Materials Science · Cross-listed from physics.plasm-ph
Experimental Characterization of Additively Manufactured Metallic Alloys for Electric Propulsion Applications
J. Chamberlain and A. Shashurin
This work explores the sputtering of additively manufactured (AM) materials for use in gridded ion source applications. The first part of the paper uses 316L stainless steel as an example to demonstrate that additively manufactured material does not exhibit adverse sputtering behavior, such as higher sputter yield, compared with conventionally manufactured material. To this end, three additively manufactured 316L stainless steel samples were exposed to the beam of a KDC-40 electrostatic gridded ion source at three distinct energy levels of 400, 600, and 800 eV on each side of the sample for a duration of one hour. The samples were masked to create a distinct boundary between treated and untreated regions, identifiable using profilometry, and were biased to -18V for testing. Samples were then examined using a Bruker optical profilometer and further processed using the open-source software Gwyddion to evaluate the sputtering yield. The sputter yield varied in the range 0.2-2 atoms/ion for 400-800 eV ions and increased with ion energy. The measured sputtering yield was fairly consistent with predictions from analytical models developed in prior literature, while exhibiting some variations potentially due to added effects of increased temperature and oxide layers. The second part of the paper demonstrates feasibility of using an additively manufactured tungsten-rhenium grids in existing KDC-40 electrostatic gridded ion source.
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Materials Science
Electron spin resonance driven photogalvanic effect in graphene-based structures
C. Bray, I. Yahniuk, L. E. Golub et al. (+13 more)
We report an electron-
spin-resonance-driven linear photogalvanic effect (LPGE) in unbiased monolayer
graphene and WSe_2/
graphene heterostructures. Under linearly polarized 45–75 GHz radiation, the photovoltage exhibits pronounced resonant features in both Faraday and Voigt geometries. Multiple resonances associated with the electron
spin resonance in
graphene are observed for both out-of-plane and in-plane
magnetic-field orientations. Their
magnetic-field positions vary linearly with frequency, their amplitudes reverse sign across the charge-neutrality point, and the resonant contribution has the opposite sign to the nonresonant Drude photogalvanic background. We develop a microscopic theory in which radiation-induced momentum
alignment followed by skew scattering generates both contributions. Their opposite signs originate from the orthogonal momentum
alignments produced by indirect Drude absorption and direct
spin-resonant transitions. The theory describes well the main features of the observed resonant photocurrent and provides a microscopic description of ESR-induced LPGE in two-dimensional systems. These results establish the photogalvanic response as a probe of ESR in unbiased micron-scale
graphene-based devices.
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All authors C. Bray, I. Yahniuk, L. E. Golub, M. Marocko, C. Consejo, B. Benhamou-Bui, Ziyang Gan, A. George, A. Turchanin, P. Sadovyi, K. Watanabe, T. Taniguchi, J. Eroms, J. Fabian, F. Teppe, S. D. Ganichev
Materials Science
Oxidation-resilient structural modifications in Nickel-functionalized 3D-graphene for hydrogen storage applications
Filippo Fincato, Ylea Vlamidis, Markus Leitgeb et al. (+6 more)
Porous materials represent a versatile solution for several applications. Indeed, the recent development of a new material, named 3D-
Graphene, which combines the exceptional characteristics of
graphene with a three-dimensional structure, opens perspectives for applications where a high surface-to-volume ratio is beneficial. In this study, we explore the functionalization of 3D-
Graphene with nickel (Ni)-nanoparticles as a strategy to enhance hydrogen storage capabilities, and we assess the influence of the NPs on hydrogen uptake and oxidation resilience. The morphology and structural properties of pristine and Ni-functionalized samples were characterized using Scanning Electron Microscopy. Additionally, X-ray Photoelectron Spectroscopy was employed to analyze the surface chemical composition of the functionalized samples. Samples have been hydrogenated supplying molecular or atomic hydrogen, and hydrogen storage performance was assessed through Thermal Desorption Spectroscopy. Afterwards, oxidation effects were systematically studied by exposing the samples to atmospheric oxygen, followed by further hydrogenation experiments. Our results indicate that Ni functionalization influences both hydrogen adsorption and oxidation behavior, with potential implications for improving the stability of the material, especially for hydrogen storage applications.
