Semiconductor crosshatch patterns form as a result of strain relaxation and dislocation pileups during growth of lattice mismatched materials. Due to their connection with the internal misfit dislocation network, these patterns are a complex fingerprint of internal strain relaxation and growth anisotropy. Therefore, these patterns not only describe the residual strain state at the surface, but could also provide an indicator of electron transport quality through the material. Here, we present a method utilizing computer thresholding and machine learning to analyze antiferromagnetic (AFM) crosshatch patterns that exhibits this correlation. Our analysis reveals optimized electron transport for moderate values of $\lambda$ (crosshatch wavelength) and $\epsilon$ (crosshatch height), roughly 1 $\mu \mathrm{m}$ and 4 nm, respectively, that define the average wave form of the pattern. Simulated two-dimensional AFM crosshatch patterns are used to train a machine learning model to correlate the crosshatch patterns to dislocation density. This model is used to evaluate the experimental AFM images and predict a dislocation density based on the crosshatch wave form. Predicted dislocation density, experimental AFM crosshatch data, and transport measurements are used to train a final model to predict electron mean free path. Our model shows electron scattering is dominated by elastic effects (e.g., dislocations) below 150 nm ${\overline{\lambda }}_{\mathrm{MFP}}$.

The chemical flexibility of the $R{M}_6{X}_6$ stoichiometry, where an $f$-block element is intercalated in the CoSn structure type, allows for the tuning of flatbands associated with kagome lattices to the Fermi level and for emergent phenomena due to interactions between the $f$- and $d$-electron lattices. Yet, $5f$ members of the “166” compounds are underrepresented compared with $4f$ members. Here, we report single-crystal growth of ${\mathrm{UCr}}_6{\mathrm{Ge}}_6$, which crystallizes in a monoclinically distorted ${\mathrm{Y}}_{0.5}{\mathrm{Co}}_3{\mathrm{Ge}}_3$-type structure. The real-space character of the modulation, which is unique within the $R{M}_6{X}_6$ family, is approximated by a $3\times 1\times 2$ supercell of the average monoclinic cell. The compound has kagome-lattice flatbands near the Fermi level and a moderately enhanced electronic heat capacity, as evidenced by its low-temperature Sommerfeld coefficient ($\gamma =86.5$ mJ ${\mathrm{mol}}^{-1} {\mathrm{K}}^{-2}$) paired with band structure calculations. The small, isotropic magnetization and featureless resistivity of ${\mathrm{UCr}}_6{\mathrm{Ge}}_6$ suggest itinerant uranium $5f$ electrons and Pauli paramagnetism. Angle-resolved photoemission spectroscopy results provide evidence for uranium $5f$ weight at the Fermi level and for a flatband near the Fermi level associated with the chromium $3d$ kagome lattice. The isotropic magnetic behavior of the uranium $5f$ electrons starkly contrasts with localized behavior in other uranium 166 compounds, highlighting the high tunability of the magnetic ground state across the material family.

Solid-state spin defects in wide-band-gap semiconductors are leading candidates for quantum information processing, but systematic identification of suitable host materials remains limited by the cost of first-principles screening across vast chemical spaces. We address this with a composition-only machine learning framework built on heterogeneous Rashomon set ensembles: by contrasting the feature attributions of seven diverse classifiers, we extract consensus design rules that no single model identifies alone—filled valence $s$-, $d$-, and $f$ shells, low chemical heterogeneity, and enrichment in C, S, Si, and O favor quantum compatibility. Screening $\approx 45000$ thermodynamically stable compounds, we identify 122 high-confidence candidates (confidence $>0.95$), recovering most experimentally verified hosts (C, $\mathrm{SiC}, \mathrm{ZnO}$, and $\mathrm{ZnS}$) and predicting unexplored materials including ${\mathrm{TiO}}_2, {\mathrm{PbWO}}_4$, and layered chalcogenides (${\mathrm{HfS}}_2, {\mathrm{ZrS}}_2$). Density-functional perturbation theory calculations on 12 representative materials validate dielectric screening as a coherence proxy ($R^2=0.89$ against experimental $T_2$), and vacancy calculations for ${\mathrm{TiO}}_2$ reveal deep, isolated midgap states favorable for spin-defect hosting. The framework provides transferable, physically grounded design principles for rational quantum materials discovery beyond traditional carbide and nitride hosts.

