Odd Triplet Superconductivity and Related Phenomena in Superconductor-Ferromagnet Structures

TL;DR

This paper explores the emergence of odd-frequency triplet superconductivity in superconductor-ferromagnet structures, revealing long-range effects, enhanced Josephson currents, and magnetic phenomena due to the proximity effect.

Contribution

It introduces the concept of odd-frequency triplet components in S/F systems and analyzes their robustness and effects, which were not previously understood.

Findings

Triplet component is insensitive to non-magnetic impurities.

Long-range penetration of triplet superconductivity in ferromagnets.

Enhanced Josephson current due to ferromagnetic influence.

Abstract

We consider novel unusual effects in superconductor-ferromagnet (S/F) structures. In particular we analyze the triplet component (TC) of the condensate generated in those systems.This component is odd in frequency and even in the momentum, which makes it insensitive to non-magnetic impurities. If the exchange field is not homogeneous in the system the triplet component is not destroyed even by a strong exchange field and can penetrate the ferromagnet over long distances. Some other effects considered here and caused by the proximity effect are: enhancement of the Josephson current due to the presence of the ferromagnet, induction of a magnetic moment in superconductors resulting in a screening of the magnetic moment, formation of periodic magnetic structures due to the influence of the superconductor, etc. We compare the theoretical predictions with existing experiments.