Materials Science
Introduction to Spectroscopy of Cr4+:YAG Transparent Ceramics
Mykhailo Chaika
This paper focuses on the spectroscopic properties of Cr4+:YAG transparent ceramic. Absorption, excitation, and emission spectra were measured over a temperature range from 5K to 300K. Low-temperature absorption spectra reveal sharp and narrow lines corresponding to partially allowed transitions from the ground state to the
crystal field splitting components of the 4T2 energy level. The shape of the excitation spectra was found to be independent of the monitored emission wavelength, indicating that Cr4+ emission originates from the lowest excited state. Low temperature emission spectra exhibit a sharp and narrow ZPL, accompanied by the vibronic sidebands extending up to ~2000 cm-1. Both absorption and emission spectra of the lowest excited state at low temperature consist of a doublet, with a splitting of 28 cm-1. The temperature dependence of the spectroscopic parameters of this doublet is reported. Based on the obtained results, possible explanations of its origin are proposed.
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Materials Science
Efficient method for calculation of low-temperature phase boundaries
Lucas Svensson, Babak Sadigh, Christine Wu et al. (+1 more)
Understanding phase stability and phase transformations is central to predicting material behavior under varying thermodynamic conditions. One of the earliest and most influential applications of density functional theory in materials science has been the prediction of pressure-induced phase transitions at 0 K. Extending these calculations to finite temperatures, however, requires accounting for thermal,
quantum, and anharmonic contributions to the free energy, often at significant computational cost. In this work, we present a general and efficient framework for calculating low-temperature phase boundaries by combining the Clausius-Clapeyron equation with the quasi-harmonic approximation. This methodology requires a minimal number of calculations, while naturally incorporating internal degrees of freedom as well as
quantum and low-order anharmonic effects. We illustrate the accuracy and efficiency of the approach by constructing the phase diagram of silica in the pressure range from -2 to 12 GPa and temperatures up to 1750 K. To this end, we employ a machine-learned interatomic potential trained on density functional theory reference data, enabling well-converged free energy estimates via efficient thermodynamic sampling and a rigorous comparison between the proposed framework and free energy integration.
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All authors Lucas Svensson, Babak Sadigh, Christine Wu, Paul Erhart
Materials Science
A new approach for measurement of Cr4+ concentration in Cr4+:YAG transparent materials: some conceptual difficulties and possible solutions
M. Chaika, R. Lisiecki, K. Lesniewska-Matys et al. (+1 more)
In the present work we provide an analysis of the accuracy of the calculation of Cr4+ concentration in Cr4+:YAG using absorption spectroscopy. We propose a new approach based on the convenient optical spectroscopy to estimate the Cr4+ concentration in Cr:YAG using survey absorption spectra. The Smakula Dexter formula is usually used for this purpose. However, the uncertainties in the values of oscillator strengths for Cr4+ absorption bands and, moreover, in the deconvolution of Cr4+ absorption spectra make it difficult to calculate the Cr4+ concentrations with high accuracy.
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All authors M. Chaika, R. Lisiecki, K. Lesniewska-Matys, O. Vovk
Materials Science
Resolving Transient Electron-Phonon Coupling with Time-Resolved Spontaneous Raman Spectroscopy
Guy Reuveni, Maya Levy Greenberg, Matan Menahem et al. (+2 more)
Understanding the interaction of charge carriers with
lattice vibrations in the quasi-
equilibrium regime is crucial for
semiconductor functionality. However, the structural signatures of these interactions are often too subtle for conventional ultrafast techniques to detect. We developed a time-resolved spontaneous Raman technique based on time-correlated single-
photon counting to track the spectral response following photoexcitation, providing sub-wavenumber spectral resolution and a few-hundred-picosecond temporal resolution. Unlike traditional pump-probe schemes, our method utilizes a modulated continuous-wave probe to maintain high spectral resolution, enabling detection of low-frequency Raman shifts down to 10 cm$^{-1}$. Applied to lightly boron-doped silicon, we resolve intra-valence band and inter-valence band electronic transitions. A coupled-mode analysis of transient
phonon asymmetry, resulting from interference with the inter-valence band transitions, reveals electron-
phonon coupling parameters that directly relate to carrier recombination. By capturing these subtle dynamical shifts, we demonstrate that this platform offers a powerful probe for investigating electron-
phonon interactions in long-lived excited states.
