We compute the thermodynamic phase diagram of 17 elemental metals with hexagonal-close-packed (hcp), face-centered-cubic (fcc), and body-centered-cubic (bcc) crystal structures using finite-temperature density functional theory. Helmholtz free-energy differences between competing hcp, fcc, and bcc phases are evaluated as functions of electronic temperature up to 7 eV, allowing us to identify solid-solid phase transitions driven by electronic entropy. The systems studied include Zr, Ti, Cd, Zn, Co, and Mg (hcp); Ni, Cu, Ag, Al, Pt, and Pb (fcc); and Cr, W, V, Nb, and Mo (bcc) in their ground-state structures. From the free-energy crossings, we extract the transition electronic temperatures and analyze systematic trends across the metallic systems. We found that all the studied systems go through one or two solid-solid phase transitions caused purely by electronic entropy except Mg and Pb. Our results establish electronic entropy as a key factor governing structural stability in metals under strong electronic excitation.

While intrinsic two-dimensional (2D) ferromagnetic (FM) materials hold great promise for spintronic applications, external control over both electrical and magnetic properties is crucial. Here, we demonstrate effective modulation of electronic and magnetic characteristics of ${\mathrm{Cr}}_2{\mathrm{Si}}_2{\mathrm{Te}}_6$ (CST) through ionic liquid gating (ILG). Upon electron doping via ILG, CST undergoes a semiconductor-to-metal transition, accompanied by remarkable enhancements in Curie temperature ($T_{\mathrm{c}}$, from 33 K to 110 K) and coercive field ($H_{\mathrm{c}}$, from 1.4 mT to 50 mT). Moreover, under high doping levels, the magnetic easy axis can be electrically switched from the out-of-plane to the in-plane direction. Theoretical calculations suggest a possible scenario in which electron doping strengthens FM coupling through a double-exchange mechanism between mixed-valence Cr ions, thereby boosting $T_{\mathrm{c}}$. These findings highlight ILG as a versatile strategy for tailoring magnetism in 2D ferromagnets and offering pathways for next-generation spintronic devices.

Comprehensive study using DC transport, specific heat, magnetization, and two-coil mutual inductance measurements unveils an understanding of three temperature regimes in $\mathrm{Sm}{\mathrm{B}}_6$: (i) $T\ge T^{*}$ ($\sim 62\mathrm{K}$), (ii) $T_g (\sim 23\mathrm{K})\le T<T^{*}$, and (iii) $T<T_g$. Onset of Kondo breakdown below $T^{*}$ releases disorder-driven magnetic fluctuations, which splits the bulk ($\sim 116\mathrm{K}$) and surface Kondo temperature ($T_k^s\approx$ 7 K). Below $T_g$, as magnetic fluctuations subside, surface Kondo screening revives, stabilizing the topological surface state and generating an in-gap feature ($\sim 2.2\mathrm{meV}$) across which Dirac-like carriers are excited. Nyquist impedance analysis reveals a crossover from purely capacitive to capacitive-inductive behavior, signalling a disorder-driven two-fluid phase of heavy quasiparticles and light, high-mobility carriers below $T_g$. We identify a characteristic length scale, ${\mathcal{L}}_{{\nu }_0}\left(T\right)$, associated with the high-mobility phase, exhibiting an almost divergent trend below $T_k^s$. These findings underscore the complex nature of surface conducting state in $\mathrm{Sm}{\mathrm{B}}_6$.

We investigate the effects of W incorporation into Cu-Zr thin film metallic glasses using molecular dynamics (MD) simulations combined with magnetron sputtering. All studies are carried out in the whole range of W concentrations (0 to 100 at.%) and the MD studies also in a wide range of incident energies (1 to 500 eV) and deposition angles (0 to ${60}^{\circ }$). Calculated x-ray diffractograms, packing factor, short-range order (bonding fractions and coordination numbers), medium-range order (network ring and common neighbor statistics), and stress are correlated with measured x-ray diffractograms and technologically important properties (hardness, hardness/Young's modulus ratio, and elastic recovery). The simulations explain the experimental results at the atomic level and provide a lot of information that is not available experimentally. Special attention is paid to nonmonotonic dependencies on the elemental composition and incident energy. Collectively, the results explain the role of W in modifying the structure and improving the mechanical properties of Cu-Zr metallic glasses, predict optimum compositions which maximize some of these properties, and contribute to the development of advanced materials for various applications.

