Spin-orbit torque magnetometry by wide-field magneto-optical Kerr effect

Tsung-Yu Tsai; Tian-Yue Chen; Chun-Ting Wu; Hsin-I Chan; Chi-Feng Pai

doi:10.1038/s41598-018-23951-w

Spin-orbit torque magnetometry by wide-field magneto-optical Kerr effect

Sci Rep. 2018 Apr 4;8(1):5613. doi: 10.1038/s41598-018-23951-w.

Authors

Tsung-Yu Tsai¹, Tian-Yue Chen¹, Chun-Ting Wu^{1

2}, Hsin-I Chan¹, Chi-Feng Pai³

Affiliations

¹ Department of Materials Science and Engineering, National Taiwan University, Taipei, 10617, Taiwan.
² Department of Computer Science and Information Engineering, National Taiwan University, Taipei, 10617, Taiwan.
³ Department of Materials Science and Engineering, National Taiwan University, Taipei, 10617, Taiwan. cfpai@ntu.edu.tw.

Abstract

Magneto-optical Kerr effect (MOKE) is an efficient approach to probe surface magnetization in thin film samples. Here we present a wide-field MOKE technique that adopts a Köhler illumination scheme to characterize the current-induced damping-like spin-orbit torque (DL-SOT) in micron-sized and unpatterned magnetic heterostructures with perpendicular magnetic anisotropy. Through a current-induced hysteresis loop shift analysis, we quantify the DL-SOT efficiency of a Ta-based heterostructure with bar-shaped geometry, Hall-cross geometry, and unpatterned geometry to be |ξ _DL | ≈ 0.08. The proposed wide-field MOKE approach therefore provides an instant and direct characterization of DL-SOT, without the need of any further interpretation on electrical signals.