Magnetic properties of superconductors with strong spin-orbit coupling

TL;DR

This paper develops a microscopic Ginzburg-Landau theory for superconductors with strong spin-orbit coupling, analyzing magnetic responses and intrinsic magnetic moments, especially in non-centrosymmetric materials like CePt$_3$Si.

Contribution

It provides a general formalism for superconductors with strong spin-orbit coupling, including non-centrosymmetric cases, and derives expressions for the intrinsic magnetic moments of Cooper pairs.

Findings

Unusual structure of gradient energy in non-centrosymmetric superconductors

General expressions for intrinsic magnetic moments of Cooper pairs

Application to CePt$_3$Si, a heavy-fermion superconductor without inversion symmetry

Abstract

We study the response of a superconductor with a strong spin-orbit coupling on an external magnetic field. The Ginzburg-Landau free energy functional is derived microscopically for a general crystal structure, both with and without an inversion center, and for an arbitrary symmetry of the superconducting order parameter. As a by-product, we obtain the general expressions for the intrinsic magnetic moment of the Cooper pairs. It is shown that the Ginzburg-Landau gradient energy in a superconductor lacking inversion symmetry has unusual structure. The general formalism is illustrated using as an example CePt$_3$Si, which is the first known heavy-fermion superconductor without an inversion center.