Among all-inorganic halide perovskites, the only known ferroelectrics are the family of ${\mathrm{CsGeX}}_3$ (X = Cl, Br, I). Here, we study their ferroelectric domain walls (DWs) and common point defects by density functional theory (DFT) calculations and investigate the interplay between DWs and defects. The most stable defects are ${\mathrm{V}}_{\text{X}}$ and ${\mathrm{V}}_{\text{Cs}}$ and the former shows low migration barriers and high mobility. In contrast to oxide ferroelectrics, the affinity between point defects and DWs is negligible, reflecting the subtle structural distortions at ${\mathrm{CsGeX}}_3$ DWs. Concomitantly, the formation energies and migration energy barriers of ${\mathrm{CsGeX}}_3$ DWs are small compared to oxides, and neither ${\mathrm{V}}_{\text{X}}$ nor ${\mathrm{V}}_{\text{Cs}}$ pin migrating DWs. The band-gap invariance across DWs and the lack of affinity towards intrinsic charged-point defects imply that conducting DWs for nanoelectronics may be challenging to realize in ${\mathrm{CsGeX}}_3$. However, shallow $p$-type defect levels and low-hole effective masses suggest that high $p$-type conductivity may be achievable in nominally ferroelectric ${\mathrm{CsGeX}}_3$. The low DW migration energy barriers and insignificant DW pinning by point defects make ${\mathrm{CsGeX}}_3$ promising materials as robust soft ferroelectrics for high-frequency switching applications with low energy dissipation.

Rotational magnetocaloric effect (RMCE) is achieved by simply rotating magnetic material in a constant magnetic field, offering a simpler and more efficient method for magnetic refrigeration compared to conventional methods. In general, strong magnetic anisotropy is required to obtain sizable RMCE, explaining why in-plane RMCE is rarely observed in thin films due to the usually weak in-plane magnetic anisotropy. In this work, we demonstrate that pronounced in-plane magnetic anisotropy can be achieved by controlling the shape of electronic phase separation ferromagnetic regions in $\mathrm{L}{\mathrm{a}}_{0.425}\mathrm{P}{\mathrm{r}}_{0.2}\mathrm{C}{\mathrm{a}}_{0.375}\mathrm{Mn}{\mathrm{O}}_3$ thin films grown on (001) $\mathrm{NdGa}{\mathrm{O}}_3$ substrates. Isothermal magnetization measurements reveal that the system exhibits an in-plane rotating entropy change $-\mathrm{\Delta }{S}_{\mathrm{rot}}=1.77\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}{\mathrm{K}}^{-1}$ near $T_{\mathrm{C}}\approx 155$ K with relative cooling power of 23.78 $\mathrm{J}\mathrm{k}{\mathrm{g}}^{-1}$. The successful realization of such sizable in-plane RMCE is important for chip-integrated solid-state refrigeration for microelectronic and spintronic platforms.

A better understanding of the mechanisms of vacancy clustering and diffusion in concentrated solid solutions is essential to improve the design of alloys with enhanced radiation tolerance and thermal stability. In this study, the kinetic activation-relaxation technique (kART) was employed to investigate vacancy cluster behavior in FeNiCr CSAs at the atomistic level. By analyzing di-, tri-, and tetravacancy clusters, we reveal that cluster stability increases with size, driven by reduced formation energies, while local chemical composition—particularly Ni's stabilizing effect and Cr's role in enhancing mobility—influences defect evolution. By computing the diffusion barriers and entropic prefactors for more than 700 000 diffusion events, we find that divacancies combine notable stability with substantial mobility, while trivacancies exhibit significant mobility despite reduced stability, enabling efficient defect recombination through short-range migration mechanisms. In contrast, tetravacancies demonstrate greater stability but significantly restricted mobility, influencing localized defect interactions and microstructural evolution. These findings provide fundamental insights into the complex interplay between cluster size and local composition that affect both the enthalpic and entropic contributions to diffusion kinetics, offering a predictive framework for rationally designing alloy compositions to optimize radiation resistance and structural integrity in advanced nuclear and aerospace applications.

