Interface migration governs microstructural evolution during phase transformations and grain growth, thereby dictating those material properties that depend on microstructure. Recent work continues to highlight the rich range of behaviors exhibited by migrating interfaces, and the complex connection between these behaviors and the underlying atomistic processes that determine coarse-grained interfacial mobility. For interfaces moving at low homologous temperatures and small driving forces, we show that significant non-Markovian effects can arise that invalidate commonly used analysis methods. Specifically, we demonstrate that solute can act as a source of such non-Markovian motion. In turn, we introduce a time-local or time convolutionless propagator approach to account for memory-dominated short and intermediate time interface dynamics. This approach extrapolates to the long-time diffusive limit, enabling robust mobility estimates from molecular simulation time windows far shorter than those required to directly observe linear mean-square displacement scaling. Comparison with solute-free boundaries validates the method and quantifies solute drag in the Cahn-Hillert sense, providing a route to extract drag coefficients and effective mobilities across a range of solute concentrations. Our results demonstrate that analysis including memory is essential for connecting atomistic simulations to continuum models and offer a practical framework for studying interface kinetics in systems with slow internal processes.

Dirac fermions in condensed matter provide a versatile platform for exploring novel electronic phenomena and fundamental physics principles. Following the discovery of graphene, it was observed that certain layered materials can host planar square nets of atoms within their lattice, featuring a two-atom basis and supporting large-bandwidth Dirac bands. To date, several families of square net materials have been identified, exhibiting Dirac semimetal or nodal-line phases that host a diverse range of electronic and magnetic quantum properties. Here, we introduce a new class of square net semimetals: the binary rare-earth diantimonide compounds. Using angle-resolved photoemission spectroscopy and density functional theory calculations on the series precursor, ${\mathrm{LaSb}}_2$, we investigate the relationship between crystal structure and electronic topology. Our results reveal that the distinctive staggered symmetry of the square net layers induces a split double nodal-line structure in the low-energy dispersion. Furthermore, we predict that this splitting of the bands is accompanied by a Rashba-2 effect, establishing the rare-earth diantimonides as a compelling platform for studying Dirac spin-transport phenomena.

Magnetic materials are of great interest for investigating spin-dependent transport properties by analysis of the anomalous Hall effect (AHE) and topological Hall effect (THE). Here we report the concurrence of large AHE and THE over a wide temperature range up to room temperature in centrosymmetric ${\mathrm{Mn}}_5{\mathrm{Ge}}_3$. Unlike previous observation of AHE in ferromagnet, only the ordinary Hall effect captured by the two-band model is observed at low temperatures without AHE, which may be attributed to the opposite contribution from intrinsic and skew-scattering mechanisms. Remarkably, our results reveal two distinct sources of THE: noncollinear spin textures and skyrmion bubbles. When ${\mu }_{0}H$ ‖ $\left[100\right]$, a large THE is observed as a result of the chiral effect caused by the spin-flop process. A giant THE can also be detected when ${\mu }_{0}H$ ‖ $\left[001\right]$, which is mainly triggered by the skyrmion bubbles observed by magnetic force microscopy. Moreover, we find the topological Hall resistivity as high as 0.93 $\mu \mathrm{\Omega }\mathrm{cm}$ at 290 K, highlighting ${\mathrm{Mn}}_5{\mathrm{Ge}}_3$ as a promising candidate for future device applications.

Optimizing the band gap of ferroelectric oxides is crucial for enhancing light absorption in specific spectral ranges. In thin-film heterostructures, however, light absorption is also strongly influenced by interfacial properties. Bismuth ferrite–chromite (BFCO) thin films for instance, behave as a p-type semiconductor due to intrinsic cationic bismuth vacancies. When epitaxially grown on niobium-doped ${\mathrm{SrTiO}}_3$, a p-n-like junction forms with a characteristic depletion region. In this work, we present a nondestructive approach to determine the depletion region width using surface photovoltage (SPV) measurements. Kelvin probe force microscopy under illumination was applied to BFCO films of varying thicknesses. A distinct transition in the SPV response at $67\pm 5\mathrm{nm}$ identifies the depletion region width and the extent of band bending. These results are corroborated by macroscopic SPV measurements with a Kelvin probe setup. From the depletion width, the acceptor concentration in BFCO, primarily attributed to bismuth vacancies, was estimated to be $\sim 0.01\%$ of the total number of Bi atoms in the ideal lattice. This method provides a powerful and noninvasive route to probe depletion widths and carrier concentrations in complex ferroelectric heterostructures.

