Highly fcc-textured Pt-Al alloy films grown on MgO(001) showing enhanced spin Hall efficiency

Abstract

We report on a systematic comparative study of the spin Hall efficiency between highly face-centered cubic (fcc)-textured Pt-Al alloy films grown on MgO(001) and poorly-crystallized Pt-Al alloy films grown on SiO${}_2$. Using CoFeB as the detector, we show that for Al compositions centering around $x=25$, mainly L1${}_2$ ordered Pt${}_{100-x}$Al${}_x$ alloy films grown on MgO exhibit outstanding charge-spin conversion efficiency. For Pt${}_{78}$Al${}_{22}$/CoFeB bilayer on MgO, we obtain damping-like spin Hall efficiency as high as ${\xi }_{\text{DL}}\sim +0.20$ and expect up to seven-fold reduction of power consumption compared to the polycrystalline bilayer of the same Al composition on SiO${}_2$. This work demonstrates that improving the crystallinity of fcc Pt-based alloys is a crucial step for achieving large spin Hall efficiency and low power consumption in this material class.

22 pages, 6 figures

References in corpus (5)

• Theory of spin Hall magnetoresistance
• Single-shot dynamics of spin-orbit torque and spin transfer torque switching in three-terminal magnetic tunnel junctions
• Spin-orbit torques in heavy metal/ferromagnet bilayers with varying strength of interfacial spin-orbit coupling
• Strong damping-like spin-orbit torque and tunable Dzyaloshinskii-Moriya interaction generated by low-resistivity Pd${}_{1-x}$Pt${}_x$ alloys
• Benchmarking of spin-orbit torque switching efficiency in Pt alloys