Self-consistent solution of Eliashberg equations for metal hydride superconductors

TL;DR

This paper presents a self-consistent method for solving Eliashberg equations to analyze superconductivity in metal hydrides, offering improved accuracy over traditional formulas and validated against experimental data.

Contribution

It introduces a self-consistent solution approach for Eliashberg equations in hydrides, contrasting with the McMillan-Allen-Dynes formula, and assesses effects of spectral functions and broadening parameters.

Findings

Self-consistent solutions align well with experimental critical temperatures.

Electron-phonon spectral functions significantly influence superconductivity predictions.

Broadening parameters from phonon lifetime affect critical temperature estimates.

Abstract

In recent years, the quest for high critical-temperature superconductors has increasingly focused on metal and molecular hydrides, which have demonstrated potential for superconductivity at or near room temperature under extremely high pressures. Such hydrides were first proposed by N. W. Ashcroft in 1968, because hydrogen-rich materials possess elevated vibrational frequencies due to the low atomic mass of hydrogen. This article presents a self-consistent solution to the Eliashberg equations for analysing superconductivity in hydrides, contrasting with the commonly used McMillan-Allen-Dynes parameterized formula. We also analyse effects of the electron-phonon spectral function and the broadening parameters arising from phonon lifetime and sample imperfections on the superconducting critical temperature. Finally, both theoretical approaches are applied to a typical metal hydride superconductor, and the reliability of self-consistent solutions is validated against the experimentally measured critical temperature.