We investigate the effect of confinement on the magnetic state of a $12\text{−}\mathrm{n}\mathrm{m}$-thick ${\mathrm{Fe}}_5{\mathrm{GeTe}}_2$ layer grown by molecular beam epitaxy. We use quantitative scanning nitrogen-vacancy magnetometry to locally extract the magnetization in rectangular uniformly in-plane magnetized microstructures, showing no enhancement of the Curie temperature compared to magnetization measurements performed before patterning the film, in contrast to previous results obtained on thick ${\mathrm{Fe}}_3{\mathrm{GeTe}}_2$ flakes. Under the application of a weak out-of-plane magnetic field, we observe the stabilization of magnetic vortices at room temperature in micrometric squares. Finally, we highlight the effect of the size of the patterned microdisks and microsquares on the stabilization of the vortices using experiments and micromagnetic simulations. Our work thus proposes and demonstrates a way to stabilize noncollinear textures at room temperature in a van der Waals magnet using confinement.

We present a comprehensive study of the anisotropic magnetoresistance (AMR) in single-crystal $\mathrm{F}{\mathrm{e}}_{1-x}\mathrm{N}{\mathrm{i}}_x\left(001\right)$ alloy films with body-centered-cubic (bcc) structures, revealing a giant current-direction dependence and significant temperature-dependent behavior. In $\mathrm{F}{\mathrm{e}}_{0.8}\mathrm{N}{\mathrm{i}}_{0.2}$, the ratio between the AMR values for current along the [100] and [110] directions reaches 87 at 5 K. This ratio exhibits a strong temperature dependence, increasing nearly an order of magnitude as the temperature decreases from 300 K to 5 K. Additionally, we identify ultralow Gilbert damping ($\alpha \sim 2.3\times {10}^{-3}$) with negligible dependence on the magnetization orientation. The intrinsic anomalous Hall conductivity is found to decrease monotonically with Ni concentration. These results not only advance our understanding of FeNi alloys but also provide valuable insights for developing materials with customized magnetoresistance and low damping for magnetic sensing and data storage applications.

We explore the interrelation between crystal structure, magnetism, and magnetodielectric behavior in the spin-cluster compound ${\mathrm{Ba}}_6{\mathrm{Nd}}_2{\mathrm{Fe}}_4{\mathrm{O}}_{15}$. Magnetization measurements indicate the emergence of long-range antiferromagnetic order at $T_{\mathrm{N}}\approx 16\mathrm{K}$, supported by corresponding anomalies in the specific heat. Magnetic isotherms display a field-induced spin-flop transition at critical fields ${\mu }_0{H}_{\mathrm{C}1}$ and ${\mu }_0{H}_{\mathrm{C}2}$. Field-dependent neutron diffraction uncovers an antiferromagnetic ground state characterized by the propagation vector ${\mathit{k}}_1=(1/2,0,0)$ for fields ${\mu }_{0}H<0.6\mathrm{T}$, which transitions to a ferrimagnetic state with ${\mathit{k}}_2=(0,0,0)$ for ${\mu }_{0}H>1.2\mathrm{T}$. In the intermediate field range ($0.6\mathrm{T}<{\mu }_{0}H<1.2\mathrm{T}$), both magnetic vectors exist. Dielectric measurements exhibit a distinct anomaly near $T_{\mathrm{N}}$, alongside a robust magnetodielectric response that persists well above the transition, indicating strong coupling between the Fe tetramer spin clusters and dipolar degrees of freedom. The resulting ${\mu }_{0}H\text{–}T$ phase diagram delineates three magnetic regimes, distinguished by shifts in propagation vectors and corresponding variations in magnetization, thermal, and dielectric properties. Furthermore, temperature-dependent synchrotron x-ray diffraction suggests a subtle magnetostrictive effect near the ordering temperature. These findings highlight the intricate magnetodielectric effect in ${\mathrm{Ba}}_6{\mathrm{Nd}}_2{\mathrm{Fe}}_4{\mathrm{O}}_{15}$ and position it as a promising candidate for magnetodielectric applications.

