High pressure structures, phase diagram and superconductivity of polonium hydrides have been systematically investigated through the first-principles calculations based on the density functional theory. With the increasing pressure, several stoichiometries (PoH, $\textrm{ PoH}_\textrm{ 2}$, $\textrm{ PoH}_4$ and $\textrm{ PoH}_6$) are predicted to stabilize in the excess hydrogen environment. All of the reported hydrides, exception of PoH, exhibit intriguing structural character with the appearing $\textrm{ H}_2$ units. Moreover, our electronic band structure and the projected density of states (PDOS) demonstrate that these energetically stable phases are metallic. The application of the Allen-Dynes modified McMillan equation with the calculated electron-phonon coupling parameter reveals that $\textrm{ PoH}_4$ is a superconductor with a critical temperature $T_c$ of 41.2-47.2 K at 300 GPa.
Categories: cond-mat.supr-con cond-mat.mtrl-sci