On the Properties of Elemental and High-Tc Superconductors in an Applied Magnetic Field in a Unified Framework

TL;DR

This paper extends a unified theoretical framework based on generalized BCS equations to analyze the properties of various superconductors in applied magnetic fields, providing new insights into their microscopic parameters and behavior.

Contribution

It demonstrates the applicability of a generalized BCS approach to superconductors in magnetic fields, including multiband systems, and offers detailed calculations of key superconducting parameters.

Findings

Effective electron-electron interaction can be enhanced by magnetic fields.

Superconductor properties are governed by a single band despite multiband Fermi surfaces.

The framework applies to a wide range of elemental and high-Tc superconductors.

Abstract

The unified approach based on the Generalized BCS equations incorporating chemical potential employed to deal with the critical temperature, gap(s) and coherence length(s) of any superconductor (SC) in an earlier paper is shown here to be also applicable when the SC is in an applied field. Presented herein are the calculated values of the following parameters related to its penetration depth and critical current density: the interaction parameter governing the formation of Cooper pairs (CPs), the number of occupied Landau levels, the number density of charge carriers, the critical velocity of CPs, and the values of chemical potential at T = Tc and zero. Our study is found to corroborate the finding reported by Rasolt and Tesanovic [Revs. Mod. Phys., 64, 709 (1992)] that in some systems the effective electron-electron interaction is enhanced with increasing magnetic field and sheds new light on the finding reported by Audouard et al. [Euro. Phys. Lett., 109, 27003 (2015)] that the properties of a superconductor in magnetic fields are controlled by a single band despite the multiband nature of the Fermi surface. The SCs dealt with are Cd, Zn, Al, In, Hg, MgB2, YBCO, Bi-2212 Bi-2223, Tl-2212, Tl-2223 and compressed H3S and LaH10.