Ferromagnetic pyrochlore and spinel materials with topological flat bands are of interest for their potential to exhibit a giant anomalous Hall effect (AHE). In this work, we present computational predictions of stability and electronic structure for 448 compositions within the pyrochlore ($A_2{B}_2{\mathrm{O}}_7$) and spinel ($A{B}_2{\mathrm{O}}_4$) frameworks. Of these, 92 are predicted to be thermodynamically stable or close (<100 meV/atom) to the convex hull, with trends deviating from expectations based on ionic radius-ratio rules. Thirteen are predicted to adopt a ferromagnetic ground state among the collinear configurations considered. Two additional materials meeting these criteria were also identified from open materials databases. Calculations of anomalous Hall angles (AHA) and conductivities reveal that 11 of the screened materials are promising candidates for spintronic applications requiring high electronic conductivity and a giant AHE. Our results suggest that the AHA can be further enhanced by tuning the Fermi level, for example, through chemical doping. Using this approach, we identify five materials whose AHA exceed 0.2 under the approximation of collinear magnetism. Notably, $\mathrm{A}{\mathrm{g}}_2\mathrm{P}{\mathrm{t}}_2{\mathrm{O}}_7$ exhibits a high AHA of 0.405 when its Fermi level is optimized. These findings provide a roadmap for the targeted synthesis of new pyrochlore and spinel compounds with enhanced AHE properties. They also broaden the compositional design space for these structures and support the discovery of high-performance materials for next-generation spintronic applications.

Nondestructive identification of deformation mechanisms at the microscopic scale is a significant challenge, yet it holds the potential to advance the understanding of damage evolution across many areas of materials mechanics. In this study, we combine spectral analysis of acoustic emission (AE) waveforms with dimensionality reduction to cluster individual AE events occurring during the deformation of a magnesium single crystal. Based on prior knowledge, according to which twinning is preferred at low stresses and slip is expected to become dominant when twinning is exhausted, we link these clusters to their related deformation mechanisms. This enables unsupervised classification of each AE event into the two deformation mechanisms. Furthermore, based on resonance ultrasound spectroscopy and modal calculations, we identify a frequency signature in AE signals, corresponding to one of the sample's resonant modes, and we associate it with slip. This allows us to define a single traceable, physically based classification parameter that performs comparably to the machine learning–based clustering. The results of both classification methods are consistent with each other and align with the expected deformation behavior and the shape of the loading curve. At the same time, they reveal detailed quantitative information at the level of individual AE events, which uncovers the evolution of the transition from twinning-dominant to slip-dominant behavior.

Accurate determination of the exciton binding energy and reduced effective mass in bulk halide perovskites is of utmost importance for the selective design of optoelectronic devices. Although these properties are currently determined by several spectroscopic techniques, complementary theoretical models are often required to bridge macroscopic and microscopic properties. Here, we present a method to determine these quantities while considering polarization effects due to carrier interactions with longitudinal optical phonons. Our approach estimates the exciton-polaron binding energy from optical absorption measurements using a recently developed Elliott-based band fluctuations (EBF) model. The reduced effective mass is obtained via the integration of this well-established EBF model with the Pollmann–Büttner exciton-polaron model, which is based on the Fröhlich polaron framework, where the strength of the electron–phonon interaction arises from changes in the dielectric properties. The procedure is applied to the family of perovskites ${\mathrm{ABX}}_3$ $(\mathrm{A}=\mathrm{MA}, \mathrm{FA}, \mathrm{Cs}; \mathrm{B}=\mathrm{Pb}; \mathrm{X}=\mathrm{I}, \mathrm{Br}, \mathrm{Cl})$, showing excellent agreement with high-field magnetoabsorption and other optical-resolved techniques. The results suggest that the Pollmann–Büttner model offers an excellent approach for determining the reduced effective mass in metal trihalide perovskites and other polar materials when combined with the EBF optical dispersion model.