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All authors Filippo Fincato, Ylea Vlamidis, Markus Leitgeb, Georg Pfusterschmied, Ulrich Schmid, Valentina Zannier, Silvia Rubini, Stefan Heun, Stefano Veronesi
Materials Science · Cross-listed from cond-mat.str-el
Rare-earth oxysulfides RE$_2$O$_2$S as model mixed-anion frustrated magnets
Austin M. Ferrenti, Ksenia Khoroshun, Mohamed Oudah et al. (+3 more)
The study of low-dimensional and anisotropic magnetism is a promising avenue for the discovery of novel
quantum phenomena. Mixed-anion materials, defined by the coordination of metal cations by two or more distinct anionic species, provide an intrinsically anisotropic platform for the tuning of structural,
magnetic, and electronic properties. In this work, we report the synthesis and characterization of a family of rare-earth oxysulfide (RE$_2$O$_2$S) antiferromagnets (AFM) possessing a triangular-bilayer slab
lattice geometry. Long-range AFM order is observed for the majority of compositions, with several (RE = Ce, Pr, Nd, Sm) having been previously unreported. Although assumed to form stoichiometrically, pair distribution function (PDF) analysis provides evidence for significant, synthesis-dependent interslab structural disorder as RE$_2$O$_{2+x}$S$_{1-x}$, resulting in significant variability in the bulk
magnetic response of the Nd member. This work highlights the tunability of frustrated
magnetic ground states in rare-earth-based mixed-anion materials, and the importance of thorough structural characterization in the discovery of new mixed-anion magnets.
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All authors Austin M. Ferrenti, Ksenia Khoroshun, Mohamed Oudah, Graham King, Jonathan Gaudet, Alannah M. Hallas
Materials Science
Bayesian Optimization for Self-Driving Materials Laboratories: From Algorithms to Physics-Informed Workflows
Yuki K. Wakabayashi and Takuma Otsuka
Self-driving laboratories (SDLs) are transforming materials research by closing the loop among synthesis, characterization, data analysis and experimental decision making.
Bayesian optimization (BO) is a decision engine for these loops because it can select experiments from scarce and noisy data while balancing exploitation and exploration. Yet real materials campaigns often depart from the standard black-box setting, involving failed or missing experiments, noise and drift, mixed variables, constraints, multiple objectives, variable cost and fidelity, transfer from historical data, batch or asynchronous operation, and prior physics knowledge. This review presents BO for materials SDLs through the lens of these practical challenges. We summarize Gaussian-process-based BO and the formulation of materials goals as quantitative objectives, then discuss major choices in surrogate modelling and acquisition. Particular emphasis is placed on physics-informed
Bayesian optimization (PIBO), in which domain knowledge enters through representations, priors, kernels, acquisition functions, and constraints. We survey achievements enabled by BO and related active-learning approaches across
semiconductors, catalysis, chemical reactions, batteries,
alloys, functional materials and
quantum materials, highlighting advances beyond parameter optimization, including new materials and synthesis routes, improved functional performance, and reusable scientific knowledge. We conclude by outlining open problems for BO-driven materials SDLs, including nonstationarity,
multimodal observations, adaptive problem formulation, and scientific
reasoning by humans, large
language models and research
agents. Addressing these challenges may advance SDLs beyond efficient optimization toward interpretable and knowledge-generating experimentation.
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Materials Science
Watching a GaN Transistor Switch: Real-Time Nanoscale Strain and Heat Dynamics
C. Corley-Wiciak, N. T. Sammler, B. Butej et al. (+16 more)
Digital and energy technologies depend on microelectromechanical and power electronic components whose performance is critically impacted by rapid, cyclic deformations. Real-time information on their operation has remained inaccessible due to the need for nanosecond and nanometer resolution in fully integrated devices. We break this limitation by imaging the complete switching cycle of an industrial GaN high electron mobility transistor through stroboscopic dark field X ray microscopy at a fourth-generation synchrotron, resolving electromechanical and thermal micro strain fields across the entire device and correlating them with time dependent voltage characteristics. Coupled simulations benchmarked against the measurements reproduce electric field
evolution and transient thermal hotspots. This combined approach provides direct insight into device physics and informs design strategies for next generation energy and information processing technologies.
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All authors C. Corley-Wiciak, N. T. Sammler, B. Butej, M. Petersmann, A.A. Corley-Wiciak, L. Neumann, Juan M. Carrillo-Larrea, P. Schmiedeke, M. Strätgen, P. A. Douissard, S. J. Leake, P. Boesecke, M. Sievers, P. Imrich, M. Nelhiebel, M. Glavanovics, D. Pogany, M. Reisinger, T.U. Schulli
Materials Science
Observation of thermal Hall effect in diamond
Marcin Matusiak, Andrzej Ptok, Maria Szlawska et al. (+1 more)
Numerous
insulators, including non-
magnetic ones, have been unexpectedly found to display a finite thermal Hall signal, which has stimulated debate about its origin. Here, we report on a study of the thermal Hall effect in two diamond single
crystals. The transverse thermal conductivity (kappa_xy) was found to peak at a temperature close to that at which the longitudinal thermal conductivity (kappa_xx) reaches its maximum. The measured kappa_xy, with an amplitude of 340 W/(m K) at B = 10 T, is the largest ever observed, while the kappa_xy/kappa_xx ratio follows the phenomenological trend identified in other
insulators. Our observation implies the existence of an intrinsic thermal Hall effect in a generic
phonon gas. We argue that the rough amplitude of both the thermal Hall angle and the thermal Hall resistivity can be accounted for by simple arguments invoking fundamental constants and
quantum-mechanical constraints on solid state cohesion.
