Comparative Measurements of Inverse Spin Hall and Magnetoresistance in YIG|Pt and YIG|Ta

TL;DR

This study compares spin Hall effects and magnetoresistance in YIG|Pt and YIG|Ta bilayers, estimating key transport parameters and confirming opposite spin Hall angles, with implications for spintronic device design.

Contribution

It provides the first direct comparison of spin Hall and magnetoresistance effects in YIG|Pt and YIG|Ta, extracting spin diffusion lengths and confirming opposite spin Hall angles.

Findings

Opposite signs of spin Hall angles in Pt and Ta.

Spin diffusion length in Ta estimated as 1.8±0.7 nm.

Similar magnetoresistance behavior explained by spin Hall magnetoresistance framework.

Abstract

We report on a comparative study of spin Hall related effects and magnetoresistance in YIG|Pt and YIG|Ta bilayers. These combined measurements allow to estimate the characteristic transport parameters of both Pt and Ta layers juxtaposed to YIG: the spin mixing conductance $G_{\uparrow \downarrow}$ at the YIG$|$normal metal interface, the spin Hall angle $\Theta_{SH}$, and the spin diffusion length $\lambda_{sd}$ in the normal metal. The inverse spin Hall voltages generated in Pt and Ta by the pure spin current pumped from YIG excited at resonance confirm the opposite signs of spin Hall angles in these two materials. Moreover, from the dependence of the inverse spin Hall voltage on the Ta thickness, we extract the spin diffusion length in Ta, found to be $\lambda_{sd}^\text{Ta}=1.8\pm0.7$ nm. Both the YIG|Pt and YIG|Ta systems display a similar variation of resistance upon magnetic field orientation, which can be explained in the recently developed framework of spin Hall magnetoresistance.