The ternary intermetallic compounds, ${\mathit{R}\mathrm{Mn}}_6{\mathrm{Sn}}_6$ ($R$ = rare-earth or alkali or alkaline-earth metal) hosting Kagome bilayer of Mn, present a class of systems that naturally allows for the interplay of magnetism and topology. In search of ferromagnetic members in these systems, we show that dimensional reduction can be an effective means to achieve ferromagnetism and large anomalous Hall conductivity. Focusing on two specific members with $R$ = Lu and Mg, our first-principles calculations show that dimensional confinement through the construction of experimentally relevant atomistically thin single bilayer kagome geometry of Mn atoms gives rise to a ferromagnetic metal with multiple Weyl points along with spin-orbit-coupling induced gapped bands. The calculated anomalous Hall conductivity in the thin film geometry turns out to be 287 and $178{\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$, comparable to that found for bulk ${\mathrm{RMn}}_6{\mathrm{Sn}}_6$ with alkali or alkaline-earth metal at $R$ site. This is of interest as thin-film geometry can be efficiently integrated to devices.

Pulsed laser epitaxial growth is characterized by high instantaneous deposition rates that lead to the nucleation of transient islands, both on surface terraces and on top of stable islands formed during previous deposition pulses. We report results from combined $\mathit{in}$ situ x-ray reflectivity and kinetic Monte Carlo (kMC) simulations. Specular reflectivity monitors interlayer transport, while diffuse scattering reveals the evolution of in-plane length scales, both during the recovery time between individual laser pulses and over multiple deposited layers. The initial stage after each laser pulse is faster than the temporal resolution of the experiment, while subsequent recovery occurs over seconds. The results suggest that transient islands on top of stable two-dimensional islands form immediately after the deposition pulse and then ripen via detachment and diffusion, leading to the slower component. kMC simulations show that the detachment energy barrier plays a dominant role in determining the recovery time constant.

Oxynitrides are used in a variety of applications including photocatalysts, high-k dielectrics, or wear-resistant coatings and often show intriguing multifunctionality. To accelerate the cooptimization of the relevant material properties of these compositionally complex oxynitride systems, high-throughput synthesis and characterization methods are desirable. In the present work, three approaches were investigated to obtain orthogonal anion and cation gradients on the same substrate by magnetron sputtering. The different approaches included varying positions of the local reactive gas inlets and different combinations of target materials. The best performing approach was applied to screen a large two-dimensional area of the quaternary phase space within the Al-Si-O-N system. This material system is a promising candidate for transparent protective coatings with variable refractive indices. With only five depositions of combinatorial libraries, an anion composition range of 0.02–0.46 O/(N+O) and a cation composition range of 0.04–0.44 Si/(Al+Si) is covered. For lower oxygen and silicon contents, a region with hardness of up to 25 GPa is observed, where the material exhibits either wurzite AlN or a composite microstructure. By increasing the deposition temperature to 400°C, an extension of this region can be achieved. At higher oxygen and silicon contents, the structure of the samples is x-ray amorphous. In this structural region, an intimate correlation between hardness and refractive index is confirmed. The results of this study introduce a practical approach to perform high-throughput development of mixed anion materials, which is transferable to many materials systems and applications.

The search for chiral topological superconductivity in magnetic topological insulator (TI)-FeTe heterostructures is a key frontier in condensed matter physics, with potential applications in topological quantum computing. The combination of ferromagnetism, superconductivity, and topologically nontrivial surface states brings together the key elements required for chiral Majorana physics. In this work, we examine the interplay between magnetism and superconductivity at the interfaces between FeTe and a series of Te-based TI overlayers. In both Te/FeTe and superconducting ${\mathrm{MnBi}}_2{\mathrm{Te}}_4/\mathrm{FeTe}$, any interfacial suppression of antiferromagnetism must affect at most a few nanometers. On the other hand, ${(\mathrm{Bi},\mathrm{Sb})}_2{\mathrm{Te}}_3/\mathrm{FeTe}$ layers exhibit near-total suppression of antiferromagnetic ordering. Ferromagnetic ${\mathrm{Cr}}_x{(\mathrm{Bi},\mathrm{Sb})}_{2-x}{\mathrm{Te}}_3$ (CBST)/FeTe bilayers exhibit net magnetization in both CBST and FeTe layers, with evidence of interactions between superconductivity and ferromagnetism. These observations identify magnetic TI/FeTe interfaces as an exceptionally robust platform to realize chiral topological superconductivity.