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All authors Marcin Matusiak, Andrzej Ptok, Maria Szlawska, Kamran Behnia
Materials Science
Muonium dynamics as a probe for depth-resolved properties of 4H-SiC
Maria Mendes Martins, Piyush Kumar, Marianne E. Bathen et al. (+5 more)
This study establishes a baseline for muonium (Mu) charge-exchange dynamics in n-type 4H-SiC through a detailed low-energy
muon spin rotation (LE-uSR) investigation. Epitaxially grown and ion-implanted samples with nitrogen and phosphorus donors were characterized to assess the effect of carrier concentration and doping method on defect formation. LE-uSR enabled nanometer scale depth profiling of near-surface and implanted regions, revealing variations in charge carrier concentration due to fixed surface charges. The temperature dependence of the diamagnetic fraction and phase provided direct evidence of the Mu0 to Mu- transition, with extracted activation energies consistent with known donor ionization energies. Additionally, high-field uSR was used to analyze the Mu dynamics, and Monte-Carlo simulations to model the Mu0 electron capture process. The simulation results offer a quantitative method to extract free electron concentrations from LE-uSR data, enhancing its capability to characterize the activation of dopants and carrier depth profiles. We demonstrate that LE-uSR is a powerful depth-resolved tool that can provide insights for optimizing the fabrication of reliable SiC devices for power electronics.
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All authors Maria Mendes Martins, Piyush Kumar, Marianne E. Bathen, Robert J. Scheuermann, Zurab Guguchia, Lasse Vines, Ulrike Grossner, Thomas Prokscha
Materials Science · Cross-listed from cond-mat.mes-hall
Chirality-Selective Phonon Pumping by Ferroelectric Dynamics
Dapeng Yao and Ping Tang
The discovery of chiral
phonons has expanded the conventional view of
lattice vibrations as passive heat carriers, opening new opportunities for phononic spintronic devices. However, their realization has been largely limited to chiral
crystals or to specific regions of momentum space in certain achiral materials. Here, we propose a generic mechanism for generating propagating chiral
phonons in an ordinary dielectric through the precession of the electric polarization in an adjacent ferroelectric. The polarization dynamics transfers its intrinsic angular momentum to the
lattice via electrostrictive coupling, thereby pumping chirality-selective
phonons whose handedness is dictated by that of the polarization precession. For a typical LiNbO$_{3}$$|$Y$_{3}$Al$_{5}$O$_{12}$ bilayer, we find that the pumping efficiency quantified by an interfacial convertance substantially exceeds those of thermally induced chiral-
phonon generation in chiral
crystals, owing to the strong electrostrictive coupling in ferroelectrics. Our work establishes ferroelectric dynamics as a versatile electrical source of chiral
phonons and provides a general route toward electrically programmable chiral-phononic and spintronic functionalities.
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Materials Science
Nuclearity of Copper Clusters on hBN/SiC Heterostructure Modulates Molecular Adsorption
Reza Khakpour, Arsalan Hashemi, Xiaoya Chang et al. (+3 more)
Defect engineering can transform inert two-dimensional (2D) materials into chemically active and electronically tunable platforms by creating anchoring sites for metal atoms and clusters. Nevertheless, precise control over the formation, thermodynamic and kinetic stability, electronic structure, and chemical reactivity of metal species confined at these defect sites remains a challenge. Here, we use density functional theory (DFT) calculations assisted by machine-learning molecular dynamics (MLMD) simulations to elucidate the stability, electronic structure, and reactivity of Cu clusters anchored at boron vacancies (VB) in hBN/SiC
heterostructures. Systematic variation of the Cu-to-vacancy ratio reveals a transition from isolated Cu atoms to multiatom Cu clusters at VB sites, with cluster growth reshaping the stability, electronic structure, and surface reactivity. Our results show that a single VB defect can be passivated by three Cu atoms, which compensate the local charge deficiency and stabilize the defect through Cu-N coordination. Capturing further Cu introduces localized midgap states that could influence the reactivity of the Cu-decorated defect sites. We probe the response of the Cu-decorated surface to chemically relevant gases CO, H2, O2, N2, H2S, and CO2, revealing implications for surface reactivity and stability. The calculations show pronounced cluster-size-dependent reactivity of Cu clusters at VB sites, with CO forming strong Cu-C bonds and O2 undergoing enhanced adsorption and molecular activation. Overall, this work identifies defect-engineered hBN/SiC as a versatile 2D platform for stabilizing Cu clusters and tuning gas-surface reactivity. By correlating Cu nuclearity at VB sites with electronic structure, molecular activation, and environmental robustness, our findings provide design guidelines for nuclearity-dependent metal functionalization of 2D
heterostructures.