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All authors Guy Reuveni, Maya Levy Greenberg, Matan Menahem, Olle Hellman, Omer Yaffe
Materials Science
AI-driven Inverse Design of Complex Oxide Thin Films for Semiconductor Devices
Bonwook Gu, Trinh Ngoc Le, Wonjoong Kim et al. (+2 more)
Bridging generative foundation models with non-
equilibrium thin-film synthesis remains a central challenge, limiting the practical impact of AI-driven materials discovery on
semiconductor dielectrics. Here, we introduce IDEAL (Inverse Design for Experimental Atomic Layers), an inverse-design platform that links generative
diffusion models, machine learning interatomic potentials, and graph neural network property predictors with atomic layer deposition (ALD). We demonstrate IDEAL using the Hf-Zr-O system as a stringent
benchmark for
semiconductor-relevant complex
oxides. The platform statistically enumerates thermodynamically plausible structures and constructs a composition-structure-property map. Crucially, it identifies a narrow composition window where low-energy tetragonal and orthorhombic phases cluster, revealing trade-offs between band gap and dielectric response. Experimental validation using atomic layer modulation (ALM) corroborates these predictions, demonstrating predictive guidance under realistic, non-
equilibrium thin-film growth. By experimentally closing the loop, IDEAL provides a transferable and generalizable route to the precision synthesis of next-generation
semiconductor dielectrics.
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All authors Bonwook Gu, Trinh Ngoc Le, Wonjoong Kim, Zunair Masroor, Han-Bo-Ram Lee
Materials Science · Cross-listed from cond-mat.mes-hall
Microscopic origin of $p$-wave magnetism
Johannes Mitscherling, Jan Priessnitz, Clara K. Geschner et al. (+1 more)
$P$-, $f$-, or $h$-wave antialtermagnets yield large non-relativistic
spin splitting with out-of-plane
spin polarization in momentum space perpendicular to the coplanar non-collinear local
magnetic moments. We provide a microscopic explanation of this unconventional
spin polarization by linking it to a previously overlooked site-compensated
spin density that orders antiparallel when projected onto opposite momenta. We verify this result both by model derivation of the out-of-plane momentum-space
spin polarization being proportional to the direct-space cross product of the coplanar non-collinear
spin order, as well as by ab initio calculations in the material candidate CeNiAsO. By providing a general classification and analytic expression for the
spin polarization of all spinful two-site tight-binding
Hamiltonians, we reveal the momentum-resolved
spin polarization as a probe of the Bloch-state geometry arising from
spin-site coupling. Furthermore, our approach allows for
geometric distinction between ferro-, alter-, and antialtermagnets. Our results provide a quantitative guidance for quantized out-of-plane momentum-space
spin polarization and large
spin splitting, and construction principles for antialtermagnets.
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All authors Johannes Mitscherling, Jan Priessnitz, Clara K. Geschner, Libor Šmejkal
Materials Science · Cross-listed from cs.LG
Physics-informed neural operator for parametric phase-field modelling of interfacial degradation and microstructural evolution
Nanxi Chen, Airong Chen and Rujin Ma
Predicting interfacial degradation and microstructural
evolution through phase-field modelling is computationally intensive, particularly for parametric studies. While neural operators such as the
Fourier neural operator (FNO) offer a promising route to acceleration, the absence of physical constraints compromises their generalisation and long-term stability. Here, we present PF-PINO, a physics-informed neural operator framework that embeds phase-field governing equation residuals directly into the training loss, together with gradient normalisation loss balancing and a staggered training scheme for coupled multi-field systems. PF-PINO is validated on four
benchmarks including pencil-electrode corrosion, electro-polishing corrosion, dendritic solidification, and spinodal decomposition, collectively probing parametric generalisation across orders-of-magnitude kinetic regimes, non-periodic boundaries with
stochastic morphologies, coupled multi-field dynamics with out-of-distribution extrapolation, and long-term autoregressive stability under complex pattern formation. Across all
benchmarks, PF-PINO reduces relative $L^2$ errors by up to an order of magnitude over FNO and achieves sub-mesh-size interface accuracy, establishing a data-efficient surrogate for high-throughput parametric phase-field assessment in computational materials science and engineering applications.
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Materials Science
Application of dual-tree complex wavelet transform for spectra background reduction
Kazimierz Skrobas, Kamila Stefanska-Skrobas, Cyprian Mieszczynski et al. (+1 more)
This paper presents a method for background removal in experimental data processing using the Dual-Tree Complex Wavelet Transform (DTCWT). The technique is based on discrete wavelet theory (DWT) and addresses limitations of commonly used numerical approaches, such as fitting or filtering methods. Compared with
Fourier-transform-based techniques, DTCWT provides improved performance for signal extraction. The proposed method is universal and enables analysis of arbitrary data ranges without restrictions on their position in time. It satisfies key requirements of signal analysis, including signal preservation and reduction of processing bias. An
algorithm for background reduction is implemented to extract and enhance meaningful spectral information. The approach is demonstrated on two different types of spectra: X-ray powder diffraction and photoluminescence measured for the $\beta-Ga_{2}O_{3}$
crystal. Practical aspects of DWT-based processing are also discussed, including the selection of wavelet families and decomposition levels. The method is available as a software package for spectral background reduction.
