Large Spin Hall Angle and Spin-Mixing Conductance in the Highly Resistive Antiferromagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>Mn</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>Au</mml:mi></mml:math>

Abstract

Antiferromagnetic materials (AFMs) have recently been attracting interest in research on spintronics due to their zero stray magnetic field, high anisotropy, and spin-orbit coupling. In this context, the bimetallic AFM ${\mathrm{Mn}}_{2}\mathrm{Au}$ has drawn attention because it exhibits unique properties and its N\'eel temperature is very high (${T}_{N}=1500\phantom{\rule{0.2em}{0ex}}\mathrm{K}$). Here, we report investigations of spin pumping and the inverse spin Hall effect (ISHE) in a ${\mathrm{Mn}}_{2}\mathrm{Au}/\mathrm{Co}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{B}$ bilayer system using ferromagnetic resonance. We find a large spin Hall angle ${\ensuremath{\theta}}_{\mathrm{SH}}=0.22$, with a spin Hall conductivity ${\ensuremath{\sigma}}_{\mathrm{SH}}=1.46\ifmmode\times\else\texttimes\fi{}{10}^{5}(\ensuremath{\hbar}/2e)\phantom{\rule{0.2em}{0ex}}{\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}1}\phantom{\rule{0.2em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}$, comparable to that of $\mathrm{Pt}$. Further, we evaluate the effective spin-mixing conductance ${g}_{\mathrm{eff}}^{\ensuremath{\uparrow}\ensuremath{\downarrow}}=3.27\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{0.2em}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}$ and intrinsic spin-mixing conductance ${g}_{r}^{\ensuremath{\uparrow}\ensuremath{\downarrow}}=8.83\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{0.2em}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}$, which are higher than the previously reported value ($1.40\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{0.2em}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}$ for ${\mathrm{Mn}}_{2}\mathrm{Au}/{\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$).

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