We report a nematic emulsion in which silicone oil droplets dispersed in a nematic liquid crystal induce conic anchoring and spontaneously stabilize elastic hexadecapolar distortions. Exploiting the symmetry and angular profile of these droplets, we develop a controlled fusion strategy to assemble three-phase compound droplets by merging hexadecapolar oil droplets with dipolar glycerol droplets, thereby producing architected multilobed structures. Upon application of an electric field, these compound droplets undergo systematic morphological evolution accompanied by defect migration and topological transitions. Landau-de Gennes simulations quantitatively reproduce director fields and defect networks, revealing an underlying connection between interfacial anchoring, elastic symmetry, and emergent morphology. These findings open avenues for electrically reconfigurable nematic emulsions as platforms for programmable control of droplet geometry and topology.

We investigate the formation, diffusion, and motion of Au-Ge nanodroplets on atomically flat Ge(111) terraces under a thermal gradient. The observations are carried out in real time, by low-energy electron microscopy. Au deposition leads to nucleation of mobile nanodroplets that exhibit biased diffusion toward the hot side of the substrate. Quantitative analysis of the droplet trajectories reveals that the diffusion coefficient scales with the droplet's radius as $D_{\mathrm{drop}}\propto R^{-2}$, consistent with a rate-limiting mechanism dominated by atom attachment/detachment at the droplet-substrate interface, as a possible interpretation. The droplet velocity shows no statistically significant dependence on droplet radius within the investigated range. In contrast, the velocity increases with increasing temperature. The effective activation energy for the droplet motion is 0.5 $\pm 0.3\mathrm{eV}$. These results provide insights into the atomic-scale mechanisms governing nanodroplet dynamics on semiconductor surfaces.

The interplay of topological surface states and magnetism gives rise to the unconventional transport behaviors such as anomalous Hall effect (AHE) and anomalous Nernst effect (ANE). The antiperovskites like ${\mathrm{Mn}}_3\mathrm{SnC}$, which are nodal-line semimetal and exhibits concurrent antiferromagnetic (AFM)-ferromagnetic (FM) ordering offer a fertile ground for anomalous transport. Here we report that the anomalous transport (AHE and ANE) in the compound is mainly dominated by the intrinsic Berry curvature effect. We establish a unified relationship between the AHE and ANE using Mott's relation. The scattering of electrons with both antiferromagnetic and ferromagnetic magnons is manifested in the anomalous Nernst signal. The ratio of anomalous Nernst conductivity to anomalous Hall conductivity $(|{\alpha }_{xy}^A/{\sigma }_{xy}^A|)$ is a sizable fraction of $k_B/e$, which points toward the stronger contribution of the Berry curvature to the ANE.

Photoemissive materials are central to a wide range of technologies, including ultrafast imaging, low-light detection, and accelerator-based light sources, where they determine the fundamental performance limits of these instruments. Despite their importance, establishing quantitative links between material synthesis, electronic structure, intrinsic photoemission properties, and device performance remains a major challenge. Here, we present a comprehensive study that bridges these aspects for Na–K–Sb photocathodes, combining controlled thin-film growth, in situ spectroscopic analysis, photoemission characterization, and investigation of the operational performance. We developed a reproducible synthesis method yielding highly homogeneous films with quantum efficiencies up to $7.5\%$ at $520\mathrm{nm}$ and a stoichiometry close to the predicted optimum. Electronic structure and photoemission properties were analyzed in a dedicated laboratory environment. Furthermore, we demonstrate the successful operation of these photocathodes in a superconducting radio-frequency photoinjector, where the photocathodes are exposed to extreme conditions, forming a particularly stringent test environment. The operational performance was analyzed over several weeks, including detailed investigation of the degradation and recovery mechanisms associated with gas exposure and electron back-bombardment. The photoemissive threshold energy was identified as a bridging parameter connecting electronic structure, photoemissive key parameters, and the degradation state. The approach provides general design principles for the development and integration of photoemissive materials across a broad range of applications. Together, these results establish a quantitative framework linking synthesis, electronic structure, and operational performance in photoemissive materials.

