Lanthanide hydrides exhibit high-temperature superconductivity at extreme pressure*

Hydrogen-rich super-hydrides are promising high-Tc superconductors, with superconductivity experimentally observed near room, temperature, as shown in recently discovered lanthanide super-hydrides at very high pressures, e.g. LaH10 at 170 GPa and CeH9 at 150 GPa. Superconductivity is believed to be closely related with the high vibrational modes of the bound hydrogen electrons. Here we study the limit of extreme pressures (above 200 GPas) where lanthanide hydrides with large hydrogen content have been observed. We focus on LaH16 and CeH16, two prototype candidates for achieving a large electronic contribution from hydrogen in the electron-phonon coupling. In this work, we propose a first-principles calculation platform with the inclusion of many-body corrections to evaluate the detailed physical properties of the Ce-H and La-H systems and to understand the structure, stability, and superconductivity of these systems at ultra-high pressure. We provide a practical approach to further investigate conventional superconductivity in hydrogen-rich super-hydrides.