Kim Sumin, Lee Hyun-Woo, Choi Gyung-Min
Department of Energy Science, Sungkyunkwan University, Suwon, 16419, South Korea.
Department of Physics, Pohang University of Science and Technology, Pohang, 37673, South Korea.
Adv Sci (Weinh). 2023 Nov;10(31):e2303831. doi: 10.1002/advs.202303831. Epub 2023 Sep 7.
Bismuth (Bi) has the strongest spin-orbit coupling among non-radioactive elements and is thus a promising material for efficient charge-to-spin conversion. However, previous electrical detections have reported controversial results for the conversion efficiency. In this study, an optical detection of a spin-orbit torque is reported in a Bi/CoFeB bilayer with a polycrystalline texture of (012) and (003). Taking advantage of the optical detection, spin-orbit torque is accurately separated from the Oersted field and achieves a giant damping-like torque efficiency of +0.5, verifying efficient charge-to-spin conversion. This study also demonstrates a field-like torque efficiency of -0.1. For the mechanism of the charge-to-spin conversion, the bulk spin Hall effect and the interface Rashba-Edelstein effect are considered.
铋（Bi）在非放射性元素中具有最强的自旋轨道耦合，因此是一种有望实现高效电荷到自旋转换的材料。然而，先前的电学检测报告了关于转换效率的有争议的结果。在本研究中，报道了在具有（012）和（003）多晶织构的Bi/CoFeB双层中对自旋轨道扭矩的光学检测。利用光学检测，自旋轨道扭矩与奥斯特场被准确分离，并实现了高达+0.5的巨大类阻尼扭矩效率，验证了高效的电荷到自旋转换。本研究还展示了-0.1的类场扭矩效率。对于电荷到自旋转换的机制，考虑了体自旋霍尔效应和界面Rashba-Edelstein效应。