Uranium nitrides (UN, ${\mathrm{U}}_2{\mathrm{N}}_3$, and ${\mathrm{UN}}_2$) are candidate materials for advanced nuclear fuels and corrosion-resistant coatings, yet achieving a unified atomic-scale model that accurately captures their behavior across stoichiometries and under extreme conditions remains challenging. In this work, we present a unified machine learning interatomic potential (MLIP) for the entire U–N system, developed within the neuroevolution potential framework. The potential is trained on a comprehensive density functional theory (DFT) dataset constructed through an iterative active learning procedure that effectively samples configuration space using farthest point sampling and random network distillation. The resulting MLIP accurately reproduces structural, elastic, vibrational, and defect properties of all major uranium nitride phases, showing close agreement with DFT and experimental reference data. It reliably predicts finite-temperature thermodynamics, defect migration barriers, nitrogen diffusion kinetics, and the stability of nonstoichiometric compounds. This transferable and efficient potential enables large-scale molecular dynamics simulations of key processes in uranium nitrides, providing a robust and efficient computational tool for microstructural evolution and phase stability in next-generation nitride-based nuclear systems.

We report on the synthesis and characterization of $\mathrm{M}{\mathrm{n}}_3\mathrm{Ga}$ thin films with controlled phase and orientation using DC magnetron sputtering. High-quality Mn-deficient hexagonal $\mathrm{M}{\mathrm{n}}_3\mathrm{Ga}$ films with C-plane and M-plane orientations were achieved on various single-crystal substrates, and their structural properties were systematically investigated by x-ray diffraction. Magnetization, Hall effect, and neutron diffraction measurements confirm the formation of antiferromagnetic order below $T_{\mathrm{N}}=460\text{–}470$ K and reveal its characteristic magnetic behavior. A sizable anomalous Hall effect is observed coexistent with weak net magnetization, consistent with the 120° noncollinear spin structure. The ability to tune both the crystal phase (hexagonal vs tetragonal) and orientation through composition and thermal treatment provides a platform for exploring the intrinsic magnetic and topological properties of $\mathrm{M}{\mathrm{n}}_3\mathrm{Ga}$, with promising implications for antiferromagnetic spintronic applications.

Magnetic refrigeration presents an energy-efficient and environmentally benign alternative to traditional vapor-compression cooling technologies. It relies on the magnetocaloric effect, in which the temperature of a magnetic material changes in response to variations in the applied magnetic field. Optimal magnetocaloric materials are characterized by a significant change in magnetic entropy under moderate magnetic fields. In this study, we systematically investigated the interatomic exchange interactions, magnetic anisotropy energy and magnetocaloric properties of $\mathrm{Mn}X$ ($X=\mathrm{N}$, P, As, Sb, Bi) using a combination of density functional theory and Monte Carlo simulations. Additionally, the magneto-optical Kerr and Faraday spectra were computed using the all-electron, fully relativistic, full-potential linearized muffin-tin orbital method. The large magneto-optical response observed in MnBi originates from the interplay between the strong exchange splitting of Mn $3d$ states and the substantial spin-orbit interaction associated with the heavy Bi atom. To extract the site-projected spin and orbital moments, spin-orbit coupling and orbital polarization correction were accounted for in the present calculation, which shows good agreement between the moments obtained from the x-ray magnetic circular dichroism sum rule analysis, spin-polarized calculation, and experimental studies. The magnetic transition temperatures predicted through Monte Carlo simulations were in good agreement with the corresponding experimental values. Our results provide a unified microscopic understanding of magnetocaloric performance and magneto-optical activity in Mn-based pnictides and establish a reliable computational framework for designing next-generation magnetic refrigeration materials.

