{0.1}$
alloy films on sapphire and langasite substrates with a 10-nm Zr adhesion layer. Sequential
vacuum annealing from room temperature to 800 $^\circ$C produces a substrate-dependent morphological pathway that is quantified by atomic force microscopy, image segmentation, height-distribution analysis, and effective coarsening metrics. Both types of films remain densely granular up to 400 $^\circ$C, undergo a sharp coarsening transition between 400 and 600 $^\circ$C, and evolve into coalesced faceted crystallites by 800 $^\circ$C. The mean projected feature area increases from $7.84 \times 10^2$ to $1.09 \times 10^5$ nm$^2$ on langasite and from $3.32 \times 10^2$ to $1.67 \times 10^5$ nm$^2$ on sapphire. Sapphire therefore develops the larger faceted crystallites, while langasite exhibits the larger roughness maximum at 600 $^\circ$C. Area distributions reveal that the 400-600 $^\circ$C transition does not uniformly shift the initial granular population but instead replaces it with a distinct large-feature ensemble. Height and roughness measurements show a pronounced maximum at 600 $^\circ$C, followed by partial smoothing at 800 $^\circ$C, consistent with rapid coalescence followed by faceting-limited growth. An effective Arrhenius analysis based on $\Delta\langle r^2\rangle$, with $\langle r^2\rangle = \langle A\rangle/\pi$, identifies the 400-600 $^\circ$C interval as the dominant coarsening window. These results show that the thermal stability of PtNi/Zr films on sapphire and langasite is governed by the coupled influence of
alloy mobility, interfacial energetics, and substrate-dependent morphological selection.
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All authors M. Awais Fiaz, M. Greenslit, R. J. Lad, Mauricio Pereira da Cunha, Luke Doucette, S. M. Hollen
Materials Science · Cross-listed from astro-ph.SR
Infrared Spectroscopy and Photochemistry of Aromatic Nitriles in Para-Hydrogen Matrices
Sam McGrath, Vincent J. Esposito, Linshan Zeng et al. (+6 more)
Motivated by recent detections of several aromatic nitriles in Taurus Molecular Cloud-1, we report laboratory and theoretical investigations of the vibrational spectroscopy and photochemistry of singly and doubly cyano-substituted benzene in solid para-hydrogen
matrices. We compare the photochemistry of cyanobenzene (benzonitrile) and three dicyanobenzene isomers initiated by excitations at 193 nm. In addition, we report the photochemistry of deuterated cyanobenzene (d$_5$-cyanobenzene), enabling us to determine the major products produced during the cyanobenzene photodissociation. The major products observed in the photolysis of all the nitriles are HCN and HNC, which are likely produced by hydrogen abstraction from para-H$_2$ by the CN radical. This indicates that the major photodissociation channel involves cleavage of the bond between the ring and the nitrile group, forming the phenyl (or cyanophenyl) radical + CN. We observe secondary photoproducts similar to those found during benzene photolysis. Our findings may aid the interpretation of recent JWST mid-infrared observations of aromatics in photodissociation regions.
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All authors Sam McGrath, Vincent J. Esposito, Linshan Zeng, Thomas H. Speak, Brendan Moore, Pavle Djuricanin, Jun Miyazaki, Takamasa Momose, Ilsa R. Cooke
Materials Science · Cross-listed from cond-mat.str-el
Anomalous temperature dependence of polaron mobility in a nonlinear double-well potential: unbiased X-propagator approach
Stefano Ragni, Osor S. Barišić, Naoto Nagaosa et al. (+1 more)
We develop an unbiased X-propagator method for calculating finite-temperature optical conductivity $\sigma(\omega)$ and dc mobility $\mu$ for arbitrary nonlinear electron-
phonon interaction. We apply it to a polaron coupled to a double-well
lattice potential, a minimal model for strongly anharmonic polar materials. At moderate coupling, the mobility exhibits three temperature regimes associated with confinement within one well, thermal competition with the barrier, and barrier-insensitive high-temperature dynamics. This sequence produces a concave temperature dependence of the mobility that is absent in conventional linear-coupling polaron models. At strong coupling, the mobility becomes nonmonotonic, and its temperature
evolution is reflected in a characteristic redistribution of optical spectral weight. For parameters relevant to SrTiO$_3$, our results qualitatively reproduce both the anomalous concave mobility and the onset of violation of the Mott-Ioffe-Regel limit, thereby supporting nonlinear coupling to a soft anharmonic
lattice mode as a microscopic mechanism for anomalous transport in dilute polar metals.
