Motivated by recent experimental breakthroughs in mixed-anion solid-state Li-ion electrolytes [Z. Liu et al., Nat. Chem. 16, 1584 (2024); F. Zhao et al., Science 390, 199 (2025)], we propose a previously unexplored mixed-halide rare-earth Na-ion solid electrolyte, ${\mathrm{Na}}_3{\mathrm{GdCl}}_4{\mathrm{Br}}_2$ (NGCB), and systematically establish its structure-transport-stability relationships using density functional theory, ab initio molecular dynamics, and grand-potential phase diagram analysis. Our computational simulations suggest that NGCB is stable dynamically, thermally, thermodynamically, and mechanically, with a wide electronic band gap of 5.73 eV and a broad electrochemical stability window of 0.57–3.65 V. Moreover, we reveal that anion mixing in NGCB generates tetrahedral anion vacancies that percolate into continuous low-barrier tetrahedral-tetrahedral $\mathrm{N}{\mathrm{a}}^{+}$ migration networks. Consequently, NGCB exhibits a high room-temperature ionic conductivity of 5.05 $\mathrm{mS}\mathrm{c}{\mathrm{m}}^{-1}$ with a low activation energy of 0.23 eV, supported by low migration barriers of 0.38–0.46 eV in two-dimensional channels and 0.40–0.45 eV in three-dimensional channels. Beyond fast ion transport, we show that anion mixing simultaneously enhances interfacial electrochemical compatibility. NGCB displays low interfacial reaction energies with high-voltage cathodes, reaching −32 $\mathrm{meV}\mathrm{ato}{\mathrm{m}}^{-1}$ with ${\mathrm{Na}}_3{\mathrm{V}}_2{\mathrm{P}}_2{\mathrm{O}}_8{\mathrm{F}}_3$. These results demonstrate a clear advantage of mixed-anion sodium solid-state electrolytes over conventional single-anion halides.

Despite extensive research on pearlite formation, the rate-controlling mechanisms of pearlite growth remain under debate. Phase field modeling has become a key tool for investigating such transformations; however, in solid-state systems where diffusion occurs both within individual phases and along their interfaces, the commonly assumed local-equilibrium boundary conditions are rarely satisfied, leading to artificial interface effects in conventional diagonal formulations. Here, we present a thermodynamically consistent nondiagonal three-phase field model formulated within the grand-potential framework to investigate pearlite growth. By introducing an Onsager-symmetric cross-coupling term between conserved and nonconserved order parameters, the model inherently recovers the correct equilibrium boundary conditions regardless of the active diffusion pathways, including bulk diffusion and interfacial diffusion. We systematically analyze four diffusion scenarios: (i) diffusion in austenite; (ii) diffusion in austenite, ferrite, and cementite; (iii) diffusion in austenite and ferrite; and (iv) diffusion in austenite combined with interfacial diffusion along austenite/ferrite and austenite/cementite boundaries. The model's quantitative performance is benchmarked against available analytical solutions for each case. Overall, the proposed framework provides a robust and thermodynamically sound approach for elucidating how different diffusion pathways control pearlite growth kinetics.

Functionalization of 2D materials and of transition metal dichalcogenides (TMDs) in particular is central for next generation devices and other applications. Here we study the effect of calcium dosing on the surfaces of clean ${\mathrm{WSe}}_2$ and ${\mathrm{WS}}_2$ in ultrahigh vacuum by x-ray photoelectron spectroscopy, low energy electron diffraction, and scanning electron microscopy. We find that Ca reacts with the chalcogens to ${\mathrm{CaSe}}_x$ or ${\mathrm{CaS}}_x$ and reduces the remaining tungsten. Ca forms an overlayer on top and causes an outdiffusion of the chalcogen. The overlayer oxidizes easily. We obtained detailed understanding of the interactions of archetypal TMD with an abundant alkali-earth element, which expands our knowledge of metal-surface interactions and of surface manipulation of 2D materials.