Using molecular dynamics simulations, we show that a widely accepted theoretical prediction for glassy-polymeric strain-hardening moduli ($G_R\propto {\rho }_e$, where ${\rho }_e$ is the entanglement density) fails badly for semiflexible polymers. By postulating that the length, energy, and strain scales controlling $G_R$ are the Kuhn length ${\ell }_K$ and statistical-segment length $b=\sqrt{{\ell }_0{\ell }_K}$ (where ${\ell }_0$ is the backbone bond length), the intermonomer binding energy $u_0$, and the incremental elastic strain ${\mathcal{S}}_{\mathrm{c}}$ required to activate Kuhn-segment-scale plastic rearrangements, we develop a scaling theory predicting that $G_R={\mathcal{S}}_{\mathrm{c}}(u_0/{\ell }_0^3){(b/{\ell }_0)}^3$ in the athermal limit. This prediction agrees quantitatively with the simulated $G_R$ values for athermal uniaxial-stress extension, and semiquantitatively with the values for athermal constant-volume simple shear, for bead-spring polymer glasses spanning a range of ${\ell }_K/{\ell }_0$ that is wider than the range spanned by real systems.

Carbon exhibits both a layered ground-state structure that produces two-dimensional (2D) nanosheets and a nonlayered diamond structure created under high pressure conditions. Motivated by this metastability relationship, we revisit the ground state structure of metal dichalcogenides that are known to have a nonlayered pyrite-type structure. Ultrathin films of pyrite-type ${\mathrm{ZnSe}}_2$ spontaneously transform into a layered phase. This phase is identified as a ground state, and the monolayer exhibits strong elastic anisotropy and a semiconducting bandgap larger than that of the pyrite phase by a factor of two. We demonstrate that a two-valued but directional potential energy surface exists along a Bain-like distortion path, hiding the layered ground state. This work implies that many 2D materials are hidden in nonlayered materials and connects 2D materials science with surface and high-pressure science.

Intermetallic nuclear fuel materials, in particular the uranium alloyed with Zr, Mo, Nb, Ti, offer superior swelling, fabrication, and fuel-cladding chemical reaction properties, among others. However, similar to pure $\alpha$-uranium, the alloyed uranium compositions exhibit susceptibility to a charge-density-wave (CDW) instability at low temperatures, which has rarely been investigated in detail. Here, we unequivocally experimentally identify CDW instability in ${\gamma }^{\prime }\text{−}{\mathrm{U}}_2\mathrm{Mo}$ using diffraction and heat capacity measurements on hitherto unreported single-phase ${\gamma }^{\prime }\text{−}{\mathrm{U}}_2\mathrm{Mo}$. We find that ${\gamma }^{\prime }\text{−}{\mathrm{U}}_2\mathrm{Mo}$ undergoes phase transformation from ordered intermetallic tetragonal ($I4/mmm$) phase to monoclinic symmetry ($C2/c$) below $T_{\mathrm{CDW}}\sim 200\mathrm{K}$, which remains stable at least up to 10 K. Ab initio molecular dynamics simulations confirm the CDW instability, and the CDW phase is determined. A detailed analysis of electronic structures and the real and imaginary parts of electronic susceptibility suggests the role of Fermi-surface nesting and hidden nesting leading to phonon instabilities that induce the CDW distortion. Our results emphasize the need for careful investigation of low-temperature CDW instability in other single-phase intermetallic nuclear fuels.

Cerium diantimonide (${\mathrm{CeSb}}_2$) is a layered heavy-fermion Kondo lattice material that hosts complex magnetism and pressure-induced superconductivity. The interpretation of its in-plane anisotropy has remained unsettled due to structural twinning, which superimposes orthogonal magnetic responses. Here we combine controlled crystal growth with magnetization and rotational magnetometry to disentangle the effects of twinning. Nearly untwinned high-quality single crystals reveal the intrinsic in-plane anisotropy: The in-plane easy axis saturates at $M_{\text{easy}}\left(4\text{T}\right)\approx 1.8{\mu }_{\text{B}}/\mathrm{Ce}$, while the in-plane hard axis magnetization is strongly suppressed, nearly linear, and comparable to the out-of-plane response. These results resolve long-standing discrepancies in reported magnetic measurements, in which in-plane metamagnetic transition fields and saturation magnetization varied significantly across previous studies. Growth experiments demonstrate that avoiding the proposed $\alpha \beta$ structural transition—through Sb-rich flux and slower cooling—systematically reduces twinning. However, powder x-ray diffraction and differential thermal analysis measurements show no clear evidence of a distinct $\beta$ phase. Our results establish a consistent magnetic phase diagram and provide essential constraints for crystal-electric field models, enabling a clearer understanding of the interplay between anisotropic magnetism and unconventional superconductivity in ${\mathrm{CeSb}}_2$.