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All authors Stefano Ragni, Osor S. Barišić, Naoto Nagaosa, Andrey S. Mishchenko
Materials Science
Spatially resolved elastic strain and lattice rotation at threading dislocations in HgCdTe/CdZnTe epilayers by dark-field X-ray microscopy
C. Yildirim, A. Benhadjira, P. Ballet et al. (+5 more)
Threading dislocations (TDs) propagating from a Cd$_{1-y}$Zn$_{y}$Te (CZT) substrate into a
liquid-phase-epitaxy Hg$_{1-x}$Cd$_{x}$Te (MCT) epilayer set the minority-carrier lifetime and dark-current floor of mid-wave infrared focal-plane arrays, yet at device-grade densities their local strain fields have been accessible only through topography, which conflates
lattice tilt and elastic strain. We apply dark-field X-ray microscopy in reflection geometry to a \SI{7}{\micro\metre}-thick (111) MCT/CZT epilayer. Shallow Bragg angle and absorption makes the signal layer dominated while the numerical aperture of the objective keeps the layer and substrate rocking curves convolved, so weak-beam images on either side of the rocking curve and their difference image the correlated defects in a single frame: dot-like substrate TDs and the elongated, in-plane island features they nucleate in the layer. Kernel average misorientation resolves each TD as a \SI{7}{\micro\metre} signature, the layer thickness, alongside axial strain lobes of $\pm(4$ to $5)\times10^{-5}$.
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All authors C. Yildirim, A. Benhadjira, P. Ballet, T. N. Tran Caliste, J. Baruchel, C. Detlefs, D. Brellier, M. P. Kabukcuoglu
Materials Science
Polar-vortex-driven interfacial strain coupling in PbTiO3/SrRuO3 Heterostructures
S. A. Raza, V. A. Stoica, H. Zheng et al. (+7 more)
Interfacial coupling in oxide
heterostructures is a central problem in condensed-matter physics, as it typically emerges at the atomic scale through local interactions mediated by
lattice polarization and strain. In this work, we investigate nanoscale polar-supertexture-driven interfacial strain coupling in (PbTiO3)16/(SrRuO3)9/(PbTiO3)16
heterostructures grown on DyScO3(110) substrates. Under appropriate epitaxial strain conditions, the PbTiO3 layers form polar
vortex superstructures with a periodicity of approximately 10 nm. We demonstrate that the resulting in-plane nanoscale strain modulation propagates into the SrRuO3 layer. Using element-specific resonant X-ray reflectivity, we probe the nanoscale strain modulations of the strontium and ruthenium sublattices at the interface, revealing strong interfacial strain coupling between the ferroelectric and ferromagnetic layers. These findings provide new insights into engineering nanoscale
magnetic modulations through interfacial strain and polarization control.
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All authors S. A. Raza, V. A. Stoica, H. Zheng, H. G. Lee, A. Ross, U. Saha, L. Q. Chen, L. W. Martin, V. Gopalan, J. W. Freeland
Materials Science
Predictive Simulation of Interphases on Li Metal Surface
Xinyu Li, Jingxuan Ding, Daniel C. Hannah et al. (+3 more)
Interphases remain the least understood components in advanced batteries. Although their properties dictate whether a new battery chemistry could perform as designed, there has never been a reliable way to predict what an interphase could arise from a new electrolyte system due to the absence of atomistic level knowledge about interphasial formation process. In this work, we attempt to develop a simulation method that can universally predict interphasial chemistries formed on Li metal surface, so that the electrolyte engineering would no longer need lengthy Edisonian approaches. By combining a transferable universal polarizable force field and a universal machine learning force field, we simulate interphasial chemistry across chemically diverse electrolyte formulations, and successfully replicate the experimental observation that fluorinated solvents promote the formation of LiF-rich interphases, whereas interphases of more organic origin arise from conventional carbonate-based electrolytes. By directly capturing these spontaneous interfacial reactions behind these interphasial chemistries, our simulations establish molecular-level relationships between electrolyte chemistry, salt concentration, decomposition pathways, and SEI properties, and opens a route toward universal and high-throughput predictive simulation of interphases that is the foundation for AI-driven electrolyte discoveries.