Sulfur-doped black phosphorus (b-P) has recently emerged as a promising candidate for next-generation electronic and optoelectronic technologies owing to its enhanced environmental stability and tunable electronic properties. In this work, we systematically investigate the effects of sulfur substitution on the elastic, mechanical, and electronic properties of b-P, with a particular focus on its auxetic behavior (i.e., negative Poisson's ratio), using first-principles density functional theory calculations. Our results unveil the fundamental origin of the intrinsic auxetic response in pristine b-P and elucidate how sulfur incorporation alters this behavior. We find that sulfur atoms distort the characteristic bowtie structural motif responsible for the negative Poisson's ratio in b-P, thereby suppressing the in-plane auxeticity. Moreover, the resulting charge redistribution also effectively quenches the out-of-plane auxetic response of b-P. With increasing sulfur content, the bulk modulus and Poisson's ratio increase, whereas the Young's modulus, shear modulus, and Debye temperature decrease. Additionally, sulfur substitution suppresses the semiconducting properties of b-P, giving rise to metallicity. These findings highlight that, although sulfur substitution enhances the environmental stability of b-P, it also substantially modifies its elastic and mechanical properties, particularly the auxetic behavior, which is an important consideration in the design of nanoscale electronic devices.

By combining Density functional theory-based first-principles simulations with a random distribution model for estimating the relative percentage of distinct types of S complexes in S-hyperdoped silicon, we predict a tunability of the insulator-to-metal transition at the critical dopant concentration that is significantly larger than previously reported for other chalcogen-hyperdoped Si systems, driven by the relative abundance of the different complexes. By assuming the possibility to tune the latter during the sample synthesis, we predict that optical absorption spectra of S-hyperdoped Si can be engineered from the short wavelength infrared to far infrared region.

A Moment Tensor Potential (MTP) is developed for equiatomic CoCrNi and CoCrFeNi alloys to enable large-scale simulations of chemical short-range order (CSRO) and defect energetics with near density functional theory (DFT) accuracy. The training database includes unary to quaternary configurations as well as DFT derived short-range ordered structures, ensuring accurate representation of thermodynamically relevant chemical environments. The MTP reproduces DFT energies, forces, stresses, and elastic constants across diverse compositions and phases. Hybrid Monte Carlo/molecular dynamics simulations recover key CSRO trends, including Cr–Cr and Fe–Fe repulsion and Ni–Cr ordering, with correct sign structure across temperature. Intrinsic stacking fault (ISF) energies are predicted to be $54\mathrm{mJ}/{\mathrm{m}}^2$ for CoCrNi and $36\mathrm{mJ}/{\mathrm{m}}^2$ for CoCrFeNi, consistent with DFT trends and sensitive to local chemical fluctuations. The potential further enables simulations of solute segregation at grain boundaries while preserving structural units. The developed MTP enables transferable, physically consistent simulations of thermodynamic stability and defect mediated mechanical response in fcc medium entropy alloys across extended length and timescales.

Microstructural engineering represents a promising avenue toward controlling the macroscopic response of high-performance magnetic materials, yet the physical origins linking microstructure to magnetic properties remain to be fully established. In this contribution, we establish magnetoplastic control over macroscopic magnetic properties by inducing high densities of extended lattice defects within the prototypical $L{2}_1$-ordered intermetallic ${\mathrm{MnCu}}_2\mathrm{Al}$, which serves as an ideal model system. We demonstrate a nearly 95% decrease in the initial net saturation magnetization following a high degree of plastic deformation, with effects that are reversible through annealing. Synchrotron X-ray diffraction and scanning electron nanodiffraction permit microscopic correlation of the changes in magnetic behavior with increasing defect content. Microstructural characterization at the single defect level, coupled with detailed first-principles modeling, suggests the presence of a local antiferromagnetic coupling within the extended defects that is at the origin of the dramatic magnetoplastic effect in these magnetic intermetallics. We ascribe these effects to the planar dissociation of dislocations hosting intervening antiphase boundaries, altering the atomic environment and, in turn, the magnetic coupling in the vicinity of dislocations.

Er-substituted yttrium iron garnet (Er:YIG) holds the potential of combining the low magnetic damping of YIG with the telecom-band optical transitions of ${\text{Er}}^{3+}$ ions, making it a suitable material for hybrid optomagnonic devices and microwave-to-optical quantum transduction. We report the epitaxial growth of ${\text{Er}}_x{\text{Y}}_{3-x}{\text{Fe}}_5{\text{O}}_{12}$ films with $x=0.008–0.2$ on (111)-oriented gadolinium gallium garnet (GGG) substrates using pulsed laser deposition. X-ray diffraction, reciprocal space mapping, and scanning transmission electron microscopy confirm single-phase, fully coherent growth with atomically sharp interfaces across the entire substitution range. Magnetometry reveals a gradual decrease in saturation magnetization with increasing Er content, consistent with antiparallel coupling between ${\mathrm{Er}}^{3+}$ spins and the net ${\mathrm{Fe}}^{3+}$ moments, along with the emergence of an in-plane uniaxial magnetic anisotropy. The ferromagnetic resonance broadens with Er content due to increased Gilbert damping and inhomogeneous linewidth broadening. Er:YIG films with $x=0.008$, most relevant for optomagnonic applications, retain nearly isotropic magnetization and exhibit a damping parameter only slightly higher than that of undoped YIG. These results identify growth and substitution conditions that preserve YIG's low-loss magnetic properties while introducing optical functionality, establishing Er:YIG as a viable platform for hybrid quantum magnonics and microwave-to-optical transduction.

