Large Spin-Orbit-Torque Efficiency and Room-Temperature Magnetization Switching in SrIrO3/ Co-Fe-B Heterostructures

Abstract

Spin-orbit-torque (SOT) switching is a potentially energy-efficient mechanism by which electrical current can control magnetization. We demonstrate room-temperature SOT switching in nanometer-thick ${\mathrm{Co}\mathrm{Fe}\mathrm{B}/\mathrm{Sr}\mathrm{Ir}\mathrm{O}}_{3}$ bilayers despite the amorphous nature of CoFeB and the interface. This behavior is attributed to the large spin Hall angle in ${\mathrm{Sr}\mathrm{Ir}\mathrm{O}}_{3}$ as well as high spin transmission at the interface that contribute to the SOT efficiency ${\ensuremath{\xi}}_{\mathrm{SOT}}$. Our bilayers exhibit large ${\ensuremath{\xi}}_{\mathrm{SOT}}$ of up to 1.4 and effective spin Hall conductivity of $0.9\ifmmode\times\else\texttimes\fi{}{10}^{5}$ ($\ensuremath{\hbar}/$2e)${\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}1}{\mathrm{m}}^{\ensuremath{-}1}$. In our bilayers, we observe unidirectional magnetoresistance and current-induced magnetization switching with a low critical current density of $1.38\ifmmode\times\else\texttimes\fi{}{10}^{10}\phantom{\rule{0.2em}{0ex}}{\mathrm{A}/\mathrm{m}}^{2}$ at room temperature. Our results are promising for heterostructures combining technologically relevant CoFeB with high spin-orbit-coupling oxides.