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All authors Xinyu Li, Jingxuan Ding, Daniel C. Hannah, Yumin Zhang, Qichao Hu, Kang Xu
Materials Science
Preserved metallicity and tunable magnetism in Zr-based Janus MXenes
S. Özcan and B. Biel
Janus MXenes provide a chemically asymmetric platform to tailor the properties of two-dimensional transition metal carbides. Here, we present a systematic first-principles study of the structural, electronic, mechanical, and
magnetic properties of Janus ZrMCX2 MXenes (M = Cr, Hf, Nb, Sc, Ti; X = F, Cl, S). All compositions exhibit negative formation energies and satisfy the Born stability criteria, supporting the energetic and mechanical stability of the Janus structures. In contrast to the metal-tosemiconductor transitions frequently reported for functionalized MXenes, we find that the metallic character is preserved in nearly all ZrMCX2 systems, despite the strong chemical asymmetry introduced by the Janus configuration. Surface functionalization nevertheless plays a key role in modulating the electronic density near the Fermi level and strongly influences the
magnetic and mechanical responses. Several compounds exhibit ferromagnetic or antiferromagnetic ground states, three display halfmetallicity, and sizable
magnetic anisotropy energies are obtained, with Neel temperatures exceeding room temperature in selected cases. Functionalization also enhances the elastic stiffness of the Janus structures. These results demonstrate that chemical asymmetry and surface termination provide effective control over
magnetic and mechanical properties while maintaining a robust metallic framework, identifying Zr-based Janus MXenes as promising model systems for metallic and spindependent two-dimensional materials.
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Materials Science
A spin-bond theory unifying non-relativistic spin splitting and emergent spin-orbit textures
S. Allende and R. M. Otxoa
Magnetic order with vanishing net magnetization can produce non-relativistic
spin-split bands, broadly categorized into even-parity altermagnets and odd-parity \(p\)-wave magnets. Here, we introduce a
spin-bond theory that unifies these seemingly distinct phenomena into a single algebraic framework. We demonstrate that non-relativistic
spin textures are fundamentally governed by two components of the electronic bond:
unitary spin phases and Hermitian
spin amplitudes. The
unitary sector generates odd-parity p-wave and emergent
spin-orbit-like textures, while the Hermitian sector generates even-parity
spin fields, including the uniform \(\Gamma\)-split and bond-structured altermagnetic limits. Beyond unifying known phases, our theory uncovers a mixed non-commuting regime that emerges when the
unitary and Hermitian sectors fail to commute, revealing an underlying non-commuting
spin-bond structure. This regime generates a non-coplanar
spin texture characterized by an even-in-momentum transverse
spin polarization, providing a direct spectroscopic fingerprint for
spin- and angle-resolved photoemission spectroscopy. Furthermore, we establish that this synthetic
spin-orbit coupling can be dynamically tuned by geometrically controlling the non-commutation of the bond sectors. By providing a microscopic foundation for such tuning, our theory paves the way for advanced applications, including field-free
spin qubits.
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Materials Science · Cross-listed from cond-mat.mes-hall
Long-range exchange interaction controls the fine structure of excited trion states in semiconductor quantum dots
M.M. Glazov and E.L. Ivchenko
We develop a microscopic theory of the long-range electron-hole exchange interaction in charged
excitons (trions) confined in
semiconductor quantum dots. While the ground-state singlet trion remains degenerate in the
spin component of unpaired charge carrier by time-reversal
symmetry, excited trion states exhibit a rich fine structure resulting from the interplay of electron-electron and electron-hole exchange interactions. We derive the effective long-range exchange
Hamiltonian for both the
spin-$3/2$ heavy-hole and a simple
spin-$1/2$ valence band models. The long-range exchange interaction mixes singlet and triplet trion configurations, giving rise to anisotropic fine-structure splittings and related polarization-dependent optical spectra determined by the
quantum-dot shape. Analytical expressions are obtained for the long-range exchange parameters. The developed theory establishes a unified microscopic description of the fine structure of excited trions in
semiconductor quantum dots and provides a framework for interpreting polarization-resolved optical spectroscopy of charged excitonic complexes.