Amorphous materials have long been used in various technological applications, including semiconductor-based electronics. However, modeling amorphous materials at an atomic scale remains challenging. The melt-quench method is commonly used to generate models of amorphous structures, but the necessary lengthy molecular-dynamics runs can make calculations prohibitively expensive, especially for ab initio molecular dynamics. Furthermore, the relevance of melt-quench to athermal techniques like low-temperature deposition is unclear. We present an alternative method for constructing amorphous structures that starts with randomly placing molecules in a large box, followed by relaxation of the cell and atomic positions. We apply this approach to a variety of amorphous systems, using ab initio density-functional theory for the energetics, and obtain good agreement with experimental densities and radial distribution functions with less computational cost than the melt-quench method.

Understanding and predicting mechanical properties such as elasticity and ductility are critical for the design of structural materials. Here, we develop a generalizable machine-learning framework to assess elastic properties and brittle-ductile tendencies across a chemically diverse space of inorganic compounds, including both binary and ternary systems. By integrating stacked ensemble learning and symbolic regression, we achieve strong predictive performance (e.g., $R^2=0.95$ for bulk modulus, $R^2=0.88$ for shear modulus, and ductile/brittle classification accuracy of 88%)—notably high for a general-purpose model spanning diverse chemistries. We also derive simple closed-form expressions using elemental and structural descriptors, enabling quick property estimation in practical settings. Finally, we apply the models to out-of-training-set compounds, including quaternary systems, and demonstrate their effectiveness in real applications. Relying only on several key basic descriptors, the physically interpretable models developed here are particularly valuable for quick screening workflows—especially for experimentalists without access to ab initio simulations.

It is well documented that the contact angle of droplets catalyzing the vapor-liquid-solid growth of III-V binary nanowires (NWs) plays the central role in their crystal phase, which can be either cubic zincblende or hexagonal wurtzite. Here, we develop a model for the contact angle selection in III-V ternary NWs. We demonstrate that the stable contact angle of ternary $A_x{B}_{1-x}C$ NWs based on group-III intermix increases with their composition $x$ for larger incorporation rates of atoms A relative to B and decreases with $x$ otherwise. This trend is reversed for $A_x{B}_{1-x}C$ NWs based on group-V intermix. The effect is due to the total balance of the effective V/III ratio for atomic fluxes entering the droplet and used for NW growth. We present some calculations of the stable contact angles vs composition for ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$, ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$, and ${\mathrm{GaP}}_x{\mathrm{As}}_{1-x}$ NWs and compare them to the recently obtained crystal phase diagrams. The developed approach unravels the role of NW radius, diffusion lengths of group-III adatoms, incorporation rates of group-V atoms in the contact angle selection, and the related crystal phase change and should be useful for understanding and controlling the crystal phase of III-V ternary NWs by the growth parameter tuning.

Thermal hysteresis is a critical design parameter for shape memory materials, particularly for shape memory ceramics, where high hysteresis may be associated with catastrophic cracking upon transformation. A direct framework for predicting hysteresis from the atomistic level does not exist, so proxies such as the interfacial compatibility condition, ${\lambda }_2$, are used for the computational design of shape memory materials. In this paper, we introduce a framework that directly links interfacial compatibility to the energy barriers encountered during the phase transformation. We derive these barriers using adjusted Nudged Elastic Band calculations for two prototypical shape memory systems: zirconia-ceria and NiTi. Although our method does not explicitly simulate the martensite-austenite interface, we demonstrate that the structural pathway followed during the transformation samples the same atomistic structures as that interface. Furthermore, we show that the different correlations observed between the two material classes are fundamentally linked to differences in their shear moduli. These results help explain why our results reveal a strong correlation between interfacial compatibility and the transformation energy barriers: the atomic distortions required to effect the transformation are present whether at interfaces or not, and are accommodated elastically. This approach establishes a computationally efficient, quantum-accurate, method for determining energy barriers directly linked to thermal hysteresis, facilitating the design of resilient shape memory materials.