Colossal magnetoresistance (CMR) has been observed across many ${\mathrm{Eu}}^{2+}$-based materials; however, its origin is not completely understood. Here we investigate the antiferromagnetic insulator ${\mathrm{EuZn}}_2{\mathrm{P}}_2$ through single crystal x-ray diffraction, transmission electron microscopy, electrical transport, magnetization, dilatometry, and electron spin resonance measurements complemented by density functional theory calculations. Our electrical resistivity data reveal a large negative magnetoresistance, $\text{MR}=\left[R\right(H)-R(0\left)\right]/R\left(0\right)$, that reaches $\text{MR}=-99.7$% at 9 T near the antiferromagnetic ordering temperature $T_N=23\mathrm{K}$. Dilatometry measurements show an accompanying field-induced lattice strain. Additionally, ${\mathrm{Eu}}^{2+}$ electron spin resonance reveals a strong ferromagnetic exchange interaction between ${\mathrm{Eu}}^{2+}$ and conduction electrons. Our experimental results in ${\mathrm{EuZn}}_2{\mathrm{P}}_2$ are consistent with a magnetic polaron scenario and suggest magnetic polaron formation as a prevailing explanation of CMR in ${\mathrm{Eu}}^{2+}$-based compounds.

We employ first-principles calculations based on hybrid density functional theory to investigate the structural and optical properties of the oxygen vacancy $\left(V_{\mathrm{O}}\right)$ and aluminum vacancy $\left(V_{\mathrm{Al}}\right)$ in $\alpha \text{−}{\mathrm{Al}}_2{\mathrm{O}}_3$, the most stable (corundum) phase of alumina. Our calculations facilitate the identification of experimental excitation and luminescence spectra with specific electronic transitions at the vacancy sites. The absorption line shape for excitation of an electron at $V_{\mathrm{O}}^0$ to the conduction-band minimum (CBM) is in excellent agreement with the 6.1 eV band detected by optical absorption spectroscopy, and we find that the 5.9 eV absorption band is generated by an internal electron transition at $V_{\mathrm{O}}^0$. We confirm that the slowly decaying 3.0 eV emission band of the $F$ center is due to a triplet-singlet transition at $V_{\mathrm{O}}^0$. Our calculations also reveal that the 4.8 eV/5.4 eV absorption and 3.8 eV emission bands assigned to the $F^{+}$ center are generated by internal transitions at $V_{\mathrm{O}}^{+1}$. The line shape for the excitation of an electron from $V_{\mathrm{O}}^{+1}$ to the CBM agrees well with an absorption band at 6.4 eV, while the recombination of an electron with $V_{\mathrm{O}}^{+2}$ also produces luminescence around 3.8 eV, but with a considerably broader line shape. For Al vacancies, we confirm that the most prevalent configuration in $\alpha \text{−}{\mathrm{Al}}_2{\mathrm{O}}_3$ is a split-vacancy configuration $V_{\mathrm{Al},\mathrm{s}}$, and we calculate migration barriers for different directions in the corundum crystal. We predict absorption and emission spectra for the excitation and recombination of an electron localized at $V_{\mathrm{Al}}^{-3}$ and $V_{\mathrm{Al},\mathrm{s}}^{-3}$ sites with the CBM. The line shapes of the two $V_{\mathrm{Al}}$ configurations overlap and are considerably broader than the spectra corresponding to $V_{\mathrm{O}}$.

