Local Density of States and Order Parameter Configurations in Layered Ferromagnet-Superconductor Structures

TL;DR

This paper investigates how the local density of states in layered ferromagnet-superconductor heterostructures is affected by various physical parameters, revealing signatures of different stable and metastable pair configurations.

Contribution

It provides a systematic analysis of the LDOS in SFS and SFSFSFS structures, highlighting the influence of magnetic exchange, interface scattering, and Fermi mismatch on electronic spectra.

Findings

Identification of stable and metastable pair amplitude configurations.

Signatures of pair configurations in the LDOS spectra.

Influence of magnetic and interface parameters on LDOS features.

Abstract

We analyze the local density of states (LDOS) of heterostructures consisting of alternating ferromagnet, $F$, and superconductor, $S$, layers. We consider structures of the $SFS$ and $SFSFSFS$ type, with thin nanometer scale $F$ and $S$ layers, within the ballistic regime. The spin-splitting effects of the ferromagnet and the mutual coupling between the $S$ regions, yield several nontrivial stable and metastable pair amplitude configurations, and we find that the details of the spatial behavior of the pair amplitude govern the calculated electronic spectra. These are reflected in discernible signatures of the LDOS. The roles that the magnetic exchange energy, interface scattering strength, and the Fermi wavevector mismatch each have on the LDOS for the different allowed junction configurations, are systematically investigated.