The brittleness or ductility of metals has long been attributed to their elastic constants, with a high Poisson ratio, or equivalently, a high Pugh ratio, favoring greater ductility. Growing evidence links ductility with their electronic structure. Consequently, it is desirable to understand how the electronic structure affects the elastic constants. Here, we examine the Ta-W binary alloy system, which evolves from ductile character at Ta-rich compositions to brittleness at high W. We show that a change in slope of the composition-dependent shear modulus near the equiatomic composition coincides with an abrupt change in the Fermi level density of states. We relate the behaviors of the elastic constants to the characters of occupied electronic orbitals close to the Fermi level. Finally, we consider additional alloy systems from groups V and VI and show that qualitatively similar behavior occurs more broadly.

The quasi-one-dimensional diamond spin chain systems have attracted significant research attention for unveiling novel quantum magnetic phenomena driven by low dimensionality and magnetic frustration. Even though several $3d$ transition-metal (TM)-based diamond chain magnets have been studied, rare-earth (RE) counterparts are still rare. Herein, we report a family of rare-earth diamond chain compounds, $\mathrm{NaB}{\mathrm{a}}_3\mathrm{R}{\mathrm{E}}_3\mathrm{S}{\mathrm{i}}_6{\mathrm{O}}_{20}$ ($\mathrm{RE}=\mathrm{Nd}$, Gd-Dy), which crystallize in an orthorhombic structure with the Ama2 space group. The structural analysis reveals that the edge-sharing ${\mathrm{REO}}_8/{\mathrm{REO}}_7$ polyhedra form an infinite diamond chain along the $c$ axis with well separation by the nonmagnetic ${\mathrm{SiO}}_4$ tetrahedra and ${\mathrm{BaO}}_7/{\mathrm{BaO}}_8$ polyhedra perpendicular to the $c$-axis, in which the nearest neighboring (NN) intra-chain RE-RE distance $d_{\mathrm{intra}}\sim 3.818-3.916\AA$ is significantly shorter than the NN inter-chain distance $d_{\mathrm{inter}}\sim 6.471-6.763\AA$. Magnetic measurements indicate no magnetic order down to 1.8 K for all family members. Specific heat characterizations on ${\mathrm{NaBa}}_3{\mathrm{Nd}}_3{\mathrm{Si}}_6{\mathrm{O}}_{20}$ and ${\mathrm{NaBa}}_3{\mathrm{Gd}}_3{\mathrm{Si}}_6{\mathrm{O}}_{20}$ reveal the formation of long-range magnetic order at $T_{\mathrm{N}}\sim 0.20$ K and $T_{\mathrm{N}}\sim 0.42$ K with large spin fluctuations at low temperatures. Furthermore, ${\mathrm{NaBa}}_3{\mathrm{Gd}}_3{\mathrm{Si}}_6{\mathrm{O}}_{20}$ exhibits a large magnetocaloric effect at temperatures below 1 K, making it an attractive candidate for sub-Kelvin magnetic refrigeration. The serial family compounds $\mathrm{NaB}{\mathrm{a}}_3\mathrm{R}{\mathrm{E}}_3\mathrm{S}{\mathrm{i}}_6{\mathrm{O}}_{20}$ provide an ideal platform for exploring novel diamond spin chain physics involving $4f$ electrons.

Chemical composition provides a powerful route to tune the electronic ground state of iron-based superconductors and other quantum materials, yet access to highly doped phases remains limited. Here we demonstrate that high-pressure thermal decomposition of hydrogen-rich precursors enables overhydrogenation of LaFeSi. Using anthracene, we synthesize tetragonal superconducting LaFeSiH, including a single hydrogen site, while ammonia borane yields a structurally distorted overhydrogenated phase, ${\mathrm{LaFeSiH}}_{1+x}$, with an orthorhombic structure. Chemical analysis reveals excess hydrogen ($x\approx$ 0.6), implying a second H site in ${\mathrm{LaFeSiH}}_{1.6}$ whose localization and occupancy are determined by neutron diffraction. In contrast to metallic LaFeSi and superconducting LaFeSiH, orthorhombic ${\mathrm{LaFeSiH}}_{1.6}$ exhibits semiconductorlike behavior. Upon hydrogen release near 100 °C, it transforms into tetragonal superconducting ${\mathrm{LaFeSiH}}_{1+\delta }$ ($\delta \ll 0.6$). These results establish the chemical flexibility of the layered $\mathrm{LaFeSi}X$ ($X$ = H, O, F) family and provide access to a high hydrogen-doping regime, creating new opportunities to investigate superconductivity in Fe-based silicides.