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All authors Kazimierz Skrobas, Kamila Stefanska-Skrobas, Cyprian Mieszczynski, Renata Ratajczak
Materials Science
Pressure-Induced Structural and Magnetic Evolution in Layered Antiferromagnet YbMn$_2$Sb$_2$
Mingyu Xu, Matt Boswell, Aya Rutherford et al. (+7 more)
Electronic states under pressure exhibit unconventional
spin and charge dynamics that provide a powerful route to uncover exotic phases in
quantum materials. Here, we present the structural,
magnetic, and electronic
evolution of YbMn$_2$Sb$_2$ under pressure. Single-
crystal X-ray diffraction reveals a pressure-induced structural transition from the space group trigonal $P\bar{3}m1$ to the monoclinic $P2_1$/$m$ phase near 3.5 GPa, which remains stable up to 10 GPa. Magnetization measurements display an anomalously weak net
magnetic moment and the absence of Curie-Weiss behavior up to 400 K, suggesting the formation of short-range Mn moment pairs that cancel macroscopically and subsequently evolve into long-range order upon cooling. Temperature-dependent resistivity shows semiconducting behavior with a transition at ~119 K at ambient pressure, while pressure induces a dramatic suppression of resistance and the emergence of metallic-like temperature dependence, stabilized beyond 5 GPa. This pressure-driven
semiconductor-metal transition is consistent with our density functional theory calculations, confirming the closing of the band gap under compression.
Neutron diffraction under pressure identifies an incommensurate
magnetic structure with antiparallel correlations between paired
spins. Together, these results demonstrate how pressure-driven structural tuning and competing exchange interactions stabilize unconventional
magnetic states in this low-dimensional
magnetic semiconductor.
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All authors Mingyu Xu, Matt Boswell, Aya Rutherford, Cheng Peng, Ying Zhou, Shuyang Wang, Zhaorong Yang, Antonio M. dos Santos, Haidong Zhou, Weiwei Xie
Materials Science · Cross-listed from cond-mat.str-el
Pressure-Stabilized MnSb$_2$ with Complex Incommensurate Magnetic Order
Mingyu Xu, Matt Boswell, Qing-Ping Ding et al. (+9 more)
Marcasite-type compounds have been proposed as promising hosts of exotic
magnetic quantum states, yet experimental realizations in stoichiometric, disorder-free systems remain limited. Here, we report the high-pressure stabilization and
magnetic characterization of MnSb$_2$, a marcasite-type compound that is thermodynamically metastable under ambient pressure. Single
crystals were synthesized using a cubic multi-anvil press, and powder and single-
crystal X-ray diffraction confirm the orthorhombic $Pnnm$ structure. These
crystals are stable at ambient pressure for a long time up to between 450-500 K. Heat-capacity measurements reveal phase transitions at approximately 220 K and 118 K.
Neutron diffraction uncovers an unconventional
magnetic ground state below 220 K.
Magnetic powder
neutron diffraction refinements reveal possible multiple
magnetic configurations that provide comparably acceptable fits to the experimental data. While most solutions are consistent with a
spin-density-wave (SDW) description, helical models systematically yield inferior agreement factors. Across a broad range of models, the Mn ordered moment reaches a maximum value of approximately 2 $\mu_B$ and remains predominantly collinear, with minimal canting along the $c$-axis. At 200 K, the
magnetic propagation vector is $q$ = (0, 0.3975, 0.3783); upon cooling, the $b$ component increases toward 0.5, reflecting a temperature-dependent
evolution of the modulation. The need for modification of the
magnetic model between high and low temperatures further highlights the complex and strongly temperature-dependent nature of the
magnetic order in this system. These results establish MnSb$_2$ as a pressure-stabilized marcasite magnet with a highly tunable, complex
magnetic ground state and a compelling stoichiometric platform for exploring unconventional
magnetic behavior, including potential altermagnetism.