Two-dimensional pentagonal materials have recently emerged as a promising platform for exploring novel magnetic phenomena. Using first-principles calculations, we systematically investigate the strain-tunable optical and magnetic properties of $\mathrm{penta}\text{−}{\mathrm{FeS}}_2$ monolayer. Our results reveal that the system stabilizes into a distinct stripy-AFM ground state under ambient conditions. This ordering is driven by strong magnetic frustration originating from the dominant third-nearest-neighbor antiferromagnetic exchange interaction $\left(\right|J_3|\gg |J_1\left|\right)$. Furthermore, biaxial strain serves as a robust knob to tune these properties. Tensile strain induces a semiconductor-metal transition, where the emergence of itinerant electrons creates a screening effect that weakens the long-range exchange interaction, triggering a phase transition from stripy-AFM to Néel-AFM. In contrast, compressive strain preserves the semiconducting gap while enhancing the interorbital hybridization. Additionally, tensile strain promotes a spin reorientation transition from in-plane to out-of-plane. Our work demonstrates the microscopic interplay among lattice geometry, electronic screening, and magnetism in $\mathrm{penta}\text{−}{\mathrm{FeS}}_2$, positioning it as a versatile candidate for magneto-optoelectronic applications.

We investigated the electronic properties of $RE{\mathrm{Ru}}_6{\mathrm{As}}_4(RE=\mathrm{La}, \mathrm{Ce}, \mathrm{Sm}, \text{and} \mathrm{Yb})$ using single-crystalline samples grown by the Bi-flux method. These compounds crystallize in the noncentrosymmetric hexagonal ${\mathrm{LiCo}}_6{\mathrm{P}}_4$-type structure, featuring chain-like and triangular arrangements of magnetic $RE$ ions. From the electrical resistivity, magnetic susceptibility, and specific heat measurements, we have found that ${\mathrm{SmRu}}_6{\mathrm{As}}_4$ and ${\mathrm{YbRu}}_6{\mathrm{As}}_4$ order antiferromagnetically below the Néel temperature of 1.5 and 9.5 K, respectively. Despite the relatively high transition temperature of ${\mathrm{YbRu}}_6{\mathrm{As}}_4$, its magnetic field-temperature phase diagram reveals that the antiferromagnetic state collapses at a low field of ${\mu }_0{H}_{\mathrm{c}}=1.7\mathrm{T}$, accompanied by an unusual nonlinear magnetization. The small critical field and characteristic magnetization curve in ${\mathrm{YbRu}}_6{\mathrm{As}}_4$ suggest an important role of competing interactions associated with magnetic frustration.

This study employed first-principles calculations to investigate the thermoelectric transport properties of the KXSb $(X=\mathrm{Ge},\mathrm{Sn},\mathrm{Pb})$ series compounds. Both the harmonic approximation (HA) and self-consistent phonon (SCP) theory were adopted, incorporating multiple phonon scattering mechanisms and spin-orbit coupling (SOC) effects. The results reveal that the chemical bonding characteristics and mechanical properties evolve systematically with increasing atomic number of X. The KXSb series exhibits pronounced lattice anharmonicity. As the atomic mass increases, the phonon spectrum progressively flattens, which, through multiple mechanisms, leads to ultralow lattice thermal conductivity. Three-phonon scattering is identified as the dominant mechanism suppressing lattice thermal conductivity, while four-phonon scattering provides an important additional contribution. In terms of electronic transport, SOC induces significant spin splitting in the band structure, substantially affecting the thermoelectric quality factor. An anomalous sign reversal of the Seebeck coefficient is observed in electrical transport, which originates from the bipolar transport effect associated with the narrow band gap and band anisotropy. Furthermore, the electrical transport performance under $n$-type doping is generally superior to that under $p$-type doping. As a consequence of these combined effects, the KXSb series exhibits excellent thermoelectric performance, with KSnSb achieving a maximum ZT of approximately 3.77 at 800 K.