Bulk orthorhombic boron (o-B14) is an intriguing, recently predicted, three-dimensional (3D) boron allotrope. Its structure is characterized by edge-sharing pentagonal bipyramids, with diverse bond lengths. These structural motifs facilitate the formation of unusual seven-center-two-electron $\pi$ bonds, predicted for the first time in 3D boron allotropes. The presence of these bonds highlights the complexity and versatility of boron chemistry under ambient conditions. Moreover, this material is predicted to be a superconductor with a critical temperature $T_c$ of 29.1 K [Phys. Chem. Chem. Phys. 25, 15400 (2023)]. In the present work, we explore the electronic and optical properties of bulk o-B14 and its monolayer and bilayer forms, including hydrogen termination, using first-principles calculations. These two-dimensional structures are predicted to be dynamically stable and to exhibit a remarkable variety of electronic behavior including semiconductivity with a band gap of 0.67 eV (bilayer), superconductivity with a $T_c$ of 24.3 K (H-terminated bilayer), and magnetism (monolayer). The plasmonic and optical responses exhibit anisotropic behavior driven by the directional bonding network, as well as absorption in the visible region of the spectrum, which suggest promising opportunities for applications in advanced optoelectronic, plasmonic, and quantum devices.

We report on the photoconductive properties of thin layers of ${\mathrm{MoS}}_2$ flakes (with layer thicknesses ranging between 25–50 nm) beyond room temperatures. Photoconductivity measurements at multiple temperatures, between 290 and 425 K were performed using a laser source of $\lambda$ = 640 nm. The variation of photocurrent with temperature at effective laser intensities, $P_{\mathrm{eff}}$ (0.1 $\mu \mathrm{W}<P_{\mathrm{eff}}<$ 0.8 $\mu \mathrm{W}$) as well as the variation of fall times of the devices as a function of increasing laser intensities was thoroughly examined and analyzed with a well established theoretical model [A. Rose, Phys. Rev. 97, 322 (1955)]. Our results indicate the possibility of achieving stable ${\mathrm{MoS}}_2$ based detectors with high photoresponsivities ($R$) $\sim {10}^2\mathrm{A}/\mathrm{W}$ and shot noise limited detectivities ($D$) $\sim {10}^{11}$ Jones, under ambient conditions and beyond room temperatures.

Controlling magnetic anisotropy (MA) in two-dimensional (2D) ferromagnetic metals is crucial for the development of spintronic devices, yet simultaneously stabilizing strong magnetism and well-defined anisotropy in the monolayer limit remains a major challenge. Previous studies have shown that tuning the STO layer thickness in ${\mathrm{SrRuO}}_3/{\mathrm{SrTiO}}_3$ (SRO/STO) superlattices can induce eightfold MA, but it remains unclear whether this behavior originates from the intrinsic properties of the isolated monolayer or relies on periodic interlayer coupling. In this work, we address this issue by synthesizing ${\mathrm{SRO}}_1/{\mathrm{STO}}_N$ superlattices and STO-capped monolayer SRO films. Our experiments reveal that changing the STO layer thickness can systematically tune the MA in the superlattices; more importantly, the STO-capped isolated monolayer simultaneously exhibits metallic transport, robust ferromagnetism, and pronounced eightfold MA with easy axes along the ${\langle 111\rangle }_{\mathrm{pc}}$ directions. These results demonstrate that single-layer SRO can stabilize a 2D correlated ferromagnetic metal and maintain eightfold MA in the fully decoupled limit, indicating that this symmetry does not rely on superlattices periodicity. Our study thus reveals an intrinsic property of single-layer SRO and provides key experimental evidence for understanding correlation-driven MA in ultrathin itinerant ferromagnets.

