Optical properties of superconducting pressurized LaH$_{10}$

TL;DR

This study uses first-principles calculations to analyze the optical properties of pressurized LaH$_{10}$, aiming to confirm its superconducting mechanism and transition temperature through optical measurements.

Contribution

It provides detailed theoretical predictions of optical properties of LaH$_{10}$ under pressure, linking them to its superconducting mechanism and transition temperature.

Findings

High transition temperature $T_c$ linked to optimized electron-phonon coupling.

Predicted optical signatures can confirm superconductivity mechanism.

Calculated properties include energy gap, isotope effect, and critical fields.

Abstract

Recently superconductivity has been discovered at around 200~K in a hydrogen sulfide system and around 260~K in a lanthanum hydride system, both under pressures of about 200 GPa. These record-breaking transition temperatures bring within reach the long-term goal of obtaining room temperature superconductivity. We have used first-principle calculations based on density functional theory (DFT) along with Migdal-Eliashberg theory to investigate the electron-phonon mechanism for superconductivity in the $Fm\bar{3}m$ phase proposed for the LaH$_{10}$ superconductor. We show that the very high transition temperature $T_c$ results from a highly optimized electron-phonon interaction that favors coupling to high frequency hydrogen phonons. Various superconducting properties are calculated, such as the energy gap, the isotope effect, the specific heat jump at $T_c$, the thermodynamic critical field and the temperature-dependent penetration depth. However, our main emphasis is on the finite frequency optical properties, measurement of which may allow for an independent determination of $T_c$ and also a confirmation of the mechanism for superconductivity.