Study of Fe Thickness Dependence on Spin-Orbit Torque Efficiency in Fe/Pt and Fe/Cr Bilayer Systems Using Current-Modulated Magneto-Optical Kerr Effect

Ferromagnet/heavy metal bilayer systems offer a robust framework for the investigation of spin-orbit torque phenomena and magnetization dynamics [1]. In this study, we epitaxially grow Fe/Pt and Fe/Cr bilayers with varying thicknesses of each layer to investigate the thickness dependence of spin-orbit torque efficiency using current-modulated magneto-optical detection. We observed a strong variation in spin-orbit torque efficiency as a function of Fe thickness in the two systems. We analyze the contributions of damping-like spin-orbit torque, which rotates the magnetization out of the plane, and field-like spin-orbit torque, which rotates the magnetization in the plane, by examining the polar (out-of-plane) and quadratic (in-plane) components of the magneto-optical Kerr effect.

Reference:

[1] Liu, L.; Pai, C.-F.; Li, Y.; Tseng, H. W.; Ralph, D. C.; Buhrman, R. A. Spin-Torque Switching with the Giant Spin Hall Effect of Tantalum. Science 2012, 336 (6081), 555–558. https://doi.org/10.1126/science.1218197.