Inducing odd-frequency triplet superconducting correlations in a normal metal

TL;DR

This paper theoretically investigates how odd-frequency triplet superconducting correlations can be induced in a normal metal via proximity effects with a superconductor and a ferromagnetic insulator, revealing distinctive signatures in the density of states.

Contribution

It introduces a theoretical framework showing the emergence and spatial behavior of triplet correlations with spin one in a diffusive normal metal.

Findings

Triplet correlations with spin one manifest as zero-energy peaks in the density of states.

Spatial scaling behavior of triplet correlations is identified.

Coexistence with singlet and other triplet correlations is possible.

Abstract

This work discusses theoretically the interplay between the superconducting and ferromagnetic proximity effects, in a diffusive normal metal strip in contact with a superconductor and a non-uniformly magnetized ferromagnetic insulator. The quasiparticle density of states of the normal metal shows clear qualitative signatures of triplet correlations with spin one (TCS1). When one goes away from the superconduting contact, TCS1 focus at zero energy under the form of a peak surrounded by dips, which show a typical spatial scaling behavior. This behavior can coexist with a focusing of singlet correlations and triplet correlations with spin zero at finite but subgap energies. The simultaneous observation of both effects would enable an unambigous characterization of TCS1.