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All authors Reza Khakpour, Arsalan Hashemi, Xiaoya Chang, Nima Ghafari Cherati, Mikko Karttunen, Tapio Ala-Nissila
Materials Science
Magnetic-configuration design for reliable Heisenberg exchange parameters
Ben Li, Stephan von Malottki and Gian-Marco Rignanese
The determination of
magnetic exchange interactions is essential for the quantitative description and predictive modeling of
magnetic materials. In this work, we present a neighbor-shell-based screening method for selecting
magnetic configurations suitable for extracting Heisenberg exchange parameters beyond nearest-neighbor from density functional theory (DFT) calculations. Using only the structure, the proposed approach identifies the linear independence of neighbor-shell contributions before any first-principles calculations instead of relying on trial-and-error generation of
magnetic configurations. We apply the proposed approach to two representative classes of
magnetic configurations: random
spin states and
spin spirals, and validate its predictions against direct DFT fitting for Fe and MnF$_2$. We show that only parameters obtained when all relevant neighbor-shell contributions are linearly independent remain transferable to other
magnetic configurations. The proposed method provides practical guidance for selecting
magnetic configurations for reliable exchange-parameter extraction and may also benefit other neighbor-shell-based models.
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Materials Science
Substitution effects in RuO$_2$ single crystals
Shubhankar Paul, Kunihiko Yamauchi, Shogo Yamashita et al. (+7 more)
RuO$_2$ has emerged as one of the leading candidates for investigating altermagnetism. Recent
quantum oscillation and angle-resolved photoemission spectroscopy measurements found the absence of altermagnetism or antiferromagnetism in pure RuO$_2$
crystals. The continuing debate over intrinsic
magnetic order in RuO$_2$ may reflect its proximity to an altermagnetic instability. In this work, we grow single
crystals of Ru$_{0.9}$V$_{0.1}$O$_2$ and investigate their structural, transport, and
magnetic properties. X-ray photoelectron spectroscopy reveals an average V oxidation state near $+4$. The paramagnetic susceptibility remains nearly unchanged up to room temperature, with no evidence of
magnetic ordering. Thus, the 10% V-substitution in RuO$_2$ does not induce altermagnetism. Electronic structure calculations for the V-substituted systems using two methods suggest that a higher level of V-substitution leads to a significant change in the density of states. These findings underscore the potential of nonmagnetic substitution in RuO$_2$ as an attractive candidate for probing altermagnetic transitions and their experimental signatures.
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All authors Shubhankar Paul, Kunihiko Yamauchi, Shogo Yamashita, Hisakazu Matsuki, Shuhei Iwashita, Mitsuhiko Maesato, Hiroshi Kitagawa, Chanchal Sow, Shingo Yonezawa, Yoshiteru Maeno
Materials Science
Optical and magneto-optical interactions in Co-doped CeO$_2$ thin films prepared by pulsed laser deposition
Martin Zahradník, Miroslav Kučera, Roman Antoš et al. (+5 more)
Magnetically doped CeO$_2$ is a dilute
magnetic semiconductor, promising for various applications in photonics, but the origin of its ferromagnetic properties is not fully understood. Here, thin films of Ce$_{1-x}$Co$_x$O$_{2-\delta}$ prepared by pulsed
laser deposition on MgO ($x=0.05$ and $0.10$) and oxidized Si ($x=0.20$) substrates were systematically studied by spectroscopic ellipsometry and magneto-optical spectroscopy. Both diagonal and off-diagonal permittivity-tensor elements were obtained. Diagonal spectra revealed two optical transitions between oxygen and cerium states. Off-diagonal spectra revealed two paramagnetic transitions involving cobalt ions, from which an essential influence of cobalt doping on resulting ferromagnetic properties of CeO$_2$ was inferred. The full permittivity-tensor spectra are provided for further use in prospective modelling of magneto-optical device concepts.