$A$-site-ordered perovskites ($A{A^{\prime }}_3{B}_4{\mathrm{O}}_{12}$) provide a structurally robust platform for exploring correlated-electron behavior, offering unusual opportunities to disentangle the roles of orbital degrees of freedom, bonding interactions, and local structural distortions. In this work, we synthesize a new $A$-site-ordered perovskite $\mathrm{PbC}{\mathrm{u}}_3{\mathrm{V}}_4{\mathrm{O}}_{12}$ under high-pressure and high-temperature conditions and perform comprehensive structural and physical characterizations. $\mathrm{PbC}{\mathrm{u}}_3{\mathrm{V}}_4{\mathrm{O}}_{12}$ crystallizes in the cubic $\mathit{Im}$-3 structure, yet its structural parameters deviate markedly from the established ionic-radius trend in the $A{\mathrm{Cu}}_3{\mathrm{V}}_4{\mathrm{O}}_{12}$ ($A=\mathrm{Mn}$, Cu, Ca) series. This deviation reveals local structural modifications driven by the ${\mathrm{Pb}}^{2+}$ lone-pair electrons. The compound exhibits metallic behavior down to at least 8 K and shows a moderately enhanced Sommerfeld coefficient, with density-functional calculations confirming the associated mass enhancement. Comparison of the experimental and theoretical magnetic susceptibilities further indicates an additional contribution from the Stoner mechanism. These results identify $\mathrm{PbC}{\mathrm{u}}_3{\mathrm{V}}_4{\mathrm{O}}_{12}$ as a rare example of a $3d$-electron metallic vanadate with moderate electronic correlations, demonstrating how $A$-site chemistry and lone-pair-induced local distortions can be used to engineer correlated electronic states in perovskite-related materials.

The investigation of vacancy diffusivity in metallic materials is crucial for advancing predictive models of radiation damage under extreme environmental conditions. In this work, positron annihilation spectroscopy was employed to systematically investigate the formation and diffusion mechanisms of irradiation-induced vacancies in cobalt-free NiFeMnCrAl high-entropy alloys (HEAs) and Ni subjected to 6 MeV proton irradiation. A broad activation energy spectrum for monovacancy migration, from 1.55 to 1.90 eV, is found owing to the lattice distortions and chemical complexity in HEAs. Vacancy clustering, which occurs in pure metals during thermal treatment, is suppressed in the HEAs. A complex energy landscape stems from the chemical diversity, and inherent lattice distortion leads to instability of vacancy clusters, slowing down long-distance defect diffusion – sluggish diffusion – thereby suppressing the formation of large vacancy clusters. This mechanism underpins the pronounced void swelling resistance under irradiation in multiple-component alloy systems.

The strongly correlated oxides with a honeycomb lattice have attracted vast attention due to their interesting magnetic behaviors and emergent quantum effects such as Majorana fermions generated from Kitaev spin liquid. High-quality single crystal samples with delicately controlled composition and strain are highly required in this area. In this work, honeycomb structure built by edge-sharing ${\mathrm{CoO}}_6$ octahedra is stabilized in ilmenite matrix by doping 4% Co into ${\mathrm{NaSbO}}_3$. By performing magnetic measurements and first principles calculations, it is suggested that honeycomb local motifs containing ${\mathrm{Co}}^{2+}$ $\left(3d^7\right)$ cobalt may exist in Co-doped ${\mathrm{NaSbO}}_3$ thin films, and exhibit ferromagnetic-like transition at ∼88 K. Meanwhile, the interlayer dipolar interaction may lead to antiferromagnetic coupling between the nearest layers. This work reveals the possibility to embed $3d^7$ honeycomb structure into an ilmenite matrix and provides a platform for future spin liquid exploration as well as quantum information technology.

Nanoglasses (NGs) consist of amorphous grains joined by glass-glass interfaces (GGIs), yet the atomic-scale mechanisms by which these interfaces control plasticity remain unsettled. Here, we combine molecular dynamics of ${\mathrm{Cu}}_{64}{\mathrm{Zr}}_{36}$ with the activation-relaxation technique to explicitly sample thermally activated events and map the potential-energy landscape of NGs with distinct interfacial geometries. We find that Cu surface segregation in the precursors persists as a diffuse enrichment at the consolidated interfaces, creating regions of local compositional and structural heterogeneity. Spatially resolved activation-energy distributions reveal that these GGIs host a persistent population of low-barrier excitations largely absent from the bulklike cores. While external strain amplifies the low-energy tail of the distribution, the onset of plasticity is dictated by the intrinsic energetic softness of the interfaces. Macroscopically, this preexisting population of soft sites suppresses abrupt shear localization, leading to a curtailed linear regime and distributed deformation. We further show that variations in mechanical response between architectures are governed by the interfacial volume fraction, while the fundamental deformation mechanism remains invariant. These results quantitatively link interfacial structure to the potential-energy landscape, establishing GGIs as preferred nucleation sites for shear transformations and providing a physics-based foundation for tailoring the mechanical response of amorphous alloys.

