Magnetoresistance of magnetic multilayers in the CPP mode:evidence for non-local scattering

TL;DR

This study investigates the magnetoresistance in magnetic multilayers in the CPP mode, revealing that layer ordering affects MR curves due to non-local electron scattering, challenging the predictions of the series resistor model.

Contribution

It demonstrates that non-local electron scattering explains MR behavior in multilayers, contradicting the assumption of layer-order independence in the series resistor model.

Findings

MR curves differ with layer ordering, contrary to model predictions

Non-local scattering accounts for observed MR differences

Results do not require spin-flip scattering or short spin diffusion length

Abstract

We have carried out measurements of the magnetoresistance MR(H) in the CPP (Current Perpendicular to the Plane) mode for two types of magnetic multilayers which have different layer ordering. The series resistor model predicts that CPP MR(H) is independent of the ordering of the layers. Nevertheless, the measured MR(H) curves were found to be completely different for the following two configurations:[Co(1nm)/Cu(20nm)/Co(6nm)/Cu(20nm)]*N and [Co(1nm)/Cu(20nm)]*N[Co(6nm)/Cu(20nm)]*N showing that the above model is incorrect. We have carried out a calculation showing that these results can be explained quantitatively in terms of the non-local character of the electron scattering, without the need to invoke spin-flip scattering or a short spin diffusion length.