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All authors Martin Zahradník, Miroslav Kučera, Roman Antoš, Martin Veis, Jan Mistrík, Lei Bi, Hyun-Suk Kim, Caroline A. Ross
Materials Science
A Hierarchical Synergistic Deep Learning Framework Integrating Composition, Structure, and Ionic Transport for Solid-State Electrolyte Discovery
Hongwei Du, Dingyang Lv, Baole Wei et al. (+5 more)
Inorganic solid-state electrolytes must combine high room-temperature ionic conductivity, a wide electrochemical window, excellent electronic insulation, and favorable mechanical compliance. Single models struggle to support reliable multi-objective screening across vast chemical spaces because of training-data distribution mismatch, cross-property
dataset heterogeneity, and scarce kinetic transport data. To overcome these limitations, we develop a hierarchical synergistic deep-learning framework that sequentially coordinates efficiency, accuracy, and reliability through four complementary modules. The in-house-developed L-G-DCNN and a multi-fidelity implementation built on DenseGNN serve as compositional and structural experts for thermodynamic coarse screening and multi-property evaluation, respectively; MatterSim and system-specific DeePMD models provide transport pre-assessment and kinetic validation. Systematic
benchmarks show that each module outperforms mainstream counterparts in its task, while retrospective validation establishes dual closed-loop verification of module-level accuracy and end-to-end workflow reliability. Applied to 30,364,908 Alex/ICSD-derived candidates, the framework identifies 97 high-performance candidates with room-temperature ionic conductivities of 0.109–59.0 mS/cm, including 94 halides, one borohydride, and two oxides. Consistency with independent experimental data confirms that 76 of the 94 halides fall within reported high-conductivity structural regions. Analysis reveals that Li$^{+}$ jump-network connectivity, rather than the number of
geometric Li sites, is the core determinant of room-temperature ionic conductivity. Li-defect engineering effectively enhances oxide transport, whereas the inherent rigidity of the O$^{2-}$ framework suggests a potential upper limit on oxide electrolyte performance.
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All authors Hongwei Du, Dingyang Lv, Baole Wei, Yongheng Li, Feng Yu, Ziheng Lu, Siqi Shi, Hong Wang
Materials Science
Exchange splitting as a descriptor for giant anomalous Hall and Nernst effects in ferromagnets
Ivan Kurniawan, Guangzong Xing, Yoshio Miura et al. (+1 more)
The anomalous Hall effect (AHE) and anomalous Nernst effect (ANE), which describe transverse electrical and thermoelectric responses in
magnetic materials, respectively, are promising for spintronic and energy-harvesting applications. Here, we employ high-throughput first-principles calculations to investigate 2251 chemically substituted tetragonal $L1_0$
alloys. Among ferromagnets, enhanced responses emerge preferentially in
alloys derived from parent compounds with small exchange splitting: no
alloy derived from FePt, the archetypal $L1_0$ ferromagnet, reaches the high-response regime, whereas NiPt- and CoIr-derived
alloys occupy it in large numbers. Small exchange splitting keeps majority- and minority-
spin bands near the Fermi level, giving chemical substitution more opportunity to modify near-Fermi-level band crossings and amplify the Berry
curvature. We predict a giant anomalous Hall conductivity of $2809\,\mathrm{S\,cm^{-1}}$ in (Co$_{0.8}$Fe$_{0.2}$)(Ir$_{0.7}$Pt$_{0.3}$) and a giant anomalous Nernst conductivity of $7.72\,\mathrm{A\,m^{-1}\,K^{-1}}$ in (Ni$_{0.8}$Co$_{0.2}$)(Pt$_{0.7}$Ir$_{0.3}$). Our results identify the exchange splitting of the parent compound as a descriptor for chemical tunability toward giant Berry-
curvature-driven transport responses.
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All authors Ivan Kurniawan, Guangzong Xing, Yoshio Miura, Keisuke Masuda
Materials Science
Direct current thermo-mechanical testing: Principles, uncertainty hierarchy, and its role in advanced materials characterisation
Abdalrhaman Koko, Sodiq Abiodun Kareem, Olajesu Favor Olanrewaju et al. (+4 more)
Direct current thermo-mechanical testing (DC-TMT), based on resistive Joule heating, enables rapid heating and cooling, steep thermal gradients and simultaneous mechanical loading, making it a powerful tool for probing deformation, phase transformations, oxidation-assisted damage and creep under conditions inaccessible to conventional furnace-based methods. Despite its growing use, DC-TMT lacks formal standardisation and is often misinterpreted as equivalent to bulk isothermal testing, overlooking intrinsic differences in thermal and mechanical fields. This review addresses that gap by consolidating four decades of research on specimen geometry, temperature measurement, strain characterisation and environmental control, and by classifying uncertainty sources as dominant, secondary and conditional. Evidence from modelling and experiment shows that temperature gradients, heating rate and gauge representativeness govern the reliability of inferred material behaviour. Applications across aluminium, steels, nickel-based superalloys, titanium
alloys, hardmetals, zirconium
alloys, shape
memory alloys and additively manufactured systems are critically assessed. The review highlights domains where DC-TMT provides reproducible mechanistic insight and conditions where direct equivalence with bulk data is not warranted. Implications include the need for transparent reporting, multi-sensor temperature validation and integration with electro-thermal modelling to enable rigorous, mechanism-focused interpretation.
