Impurity and band effects competition on the appearence of Inverse Giant Magnetoresistence in Cu/Fe multilayers with Cr

TL;DR

This study investigates how impurity and band effects influence the emergence of inverse giant magnetoresistance in Cu/Fe multilayers with Cr, considering different geometries and comparing theoretical results with experiments.

Contribution

It demonstrates that Cr band effects are essential to explain the experimental GMR behavior in Cu/Fe/Cr multilayers, highlighting the role of hybridization and interface roughness.

Findings

Cr band effects are necessary to explain experimental GMR curves.

Interface roughness enhances IGMR in CIP geometry.

Stronger Cr/Fe hybridization increases IGMR tendency.

Abstract

We have studied the dependence of impurity vs. band effects in the appearance of inverse giant magnetoresistance (IGMR) in Cu/Fe superlattices whit Cr. Current in plane (CIP) and current perpendicular to the plane (CPP) geometries are considered. For the calculation of the conductivities we have used the linearized Boltzmann equation in the relaxation time approximation. Cr impurity effects are taken into account through the spin dependent relaxation times and the band effects through the semiclassical velocities obtained from the LDA calculated electronic structure. The larger the Cr/Fe hybridization strength, the bigger is the tendency towards IGMR. In particular, in CIP geometry roughness at these interfaces increases the IGMR range. The results are compared with experiments and we conclude that the experimental GMR curves can only be explained if Cr bands are present.