${\mathrm{Ba}}_4{\mathrm{SbRu}}_3{\mathrm{O}}_{12}$ crystallizes with a structure that consists of clusters of three face-sharing Ru-centered octahedra $\left({\mathrm{Ru}}_3{\mathrm{O}}_{12}\right)$ connected via Sb-centered octahedra. Rietveld refinements of both x-ray and neutron powder diffraction data confirm the absence of Sb/Ru antisite mixing. Variable temperature neutron diffraction measurements reveal a phase transition on cooling below 100 K from the aristotype structure with $R\overline{3}m$ symmetry to a monoclinic structure with $\mathrm{C}2/m$ symmetry. The phase transition is driven by displacements of $\mathrm{B}{\mathrm{a}}^{2+}$ cations and, as such, only subtly perturbs the geometry of the ${\mathrm{Ru}}_3{\mathrm{O}}_{12}$ clusters. The Ru $4d$ orbitals overlap to form delocalized molecular orbitals that span the trioctahedral cluster. At high temperature (T ≥ 200 K), the cluster adopts an $S=3/2$ intermediate spin state, but upon cooling to low temperature, susceptibility data suggest a gradual transition to an $S=1/2$ low spin state. The presence of $\mathrm{S}{\mathrm{b}}^{5+}$ ions with a [Kr] $4d^{10}$ electron configuration minimizes interlayer superexchange interactions between clusters, thereby maintaining the frustration of the 2D triangular network. ${\mathrm{Ba}}_4{\mathrm{SbRu}}_3{\mathrm{O}}_{12}$ shows no signs of magnetic ordering down to 0.3 K, yet Curie-Weiss fitting of high-temperature susceptibility suggests strong antiferromagnetic interactions $({\theta }_{\mathrm{CW}}=-378 \mathrm{K})$. The low-temperature specific heat evolves linearly with temperature, suggestive of a gapless quantum spin liquid. The combination of small magnetic quantum number, minimal chemical disorder, geometric frustration, and lack of long-range magnetic order makes ${\mathrm{Ba}}_4{\mathrm{SbRu}}_3{\mathrm{O}}_{12}$ an intriguing quantum spin liquid candidate that merits further study.

Magnetic compensation in rare-earth iron garnets (REIGs) offers a unique setting in which competing sublattice moments can give rise to non-collinear (canted) magnetic configurations, where the sublattice magnetizations are not aligned with each other or with the external magnetic field. We show that this compensation regime can possibly also host nontrivial magnetic textures. To explore this behavior, we investigated (111)-oriented epitaxial ${\mathrm{Tb}}_3{\mathrm{Fe}}_5{\mathrm{O}}_{12}$/Pt heterostructures across the compensation temperature region using combined transverse magneto-transport and polar Kerr microscopy. Notably, we observe a topological Hall–like signal in the vicinity of the compensation temperature, a feature often interpreted as evidence for skyrmions in the absence of direct imaging. Here, in contrast, complementary Kerr microscopy reveals instead a non-collinear multidomain state which collapses outside the compensation regime, correlating directly with the appearance and disappearance of the spin Hall topological Hall effect (SH-THE) signal. These observations cannot be accounted for by a simple multi-anomalous-Hall-effect model, ruling out common artifacts as the origin, but indicate a topologically nontrivial contribution to the Hall response. These results establish strained REIG films as a tunable platform for exploring topological responses arising from compensation-driven non-collinear ferrimagnetic phases.

