CaLi2 superconductor under the pressure of 100 GPa: the thermodynamic critical field and the specific heat

TL;DR

This study investigates the thermodynamic properties of CaLi2 superconductor at 100 GPa pressure, revealing how the Coulomb pseudopotential influences critical fields and heat capacities, with results deviating from BCS predictions.

Contribution

The paper provides detailed calculations of thermodynamic critical field and specific heat for CaLi2 under high pressure using Eliashberg theory, including new interpolation formulas for key parameters.

Findings

Critical field decreases with increasing Coulomb pseudopotential.

Specific heat jump at T_C reduces as μ* increases.

The ratio R_C deviates from BCS value, decreasing with μ*.

Abstract

In the paper, the thermodynamic properties of the CaLi$_2$ superconductor have been studied. It has been assumed the high value of the pressure: $p=100$ GPa. The thermodynamic critical field ($H_{C}$) and the specific heats for the superconducting and normal state ($C^{S}$ and $C^{N}$) have been obtained. The calculations have been made within the framework of the Eliashberg approach for the wide range of the Coulomb pseudopotential: $\mu^{\star}\in<0.1,0.3>$. It has been shown that the low-temperature critical field and the specific heat jump at $T_{C}$ strongly decrease if $\mu^{\star}$ increases. The value of the dimensionless ratio $R_{C}\equiv(C^{S}-C^{N})/C^{N}$ at the critical temperature differs significantly from the value predicted by the BCS model. In particular, the parameter $R_{C}$ decreases from 1.83 to 1.73 with the increase of the Coulomb pseudopotential value. In the paper, the interpolation formulas for the functions $T_{C}(\mu^{\star})$ and $R_{C}(\mu^{\star})$ have been also given.