The role of interface transparency and spin-dependent scattering in diffusive ferromagnet/superconductor heterostructures

TL;DR

This paper numerically investigates how interface transparency and spin-dependent scattering influence the density of states and Josephson current in diffusive ferromagnet/superconductor heterostructures, revealing effects on the 0-$\

Contribution

It introduces a comprehensive numerical model that accounts for arbitrary interface transparency and spin scattering, advancing understanding of proximity effects in ferromagnet/superconductor systems.

Findings

Zero-energy peak and minigap depend on magnetic impurity concentration.

Large residual supercurrent at 0-$\

Uniaxial spin-flip scattering affects 0-$\

Abstract

We present a numerical study of the density of states in a ferromagnet/superconductor junction and the Josephson current in a superconductor/ferromagnet/superconductor junction in the diffusive limit by solving the Usadel equation with Nazarov's boundary conditions. Our calculations are valid for an arbitrary interface transparency and arbitrary spin-dependent scattering rate, which allows us to explore the entire proximity-effect regime. We first investigate how the proximity-induced anomalous Green's function affects the density of states in the ferromagnet for several values of the exchange field. In each case, we consider the effect of the barrier transparency and allow for various concentrations of magnetic impurities. In particular, we address how the zero-energy peak and minigap observed in experiments may be understood in terms of the interplay between the singlet and triplet anomalous Green's function and their dependence on the concentration of magnetic impurities. We also investigate the role of the barrier transparency and spin-flip scattering in a superconductor/ferromagnet/superconductor junction. We suggest that such diffusive Josephson junctions with large residual values of the supercurrent at the 0-$\pi$ transition, where the first harmonic term in the current vanishes, may be used as efficient supercurrent-switching devices. It is also found that uniaxial spin-flip scattering has very different effect on the 0-$\pi$ transition points depending on whether one regards the width- or temperature-dependence of the current.