Superconductivity Induced Ferromagnetism In The Presence of Spin-Orbit Coupling

TL;DR

This paper explores how superconductivity and spin-orbit coupling can induce ferromagnetic order among magnetic impurities, challenging the traditional view that these phenomena are mutually exclusive.

Contribution

It introduces a theoretical model showing superconductivity can mediate ferromagnetic interactions via spin-orbit coupling, explaining recent experimental observations.

Findings

Long-range impurity interactions decay as a power law

Superconductivity enables ferromagnetic order among impurities

Explains remanent flux in Fe(Se,Te) superconductors

Abstract

We investigate the behavior of magnetic impurities placed on the surface of superconductor thin films with spin-orbit coupling. Our study reveals long-range interactions between the impurities, which decay according to a power law, mediated by the supercurrents. Importantly, these interactions possess a ferromagnetic component when considering the influence of the electromagnetic field, leading to the parallel alignment of the magnetic moments in the case of two impurities. In a Bravais lattice of magnetic impurities, superconductivity facilitates the establishment of ferromagnetic order within specific parameter ranges. These findings challenge the conventional understanding that ferromagnetism and superconductivity are mutually exclusive phenomena. Our theoretical framework provides a plausible explanation for the recently observed remanent flux in iron-based superconductors, particularly Fe(Se,Te).