Signatures of retroreflection and induced triplet electron-hole correlations in ferromagnet/s-wave superconductor structures

TL;DR

This paper theoretically investigates how triplet electron-hole correlations and retroreflection signatures manifest in ferromagnet/s-wave superconductor junctions, emphasizing the role of spin-active barriers and magnetization orientation.

Contribution

It introduces a comprehensive theoretical model analyzing the effects of spin-active barriers and magnetization on triplet correlations and tunneling conductance in ferromagnet/superconductor junctions.

Findings

Triplet correlations are induced by magnetization phase coupling.

Spin-filter barriers enhance triplet pairing signatures.

Retroreflection affects tunneling conductance measurements.

Abstract

We present a theoretical study of a ferromagnet/s-wave superconductor junction to investigate the signatures of induced triplet correlations in the system. We apply the extended BTK-formalism and allow for an arbitrary magnetization strength/direction of the ferromagnet, a spin-active barrier, Fermi-vector mismatch, and different effective masses in the two systems. It is found that the phase associated with the $xy$-components of the magnetization in the ferromagnet couples with the superconducting phase and induces spin-triplet pairing correlations in the superconductor, if the tunneling barrier acts as a spin-filter. This feature leads to an induced spin-triplet pairing correlation in the ferromagnet, along with a spin-triplet electron-hole coherence due to an interplay between the ferromagnetic and superconducting phase. As our main result, we investigate the experimental signatures of retrorelection, manifested in the tunneling conductance of a ferromagnet/s-wave superconductor junction with a spin-active interface.