Giant spin Hall effect in half-Heusler alloy topological semimetal YPtBi grown at low temperature

Half-Heusler alloy topological semimetal YPtBi is a promising candidate for an efficient spin source material having both large spin Hall angle theta(SH) and high thermal stability. However, high-quality YPtBi thin films with low bulk carrier density are usually grown at 600 ?, which exceeds the limitation of 400 ? for back end of line (BEOL) process. Here, we investigate the crystallinity and spin Hall effect of YPtBi thin films grown at lower growth temperature down to 300 ?. Although both effective spin Hall angle and spin Hall conductivity degraded with lowering the growth temperature to 300 ? due to degradation of the interfacial spin transparency, they were recovered by reducing the sputtering Ar gas pressure. We achieved a giant theta(SH) up to 7.8 and demonstrated efficient spin-orbit torque magnetization switching by ultralow current density of similar to 10(5) A/cm(2) in YPtBi grown at 300 ? with the Ar gas pressure of 1 Pa. Our results provide the recipe to achieve giant theta(SH) in YPtBi grown at lower growth temperature suitable for BEOL process.

Automated summary

The researchers investigated the crystallinity and spin Hall effect of YPtBi thin films grown at lower growth temperature (down to 300 ℃). Although both effective spin Hall angle and spin Hall conductivity degraded with lowering the growth temperature to 300 ℃, they were recovered by reducing the sputtering Ar gas pressure.