Ternary semiconductors with chalcopyrite structure are of growing interest for electronic, energy-conversion, and spintronic applications. Using angle-resolved photoemission spectroscopy, we directly map the band structure of ${\mathrm{CdGeAs}}_2$, the prototypical chalcopyrite described by a modified Kane model that predicts the coexistence of flat bands and highly dispersive linear states. The combined effect of tetragonal distortion and broken inversion symmetry reduces the band degeneracy, allowing us to resolve three distinct states at the top of the valence band, with band velocities comparable to those reported in Dirac semimetals. We further probe the spin-to-charge conversion properties of ${\mathrm{CdGeAs}}_2$ by optically injecting spin-polarized carriers and detecting the resulting inverse spin Hall effect (ISHE). The photon-energy dependence of the ISHE signal and theoretical calculations of the optically injected spin polarization allow us to identify the specific valence-to-conduction transitions responsible for net spin accumulation and to estimate the spin diffusion length. These results demonstrate that chalcopyrite semiconductors provide a versatile platform for optospintronics.

The recent experimental observation of thermal rectification in a graphite Tesla valve suggests a phonon hydrodynamic mechanism beyond linear regime whose physical origin remains yet elusive. Here we uncover the correlation between nonreciprocal heat transfer and nonlinear phonon hydrodynamics by directly solving the nonlinear phonon Boltzmann transport equation with first-principles input. Pronounced thermal rectification and an unexpected crossover are unveiled in a prototypical asymmetric graphite ribbon. We reveal two underlying nonlinear effects including large phonon drift velocity and temperature-dependent phonon scattering rates which are dominant in hydrodynamic and diffusive regimes, respectively. Furthermore, the crossover behavior in graphite is shown to be governed by the competition between collective phonon drift and phonon excitation. This work thus establishes a theoretical framework for nonreciprocal phonon heat transport in nonlinear hydrodynamic regime and offers guidance for future theoretical and experimental studies on thermal functional devices based on collective phonon flow.

Improving the spin mixing conductance at the ferromagnet/heavy metal (FM/HM) interface with a low Gilbert damping constant in the FM layer is a key requirement for developing efficient spintronic devices. To evaluate the potential of ${\mathrm{Co}}_2\mathrm{Fe}{\mathrm{Ga}}_{0.5}{\mathrm{Ge}}_{0.5}$ as the FM layers in such structures, epitaxial ${\mathrm{Co}}_2\mathrm{Fe}{\mathrm{Ga}}_{0.5}{\mathrm{Ge}}_{0.5}$ single-layer and ${\mathrm{Co}}_2\mathrm{Fe}{\mathrm{Ga}}_{0.5}{\mathrm{Ge}}_{0.5}/\mathrm{Pt}$ bilayer films were deposited on MgO substrates using magnetron sputtering, and their Gilbert damping constants were evaluated from ferromagnetic resonance spectra. While the single-layer samples exhibit a low damping constant of $\sim 1.07\times {10}^{-3}$, an enhancement in the damping constant was observed in the bilayer samples due to spin pumping across the ${\mathrm{Co}}_2\mathrm{Fe}{\mathrm{Ga}}_{0.5}{\mathrm{Ge}}_{0.5}/\mathrm{Pt}$ interface, from which relatively large spin mixing conductance ($g_{\mathrm{eff}}^{\uparrow \downarrow }$) of $\left(2.78\pm 0.09\right)\times {10}^{19}{\mathrm{m}}^{-2}$ was evaluated. Further, to investigate the effect of interface property on $g_{\mathrm{eff}}^{\uparrow \downarrow }$, ultrathin ($\sim 0.2$ nm) Cu, Ni, Ru, Ta, or Cr insertion layers were introduced between the ${\mathrm{Co}}_2\mathrm{Fe}{\mathrm{Ga}}_{0.5}{\mathrm{Ge}}_{0.5}$ and Pt. Inserting a nonmagnetic (NM) Cu layer results in a pronounced decrease of $g_{\text{eff}}^{\uparrow \downarrow }$, whereas the FM Ni layer leaves $g_{\text{eff}}^{\uparrow \downarrow }$ nearly unchanged. In the case of Ru and Ta insertion layers, a modest reduction in $g_{\text{eff}}^{\uparrow \downarrow }$ is observed despite their NM nature. The antiferromagnetic Cr insertion layer also causes a small decrease in $g_{\text{eff}}^{\uparrow \downarrow }$. The observed change in $g_{\mathrm{eff}}^{\uparrow \downarrow }$ depends on the insertion material, indicating that their physical properties, such as magnetic, nonmagnetic, antiferromagnetic, light or heavy metal, reflect on $g_{\mathrm{eff}}^{\uparrow \downarrow }$.