Recent predictions of metastable high-temperature hydride superconductors give hope that superconductivity at ambient conditions is within reach. In this work, we predict RbPH3 as a new compound with a superconducting critical temperature around 100 K at ambient pressure, dynamically stabilized thanks to ionic quantum anharmonic effects. RbPH3 is thermodynamically stable at 30 GPa in a perovskite Pm3ˉm phase, allowing its experimental synthesis at moderate pressures far from the megabar regime. With lowering pressure it is expected to transform to a R3m phase that should stay dynamically stable thanks to quantum fluctuations down to ambient pressures. Both phases are metallic, with the R3m phase having three distinct Fermi surfaces, composed mostly of states with phosphorus and hydrogen character. The structures are held together by strong P-H covalent bonds, resembling the pattern observed in the high-temperature superconducting H3S, with extra electrons donated by rubidium. These results demonstrate that quantum ionic fluctuations, neglected thus far in high-throughput calculations, can stabilize at ambient pressure hydride superconductors with a high critical temperature.
@article{arxiv.2411.03822,
title = {Ambient pressure high temperature superconductivity in RbPH$_3$ facilitated by ionic anharmonicity},
author = {Đorđe Dangić and Yue-Wen Fang and Tiago F. T. Cerqueira and Antonio Sanna and Miguel A. L. Marques and Ion Errea},
journal= {arXiv preprint arXiv:2411.03822},
year = {2024}
}