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

TL;DR

This study demonstrates that highly fcc-textured Pt-Al alloy films grown on MgO(001) exhibit significantly enhanced spin Hall efficiency compared to poorly-crystallized films, promising lower power consumption in spintronic devices.

Contribution

It reveals that improving crystallinity in Pt-Al alloys substantially boosts spin Hall efficiency, highlighting the importance of substrate choice and film texture.

Findings

High damping-like spin Hall efficiency of ~0.20 on MgO.

Up to seven-fold reduction in power consumption compared to polycrystalline films.

Crystallinity is crucial for maximizing spin Hall effects in Pt-based alloys.

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 $\xi_\textrm{DL} \sim +0.20$ 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.