We perform nanoindentation simulations for both the prototypical face-centered cubic metal copper and the body-centered cubic metal tungsten with an adaptive-precision description of interaction potentials including different accuracy and computational costs. We combine both a computationally efficient embedded atom method (EAM) potential and a precise but computationally less efficient machine learning potential based on the atomic cluster expansion (ACE) into an adaptive precision (AP) potential tailored for the nanoindentation. The numerically more expensive ACE potential is employed selectively only in regions of the computational cell where high precision is required. The comparison with pure EAM and pure ACE simulations shows that for Cu, all potentials yield similar dislocation morphologies under the indenter with only small quantitative differences. In contrast, markedly different plasticity mechanisms are observed for W in simulations performed with the central-force EAM potential compared to results obtained using the ACE potential. ACE is able to describe accurately the angular character of bonding, which is in W due to its half-filled $d$ band. All ACE-specific mechanisms are reproduced in the AP nanoindentation simulations, however, with a significant speedup of 20–30 times compared to the pure ACE simulations. Hence, the AP potential overcomes the performance gap between the precise ACE and the fast EAM potential by combining the advantages of both potentials.

Disorder in high entropy alloys, arising from the random distribution of multiple elements, plays a crucial role in their novel properties desirable for various advanced engineering applications. We investigate the role of compositional and structural disorder on the electronic structure of osmium-based superconducting high entropy alloys, ${(\mathrm{Ru}/\mathrm{Re})}_{0.35}{\mathrm{Os}}_{0.35}{\mathrm{Mo}}_{0.10}{\mathrm{W}}_{0.10}{\mathrm{Zr}}_{0.10}$, using photoemission spectroscopy and density functional theory (DFT). Elemental and cumulative core level shifts are found to be commensurate with elemental electronegativities and valence electron counts (VEC), respectively. Valence band spectra together with DFT results indicate that the crystal structure plays an important role in deciding the electronic structure of these high entropy alloys. Through temperature dependent high-resolution spectra, we unveil strongly suppressed spectral density of states (SDOS) in the close vicinity of Fermi level. Energy and temperature dependence of the SDOS in accordance with Altshuler-Aronov theory confirms localization of charge carriers in the presence of strong intrinsic disorder. Computed electron-phonon coupling strength and superconducting transition temperature aligning reasonably well with experiments further shed light on phonon-mediated pairing mechanism and role of disorder in these systems. Our results provide a way forward to the understanding of superconducting high entropy alloys through strategic control of disorder, VEC, and crystal structure.

Magneto-optical materials with low optical absorption are essential for realizing nonreciprocal light propagation in integrated photonic circuits. Among them, cerium-substituted yttrium iron garnet (Ce:YIG) stands out for its exceptionally high Faraday rotation. In this work, we investigate how film thickness and deposition atmosphere influence the structural, magnetic, and magneto-optical properties of Ce:YIG (${\mathrm{Ce}}_1{\mathrm{Y}}_2{\mathrm{Fe}}_5{\mathrm{O}}_{12}$) films. Using pulsed laser deposition in argon and oxygen environments, we grew coherently strained, smooth films on (111)-oriented gadolinium gallium garnet (GGG) substrates, with thicknesses up to 220 nm. Films grown in argon exhibit a significantly expanded out-of-plane lattice parameter, inducing perpendicular magnetic anisotropy, whereas those deposited in oxygen display in-plane magnetization. Remarkably, Ce:YIG films grown in argon show up to a twofold increase in magneto-optical activity compared to their oxygen-grown counterparts, achieving a Faraday rotation of $5.0{}^{\circ }/\mu \mathrm{m}$ at 780 nm. This enhancement is attributed to prolonged electronic relaxation times and longer-lived excitations in the more heavily strained films.

Predicting and explaining charge carrier transport in halide perovskites is a formidable challenge because of the unusual vibrational and electron-phonon coupling properties of these materials. This study explores charge carrier transport in two prototypical halide perovskite materials, methylammonium lead tribromide (${\mathrm{MAPbBr}}_3$) and methylammonium lead triiodide (${\mathrm{MAPbI}}_3$), using a dynamic disorder model. Focusing on the role of real-space transport channels, we analyze temporal orbital occupations to assess the impact of material-specific on-site energy levels and spin-orbit coupling (SOC) strengths. Our findings reveal that both on-site energies and SOC magnitude significantly influence the orbital occupation dynamics, thereby affecting charge dispersal and carrier mobility. In particular, energy gaps across on-site levels and the halide SOC strength govern the filling of transport channels over time. This leads us to identify the $pp\pi$ channel as a critical bottleneck for charge transport and to provide insights into the differences between electron and hole transport across the two materials.