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All authors Mingyu Xu, Matt Boswell, Qing-Ping Ding, Cheng Peng, Aashish Sapkota, Qiang Zhang, Danielle Yahne, Sergey. L. Bud'ko, Yuji Furukawa, Paul. C. Canfield, Raquel A. Ribeiro, Weiwei Xie
Materials Science
Nonlinear Hall Effect in Metal-Organic Frameworks
Sarbajit Mazumdar, Jagadish N S, Awadhesh Narayan et al. (+3 more)
We propose metal-organic frameworks (MOFs) as tunable platforms for nonlinear
Hall responses. A universal analytical downfolding scheme maps $C_3$-symmetric frameworks onto
star- and honeycomb-
lattice models, reproducing first-principles Dirac features.
Spin-orbit coupling and broken inversion
symmetry gap the Dirac cones, generating Berry-
curvature hot spots.
Symmetry analysis identifies tailored synthetic pathways, including linker design, as intrinsic routes to engineer nonlinear
Hall transport beyond strain and substrate control.
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All authors Sarbajit Mazumdar, Jagadish N S, Awadhesh Narayan, Giorgio Sangiovanni, Ronny Thomale, Arka Bandyopadhyay
Materials Science
On the origin of diverse interlayer charge redistribution in transition-metal dichalcogenides
Yu-Meng Gao, Nie-Wei Wang, Shi-Xuan Yuan et al. (+3 more)
The interlayer quasi-chemical-bonding (QCB) interactions of two-dimensional (2D) layered materials promote the research field of interlayer-engineering and cause interlayer charge density redistributions (ICDRs). The ICDRs have been reported experimentally and theoretically, which show different redistributions, e.g., accumulation, depletion, or a more complicated behavior. The underlying mechanism for the different ICDRs remain to be elucidated. In the current work, via a systematic theoretical study of the ICDRs of transition metal dichalcogenides with different number of d-electrons filling (d^0 TiS2, d^1 NbS2, and d^2 MoS2) in T and H phases, we reveal three mechanisms based on the coexistence of different types of interlayer QCB interactions. Mechanism (1) is from a competition between two types of interlayer interactions: namely, the interlayer interaction between fully occupied energy levels (in short: o-o interaction) depletes electrons in the overlap region while that between occupied and empty levels (o-e interaction) promotes electron accumulation; and the competition between them leads to that the d^0 TiS2 tends to electron accumulation in T phase than in H phase. Mechanism (2), the interlayer interaction between half-filled levels (h-h interaction) promotes the electron accumulation of d^1 NbS2. Mechanism (3), the interlayer interaction of multiple filled-levels of d^2 MoS2 (namely, the multi-level o-o interaction) leads to a more complicated ICDR. The current study provides a unified understanding to the different ICDRs of van der Waals materials and paves the way for further exploration of their electronic properties and applications.
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All authors Yu-Meng Gao, Nie-Wei Wang, Shi-Xuan Yuan, Wen-Xin Xia, Jiang-Long Wang, Xing-Qiang Shi
Materials Science
Comprehensive structural and optical analysis of differently oriented Yb-implanted $\beta$-Ga$_2$O$_3$
Joanna Matulewicz, Renata Ratajczak, Mahwish Sarwar et al. (+9 more)
This study presents investigations of Yb-doped $\beta$-Ga$_2$O$_3$, an ultrawide bandgap
semiconductor with potential use in future power and optoelectronic devices operating in high-radiation environments. The research has focused on the problem of structural damage caused by the implantation of Yb-ions into three differently oriented
crystals and the optical response of created systems. The (001), (010), and (-201)-oriented $\beta$-Ga$_2$O$_3$
crystals were implanted with three different fluences of 150 keV Yb ions and examined using a variety of experimental techniques: high-resolution X-ray diffraction (HRXRD), Rutherford backscattering spectrometry in channeling mode (RBS/c), Raman and photoluminescence (PL) spectroscopies, to provide comprehensive information about studied systems. Furthermore, the RBS/c studies were supported by Monte Carlo simulations. The results show distinctions between differently oriented
crystals. In particular, (010)-oriented
crystals are characterized by the lowest concentration of extended defects and the presence of compressive stress. In contrast, samples with the other two orientations exhibit tensile stress and significantly higher levels of extended defects. Interestingly, the PL spectra of (010)-oriented $\beta$-Ga$_2$O$_3$ show the lowest emission from Yb$^{3+}$ ions, suggesting that specific types of extended defects, whose formation is more favorable in the other two orientations than in (010), enhance Yb$^{3+}$ luminescence instead of suppressing it.