Ferroelectric materials are a class of dielectrics that exhibit spontaneous polarization which can be reversed under an external electric field. The emergence of ferroelectric order in incipient ferroelectrics is a topic of considerable interest from both fundamental and applied perspectives. Despite evidence from first-principles calculations that strain triggers ferroelectricity in ${\mathrm{KTaO}}_3$, conventional methods cannot reliably characterize the soft-mode dynamics that govern its ferroelectric behavior. In this study, we investigate the impact of in-plane uniaxial and biaxial strain, ranging from 0 to 1%, on pristine ${\mathrm{KTaO}}_3$ to explore its potential for ferroelectricity induction via inversion symmetry breaking. By integrating density-functional theory calculations with the stochastic self-consistent harmonic approximation assisted by on-the-fly machine learned force fields, we obtain accurate structural information and dynamical properties under varying strain conditions while incorporating higher-order anharmonic effects. Employing the Berry-phase method, we obtained the ferroelectric polarization of the strained structures over the entire temperature range up to 300 K. Our findings provide valuable insights into the role of strain in stabilizing ferroelectricity in ${\mathrm{KTaO}}_3$, offering guidance for future experimental and theoretical studies on strain-engineered ferroelectric materials.

Anomalous relaxation is one of the hallmarks of disordered systems. Following perturbation by an external source, many glassy, jammed, and amorphous systems relax as a stretched or compressed exponential as a function of time. However, despite their ubiquity, the origins of and the connection between these phenomenological relaxation functions remain to be understood. Here, we observe a tunable crossover from stretched- to compressed-exponential relaxation by photoexciting single crystal ${\mathrm{Ca}}_3{\mathrm{Ru}}_2{\mathrm{O}}_7$ across a structural phase transition. We present a simple lattice model that shows how spatial inhomogeneity and local, strain-mediated interactions cooperate to produce the dynamical crossover. Our work reveals anomalous relaxation dynamics in an idealized single crystal material and establishes photoexcited solids as promising platforms for probing the mechanisms underlying anomalous relaxation.

Electrical switching of antiferromagnets (AFM) is critical for AFM spintronics. However, electrical pulse-induced Néel vector reorientation in AFM insulators, while predicted to occur at much faster timescales than ferromagnetic switching, has only been demonstrated in the quasi-DC regime. Here we report reliable current-induced AFM switching in $\mathrm{Pt}/\alpha \text{-F}{\mathrm{e}}_2{\mathrm{O}}_3$ bilayers using electrical pulses with various durations spanning three orders of magnitude down to 0.3 ns. Together with COMSOL simulations of temperature distributions in our samples for various pulse widths, our results suggest that thermally assisted spin-orbit torque likely play an important role for sub-ns pulses. This work demonstrates the viability of electrical switching of AFM spins using sub-ns pulses.

Topological properties and topological superconductivity in real materials have attracted intensive experimental and theoretical attentions recently. The topological electronic properties of pressure-induced superconductors ${\mathrm{BiH}}_2$ have been studied based on first-principles electronic structure calculations. Recent experiments have revealed that ${\mathrm{BiH}}_2$ exhibits five distinct phases under high pressure, our studies show that $Cmcm\text{−}{\mathrm{BiH}}_2, Pnma\text{−}{\mathrm{BiH}}_2, Pnnm\text{−}{\mathrm{BiH}}_2$, and $P{2}_1/m\text{−}{\mathrm{BiH}}_2$ are all topological metals defined on curved Fermi levels, while the $P{2}_1{2}_1{2}_1\text{−}{\mathrm{BiH}}_2$ holds Weyl points near the Fermi level. The topological surface states (TSSs) and Fermi arcs of ${\mathrm{BiH}}_2$ right cross the Fermi level and hold helical spin textures. Considering the fact that the ${\mathrm{BiH}}_2$ exhibit high superconducting transition temperatures ($T_c$) of $\sim 70$ K under pressure confirmed by recent experiments, the superconducting bulks will induce superconductivity in the TSSs via the proximity effect. Thus, the hydride superconductors ${\mathrm{BiH}}_2$ may provide a promising platform for exploring topological superconductivity and Majorana zero modes.