The structure and superconductivity of $\mathrm{WT}{\mathrm{e}}_2$ under pressure are investigated using ab initio calculations combined with high-pressure synchrotron x-ray diffraction and Raman spectroscopy. We find that the emergence of superconductivity in $\mathrm{WT}{\mathrm{e}}_2$ under pressure can be attributed to the phase transition from ambient $T_d$ phase to the monoclinic $1T$′ structure phase at around 4–5 GPa, which is associated with a sliding of the $\mathrm{WT}{\mathrm{e}}_2$ layers, resulting in a critical point in the changes of Te-Te interlayer distance. This phase transition introduces an inversion center and eliminates the topological Weyl fermions in the $T_d$ structure. Electron-phonon coupling calculations predict a similar $T_c$ as the reported value, implying that $\mathrm{WT}{\mathrm{e}}_2$ might belong to conventional normal Bardeen-Cooper-Schrieffer superconductors.

The electronic structure, phonon dispersions, and electron-phonon (EP) coupling in Fe₂Se₂/SrTiO₃ (FeSe/STO) thinnest films are studied based on the first-principles calculations. It is found that the FeSe/STO interface with lattice strain leads to a change of band structures and a significant enhancement of the EP coupling, the latter being close related to interface-induced ferroelectric phonons coupled to electrons on the FeSe monolayer. In the FeSe/STO system, T_c of phonon-induced superconductivity is estimated to be much greater than that in the bulk FeSe, but still well below the experimental value of an FeSe monolayer on the STO substrate, indicating that the electron-phonon mechanism alone cannot explain its high T_c.

A systematic structure search in the Ce-H system under pressure reveals novel stable phases with intriguing electronic properties. Several cerium hydrides, CeH${}_4$ , CeH${}_9$ , and CeH${}_{10}$ , were found to be dynamically stable. Electron-phonon calculations coupled to Bardeen-Cooper-Schrieffer arguments indicate that they might be high-$T_c$ superconductors. In particular, the maximum $T_c$ values for $F\overline{4}3m$ -CeH${}_9$ and $Fm\overline{3}m$ -CeH${}_{10}$ are 142 K and 168 K at 94 GPa. These findings may pave the way for achieving room temperature superconductors in dense hydrogen-rich compounds.

We report details of single-crystal growth of stoichiometric bismuthide ${\mathrm{PtBi}}_2$ whose structure consists of alternate stacking of a Pt layer and Bi bilayer along the $c$ axis. The compound crystallizes in space group $P3$ with a hexagonal unit cell of $a=b=6.553\text{Å},c=6.165\text{Å}$. Its $T$-dependent resistivity is typical of a metal whereas a large anisotropy was observed for the in-plane and interplane electrical transport. The magnetization data show opposite sign for fields parallel and perpendicular to the Pt layers, respectively. The magnetic field response of this material shows clearly two types of charge carriers, consistent with the multiple Fermi surfaces revealed in our band structure calculations. The hydrostatic pressure is shown to suppress the resistivity at high $T$ systematically but has little bearing on its low-$T$ transport. Through calorimetric measurements, the density of states at the Fermi level and the Debye temperature are determined to be 0.$94{\mathrm{eV}}^{-1}$ per molecule and 145 K, respectively. In addition, the electronic structures and parity analyses are also presented. We find a minimum value of 0.05 eV gap opening at around 2 eV under the Fermi level by invoking spin-orbit interaction. A slab calculation further indicates a surface Dirac cone appearing in the gap of bulk states. We discuss the possibility of $\mathrm{PtBi}{}_2$ being a candidate for a bulk topological metal, in analogy to the recently proposed topological superconductor $\beta \text{−}{\mathrm{PdBi}}_2$.