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All authors Joanna Matulewicz, Renata Ratajczak, Mahwish Sarwar, Ewa Grzanka, Vitalii Ivanov, Damian Kalita, Cyprian Mieszczynski, Przemyslaw Jozwik, Slawomir Prucnal, Ulrich Kentsch, Rene Heller, Elzbieta Guziewicz
Materials Science · Cross-listed from cond-mat.mes-hall
Magneto-optical Response of 5-SL MnBi$_2$Te$_4$ in Spin-Flip States
Shahid Sattar, Roman Stepanov, A. H. MacDonald et al. (+1 more)
Magneto-optical effects like Kerr and Faraday rotations provide a direct probe of topological order in thin films of the
magnetic topological
insulator MnBi$_2$Te$_4$ (MBT). Motivated by recent experimental studies of
spin-flip/flop transitions in MBT thin films, we investigate the interplay between interlayer
spin configurations, topological order, and magneto-optical response in five septuple-layer (5-SL) MBT using first-principles calculations and a simplified coupled-Dirac-cone model. Our results reveal that, despite possessing a non-zero out-of-plane magnetization, 5-SL MBT thin films can be either ${\cal C}=+1$ topological
insulators or ${\cal C}=0$ topologically trivial
insulators depending on the relative
spin orientations of the top and bottom SLs. We evaluate the Faraday and Kerr rotation angles using tight-binding models derived from ab-initio calculations and by comparing our results with those of a simplified coupled Dirac-cone model clarify the macroscopic mechanisms underlying the magneto-optical response of
spin-flip states. These theoretical findings highlight the tunability of topological and magneto-optical properties in MBT thin films and provide microscopic insight into the emergence of complex topological order in layered
antiferromagnetic materials.
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All authors Shahid Sattar, Roman Stepanov, A. H. MacDonald, C. M. Canali
Materials Science · Cross-listed from cond-mat.str-el
Bulk magnetic properties of distorted square lattice compounds M'-LnTaO4 (Ln = Tb, Dy, Ho, Er)
Nicola D. Kelly, Ivan da Silva and Siân E. Dutton
We report bulk
magnetic properties of the monoclinic lanthanide tantalates, M'-LnTaO4 (Ln = Tb, Dy, Ho, Er), where the
magnetic Ln3+ ions are arranged on a distorted 2D square
lattice. The heavier analogue M'-YbTaO4 has been investigated as a
spin-orbit-coupled, quasi-two-dimensional frustrated magnet, and the properties of the other M'-LnTaO4 are expected to vary depending on the electronic configuration of the Ln ion, namely Kramers vs non-Kramers behaviour and different
crystal electric field parameters. In this work, powder
neutron diffraction is used to confirm the
crystal structure for Ln = Tb, Ho, Er, and to determine the
magnetic structure of M'-TbTaO4, which displays long-range
antiferromagnetic (AFM) order below T_N = 2.1 K. The Tb3+ moments are aligned primarily along the c-axis with AFM nearest-neighbour interactions. Susceptibility data suggest that M'-DyTaO4 may display short-range ordering around 2.7 K, while M'-HoTaO4 and M'-ErTaO4 show AFM correlations but do not order above 1.8 K. Measurements of the
magnetic specific heat provide evidence for a Kramers doublet ground state in M'-ErTaO4, similar to its heavier analogue M'-YbTaO4.
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Materials Science
DFT calculations of magnetocrystalline anisotropy energy with fixed spin moment
Justyn Snarski-Adamski, Joanna Marciniak, Wojciech Marciniak et al. (+2 more)
The development of new-generation permanent magnets is based on experimental efforts and innovative theoretical tools for modeling
magnetic properties. Magnetocrystalline anisotropy energy (MAE) - one of the main intrinsic properties of permanent magnets - can be calculated using density functional theory (DFT). However, MAEs determined with different exchange-correlation potentials can vary widely. We show how these seemingly contradictory results can be reconciled using the fully relativistic fixed
spin moment (FR-FSM) method. This is because the
equilibrium pairs [MAE, $m_s$] calculated with different exchange-correlation potentials overlap with the MAE($m_s$) curve determined from the FR-FSM method ($m_s$ denotes the
spin magnetic moment). The FR-FSM method also enables the hypothetical maximum MAE value for a given material to be estimated. In the case of
magnetic alloys, MAE(FSM) analysis allows the optimal alloying additions to be determined in order to improve the MAE value. The high independence of the MAE($m_s$) works well for exchange-correlation functionals such as LDA and GGA. However, it is not a universal measure and varies with changes in the value of the U parameter when using LDA+U or GGA+U functionals. Concluding, the framework we describe for MAE versus FSM calculations can be a useful tool in the design of new permanent magnets.