The ability to minimize low-temperature acoustic loss in amorphous materials would have implications in fields as wide-ranging as gravitational wave detection and quantum computing. In this paper, we measure the internal friction between $300\mathrm{mK}$ and room temperature of several thin silica films deposited by ion beam sputtering onto ultra-high-$Q$ silicon resonators. The measurements reveal internal configurations of as-deposited films that are markedly different from that of bulk silica. Over a broad temperature range, the films' internal frictions differ from one another by a factor of two; by contrast, a review shows that sub-MHz internal friction measurements of bulk silica fall within a 35% band with a pronounced main absorption peak between $20\mathrm{K}$ and $40\mathrm{K}$. This peak is absent in the films presented here, except for one film that had been annealed at $900{}^{\circ }\mathrm{C}$. Annealing at $500{}^{\circ }\mathrm{C}$ erased the thermal histories of the other thin films to create internal friction values that are consistent from film-to-film but yet still markedly different from those of the bulk below $100\mathrm{K}$, while creating the steep bulk-like drop-off above $100\mathrm{K}$ that the as-deposited films lacked. In the context of theoretical structural modeling, our results suggest that exposure to temperatures of at least $900{}^{\circ }\mathrm{C}$ is needed to form the network of tetrahedra considered characteristic of amorphous silica. The present measurements, especially when compared alongside previous work, appear to show that these structures are suppressed in many thin film preparations. These measurements also show, for as-deposited films, an excess of excitations in the 0.15–$0.3\mathrm{eV}$ range which can be annealed away to bring about the $Q^{-1}$ drop-off above the main absorption peak. The shear moduli of all the films are qualitatively similar to bulk silica, with a positive temperature coefficient above a minimum near $60\mathrm{K}$ and a negative temperature coefficient below.

The discovery of novel carbon allotropes—from fullerenes and nanotubes to graphene—has greatly advanced contemporary materials research. Beyond conventional atomic crystals, superatomic solids provide an attractive platform for exploring structure-property relationships arising from their unique hierarchical architectures. Here, using state-of-the-art first-principles calculations, we propose a three-dimensional (3D) diamond-like fullerene (${\mathrm{C}}_{60}$) phase, dubbed fullerdiamond (FLD), constructed by substituting each carbon atom in diamond with a ${\mathrm{C}}_{60}$ superatom, where each ${\mathrm{C}}_{60}$ covalently connects to its four neighbors via four 66/66 [2+2] cycloadditions. Our calculations reveal that FLD is structurally stable, with the lowest density (1.098 $\mathrm{g}/{\mathrm{cm}}^3$) among diamond-type structures and anisotropic Young's moduli of $50.91\sim 85.35$ GPa. Its electronic structure exhibits a sizable indirect band gap of 1.83 eV and two distinctive features: (i) an accidental pseudo-Dirac cone (∼57 meV gap) in the conduction band arising from antibonding coupling between LUMO states of neighboring ${\mathrm{C}}_{60}$ superatoms, and (ii) a narrow flat band (∼104 meV) in the valence band. Moreover, a tensile strain of ∼3% along the [100] direction weakens the antibonding orbital coupling between neighboring ${\mathrm{C}}_{60}$ superatoms through elongation of the inter-cage [2+2] cycloaddition bonds, reducing the accidental pseudo-Dirac gap to ∼4 meV and narrowing the flat band width to ∼88 meV. This strain-tunable electronic behavior—arising from the sensitivity of inter-${\mathrm{C}}_{60}$ orbital coupling to lattice deformation—establishes a conceptual bridge between fullerene molecular physics and diamond-like 3D superatomic solid physics. Our findings highlight FLD as a promising platform for tuning electronic and optical properties in lightweight carbon-based materials.

A rod with rounded ends is a noteworthy morphology, naturally encountered from large-scale roots to cells, and synthetically conceived down to nanomaterials. Rod-shaped anisotropic nanocrystals—especially those grown on pre-synthesized spherical seeds—play a major role in areas as different as photonics, cancer therapy, and photocatalysis. Nonetheless, despite decades of intense research, the anisotropic growth laws of nanorods (NRs) remain elusive. Here, we propose a general two-surface tension thermodynamic model that allows determining these axial and radial NR growth rates by reaction and diffusion. Depending on the initial seed size, three growth modes are predicted: either 3d, where both length and diameter grow simultaneously, 1d, where NRs just grow in one direction, and 1d-3d, showing the two growth modes sequentially. Modeling also shows that NRs lengthening and widening are driven by the surface tension ratio between the cylindrical core and the hemispherical tips. The confrontation of this model with kinetics data published on both high-symmetry face-centered-cubic (FCC) and lower-symmetry hexagonal close-packed (HCP) Wurtzite nanocrystals, as well as new experiments on Wurtzite CdSe-CdS NRs, confirms the existence of these three growth modes under reaction-limited conditions. From a practical point of view, they enable the determination of the axial/radial kinetic reaction rates along with surface tensions, and experimentally predict the seed-dependent growth and morphology of the NRs beyond the already well-established synthetic strategies for targeted applications. Finally, the few data published on the growth of Smectic A ligaments in the isotropic phase after a quench in temperature show a qualitative agreement with behaviors expected from a two-surface tension diffusion-limited mechanism.

