Gilbert damping in magnetic multilayers with perpendicular anisotropy

摘要

The magnetic materials with large perpendicular magnetic anisotropy (PMA) and low Gilbert damping constant are quite attractive since they not only have sufficient thermal stability but enable efficient writing in microwave assisted magnetic recording (MAMR) and spin transfer torque based magnetic random access memory (STT-RAM). Recently, we have studied the relationship between Gilbert damping a and PMA of Co-based multilayers, and reported that the a is closely related with thickness ratio of the multilayers, while almost independent of their PMA, suggesting the possibility to obtain the multilayers with high PMA and low damping. In this talk, we summarize the Gilbert damping and anisotropy field of the Co-based multilayers which were evaluated independently by time resolved magneto-optical Kerr effect (TRMOKE) and coplanar waveguide ferromagnetic resonance (CPW-FMR), and discuss systematically the variation of the PMA and Gilbert damping with their layered structures.