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All authors Justyn Snarski-Adamski, Joanna Marciniak, Wojciech Marciniak, Justyna Rychły-Gruszecka, Mirosław Werwiński
Materials Science · Cross-listed from cs.RO
Receptogenesis in a Vascularized Robotic Embodiment
Kadri-Ann Pankratov, Leonid Zinatullin, Hans Priks et al. (+6 more)
Equipping robotic systems with the capacity to generate $\textit{ex novo}$ hardware during operation extends physical adaptability. Unlike modular systems that rely on discrete component integration pre- or post-deployment, we envision physical adaptation through continuous in-body development via hardware synthesis. Drawing inspiration from circulatory systems that redistribute mass and function in biological organisms, we utilize fluidics to restructure the material interface, a capability currently unmatched in robotics. Here, we realize this proof-of-concept hardware generation through a vascularized robotic composite designed for programmable material synthesis, demonstrated via receptogenesis - the on-demand construction of sensors. By coordinating the fluidic transport of precursors with external localized UV irradiation, we drove an $\textit{in situ}$ photopolymerization that chemically reconstructed the vasculature from the inside out. This reaction converted precursors with photolatent initiator into a solid dispersion of UV-sensitive polypyrrole in PETG, establishing a sensing modality validated by a characteristic decrease in electrical impedance. The newly synthesized sensor closed a local control loop in real time to regulate wing flapping in a moth-inspired robotic demonstrator. Our work is a proof-of-concept materials basis for $\textit{ex novo}$ hardware generation in a vascularized composite - a step towards situated
robots adapting to environmental cues.
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All authors Kadri-Ann Pankratov, Leonid Zinatullin, Hans Priks, Adele Metsniit, Urmas Johanson, Tarmo Tamm, Alvo Aabloo, Edoardo Sinibaldi, Indrek Must
Materials Science
Ab initio simulation of the first-order proton-ordering transition in water ice
Qi Zhang, Sicong Wan and Lei Wang
Proton ordering in water ice is a paradigmatic order-disorder transition in a locally constrained system. The ice rules require exactly two hydrogens close to each oxygen, restricting the disorder to an exponentially large yet strongly correlated
manifold of hydrogen-bond configurations. Within this constrained space, meV-scale energy differences drive the transition from disordered ice Ih to ordered ice XI, while distinct configurations are separated by eV-scale barriers. These barriers hinder equilibration in experiments, and efficient sampling of this space with the required energy accuracy has remained a long-standing challenge in simulation. We address this by combining a machine learning interatomic potential with loop updates that preserve the ice rules and continuous updates of atomic coordinates, enabling
equilibrium sampling with ab initio accuracy and capturing configurational entropic effects. In systems of up to 360 water molecules, with over 10^6 samples retained per temperature point, the simulations reveal clear first-order transition signatures at 83 K: a negative Binder cumulant, a bimodal potential energy distribution, and a sharp step in the
lattice aspect ratio.
Nuclear quantum effects are estimated to lower the transition temperature by approximately 20 K, bringing the prediction closer to the experimental value of 72 K.
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Materials Science
Optically driven thermodynamic transition from free- to locked-epitaxy
Renhong Liang, Mao Ye, Yiran Ying et al. (+6 more)
Controlling crystallographic orientation in quasi-van der Waals (vdW) epitaxy remains a fundamental challenge, especially for material systems located near the boundary between weakly and strongly coupled growth regimes. In such marginal systems, epitaxial selection is governed by a delicate thermodynamic competition between surface-energy penalties and interfacial interaction gains, giving rise to two archetypal limits: vdW-dominated free-epitaxy and strong interfacial coupling dominated locked-epitaxy. However, dynamically driving transitions between these regimes has remained elusive. Here, we demonstrate that external light irradiation can deterministically induce such a transition. Using the thermodynamically frustrated Fe4N/mica interface as a model system, we show that photo-excited carriers act as a chemical potentiator, significantly enhancing the interfacial chemical affinity. Within a quantitative thermodynamic description, this optical modulation increases the locking criterion (I_lock)-defined as the ratio of interfacial energy gain to surface-energy cost-beyond its critical threshold. As a result, the system switches from vdW-dominated free-epitaxy with (001) orientation to chemically locked-epitaxy with (111) orientation. Our findings establish light as a non-invasive and switchable control knob to dynamically reconfigure the interfacial energy landscape in quasi-vdW epitaxy, enabling programmable access to distinct epitaxial states beyond intrinsic material limitations.