We report on the metamagnetic transition observed in oxides ${\mathrm{Ba}}_2{Ln\mathrm{FeO}}_5$ ($\mathit{Ln}$ = Tb, Dy, Ho, Er, Yb), which contain two magnetic sublattices: ${\mathrm{Fe}}^{3+}$ and ${Ln}^{3+}$. The magnetic ordering in these materials results from a competition between several types of interaction (Fe-Fe, Fe-$\mathit{Ln}$, and $\mathit{Ln}-\mathit{Ln}$), combined in most cases with a strong easy-axis anisotropy of the ${Ln}^{3+}$ magnetic moments induced by the crystal electric field (CEF). A specific mechanism is proposed to account for the peculiar metamagnetism in this class of materials, and its variation along the $\mathit{Ln}$ series. This study is based on a set of results including magnetization, x-ray magnetic circular dichroism, neutron powder diffraction, and calculations of the CEF.

Diamond is renowned for supreme hardness and supersized electronic bandgap, but knowledge is surprisingly incomplete on its prominent mechanical and electronic benchmarks under large loads. Here, using first-principles calculations, we create global mapping of extremal stress (GMES) and related strain and modulus profiles to bring out fresh perspectives on material behaviors at different scales (small versus large) and varieties (tension, compression or shear) of loads, unveiling patterns and trends of mechanical properties and record-shattering maximal stress. Moreover, we construct global mapping of electronic bandgap (GMEB) profiles to set benchmarks for rational modulation of electronic properties of diamond. This distinct protocol offers a fresh expansive view of key benchmarks beyond the prevailing paradigm, highlighting global emergent behaviors of extreme mechanics and electronics of diamond under ultimate elastic strain engineering.

${\mathrm{CuLa}}_2{\mathrm{Ge}}_2{\mathrm{O}}_8$ forms a distorted triangular lattice of quantum spin-1/2 ${\mathrm{Cu}}^{2+}$ ions. A crystal growth method was developed using the traveling-solvent floating zone technique, resulting in the synthesis of a large single crystal ($4\mathrm{mm}\times 4\mathrm{mm}\times 10$ mm). The crystal was characterized with regard to phase purity and crystallinity using powder x-ray diffraction, energy dispersive x-ray analysis, and Laue diffraction, and found to be of excellent quality. The magnetic properties were characterized using dc-susceptibility, magnetization, and heat capacity measurements, which revealed weak magnetic frustration with long-range magnetic order occurring below $T_N=1.14\left(1\right)$ K. The magnetic structure determined using neutron powder diffraction is a commensurate, noncollinear antiferromagnetic structure, different from the ${120}^{\circ }$ order of an equilateral triangular antiferromagnet. The ordered moments lie in the bc-plane, with components $m_b=0.50\left(3\right) {\mu }_B$ and $m_c=0.73\left(5\right) {\mu }_B$ along the b- and c-axes respectively, giving a total ordered moment of $M_{\mathrm{total}}=0.89\left(6\right){\mu }_B/{\mathrm{Cu}}^{2+}$ at 20 mK.

We investigate the low-temperature spin dynamics of epitaxial lithium aluminum ferrite (LAFO) thin films using broadband ferromagnetic resonance (FMR) spectroscopy from 0.44 to 68 K. The results reveal a crossover from conventional cubic anisotropy-dominated behavior at higher temperatures to pronounced linewidth broadening and higher-order anisotropy contributions at cryogenic temperatures. With the magnetic field oriented along the [100] crystallographic direction, the resonance is well-captured by fourfold in-plane and out-of-plane uniaxial anisotropies. In contrast, measurements with the field along the [110] direction reveal the presence of an unusually large sixth-order cubic anisotropy term that is symmetry-suppressed for [100] but becomes apparent under this field orientation at ultralow temperatures, indicating a substantial modification of the anisotropy landscape. Independent linewidth analysis shows a pronounced peak near 8 K and a subtle monotonic enhancement with decreasing temperatures below 2 K, features consistent with dissipation mediated by a bath of two-level systems (TLS) arising from antisite defects and localized ${\mathrm{Fe}}^{3+}$ moments. Comparison with TLS-based models demonstrates that both exchange-coupled impurities and nearly free paramagnetic centers contribute to the observed damping. Our results establish LAFO as a model ferrite system where disorder-induced TLS limit spin coherence at ultralow temperatures, providing new insights into anisotropy engineering, magnetic relaxation, and the design of ferrimagnetic insulators for coherent magnonics. These findings offer a framework for future optimization of growth conditions.

