Spin-Hall and Anisotropic Magnetoresistance in Ferrimagnetic Co-Gd / Pt layers

TL;DR

This study investigates how the spin-Hall and anisotropic magnetoresistance in Co-Gd/Pt bilayers depend on Gd composition, revealing different scattering mechanisms and a compensation point where AMR vanishes.

Contribution

It provides the first detailed analysis of composition-dependent SMR and AMR in ferrimagnetic Co-Gd/Pt layers, highlighting their distinct behaviors and underlying mechanisms.

Findings

AMR changes sign and vanishes near compensation point

SMR remains relatively constant across compositions

Different scattering mechanisms drive AMR and SMR

Abstract

We present the Co-Gd composition dependence of the spin-Hall magnetoresistance (SMR) and anisotropic magnetoresistance (AMR) for ferrimagnetic Co100-xGdx / Pt bilayers. With Gd concentration x, its magnetic moment increasingly competes with the Co moment in the net magnetization. We find a nearly compensated ferrimagnetic state at x = 24. The AMR changes sign from positive to negative with increasing x, vanishing near the magnetization compensation. On the other hand, the SMR does not vary significantly even where the AMR vanishes. These experimental results indicate that very different scattering mechanisms are responsible for AMR and SMR. We discuss a possible origin for the alloy composition dependence.