From direct to inverse GMR: Introduction of Cr in Fe/Cu superlattices

Abstract

It is well known that layered systems can present giant magnetoresistance (GMR). Particularly, the multilayers FeN/Cu8/Fe M/Cr/ FeM/Cu8 show inverse GMR. That is, the electrical conductivity decreases with the applied magnetic field. In the most common multilayers the conductivity increases with the applied field and this kind of GMR is called direct. In general the GMR is attributed to spin-dependent scattering in the bulk and mainly at interfaces. In this work we calculate the electronic band contribution to the GMR for Fe3/Cu 4/Fe/Cr/Fe/Cu4 and Fe3/Cu4 multilayers within the semiclassical approximation. The electrical conductivity is obtained in the ballistic and diffusive regimes. The results show a large change in the GMR behavior when one layer of Cr is introduced within the Fe layers. The GMR calculated in the CPP configuration (current flowing perpendicular to layers) of Fe3/Cu4 is of the direct type, with a value of about 40% while that obtained for Fe3/Cu 4/Fe/Cr/Fe/Cu4 is inverse and of the order of 45%. In the CIP configuration (current flowing parallel to the layers) the calculated GMR is direct with a value of about 35% for the system without Cr while, by the introduction of Cr, we obtain also a direct GMR but of about 3%. © 2001 Published by Elsevier Science B.V.