Superconductivity of $LaH_{10}$ and $LaH_{16}$ polyhydrides

TL;DR

This paper predicts new high-pressure lanthanum hydrides with high superconducting transition temperatures, revisits known compounds' superconductivity, and provides detailed theoretical insights into their properties.

Contribution

It reports the discovery of a new $LaH_{16}$ phase, revises the $T_C$ of $LaH_{10}$ using advanced calculations, and analyzes their superconducting properties at high pressures.

Findings

Predicted $LaH_{16}$ stability above 150 GPa with $T_C$ of 156 K at 200 GPa.

Revised $T_C$ of $LaH_{10}$ up to 271 K from first-principles calculations.

Multiple polymorphs of $LaH_{10}$ may explain experimental $T_C$ variations.

Abstract

We explore high-pressure phase stability and superconductivity of lanthanum hydrides $LaH_m$ (m=4-11,16). We predict stability of a hitherto unreported polyhydride $P6/mmm$-$LaH_{16}$ at pressures above 150 GPa; at 200 GPa its predicted superconducting $T_C$ is 156 K, critical field $\mu_0$$H_C$(0) ~ 35 T and superconducting gap is up to 35 meV. We revisit superconductivity of the recently discovered $LaH_{10}$ and find its $T_C$ to be up to 259 K (170 GPa) from solving the Eliashberg equation and 271 K from solving the gap equation in SCDFT which also allowed us to compute the Coulomb pseudopotential $\mu^*$ for $LaH_{10}$ and $LaH_{16}$. Presence of several polymorph modifications of LaH10 may explain the variety in the experimentally measured $T_C$ values for $LaH_{10}$ [1,2]