In Dirac and Weyl semimetals with a flat band, the Seebeck coefficient ($S$) can be enhanced by the energy filtering effect in wave number space through electron-phonon interaction (EPI). Especially, topological B20-type semimetal thin films are promising materials because their Dirac or Weyl fermions are robust against defect scattering, making EPI dominant carrier scattering in the thin films. Here, we propose a strategy of raising this EPI-induced $S$ enhancement effect (ESE) by enhancing EPI at room temperature (RT) via phonon frequency control. By using two atoms with a similar mass in topological B20 materials, the projected phonon density of states (DOS) of two atoms are mainly tuned within the frequency range below $200\mathrm{c}{\mathrm{m}}^{-1}$ (RT thermal energy), leading to the increased total phonon DOS at RT related to EPI enhancement. In this study, focusing on topological B20-CoGe with Dirac-like and flat bands, where Co and Ge have similar masses, we demonstrate raising ESE in an epitaxial B20-CoGe thin film experimentally and theoretically. Although B20-CoGe is unstable under atmospheric pressure, the epitaxial growth of B20-CoGe thin films is achieved on Si substrates by the seed-assisted epitaxy method. The good agreement between experimental results and calculated $S$ values with EPI is observed. The epitaxial B20-CoGe thin film shows the thermoelectric power factor of $\sim 5.8\mu \mathrm{W}\mathrm{c}{\mathrm{m}}^{-1}{\mathrm{K}}^{-2}$, which is comparable to group IV element-based typical thermoelectric semiconductor thin films although B20-CoGe is a semimetal. Furthermore, the use of a heavier Ge atom resulted in lower thermal conductivity. The proposed strategy opens a new approach to realize a high thermoelectric performance (at RT) thin film on a Si platform.

Deorbitalization of a conventional meta-generalized-gradient exchange-correlation approximation replaces its dependence upon the Kohn-Sham (KS) kinetic energy density with a dependence on the density gradient and Laplacian. In principle, that simplification should provide improved computational performance relative to the original meta-generalized-gradient-approximation form because of the shift from an orbital-dependent generalized KS potential to a true KS local potential. Often that prospective gain is lost because of problematic roughness in the density caused by the density Laplacian and consequent roughness in the exchange-correlation potential from the resulting higher-order spatial derivatives of the density in it. We address the problem by constructing a deorbitalizer based on the “${\mathrm{r}}^2\mathrm{SCAN}$ piecewise polynomial”  (RPP) deorbitalizer from A. D. Kaplan and J. P. Perdew [Phys. Rev. Mater. 6, 083803 (2022)] with comparative smoothness of the potential along with retention of constraint satisfaction as design goals. Applied to the ${\mathrm{r}}^2\mathrm{SCAN}$ exchange-correlation functional presented by J. W. Furness et al. [J. Phys. Chem. Lett. 11, 8208 (2020)], we find substantial timing improvements for solid-state calculations over both ${\mathrm{r}}^2\mathrm{SCAN}$ and its earlier deorbitalization for high-precision calculations of structural properties, while improving upon the accuracy of RPP deorbitalization for both solids and molecules.

Using ab initio methodology, we reveal a strain‐mediated approach to precisely tune the magnetoelectric coupling and spin-driven emergent polarization of ${\mathrm{NiX}}_2$ (X = I, Br) monolayers. In the absence of strain, these systems spontaneously stabilize noncollinear spin states that break the inversion symmetry, inducing a ferroelectric polarization in the plane of the material. We show that biaxial and uniaxial strains broadly modulate the magnetoelectric response in these materials through two distinct mechanisms: ($\text{i}$) direct modification of the magnetoelectric tensor components, and ($\text{ii}$) tuning of the characteristic propagation vectors of a spin texture. This dual mechanism enables rather precise control over the magnitude of the spin‐induced electric polarization of these materials. With respect to the achievable magnitude of the electric polarization, we demonstrate the critical role of third nearest‐neighbor spin‐pair contributions, which can increase under strain to levels that compete with or even exceed the polarization driven by first nearest-neighbor effects. These findings offer important insights into low-dimensional piezomagnetoelectricity and expand the possibilities for designing multifunctional 2D straintronic devices.