${\mathrm{Th}}_2{\mathrm{Zn}}_{17}\text{−}\mathrm{type}$ structure-based permanent magnets, such as ${\mathrm{Sm}}_2{\mathrm{Fe}}_{17}{\mathrm{N}}_3$, offer strong potential as alternatives to neodymium magnets (NdFeB), but their practical use is limited by phase stability and the scarcity of Sm. Ce-based counterparts, particularly ${\mathrm{Ce}}_2{\mathrm{Fe}}_{17}{\mathrm{N}}_3$, are attractive low-cost candidates, yet their intrinsic planar magnetic anisotropy restricts permanent-magnet performance. Here, we induce uniaxial magnetic anisotropy in ${\mathrm{Ce}}_2{\mathrm{Fe}}_{17}{\mathrm{N}}_3$ through two approaches: (i) Co substitution on the Fe sublattice and (ii) partial substitution of Ce with Sm. Combined density functional theory and experimental results show that both strategies modify the $3d\text{–}4f$ interactions and band filling, yielding magnetization values up to $\sim 1.2\mathrm{T}$ and magnetocrystalline anisotropy energies exceeding $1\mathrm{MJ}/{\mathrm{m}}^3$ for Co-alloyed compositions, with significantly larger anisotropy achieved upon Sm substitution. In addition, the Sm-substituted ${\mathrm{Ce}}_2{\mathrm{Fe}}_{17}{\mathrm{N}}_3$ samples exhibit enhanced high-temperature stability compared to ${\mathrm{Sm}}_2{\mathrm{Fe}}_{17}{\mathrm{N}}_3$. These findings demonstrate that ${\mathrm{Ce}}_2{\mathrm{Fe}}_{17}{\mathrm{N}}_3$-based alloys can deliver magnetic performance suitable for permanent-magnet applications while reducing cost and reliance on critical rare-earth elements, and they provide practical design guidelines for rare-earth-lean magnets for energy and industrial applications.

We explore the intriguing topological itinerant magnet ${\mathrm{MgMn}}_6{\mathrm{Sn}}_6$, characterized by bilayer kagome Mn layers encasing a hexagonal Sn layer. Using ab initio density functional theory and dynamical mean-field theory calculations, we uncover the complex electronic properties and many-body configuration of its magnetic ground state. This frustrated many-body state stabilizes the ferromagnetic ground-state sector, providing the time-reversal–symmetry-broken background required for the nontrivial electronic structure. Consequently, the exchange-split topological bands and associated Berry-curvature response are intrinsically linked to the magnetic ground state. Our band dispersion calculations reveal a mirror symmetry-protected nodal line in the $k_z$ = 0 plane. When spin-orbit coupling is introduced, a gap is formed along the nodal line due to broken time-reversal symmetry with magnetic ordering, leading to substantial intrinsic Berry curvature. We identify Dirac fermions, van Hove singularities, and a flat band near the Fermi energy $\left(E_F\right)$, with spin-orbit coupling introducing a finite gap at key points. The unique proximity of the flat band to $E_F$ suggests potential instabilities. Spin-orbit coupling opens a 10 meV gap at the point of contact between the quadratic and flat bands, bestowing a nonzero ${\mathbb{Z}}_2$ invariant. This leads to a significant spin Hall conductivity. Despite the presence of large incoherent scattering due to electronic interactions, band crossings and flat band features persist at finite temperatures since the scattering does not impact these features near $E_F$. ${\mathrm{MgMn}}_6{\mathrm{Sn}}_6$ exhibits intriguing topological and magnetic properties, with promising applications in spintronics.

