Spin-orbit torques in Ta/TbxCo100-x ferrimagnetic alloy films with bulk perpendicular magnetic anisotropy

We quantified the bulk perpendicularmagnetic anisotropy (PMA) and spin-orbit torques (SOTs) in bilayer Ta/TbxCo100-xferrimagnetic alloyfilms with varying Tb concentration. Thecoercivity increases dramatically with increasing TbxCo100-x thickness and is enhanced by the presence of aTa underlayer. TheTa underlayer simultaneously serves as a source of SOT due to the spin Hall effect, which we show provides an efficient means to manipulate the magnetization in bulk PMAmaterials. It is further shown that the sign of the anomalous Hall voltage is different for rare-earth (RE) and transition-metal (TM) dominated alloy compositions, whereas the sign of the SOT effective field remains the same, suggesting that the former is related to the TM sublattice magnetization whereas the latter is related to the net magnetization. Our results suggest that Ta/TbxCo100-x is a potential candidate for spin-orbitronic device applications and give insight into spin transport and SOTs in rare-earth/transition-metal alloys.

Source: Applied Physics Letters - December 5, 2016 Category: Physics Authors: Kohei Ueda, Maxwell Mann, Chi-Feng Pai, Aik-Jun Tan and Geoffrey S. D. Beach Source Type: research