Experimental and theoretical study of field-dependent spin splitting at ferromagnetic-insulator-superconductor interfaces

TL;DR

This study combines experiments and theory to analyze how magnetic proximity effects influence spin splitting at ferromagnetic-insulator-superconductor interfaces, revealing the effective interface spin and matching conductance measurements.

Contribution

It introduces a theoretical model for spin-dependent effects at FI-S interfaces and validates it with experimental data, providing new insights into interface spin properties.

Findings

Good agreement between theory and experiment for differential conductance

Effective interface spin determined as J ≈ 0.74ħ

Model depends on few parameters from experimental setup

Abstract

We present a combined experimental and theoretical work that investigates the magnetic proximity effect at a ferromagnetic-insulator - superconductor (FI-S) interface. The simulation is based on the boundary condition for diffusive quasiclassical Greens functions, that accounts for arbitrarily strong spin-dependent effects and spin-mixing angles. The experimentally found differential conductance of an EuS-Al heterostructure is compared with a theoretical calculation. With the assumption of a uniform spin-mixing angle that depends on the externally applied field, we find good agreement between theory and experiment. The theory depends only on very few parameters, mostly specified by the experimental setup. We determine the effective spin of the interface moments as $ J\approx 0.74\hbar $.