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All authors Abdalrhaman Koko, Sodiq Abiodun Kareem, Olajesu Favor Olanrewaju, Rachael Williams, Justus Uchenna Anaele, Yuanbo T. Tang, Bryan Roebuck
Materials Science · Cross-listed from physics.optics
Generalizing Thermal Transport in High-Contrast Metamaterials through Interfacial Fresnel Reflection
Seung Hyeon Ham, Yu Min Kim, In Hyeok Choi et al. (+1 more)
The rapid growth of generative AI has intensified the need for efficient heat dissipation in large-scale data centers. To control heat flow, thermal metamaterials with layered structures have been widely used, which impart the anisotropic properties of thermal conductivities. However, the conventional effective medium approximation (EMA) often fails to provide accurate predictions in systems with a high thermal conductivity contrast between adjacent layers embedded in a background medium. Here, we generalize the EMA by introducing two corrective coefficients that extend its validity to regimes where the conventional EMA was previously inapplicable, i.e., high-contrast thermal metamaterials with the background medium. Notably, one of these coefficients that we proposed has the same mathematical form as the Fresnel reflection coefficient in optics. This allows us to interpret the "reflection-like" behavior of heat flow as it penetrates adjacent layers with high thermal contrast. Our findings suggest that heat
diffusion, traditionally viewed as a purely dissipative process, can be understood intuitively through the framework of ray optics.
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All authors Seung Hyeon Ham, Yu Min Kim, In Hyeok Choi, Jeong Woo Han
Materials Science · Cross-listed from physics.chem-ph
Battery Recycling: Mechanistic Modelling of LiCoO$_2$ Leaching with Coupled Diffusion-Reaction Kinetics and Film Passivation
Uddipta Sarma and Ganesh Madabattula
We developed a new mechanistic model for lithium and cobalt recovery during acidic-reductive leaching from LiCoO$_2$. The system considers HCl as an acid and H$_2$O$_2$ as a reducing
agent. The model tracks conversion of LCO, the particle radius, the acid, H$_2$O$_2$, formation-dissolution dynamics of Co$_3$O$_4$ film, the film thickness, recovery of lithium and cobalt, and moles of O$_2$. We introduced the film passivation effects for reduced recovery in the absence of H$_2$O$_2$. We validated the model against the experimental data of recovered Li and Co reported in literature at three acid concentrations (0.5 M, 1.5 M, and 2.5 M) and four H$_2$O$_2$ concentrations (0%, 0.2%, 0.4%, and 0.6% (v/v)). The model works reasonably well at 0.5 M and 1.5 M HCl for the 0% and 0.6% concentrations of H$_2$O$_2$. At 2.5 M HCl, the model over-predicts the data in the presence of H$_2$O$_2$, while it works well at 0% H$_2$O$_2$. We suggest pathways for further improvements in the model. The comprehensive mechanistic modelling framework for the leaching with a full list of the equations, the parameters, and the variables, reported for the first time, can be extended to other cathode chemistries and acid-reductive leaching systems.
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Materials Science
Parity-controlled electron-hole interference in exciton-phonon coupling
Michael O. Atambo
We demonstrate that
exciton-
phonon coupling in polar
semiconductors is governed by a parity-controlled interference selection rule. By performing an exact multipole expansion of the excitonic form factor and validating it against numerical integration of hydrogenic envelope functions, we show that the long-range infrared divergence of the Fröhlich interaction is exactly canceled for elastic scattering between excitonic states of the same parity. The ground-state
exciton is thereby protected from long-wavelength polar
phonons by destructive electron-hole interference. In contrast, transitions between states of opposite parity exhibit constructive interference, preserving a finite, robust coupling to macroscopic polar fields independent of band-structure details. Mass asymmetry between the electron and hole activates higher-order multipole terms in the elastic channel but leaves the constructive inelastic channel essentially unaffected. The selection rule is dimensionally invariant, applying to bulk and two-dimensional systems alike, and naturally explains the anomalously weak
phonon dressing observed in halide perovskites as well as the strong
phonon sidebands in transition-metal dichalcogenides. Our framework provides a universal, analytically exact criterion for
exciton-
phonon coupling strength, offering a design principle for engineering excitonic materials with tailored
phonon interactions.
