Thermodynamics of the hydrogen dominant potassium hydride superconductor at high pressure

TL;DR

This study analyzes the thermodynamic properties of the hydrogen-rich potassium hydride superconductor KH6 under high pressure using Eliashberg theory, revealing decreasing properties with pressure and strong-coupling behavior beyond BCS theory.

Contribution

It provides a comprehensive thermodynamic analysis of KH6 superconductor at high pressures using Eliashberg theory, highlighting its strong-coupling nature and pressure-dependent properties.

Findings

Superconducting transition temperature decreases with pressure.

KH6 exhibits strong-coupling superconductivity beyond BCS predictions.

Thermodynamic properties decline as hydrogen lattice molecularizes with pressure.

Abstract

In the present paper we report comprehensive analysis of the thermodynamic properties of novel hydrogen dominant potassium hydride superconductor (KH$_{6}$). Our computations are conducted within the Eliashberg theory which yields quantitative estimations of the most important thermodynamic properties of superconducting phase. In particular, we observe, that together with the increasing pressure all the thermodynamic properties decrease, e.g. $T_{C} \in \left< 72.91 , 55.50 \right>$ K for $p \in \left< 166 , 300 \right>$ GPa. It is predicted that such decreasing behavior corresponds to the decreasing hydrogen lattice molecularization with increasing pressure value. Futhermore, by calculating the dimensionless thermodynamic ratios, familiar in the Bardeen-Cooper-Schrieffer theory (BCS), it is proved that KH$_{6}$ material is a strong-coupling superconductor and cannot be quantitatively described within the BCS theory.