Observation of out-of-plane spin-orbit torque in a polycrystalline <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Py</mml:mi> <mml:mtext>/</mml:mtext> <mml:msub> <mml:mi>IrMn</mml:mi> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> heterostructure

Abstract

The generation of on-demand out-of-plane spin polarization (${\mathbit{\ensuremath{\sigma}}}_{z}$) promises an efficient field-free switching of perpendicular nanomagnet has been limited mostly in the single crystal materials. For a direct technological application, it is desired to have an out-of-plane spin current generation from polycrystalline sputtered films rather than expensive single crystalline films. Here, we report the observation of out-of-plane and in-plane torques generated by the $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{z}$ and $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{x}$ spin polarization in the polycrystalline antiferromagnet ${\mathrm{IrMn}}_{3}$/permalloy (Py) heterostructure. A comparatively high value of out-of-plane spin torque ratio of 0.024 has been observed with a large out-of-plane spin Hall conductivity of $\ensuremath{\approx}2.82\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{4pt}{0ex}}(\frac{\ensuremath{\hbar}}{2e}){(\mathrm{\ensuremath{\Omega}}\mathrm{m})}^{\ensuremath{-}1}$. Additionally, we have investigated the underline mechanism and the fundamental role of $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{z}$ spins in the context of external field-free magnetization switching of a perpendicular magnetic anisotropy (PMA) material. Our findings provide a new perspective on generation and detection of out-of-plane spin polarization in antiferromagnet material and manipulate the magnetization for the development of the next generation high-density, low-power consumption, logic device applications.

Topics & Concepts