The question of the size effects in metal film resistivity is revisited through a systematic analysis of its temperature dependence ${\rho }_f\left(T\right)$ (4–300 K) for increasing layer thickness (4.1–216 nm). Ag-based model thermal-control coatings involving symmetric ZnO/Ag/ZnO interfaces are used as test beds for the Mayadas-Shatzkes model [Phys. Rev. B 1, 1382 (1970)]. All contributions to electron scattering, i.e., intragrain, grain boundaries (GBs) and interfaces, are considered while taking into account the actual film microstructure as determined from x-ray scattering. Encapsulated Ag films are studied as-deposited but also after a recrystallization annealing. The electron reflection coefficient $R$ at GBs and the interface scattering parameter $p$ are deduced from ${\rho }_f\left(T\right)$ fits. They are found to vary with film thickness and microstructure. The grain disorientation seems to drive $R$, which remains below $\sim 0.1$ as expected for a perturbation parameter in the M-S model. In parallel to grain coarsening, the observed increase in $R$ upon annealing is assigned to the most disoriented and healing-resilient GBs. The metal interfaces are found strongly scattering for electrons in as-deposited samples ($p\simeq 0$) but become nearly perfect reflectors after annealing ($p\simeq 1$). But no cleat-cut correlation of $p$ with interface roughness can be evidenced. A tentative explanation based on the electronic structure of the interfaces is proposed. Inconsistent results are obtained with the widespread procedure of thickness dependent resistivity fits, which implicitly assumes constant $R$ and $p$ values. Beside an increased role of intragrain contribution for the thicker films having the larger grains, it is shown that no single scattering mechanism dominates the film resistivity as expected from the implicit breakdown of the Matthiessen rule as derived from the M-S equation.

We use a recently developed machine-learned moment tensor potential (MTP) trained on data generated with the density functional theory and tailored to amorphous silicon coupled with the activation-relaxation technique nouveau (ARTn) to identify and classify two-level systems (TLSs). The samples generated using MTP recover experimental results and provide average structural and dissipative properties similar to those obtained with a modified Stillinger-Weber potential, including radial distribution function, defect concentration, and internal friction. Atomistic details, however, are significantly different, including the density and type of TLS. In particular, we find that while the density of the TLS involving a bond-hopping mechanism is similar for the two potentials, more complex TLSs, such as those involving a Wooten-Winer-Weaire bond exchange, are about twice as common. Analysis also shows that TLSs, for MTP-based models, are mostly isolated and oscillate independently from each other.

The layered 122-type diluted ferromagnetic semiconductor $(\mathrm{Ba},\mathrm{K}){(\mathrm{Zn},\mathrm{Mn})}_2{\mathrm{As}}_2$ has attracted much attention both for its high Curie temperature up to $\sim 230$ K and for the independent control of charge-carrier and spin concentrations through doping K and Mn atoms at the Ba and Zn sites, respectively. In order to unveil the nature of the ferromagnetism in $(\mathrm{Ba},\mathrm{K}){(\mathrm{Zn},\mathrm{Mn})}_2{\mathrm{As}}_2$, its magnetization process has been studied by x-ray magnetic circular dichroism (XMCD) at the Mn $L_{2,3}$ edge in a wide range of temperature and magnetic field. The average magnetization of the Mn atoms as a function of magnetic field ($M\text{–}H$ curves) at various temperatures could be successfully explained by a mixture of paramagnetic (PM), superparamagnetic (SPM), and ferromagnetic (FM) components as previously reported for GaMnAs, revealing the complex nature of the ferromagnetism in $(\mathrm{Ba},\mathrm{K}){(\mathrm{Zn},\mathrm{Mn})}_2{\mathrm{As}}_2$. The average magnetization of the SPM clusters of different sizes and the FM regions were found to be small compared to those in GaMnAs, which we attribute to the antiferromagnetic interaction between nearest-neighbor Mn atoms in $(\mathrm{Ba},\mathrm{K}){(\mathrm{Zn},\mathrm{Mn})}_2{\mathrm{As}}_2$ on the basis of recent theoretical predictions.