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Materials Science
Interpretable physics-informed retrieval-augmented generation language model for end-to-end inorganic crystal synthesis planning
Wei-Jian Jiang, Ye-Nan Sha, Hui Guo et al. (+7 more)
Synthesis planning for inorganic materials requires predicting both synthesizability and viable routes by linking microscopic thermodynamic stability with macroscopic synthesis methods, precursors, and processing conditions. Here, we develop an interpretable Physics-Informed
Retrieval-Augmented Generation
Language Model (PIRAG-LM) for end-to-end inorganic
crystal synthesis planning. We construct a material-centered Structured Synthesis Knowledge Base (SSKB) containing route-level records for 13,820 experimentally synthesized inorganic
crystals. PIRAG-LM retrieves historical precedents using chemical, structural, and thermodynamic similarity, then employs a structured LLM
reasoning module to propose routes, precursors, and processing conditions and assess thermodynamic feasibility, kinetics, and accessibility. It achieves 91.4% accuracy in synthesis-method prediction, compared with 72.1% for the LLM alone, and generalizes to materials reported after the knowledge cutoff. Because the framework relies on
retrieval rather than parametric memorization, its performance can be improved by expanding the SSKB without retraining the
language model. Guided by PIRAG-LM, we experimentally synthesize five new compounds: BaMo0.3In0.7O2.95, BaNb0.4In0.6O2.9, Hg[B(CN)4]2, CoCo(CN)6, and SrNb2Fe2(PO4)6, via solid-state and solution routes. These results demonstrate an interpretable machine-learning approach that helps bridge computational materials discovery and experimental realization.
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All authors Wei-Jian Jiang, Ye-Nan Sha, Hui Guo, Jie Chen, Yu-Cai Liang, Ke Zhou, Qi-Long Gao, Dong-Lin Han, Xin-Gao Gong, Wan-Jian Yin
Materials Science · Cross-listed from cond-mat.mes-hall
Quantum geometric signatures of Link-Unlink transitions and nonlinear Hall response in Hopf-link semimetals
Kamalesh Bera, Arijit Saha and Debashree Chowdhury
Quantum geometry, comprising of
quantum metric and Berry
curvature, plays a significant role in the electronic transport properties of solids. In this work, we theoretically investigate the
quantum geometric properties of a Hopf-link semimetal, a distinct topological class that is charecterized by a nodal link-unlink transition. We compute the interband optical conductivity of the Hopf link, which effectively distinguishes between linked and trivial phases. While recent studies establish
quantum metric dipole-mediated scattering-free nonlinear Hall effect, this effect becomes even more fascinating in systems where the Berry-
curvature-dipole contribution to nonlinear Hall conductivity vanishes. Owing to the underlying $PT$
symmetry of the Hopf-link semimetal, the Berry
curvature and its corresponding contribution to the nonlinear Hall effect are entirely suppressed. Consequently, by introducing an appropriate perturbation, a finite nonlinear Hall conductivity emerges solely due to the
quantum metric in the Hopf semimetal. Notably, this purely intrinsic,
symmetry-driven nonlinear response remains entirely unmixed with extrinsic components.
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Materials Science
Realization of Air-Stable Two-Dimensional Superconductor Nb2Pd3Te5 With Quasi-One-Dimensional Pair Density Modulation
Jiayi Wang, Hui Guo, Hao Zhang et al. (+12 more)
Two-dimensional (2D)
superconductors provide a fertile platform for exploring reduced-dimensional superconductivity and emergent
quantum phenomena. Incorporating quasi-one-dimensional (quasi-1D) structural motifs into 2D
superconductors offers a powerful route to engineer strong electronic anisotropy, enabling unconventional superconducting states and anisotropic superconducting transport functionalities. However, such systems remain rarely realized. Here we report the realization of a 2D
superconductor Nb2Pd3Te5, exhibiting an intrinsic quasi-1D pair density modulation. Monolayer and bilayer Nb2Pd3Te5 is synthesized via van-der-Waals epitaxy. Using ultralow-temperature scanning tunneling microscopy/spectroscopy, we observe the quasi-1D
crystal structure and superconductivity below ~0.6 K with a pronounced quasi-1D pair density modulation. Remarkably, both monolayer and bilayer Nb2Pd3Te5 show strong air stability. Our findings establish atomically 2D Nb2Pd3Te5 as a robust and promising platform for exploring novel low-dimensional
quantum phenomena and anisotropy-enabled superconducting devices.
