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

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 Blonder-Tinkham-Klapwijk formalism and allow for an arbitrary magnetization strength and 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 phases. 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.