Phonon-mediated superconductivity in transition-metal trioxides XO3 (X = Ru, Re, Os, Ir, Pt) under pressure

A recent experiment by Shan {\it et al} [arXiv:2304.09011] found that rhenium trioxide ReO${}_3$, a simple metal at the ambient pressure, becomes superconducting with a transition temperature as high as 17 K at 30 GPa. In this paper, we analyze the electron-phonon origin of superconductivity in rhombohedral ReO${}_3$ in detail. In addition, we also conduct a high-throughout screening of isostructural transition-metal trioxides XO${}_3$ in searching for potential pressure-induced superconductors. Totally twenty-eight XO${}_3$ compounds have been studied, in which four candidates RuO${}_3$, OsO${}_3$, IrO${}_3$ and PtO${}_3$ are predicted superconducting with the transition temperatures of 26.4, 30.3, 0.9 and 2.8 K at 30 GPa, respectively. Both IrO${}_3$ and PtO${}_3$ stay superconducting even at the ambient pressure. In ReO${}_3$, RuO${}_3,$OsO${}_3$ and IrO${}_3$, the conduction electrons around the Fermi level are dominantly from the X-d and the O-2p orbitals, and their electron-phonon coupling originates from the lattice dynamics of both the heavier transition-metal-atom and the oxygen-atom. Inclusion of spin-orbital coupling would mildly suppress the transition temperatures of these transition-metal trioxide superconductors except RuO${}_3$.