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All authors Renhong Liang, Mao Ye, Yiran Ying, Longlong Shu, Renkui Zheng, Haitao Huang, Jianhua Hao, Shuk-Yin Tong, Shanming Ke
Materials Science
Material-Property-Field-based Deep Neural Network in Hopfield Framework
Yanxiao Hu, Ye Sheng, Caichao Ye et al. (+6 more)
Current deep neural networks (DNNs) used in materials modeling often lack explicit physical structure and clear analytical formulations tailored to material systems, which can limit their interpretability. In this work, we integrate Material Property Fields (MPF) with the Hopfield network architecture and propose an analytically structured DNN framework named mPFDNN. MPF provides a unified framework that represents physical properties of materials as an analytical field built upon pairwise interactions, rigorously respecting fundamental
symmetries, while also enabling a physically legitimate decomposition of property distributions at the atomic level. Although the Hopfield model was originally developed for Ising-like systems, we show that its dynamical
evolution strategy can be naturally extended to the MPF framework. By reformulating nonlinear interatomic interactions as "hidden
neurons", MPF can be extended into a deep yet analytically tractable DNN architecture that progressively captures an increasingly connected interaction landscape. This framework also provides a unified perspective that connects linear expansions and nonlinear DNN architectures within a common interaction-based formulation. Extensive validation across diverse systems, including inorganic
crystals, organic molecules, and aqueous solutions, and across multiple target properties, shows that mPFDNN achieves competitive predictive accuracy while offering a physically motivated framework for structure-property mapping in chemistry, physics, and materials science.
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All authors Yanxiao Hu, Ye Sheng, Caichao Ye, Wenxing Qian, Xiaoxin Xu, Yabei Wu, Jiong Yang, William A. Goddard III, Wenqing Zhang
Materials Science
Ultralight High-Entropy Nanowire Scaffolds for Extreme-Temperature Functionality
Cameron S. Jorgensen, Corisa Kons, William Stallions et al. (+3 more)
High-
entropy alloys (HEAs) combine compositional disorder with exceptional functional tunability, yet their inherently high-density limits use in lightweight systems. Here, we introduce
entropy-architected nanowire metamaterials, a class of materials that couple configurational
entropy with structural porosity to achieve metal-like functionality at ultralow density. FeCoNiCrCu HEA nanowires were electrodeposited into porous templates and freeze-cast into three-dimensional “bird`s-nest“ scaffolds with densities below 1 $\%$ of the bulk metal. The resulting architectures retain a disordered face-centered-cubic phase, exhibit Curie temperatures exceeding 1000 K, and deliver thermal diffusivity ($\approx0.211$ mm$^2$ s$^{-1}$) comparable to titanium
alloys. Structural and spectroscopic analyses reveal nanoscale Cu segregation that enhances
magnetic ordering and thermal stability. These findings demonstrate that configurational
entropy and architectural hierarchy can be co-engineered to yield lightweight, high-temperature functional materials for extreme-environment applications.
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All authors Cameron S. Jorgensen, Corisa Kons, William Stallions, Austin C. Houston, Gerd Duscher, Dustin A. Gilbert
Materials Science · Cross-listed from quant-ph
Reconfigurable Superconducting Quantum Circuits Enabled by Micro-Scale Liquid-Metal Interconnects
Zhancheng Yao, Nicholas E. Fuhr, Nicholas Russo et al. (+3 more)
Modular architectures are a promising route toward scalable superconducting
quantum processors, but finite fabrication yield and the lack of high quality temporary interconnects impose fundamental limitations on system size. Here, we demonstrate chip-scale
liquid-metal interconnects that show promise for plug-and-play superconducting
quantum circuits by enabling non-destructive module replacement while maintaining high microwave performance. Using gallium-based
liquid metals, we realize high-quality inter-module signal and ground interconnects, comparable in performance to conventional coplanar waveguide resonators. We illustrate consistent device characteristics across three thermal cycles between room temperature and 15 mK, as well as the ability to reform superconducting connections following module replacement. A width-dependent resonance frequency shift reveals a significant kinetic inductance fraction, which we attribute to the presence of $\beta$-phase tantalum as confirmed by X-ray characterization. Finally, we investigate power-dependent loss mechanisms and observe high-power dissipative nonlinearities qualitatively consistent with a readout-power heating model. These results establish
liquid metals as viable chip-scale interconnects for reconfigurable, modular superconducting
quantum systems.
