Searching for experimentally feasible intrinsic quantum anomalous Hall (QAH) insulators is of great significance for dissipationless electronics applications. Here we predict, based on density functional theory (DFT), that four monolayer transition metal tri-bromides (VBr₃, FeBr₃, NiBr₃, and PdBr₃) are endowed with intrinsic half-metallicity and possess quantum anomalous Hall insulating phases. DFT+U calculations reveal that the VBr₃, NiBr₃, and PdBr₃ monolayers undergo nontrivial to Mott insulator transitions with increasing on-site Hubbard Coulomb interaction U at 0.5, 2 and 3 eV. The gap opening induced by the spin–orbit coupling drives the systems into the QAH state. The Curie temperatures of the VBr₃, NiBr₃, and PdBr₃ monolayers are ∼190, 100 and 110 K. Additionally, the calculated cleavage energies suggest that the freestanding VBr₃, FeBr₃, NiBr₃, and PdBr₃ monolayers can be easily produced by exfoliation using adhesive tape, which may stimulate experimental research interest to achieve QAH phases.

Hydrogen-rich superconductors are promising candidates to achieve room-temperature superconductivity. However, the extreme pressures needed to stabilize these structures significantly limit their practical applications. An effective strategy to reduce the external pressure is to add a light element M that binds with H to form ${\mathrm{MH}}_x$ units, acting as a chemical precompressor. We exemplify this idea by performing ab initio calculations of the Ac–Be–H phase diagram, proving that the metallization pressure of Ac–H binaries, for which critical temperatures as high as 200 K were predicted at 200 GPa, can be significantly reduced via beryllium incorporation. We identify three thermodynamically stable (${\mathrm{AcBe}}_2{\mathrm{H}}_{10}, {\mathrm{AcBeH}}_8$, and ${\mathrm{AcBe}}_2{\mathrm{H}}_{14}$) and four metastable compounds (fcc ${\mathrm{AcBeH}}_8, {\mathrm{AcBeH}}_{10}, {\mathrm{AcBeH}}_{12}$ and ${\mathrm{AcBe}}_2{\mathrm{H}}_{16}$). All of them are superconductors. In particular, fcc ${\mathrm{AcBeH}}_8$ remains dynamically stable down to 10 GPa, where it exhibits a superconducting-transition temperature $T_{\text{c}}$ of 181 K. The Be–H bonds are responsible for the exceptional properties of these ternary compounds and allow them to remain dynamically stable close to ambient pressure. Our results suggest that high-$T_{\text{c}}$ superconductivity in hydrides is achievable at low pressure and may stimulate experimental synthesis of ternary hydrides.

Topological quantum materials have significant potential for application as anode materials due to their intrinsically high electronic conductivity against perturbation from defects or impurities. In this work, we utilize a combination of a swarm-intelligence structure search method and first-principles calculations to predict the global minimum of a BeN monolayer, suggesting it as a promising nodal-line semimetal anode for Li-ion batteries. BeN anode demonstrates a substantial specific capacity of 3489 mAh/g and a low average open-circuit voltage of 0.15 V, resulting in an ultrahigh energy density of 9681 mWh/g (referenced to the standard hydrogen electrode potential). This energy density represents the highest among all two-dimensional (2D) topological quantum anodes and surpasses that of most currently known 2D anode materials for Li-ion batteries. Furthermore, the formation of a vacancy in the BeN monolayer induces a unique “self-doping” effect that promotes high electronic conductivity. Additionally, the BeN monolayer exhibits a diffusion energy barrier of 0.30 eV for Li-ion migration, a small-scale area expansion of 0.96% during the process of lithiation, and excellent wettability with the contacted electrolytes. Published by the American Physical Society 2024

Pressure-stabilized LaN₉ and LaN₈ compounds hold the potential as high-energy density materials.

The recent observation of high critical temperature T _c in lanthanum and Yttrium hydrides confirms the key role of hydrogen cage (H-cage) in determining high superconductivity. Here, we present a new class of metastable H₁₂ clathrate structures based on the icosahedral cI24-Na that can be stabilized by incorporation of metal elements. Analysis shows that the charge transfer from metal atoms to H atoms contributes to forming the H₁₂ clathrate. Nine dynamically stable structures are identified to exhibit superconductivity, and a maximum T _c of 28 K is found in voids-doped Mo₆H₂₄. Calculations reveal that the low T _c is attributed to the weak interaction between H atoms in each cage due to the long H–H distance. The current results provide a possible route to design H-cage containing superconductors.