We report investigations into a new kind of multiferroic heterostructure consisting of a two-dimensional ferromagnetic 1T-phase ${\mathrm{FeCl}}_2$ monolayer and a sliding-ferroelectric bilayer-GaSe using first principles calculations. In this study, we determine the structural and electronic properties, energy band alignments, magnetic anisotropy, binding energies, interfacial charge transfer, and electric dipole moments of different stackings of $1\mathrm{T}\text{−}{\mathrm{FeCl}}_2/\mathrm{bilayer}\text{−}\mathrm{GaSe}$. The generalized gradient approximation of the Perdew–Burke–Ernzerhof (GGA-PBE) and Heyd-Scuseria-Ernzerhof (HSE) functionals predict half-metallicity, while the regularized-restored strongly constrained and appropriately normed (${\mathrm{r}}^2\mathrm{SCAN}$) functional opens a band gap in the spin-down Fe $3d$ states upon releasing symmetry constraints. The total magnetic moment of the ${\mathrm{Fe}}^{2+}$ ion (4.00 ${\mu }_B$) remains unchanged in the heterostructures for both polarization directions. The magnetic anisotropy energy of all stacking configurations considered indicates an in-plane easy magnetization axis, arising from the Fe-$d_{xz}$ orbitals under both polarization directions. All stackings exhibit Ohmic-type electrical conductivity, indicating charge transfer across the interfaces. Hence, this study presents a theoretical framework for designing artificial multiferroics that simultaneously maintain both ferromagnetic and ferroelectric properties, enabling future technological developments.

We report the epitaxial stabilization of GdAuSb films and GdAuSb/LaAuSb superlattices via molecular beam epitaxy on (0001)-oriented ${\mathrm{Al}}_2{\mathrm{O}}_3$ substrates. GdAuSb crystallizes in the Au-Au dimerized YPtAs structure type (space group $P{6}_3/mmc$), the same structure as the Dirac semimetal LaAuSb. Angle-resolved photoemission spectroscopy (ARPES) measurements show similar near $E_F$ bandstructures for GdAuSb and LaAuSb, plus a rigid band shift for GdAuSb toward more holelike behavior and corelike Gd $4f$ states $\sim 9\mathrm{eV}$ below the Fermi energy. LaAuSb/GdAuSb superlattices exhibit sharp superlattice fringes by x-ray diffraction and atomically precise interfaces by scanning transmission electron microscopy. Superlattices display two transitions in temperature-dependent resistvity, compared to a single Néel temperature for thick GdAuSb films. Superlattices of $Ln\mathrm{AuSb}$ materials ($Ln=$ rare earth) with atomically abrupt interfaces offer an epitaxial platform for control of magnetic and topological order via tunable intralayer exchange and reduced dimensionality.

Single crystals of the ternary transition metal silicide ${\mathrm{Zr}}_2{\mathrm{Ru}}_3{\mathrm{Si}}_4$ were successfully grown using flux method, and their superconducting properties were systematically investigated. ${\mathrm{Zr}}_2{\mathrm{Ru}}_3{\mathrm{Si}}_4$ crystallizes in a monoclinic structure featuring a quasi-one-dimensional structural framework. Electrical resistivity, magnetic susceptibility, and specific-heat measurements reveal bulk superconductivity with a transition temperature $T_c$ of 5.0 K. The temperature dependence of the upper critical field exhibits nearly isotropic behavior for different field orientations, indicating weak anisotropy in the superconducting state. Analysis of specific-heat data suggests a fully gapped $s$-wave superconducting order parameter. The electron-phonon coupling constant estimated from the McMillan equation indicates moderately strong coupling. Additional superconducting parameters, including the coherence length, penetration depth, and Ginzburg-Landau parameter, confirm that ${\mathrm{Zr}}_2{\mathrm{Ru}}_3{\mathrm{Si}}_4$ is a type-II superconductor in the dirty limit. These results provide detailed experimental insight into the superconducting behavior of single-crystalline ${\mathrm{Zr}}_2{\mathrm{Ru}}_3{\mathrm{Si}}_4$ and offer a valuable experimental basis for future studies of its electronic band structure and the potential interplay between superconductivity and the predicted nontrivial topological electronic states.

