Large fieldlike torque in amorphous Ru2Sn3 originated from the intrinsic spin Hall effect

We investigated temperature dependent current driven spin-orbit torques in magnetron sputtered Ru2Sn3 (4 and 10 nm)/Co20Fe60B20 (5 nm) layered structures with in-plane magnetic anisotropy. The room temperature dampinglike and fieldlike spin torque efficiencies of the amorphous Ru2Sn3 films were measured to be 0.14 +/- 0.008 (0.07 +/- 0.012) and -0.03 +/- 0.006 (-0.20 +/- 0.009), for the four (10 nm) films, respectively, by utilizing the second-harmonic Hall technique. The large fieldlike torque in the relatively thicker Ru2Sn3 (10 nm) thin film is unique compared to the traditional spin Hall materials interfaced with thick magnetic layers with in-plane magnetic anisotropy which typically have dominant dampinglike and negligible fieldlike torques. Additionally, the observed room temperature fieldlike torque efficiency in Ru2Sn3 (10 nm)/CoFeB (5 nm) is up to three times larger than the dampinglike torque (-0.20 +/- 0.009 and 0.07 +/- 0.012, respectively) and 30 times larger at 50 K (-0.29 +/- 0.014 and 0.009 +/- 0.017, respectively). The temperature dependence of the fieldlike torques shows dominant contributions from the intrinsic spin Hall effect while the dampinglike torques show dominate contributions from the extrinsic spin Hall effects, skew scattering, and side jump. Through macrospin calculations, we found that including fieldlike torques on the order of or larger than the dampinglike torque can reduce the switching critical current and decrease magnetization procession for a perpendicular ferromagnetic layer.

Automated summary

This study investigated the temperature dependent current driven spin-orbit torques in layered structures with in-plane magnetic anisotropy consisting of Ru2Sn3/Co20Fe60B20 films. It was found that the amorphous Ru2Sn3 films exhibit unique fieldlike torque behavior in comparison to traditional spin Hall materials, with significant differences in torque efficiencies at room temperature and 50K. The research also revealed the impact of different types of spin Hall effects on the observed torques, with implications for reducing critical current and magnetization procession in ferromagnetic layers.