Interlayer exchange coupling in Fe/Cr multilayers

TL;DR

This paper explores the origin of long-period oscillations in interlayer exchange coupling in Fe/Cr multilayers, linking oscillation periods to Fermi surface extremal vectors and calculating coupling strength with a realistic model.

Contribution

It introduces a detailed calculation of exchange coupling in Fe/Cr multilayers using a tight-binding model with spin-orbit interaction, identifying key extremal vectors responsible for observed oscillations.

Findings

Oscillation periods linked to Fermi surface extremal vectors.

Largest coupling strength from the extremal vector at the N point.

Growth directions (001) and (110) show similar dominant vectors.

Abstract

We investigate the origin of the long period oscillation of the interlayer exchange coupling in Fe/Cr trilayer systems. Within the stationary phase approximation the periods of the oscillations are associated with extremal vectors of the Fermi sphere of Cr. Using a realistic tight-binding model with spin-orbit interaction we calculate the coupling strength for each extremal vector based on the spin-asymmetry of the reflection amplitude for a propagating state impinging from the Cr to Fe layer. We find that for (001) and (110) growth direction the biggest coupling strength comes from the extremal vector centered at the ellipsoid N of the Fermi surface of Cr.