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All authors Jiayi Wang, Hui Guo, Hao Zhang, Haowei Chen, Peixuan Li, Xianghe Han, Ziang Wang, Siyu Xu, Qian Fang, Haohao Xu, Shixuan Du, Chengmin Shen, Hui Chen, Wang Yao, Hong-Jun Gao
Materials Science
Beyond linear stability: Heterogeneity-induced fingering of crack fronts
Manish Vasoya, Laurent Ponson and Veronique Lazarus
We investigate the stability of elastic interfaces beyond the linear regime by considering penny-shaped crack fronts propagating through toughness heterogeneities. Using fracture mechanics simulations, we drive crack fronts through arrays of obstacles with tunable toughness contrast. At low contrast, the crack front stiffness remains finite and stabilizes front perturbations. Above a critical threshold, however, the stiffness vanishes and the front destabilizes into long fingers that evolve into daughter cracks propagating between obstacles while the original crack remains pinned. Near threshold, the crack front response displays the characteristic square-root scaling behavior of classical saddle-node bifurcations. Yet, our analysis reveals a fundamentally different mechanism: the stable energy-minimizing crack-front configuration disappears without colliding with an unstable counterpart. Instead, the instability originates from a global loss of Griffith-compatible
equilibria governed by the nonlocal interactions along the crack front. Beyond fracture mechanics, these findings point toward a broader class of collective global bifurcations in nonlocal elastic interfaces and may help rationalize the brittle-to-quasibrittle transition in heterogeneous solids.
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Materials Science · Cross-listed from cond-mat.supr-con
Distinct Surface and Bulk Superconductivity in the Kagome Superconductor SrSn$_3$
Qun Zhu, Yong-Wei Wang, Ji-Hai Zhang et al. (+6 more)
Surface and bulk superconductivity may possess fundamentally different superconducting properties in
quantum materials with nontrivial electronic structures, yet their superimposed spectroscopic signatures often prevent direct experimental access to each superconducting channel. Here we reveal, in epitaxial films of the kagome
superconductor SrSn$_3$, distinct surface and bulk superconducting channels with markedly different superconducting gaps, upper critical fields, and
vortex-core electronic states by tuning the tunneling junction resistance in scanning tunneling spectroscopy. The surface superconductivity is characterized by a thickness-independent superconducting gap and an enhanced upper critical field, whereas the bulk superconducting channel exhibits a larger superconducting gap that decreases with reducing film thickness and a much lower upper critical field. Within
magnetic vortex cores, robust non-split zero-bias conductance peaks are observed exclusively in the surface superconducting channel, while pronounced zero-bias suppression is consistently associated with the bulk superconducting channel. These findings demonstrate that the
vortex-core electronic structure depends sensitively on the underlying superconducting channel, providing new insight into
vortex-bound states in topological
quantum materials.
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All authors Qun Zhu, Yong-Wei Wang, Ji-Hai Zhang, Qiang-Jun Cheng, Chen-Yu Hu, Jun-Zhong Wang, Qi-Kun Xue, Xu-Cun Ma, Can-Li Song
Materials Science
High-throughput Discovery of Magnetic Rare Earth Transition Metal Alloys
Shuo Tao, Osman Goni Ridwan, Liqin Ke et al. (+1 more)
We present an accelerated materials discovery framework that combines
diffusion-based
crystal structure generation with hierarchical screening to identify new rare-earth–transition-metal magnets simultaneously achieving high magnetization and thermodynamic stability. Using this workflow, we systematically explored over 3000 binary (R-T) and ternary (R-T-T$'$) compositions spanning R~$\in \{\text{Y, Sm}\}$, T~$\in \{\text{Fe, Co, Ni}\}$, and T$' \in \{\text{Ti, V, Cr, Mn, Cu, Zn}\}$, and filtered approximately 240{,}000 generated
crystal structures through machine-learning interatomic potential prescreening and
spin-polarized density functional theory validation. We identify 300+ low-energy
magnetic candidates within 0.1~eV/atom above the convex hull at the DFT level, including 5 thermodynamically stable phases. The highest saturation magnetization reaches ${\sim}1.8$~T in Fe-rich binary and ternary phases (SmFe$_{12}$, YFe$_{12}$, YFe$_{18}$Ti and Sm$_2$Fe$_{16}$Mn).
Symmetry analysis reveals that the majority of ternary candidates are subgroup derivatives of known binary prototypes through Wyckoff site splitting that accommodates T$'$ substitution. Site-resolved
magnetic moment analysis further shows that Mn aligns ferromagnetically with the Fe sublattice with minimal magnetization loss, whereas Cr couples antiferromagnetically, providing systematic guidance for dopant selection. These findings demonstrate a generalizable strategy for targeted
magnetic materials discovery and suggest that extending generative searches to larger unit
cells ($>$20 atoms) with higher Fe fractions is a promising route toward stable phases with saturation magnetization exceeding 1.8~T.
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All authors Shuo Tao, Osman Goni Ridwan, Liqin Ke, Qiang Zhu