Inverse spin Hall effect and spin pumping in the polycrystalline noncollinear antiferromagnetic Mn3Ga

Abstract

Noncollinear antiferromagnetic (AFM) materials have drawn research interest because they exhibit large anomalous Hall effect at room temperature (RT) due to large Berry curvature. ${\mathrm{Mn}}_{3}\mathrm{Ga}$ is a noncollinear AFM in which the order of Mn magnetic moments is arranged in inverse triangular configuration on a kagome lattice. It makes ${\mathrm{Mn}}_{3}\mathrm{Ga}$ a promising candidate for inverse spin Hall effect (ISHE) study which has not been studied before. In this work, investigation of ISHE and spin pumping in polycrystalline ${\mathrm{Mn}}_{3}\mathrm{Ga}$/CoFeB heterostructures at RT has been performed. Angle-dependent measurements of ISHE have been performed in order to disentangle various spin-rectification effects. Spin-mixing conductance (${g}_{\mathrm{eff}}^{\ensuremath{\uparrow}\ensuremath{\downarrow}})$, spin Hall angle $({\ensuremath{\theta}}_{SH})$, and spin Hall conductivity (${\ensuremath{\sigma}}_{SH}$) are evaluated to be $(5.0\ifmmode\pm\else\textpm\fi{}1.8)\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}, 0.31\ifmmode\pm\else\textpm\fi{}0.01$, and $7.5\ifmmode\times\else\texttimes\fi{}{10}^{5}\phantom{\rule{0.28em}{0ex}}(\ensuremath{\hbar}/2e)\phantom{\rule{0.16em}{0ex}}{\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}1\phantom{\rule{4pt}{0ex}}}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}$, respectively. The observed value of ${\ensuremath{\theta}}_{SH}$ is higher than ${\mathrm{Mn}}_{3}\mathrm{Sn}$ and comparable to the ${\mathrm{IrMn}}_{3}$, which is also a noncollinear AFM. Large spin Hall angle makes ${\mathrm{Mn}}_{3}\mathrm{Ga}$ a promising candidate for future spintronics devices.