Superconductor-insulator-ferromagnet-superconductor Josephson junction: From the dirty to the clean limit

TL;DR

This paper analyzes the proximity effect and Josephson current in SIFS junctions across dirty and clean limits, revealing how impurity scattering and interface properties influence superconducting behavior and critical current in ferromagnetic layers.

Contribution

It provides a comprehensive theoretical comparison of dirty and clean limits in SIFS junctions using Eilenberger equations, extending understanding of impurity effects and interface roles.

Findings

Decay length and oscillation period depend nonmonotonically on ferromagnet properties.

Eilenberger functions show different behaviors in dirty and clean regimes.

Results help interpret experimental critical current dependencies on ferromagnet thickness.

Abstract

The proximity effect and the Josephson current in a superconductor-insulator-ferromagnet-superconductor (SIFS) junction are investigated within the framework of the quasiclassical Eilenberger equations. This investigation allows us to compare the dirty and the clean limits, to investigate an arbitrary impurity scattering, and to determine the applicability limits of the Usadel equations for such structures. The role of different types of the FS interface is analyzed. It is shown that the decay length and the spatial oscillation period of the Eilenberger function may exhibit a nonmonotonic dependence on the properties of the ferromagnetic layer such as exchange field or electron mean free path. The results of our calculations are applied to the interpretation of experimentally observed dependencies of the critical current density on the ferromagnet thickness in Josephson junctions containing a Ni layer with an arbitrary scattering.