Park, Eun-Sang Lee, Dong-Kyu Xue, Fei Min, Byoung-Chul Koo, Hyun Cheol Haney, Paul M. Kim, Kyoung-Whan Lee, Kyung-Jin 2024-01-19T10:03:44Z 2024-01-19T10:03:44Z 2023-03-16 2023-02 2469-9950 https://pubs.kist.re.kr/handle/201004/114013 The symmetry of normal metal/ferromagnet bilayers allows spin-orbit torques (SOTs) to simultaneously have two distinct angular dependences on the magnetization direction <SIC>m. The most well-studied forms of SOT consist of the conventional fieldlike and dampinglike torques, which we label as "lowest-order" SOT. There are additional SOT forms associated with spin polarization different from that of the lowest-order SOT, and which contain an extra factor of m<SIC> dependence. We label these as "higher-order" SOT. Understanding SOT-driven magnetization dynamics requires detailed information about the full angular dependence. In this paper, we measure both the lowest-order and higher-order angular dependences of SOTs in three types of bilayers, Pt/Co, Ta/CoFeB, and W/CoFeB, using harmonic Hall measurements. It is found that the higher-order SOT is negligible for Pt/Co and Ta/CoFeB, whereas it is dominant over the lowest-order one for W/CoFeB. Macrospin simulations show that the higher-order SOT can significantly affect the magnetization dynamics, which is qualitatively in line with SOT-induced switching experiments. English AMER PHYSICAL SOC Strong higher-order angular dependence of spin-orbit torque in W/CoFeB bilayer Article 10.1103/PhysRevB.107.064411 1 Physical Review B, v.107, no.6 Physical Review B 107 6 N scie scopus 000931987700003 2-s2.0-85148420461 Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Materials Science Physics Article CURRENT-DRIVEN DYNAMICS PERPENDICULAR MAGNETIZATION LOW-POWER SYMMETRY