Spin pumping and inverse spin Hall effect in CoFeB/IrMn heterostructures

TL;DR

This study investigates spin pumping and inverse spin Hall effect in CoFeB/IrMn heterostructures, demonstrating efficient spin to charge conversion and the dominance of spin pumping over other effects, with implications for spintronics devices.

Contribution

First detailed analysis of ISHE and spin pumping in CoFeB/IrMn heterostructures, highlighting the role of antiferromagnetic IrMn in spin conversion efficiency.

Findings

Higher damping indicates spin pumping via IrMn.

Spin pumping confirmed by angle-dependent ISHE measurements.

Real part of spin mixing conductance is approximately 0.704 x 10^{18} m^{-2}.

Abstract

High spin to charge conversion efficiency is the requirement for the spintronics devices which is governed by spin pumping and inverse spin Hall effect (ISHE). In last one decade, ISHE and spin pumping are heavily investigated in ferromagnet/ heavy metal (HM) heterostructures. Recently antiferromagnetic (AFM) materials are found to be good replacement of HMs because AFMs exhibit terahertz spin dynamics, high spin-orbit coupling, and absence of stray field. In this context we have performed the ISHE in CoFeB/ IrMn heterostructures. Spin pumping study is carried out for $Co_{40}Fe_{40}B_{20} (12\ nm)/ Cu (3\ nm)/ Ir_{50}Mn_{50} (t\ nm)/ AlO_{x} (3\ nm)$ samples where \textit{t} value varies from 0 to 10 nm. Damping of all the samples are higher than the single layer CoFeB which indicates that spin pumping due to IrMn is the underneath mechanism. Further the spin pumping in the samples are confirmed by angle dependent ISHE measurements. We have also disentangled other spin rectifications effects and found that the spin pumping is dominant in all the samples. From the ISHE analysis the real part of spin mixing conductance (\textit{$g_{r}^{\uparrow \downarrow}$}) is found to be 0.704 $\pm$ 0.003 $\times$ $10^{18}$ $m^{-2}$.