Spin-orbit torque switching of ultralarge-thickness ferrimagnetic GdFeCo

Abstract

We report on spin-orbit torque measurements in ferrimagnetic ${\mathrm{Gd}}_{21}{({\mathrm{Fe}}_{90}{\mathrm{Co}}_{10})}_{79}$ films with bulk perpendicular magnetic anisotropy and thicknesses up to $30\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$. The dampinglike and fieldlike torques have been quantified using second harmonic Hall voltage detection. Both torques show an inverse linear dependence on the thickness that is indicative of the interfacial nature of the torques. The spin-Hall angle remains constant over the thickness range of 10 to $30\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$ ${\mathrm{Gd}}_{21}{({\mathrm{Fe}}_{90}{\mathrm{Co}}_{10})}_{79}$. Remarkably, we find that this interfacial torque is able to switch a $30\text{\ensuremath{-}}\mathrm{nm}$-thick ${\mathrm{Gd}}_{21}{({\mathrm{Fe}}_{90}{\mathrm{Co}}_{10})}_{79}$ film with a reasonably large thermal stability of $\ensuremath{\approx}100\phantom{\rule{0.16em}{0ex}}{k}_{B}T$.