Exchange Coupling Between Iron Layers Separated by BCC Copper

TL;DR

This paper investigates how the exchange coupling between iron layers separated by BCC copper varies with spacer thickness and temperature, revealing the dominant role of Fermi surface extrema and complex temperature effects.

Contribution

It provides a detailed calculation of exchange coupling in Fe/Cu/Fe trilayers, highlighting the influence of Fermi surface features and temperature dependence on magnetic interactions.

Findings

Coupling is mainly influenced by three Fermi surface extrema.

The dominant contribution comes from the 'belly' at the Γ-point.

Temperature effects can increase coupling for certain spacer thicknesses.

Abstract

The exchange coupling between Fe layers separated by BCC Cu is calculated for Fe/Cu/Fe (001) trilayers. It is shown that the coupling is basically regulated by three extrema of the bulk BCC Cu Fermi surface. The contributions from those extrema are all of the same order of magnitude, but that associated with the ``belly'' at the $\Gamma$-point dominates. The calculated temperature dependence of the coupling varies considerably with spacer layer thickness. Individually, the amplitudes of these extrema contribution decrease with temperature, each according to a different rate. Such an effect may cause an actual increase of coupling with temperature for some Cu thicknesses.