Quantum size effect (QSE) on the electronic structures of nanoscale antiferromagnets with a monolayer (ML) thickness is of fundamental importance in antiferromagnetic (AFM) spintronics. Here, we have carried out systematic studies on the size-dependent unoccupied electronic states of ML Mn nanoislands on Ag(111) by employing scanning tunneling microscopy/spectroscopy (STM/STS) together with density-functional theory (DFT). According to bias-dependent height profiles, a lower apparent height has been found on the larger Mn island within a bias voltage range of $\pm 1.0\mathrm{eV}$, suggesting a smaller Mn–Ag interlayer distance. Additionally, a single broad $\text{d}I\text{/d}U$ peak from small Mn islands gradually evolves into two distinct peaks at approximately $1.3\text{eV}$ (peak 1) and $1.5\text{eV}$ (peak 2) as the island size increases. On top of that, peaks 1 and 2 move about $0.37\pm 0.05\mathrm{eV}$ and $0.30\pm 0.03\mathrm{eV}$ toward lower energy positions when the area size of the ML Mn island increases. Given the projected density of states (PDOS) deduced from orbital-dependent electronic band structures of ML Mn/Ag(111), two unoccupied $\mathrm{d}I/\mathrm{d}U$ peaks originate from the contributions of out-of-plane Mn-$3d$ orbitals. Further PDOS comparison analyses reveal that the Mn–Ag interlayer coupling develops a stronger energy shift in unoccupied states than the Mn–Mn atomic bonding, yielding the two-peak feature in $\mathrm{d}I/\mathrm{d}U$ spectra resolved experimentally.

We study the effect of the spatial distribution of active force dipoles on the folding pathways and mechanical stability of rigid-elastic networks using Langevin dynamics simulations. While it has been shown by D. Majumdar, et al. [J. Chem. Phys. 163, 114902 (2025)] that a sharp collapse transition is evident in triangular (elastic) bead-spring networks under the action of contractile (or extensile) force dipoles distributed randomly across the network, here, we show that when the spatial distribution is correlated, e.g., like a patch in the center (“active core” model) or a bandlike distribution along the periphery (“active periphery” model), the network undergoes only a partial decrease in size even at large forces, thereby showing an enhanced mechanical stability just from a spatial rearrangement of the active dipoles. Furthermore, an active periphery network exhibits higher mechanical stability initially, for a range of forces, beyond which the active core network becomes more stable. Active fluctuation induced deformation becomes irreversible beyond a threshold force amplitude, which depends on the type of distribution; for a uniform distribution of active dipoles, the irreversibility threshold almost coincides with the critical collapse point, it decreases for the active core network, and is decreased further for the active periphery network. It is demonstrated that irreversibility arises due to plastic deformations, specifically crease formation, which remains irreversible even after the force is turned off or reversed. The folding pathways depend weakly on the temporal stochasticity of the active links, but are highly sensitive to any defects (missing bonds) in the network. Our findings, therefore, suggest active force localization (or delocalization) as a prime method to dynamically alter the mechanical stability and reversibility of the underlying elastic network.

Epitaxial thin films of the lamellar transition metal dichalcogenide ${\mathrm{NiTe}}_2$ have been grown by molecular beam epitaxy on GaAs(111)B substrates. Using in-plane grazing-incidence x-ray diffraction measurements, we show that two distinct epilayers form during growth: (1) an epitaxial interface contact layer, with a 2D hexagonal lattice structure with in-plane lattice parameter matching the GaAs(111)B surface, and (2) the epitaxial ${\mathrm{NiTe}}_2$ thin film. The in-plane lattice constant of the ${\mathrm{NiTe}}_2$ film is observed to increase while the out-of-plane parameter decreases, both approaching their bulk values, as the film thickness increases. The interfacial contact layer is ascribed to Te atoms substituting for the upper As atoms of the GaAs(111)B (2x2) surface on exposure to Te at the onset of growth, forming a (1x1) Ga–Te hexagonal contact layer with no dangling bonds, which acts as a quasi-van der Waals substrate. We show that a similar contact layer is seen also in the growth of other Te and Se compounds. The presence of this interfacial contact layer, which seems universal for chalcogenide growth on GaAs(111)B, may have significance for understanding the electronic and optical properties of epitaxial layered materials in contact with the substrate.

