Second group of high-pressure high-temperature lanthanide polyhydride superconductors

Rare-earth polyhydrides formed under pressure are promising conventional superconductors, with the critical temperature Tc in compressed LaH10 almost reaching room temperature. Here, we report a systematic computational investigation of the structural and superconducting properties of
rare-earth (RE) polyhydrides formed under pressure across the whole lanthanide series. Analyses of the electronic and dynamical properties and electron-phonon coupling interaction for the most hydrogen-rich hydrides REHn (n = 8, 9, 10) that can be stabilized below 400 GPa show that enhanced Tc correlates with a high density of H s-states and low number of RE f-states at the Fermi level. In addition to previously predicted and measured LaH10 and CeH9, we suggest YbH10 and LuH8 as additional potential high-Tc superconducters. They form a `second island' of high-Tc superconductivity amongst the late lanthanide polyhydrides, with an estimated Tc of 102 K for YbH10 at 250 GPa.