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Materials Science · Cross-listed from physics.app-ph
200 mm Wafer-Scale Monolithic 3D Integration of Atomic Layer-Deposited Oxide Semiconductors
Chang Niu, Linjia Long, Luqi Zheng et al. (+9 more)
Monolithic 3D (M3D) integration offers a pathway to overcome the scaling limits of conventional silicon complementary metal-oxide-
semiconductor (CMOS) technology by extending dense vertical stacking of multifunctional logic and
memory devices. Here, we demonstrate wafer-scale M3D integration of three tiers of atomic-layer-deposited (ALD) indium oxide (InOx)-based devices (>100,000 fabricated), including ferroelectric, enhancement-mode, and depletion-mode field-effect transistors, on 200 mm silicon wafers. We achieve threshold voltage standard deviation as low as 0.04 V, average electron mobility up to 91.6 cm2V-1s-1, and fully functional cross-tier
circuits. A four-tier 3D computing-in-
memory (CIM) accelerator targeting large
language model workloads is developed using a custom InOx process design kit, delivering 1.4x to 2.9x speedup and comparable energy-delay product improvements over 2D baselines. These results establish ALD InOx M3D integration as a scalable and CMOS-compatible platform for next-generation artificial intelligence hardware and advanced electronics.
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All authors Chang Niu, Linjia Long, Luqi Zheng, Shuting Du, Jian-Yu Lin, Kisoo Nam, Zehao Lin, Chang Liu, Juanjuan Lu, Haiyan Wang, Haitong Li, Peide D. Ye
Materials Science
Time-resolved study of carbonization and growth of ultrathin 3C-SiC on Si(111) under ultra-high vacuum
Pranjali Jadhao, Mojdeh Fallahpour, Josef Polčák et al. (+6 more)
The early-stage formation of silicon carbide (SiC) on Si(111) by ethylene exposure under ultra-high
vacuum (UHV) was investigated to resolve the time-dependent chemical and morphological
evolution of an ultrathin layer. Clean Si(111) substrates were exposed to C$_2$H$_4$ at 800 {\deg}C for 2 min to 4 h, and the surfaces followed by in-situ X-ray photoelectron spectroscopy (XPS) and ex-situ AFM, SEM, AES, SIMS and TEM. Si 2p and C 1s peak analysis shows the progressive conversion of elemental silicon into a carbidic Si-C phase, the SiC fraction overtaking the elemental component between 120 and 160 min and saturating near 80-81% beyond 180 min, leaving about 19-20% residual elemental silicon. Correlative SEM and AFM reveal a parallel morphological progression, from sparse isolated islands to a coalesced, near-continuous layer. AES depth profiling confirms carbon incorporated into the near-surface region rather than weakly adsorbed as contamination, assigning the islands to early SiC
nuclei. TEM confirms the zinc-blende
lattice and the presence of cubic silicon carbide (3C-SiC). Together, these results provide a time-resolved picture of SiC nucleation, coalescence and layer growth on Si(111), relevant to 3C-SiC heteroepitaxy, and can be utilized in the optimization of SiC/Si(111) templates for growth of III-nitride and other carbide systems on silicon (e.g. Mo$_2$C).
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All authors Pranjali Jadhao, Mojdeh Fallahpour, Josef Polčák, Eva Kolíbalová, Michal Horák, Jan Michalička, Petr Bábor, Stanislav Voborný, Tomáš Šikola
Materials Science
Magnetotransport evolution and nonlinear Hall effect in altermagnetic MnTe
Wei Zhou, Zhifeng Xue, Yunxing Li et al. (+6 more)
Hexagonal MnTe is a prototypical semiconducting altermagnet whose properties are heavily influenced by intrinsic disorder, yet how the resulting diverse transport regimes shape its magnetotransport behavior remains to be clarified alongside the role of relativistic
spin-orbit coupling (SOC). Here, we present a systematic study of the anisotropic magnetoresistance (AMR), planar Hall effect (PHE), and nonlinear transport in MnTe bulk single
crystals. Below the Néel temperature (TN ~ 304 K), the emergence of high-order harmonics in AMR and PHE within the high-temperature metallic regime reveals the interplay of
magnetic order, crystalline
symmetry, and SOC. At relatively lower temperatures, the disappearance of higher-order
symmetries coincides with a transport crossover into the hopping conduction regime, suggesting that carrier localization diminishes the transport sensitivity to the Fermi-surface
topology. In addition, we detect distinct second-order nonlinear Hall signals, providing evidence for a macroscopic inversion-asymmetric response in altermagnetic MnTe. Extending the investigations into the localized regime provides key insights into the subtle role of disorder and SOC in macroscopic charge transport. Our work thus underscores the necessity of exploring magnetotransport across diverse conducting regimes to comprehensively understand altermagnetic properties.
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All authors Wei Zhou, Zhifeng Xue, Yunxing Li, Nannan Tang, Ye Tao, Dingyong Zhong, Jiawei Luo, Donghui Guo, Huichao Wang