Two-dimensional (2D) iron trihalides $(\mathrm{Fe}{X}_3, X=\mathrm{F}, \mathrm{Cl}, \mathrm{Br}, \mathrm{I})$ are an emerging family of van der Waals magnets whose fundamental physical properties are not yet fully understood. In this work, we present a systematic first-principles study incorporating hybrid functional (HSE06) calculations and Hubbard U corrections to unravel the spin state, magnetic order, electronic structure, and doping response in monolayer $\mathrm{Fe}{X}_3$. The high-spin $(S=5/2)$ state is unequivocally established as the universal local ground state across the series. A chemical tuned magnetic transition is identified: ${\mathrm{FeF}}_3$ adopts Néel-type antiferromagnetic (AFM) order, while ${\mathrm{FeCl}}_3$, ${\mathrm{FeBr}}_3$, and ${\mathrm{FeI}}_3$ are ferromagnetic (FM) semiconductors with Curie temperatures $\left(T_C\right)$ monotonically increasing from 154 K to 238 K. This trend is driven by the competition between direct AFM exchange and halogen-mediated FM superexchange. Electronically, ${\mathrm{FeCl}}_3$ and ${\mathrm{FeBr}}_3$ are identified as bipolar magnetic semiconductors, exhibiting a perfect linear scaling of the band gap with halogen electronegativity. An effective tight-binding model derived from maximally Wannier functions reveals a progressive increase in crystal-field splitting $\left({\mathrm{\Delta }}_{\mathrm{oct}}\right)$ from 3.36 eV to 4.22 eV, underpinning the evolving orbital hierarchy across iron trihalides. Crucially, electron doping induces a nonmonotonic magnetic evolution, from FM to geometrically frustrated AFM (zigzag/stripy), culminating in a reentrant FM state, driven by the competition between kinetic energy minimization and orbital-selective electron correlations. Finally, bilayer systems exhibit a universally robust interlayer AFM coupling driven by $p_z$ orbital-mediated superexchange across the van der Waals gap. Our work provides a complete microscopic picture of the basic magnetic and electronic properties of the 2D $\mathrm{Fe}{X}_3$, establishing them as a highly versatile material platform for tunable magnetism and spintronics.

Ferroelectric hafnia ($\mathrm{Hf}{\mathrm{O}}_2$) holds promise for next-generation memory and logic applications because of its CMOS compatibility. However, the high coercive field required for polarization switching in $\mathrm{Hf}{\mathrm{O}}_2$ remains a critical challenge for efficient device operations. Using first-principles calculations and phenomenological modeling, we predict that hole-doping can reduce the coercive field from 8 MV/cm in undoped hafnia to 6 MV/cm in hafnia doped with 0.2 holes per formula unit (f.u.). In the absence of doping, the reversal of polarization of the $Pca{2}_1$ phase is preferred through the nonpolar, tetragonal $P{4}_2/nmc$ phase. This switching pathway involves the coupling of three hard distortion modes that render undoped hafnia as an improper ferroelectric. The overall energy barrier through this pathway remains unchanged ($\sim 80$ meV/f.u.) upon hole-doping. However, the introduction of holes hardens the polar ${\mathrm{\Gamma }}_2^{-}$ distortion mode that connects the polar $Pca{2}_1$ phase to the nonpolar, orthorhombic Pbcm phase, and reduces the energy barrier from 180 meV/f.u. in undoped hafnia to 80 meV/f.u. at 0.2 holes/f.u. The activation of the latter switching pathway through the Pbcm phase can lead to a reversal in the polarization direction. Overall, hole-doping makes the switching pathway through the Pbcm phase competitive, and renders hafnia as a proper ferroelectric with a lower coercive field.

Transition-metal dichalcogenides host a variety of charge-density-wave phases that couple lattice, charge, and correlation effects. In $1T\text{−}{\mathrm{TaS}}_2$, the commensurate and nearly commensurate states are well characterized, yet the transition near 350 K into the incommensurate phase has lacked direct momentum-resolved insight. Here, we use temperature-dependent angle-resolved photoemission spectroscopy to track the electronic structure across this transition. We observe a suppression of quasiparticle spectral weight at the Brillouin-zone center, coincident with the transport anomaly, but without clear evidence of a full band-gap opening. The transition appears to involve momentum-dependent redistribution of spectral weight, consistent with a loss of coherence that reshapes the Fermi surface while leaving conduction dispersions largely intact. These results suggest that the nearly commensurate–incommensurate transition may not align with a conventional metal-insulator transition picture, but rather as an electronic reconstruction driven by loss of coherence. Our work provides new microscopic insight into the resistivity anomaly near room temperature and may guide design principles for collective electronic switching in transition-metal dichalcogenides.