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All authors Zhancheng Yao, Nicholas E. Fuhr, Nicholas Russo, David W. Abraham, Kevin E. Smith, David J. Bishop
Materials Science
Impact of spin–orbit coupling on orbital diamagnetism in a narrow-gap semiconductor $\mathrm{Pb}_{1-x}\mathrm{Sn}_x\mathrm{Te}$
Yuki Mitani and Yuki Fuseya
We study the influence of
spin–orbit coupling (SOC) on orbital magnetism in $\mathrm{Pb}_{1-x}\mathrm{Sn}_x\mathrm{Te}$, a narrow-gap
semiconductor. Using the $\pi$-
matrix method, we calculate material-specific Landau levels and evaluate the magnetization, fully including interband effects. The system exhibits diamagnetism for both $x = 0$ and $x = 0.35$, with the latter showing a stronger response due to its smaller gap. The magnitude of diamagnetism increases monotonically with SOC strength, particularly in strong
magnetic fields. To clarify the underlying mechanism, we introduce the free–Zeeman–Dirac (fZD) model and fit its parameters to the calculated Landau levels. The analysis reveals that SOC enhances the Dirac-type interband contribution relative to the Zeeman term, leading to increased diamagnetism. These results demonstrate that SOC can play a key role in orbital magnetism through interband effects.
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Materials Science
Spectral Indicators of Piezomagnetically Induced Symmetry Breaking in Altermagnets
N. Sasabe, H. Koizumi, Y. Ishii et al. (+1 more)
Recent developments in the multipole reformulation of X-ray absorption spectroscopy (XAS) have provided a unified framework to describe
magnetic and orbital responses in terms of ferroic multipole order parameters. X-ray
magnetic circular dichroism (XMCD) is known to probe
spin, orbital, and anisotropic
magnetic dipole (AMD) moments. Its applications to altermagnets and noncollinear antiferromagnets have revealed that the XMCD response is often governed by the ferroic states of the AMD in the photo-excited states rather than by conventional
magnetic dipoles in the ground states. In this work, we extend the multipole-based analysis to X-ray
magnetic linear dichroism (XMLD) and demonstrate that XMLD in altermagnets can be understood as a manifestation of piezomagnetic effects: linear couplings between
magnetic dipole and electric quadrupole moments. Using
symmetry analysis combined with exact diagonalization calculations of $L_{2,3}$-edge XAS, we systematically investigate representative altermagnets, including $\alpha$-MnTe, MnF$_2$, and CrSb. We show that the ferroic ordering of higher-rank
magnetic multipoles, particularly spinful
magnetic octupoles, gives rise to characteristic field-odd XMLD signals that directly reflect the underlying piezomagnetic response tensors allowed by
magnetic point-group
symmetry. Furthermore, we discuss XMCD signals induced by piezomagnetic effects, in which strain generates
magnetic dipole moments. Our results establish XMLD and XMCD as element-specific probes of magnetoelastic multipole order in altermagnets and provide a general
symmetry-based pathway to identify hidden ferroic multipoles and strain-controllable
spin phenomena beyond conventional ferromagnetism.
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All authors N. Sasabe, H. Koizumi, Y. Ishii, Y. Yamasaki
Materials Science
Field-Programmable Topological Torons in Chiral Nematic Liquid Crystals
Adithya Pradeep, Urban Mur, Ji Qin et al. (+7 more)
Torons are three-dimensional double-twist
solitons in
chiral nematic
liquid crystals that form localised director configurations protected by
topology and bounded by closed defect loops. They behave as particle-like entities while retaining a fully reconfigurable optical response. Here it is shown experimentally that individual torons can be created, steered and parked on demand using tailored alternating-current electric fields in planar
cells, enabling deterministic control of both position and trajectory. By tuning the ratio of
cell thickness to cholesteric pitch and systematically adjusting waveform parameters, including amplitude, modulation frequency, duty-cycle asymmetry and small DC offsets, robust toron nucleation is achieved and programmable translation is realised along arbitrary in-plane directions with submicrometre placement accuracy. Directional transport is controlled within a defined frequency and temperature window and can be reversed by changing modulation conditions even at zero offset. A dedicated graphical interface enables real-time switching between waveform presets so that torons follow scripted paths and draw user-defined shapes. Quantitative Landau-de Gennes Q-tensor simulations reproduce toron nucleation and the ensuing translational dynamics, supporting an interpretation in which waveform-controlled director reorientation, reorientation-driven flow and rectified polarity-sensitive coupling jointly bias the drift. Finally, three proof-of-concept functions are demonstrated: a software-defined
liquid-
crystal racetrack
memory analogue with optical readout, deterministic path writing for reconfigurable patterning, and toron-mediated pick-and-place transport of microparticles for micromanipulation.
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All authors Adithya Pradeep, Urban Mur, Ji Qin, Jonghyeon Ka, Waqas Kamal, Tianxin Wang, Junseok Ma, Jianming Wang, Steve J. Elston, Stephen M. Morris