Thickness dependence of spin Hall magnetoresistance in FeMn/Pt bilayers

TL;DR

This study reveals that spin Hall magnetoresistance in FeMn/Pt bilayers is significantly larger than in similar systems, varies non-monotonically with layer thicknesses, and allows extraction of key spin transport parameters.

Contribution

It provides the first detailed analysis of thickness-dependent spin Hall magnetoresistance in FeMn/Pt bilayers, including key spin transport parameters and their relation to the spin orbit torque effect.

Findings

Spin Hall magnetoresistance is an order of magnitude larger than in similar bilayers.

The magnetoresistance depends non-monotonically on FeMn and Pt thicknesses.

Spin Hall angle, spin diffusion length, and spin mixing conductance were quantitatively determined.

Abstract

We investigated spin Hall magnetoresistance in FeMn/Pt bilayers, which was found to be one order of magnitude larger than that of heavy metal and insulating ferromagnet or antiferromagnet bilayer systems, and comparable to that of NiFe/Pt bilayers. The spin Hall magnetoresistance shows a non-monotonic dependence on the thicknesses of both FeMn and Pt. The former can be accounted for by the thickness dependence of net magnetization in FeMn thin films, whereas the latter is mainly due to spin accumulation and diffusion in Pt. Through analysis of the Pt thickness dependence, the spin Hall angle, spin diffusion length of Pt and the real part of spin mixing conductance were determined to be 0.2, 1.1 nm, and $5.5 * 10^{14} {\Omega}^{-1} m^{-2}$, respectively. The results corroborate the spin orbit torque effect observed in this system recently.