Oxygen vacancies are critical for determining the electrochemical performance of fast oxygen ion conductors. The perovskite ${\mathrm{La}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{CoO}}_3$, known for its excellent mixed ionic-electronic conduction, has attracted significant attention due to its favorable vacancy characteristics. In this study, we employ first-principles calculations to systematically investigate the impact of $3d$ transition-metal doping on the oxygen vacancy formation energies in the perovskite. Two magnetic states, namely the ferromagnetic and paramagnetic states, are considered in our models to capture the influence of magnetic effects on oxygen vacancy energetics. Our results reveal that the oxygen vacancy formation energies are strongly dependent on both the dopant species and the magnetic state. Notably, the magnetic states alter the vacancy formation energy in a dopant-specific manner due to double exchange interactions, indicating that relying solely on the ferromagnetic ground state may result in misleading trends in doping behavior. These findings emphasize the importance of accounting for magnetic effects when investigating oxygen vacancy properties in perovskite oxides.

${\mathrm{Sr}}_2{\mathrm{IrO}}_4$ (Sr214) and related iridates have emerged as key platforms for fundamental correlated-electron physics and for potential applications such as magnonics. Here, we report the epitaxial growth of high-quality Sr214 thin films using reactive off-axis sputtering. Conventional pulsed-laser deposition of Sr214 suffers from limitations arising from the volatility and decomposition of iridates, which often result in parasitic Ruddlesden–Popper phases and iridium vacancies. By employing sputtering, we mitigate these issues and achieve stable growth conditions that allow precise mapping of the phase diagram. Systematic variation of the growth temperature reveals that Sr214 stabilizes within a window between $825{}^{\circ }\mathrm{C}$ and $1050{}^{\circ }\mathrm{C}$, with optimal crystallinity and thickness obtained at $840{}^{\circ }\mathrm{C}$. Raman spectroscopy provides sensitive diagnostics of iridium vacancies, with defect-induced phonon modes and peak intensity ratios correlating strongly with the $c$-axis lattice parameter. Our results establish reactive sputtering as a robust route for integrating Sr214 into oxide electronic and magnonic device architectures.

The magnetic material ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ (MBT) has garnered significant attention due to its unique combination of long-range antiferromagnetism and nontrivial topological electronic properties. However, experimental measurements report inconsistent magnetizations, which could be attributed to a variety of intrinsic defects. To date, a comprehensive investigation of defect-engineered MBT systems has not yet been established. Employing state-of-the-art $abinitio$ techniques, this work systematically investigates the influence of various experimentally reported defects on the magnetic properties of bulk and monolayer MBT at different concentrations. Mn-vacancy and Mn-rich defects are found to enhance the ferromagnetism of bulk MBT. The investigation of Mn-rich and intermixing defects in the monolayer reveals that subtle structural and electronic modifications can alter the magnetic coupling. Projection onto a Heisenberg Hamiltonian demonstrates that defects modify exchange interactions, thereby giving rise to distinct magnetic ground states. This work sheds light on magnetic coupling mechanisms and provides guidelines for the experimental control of magnetism in ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$.

The magnetic damping of spin-pumping heterostructures consisting of Pt and ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$ (Permalloy, Py) thin films is studied via temperature- and frequency-dependent ferromagnetic resonance (FMR). Additional magnetic and structural characterization is done by transmission electron microscopy (TEM), x-ray absorption spectroscopy, and x-ray magnetic circular dichroism (XMCD). The frequency-dependence of the FMR linewidth allows to extract the Gilbert damping parameter $\alpha$ as a function of temperature. Py in direct contact with Pt exhibits a strong enhancement of $\alpha \left(T\right)$, and the dependence on the thickness of the Py layer suggests this to be an interfacial effect. The enhanced $\alpha \left(T\right)$ is accompanied by an induced magnetic polarization of the Pt as evidenced by XMCD, while the other magnetic properties of Py as measured with FMR and static magnetometry remain virtually unchanged. The increase of $\alpha \left(T\right)$ can be efficiently suppressed by the insertion of an Al-spacer layer between Pt and Py as thin as 1 nm, which coincides with the loss of the magnetic polarization of Pt.