High frequency out-of-plane oscillation with large cone angle in mag-flip spin torque oscillators for microwave assisted magnetic recording

摘要

We investigated spin torque induced magnetization dynamics in the mag-flip spin torque oscillators (STOs) of diameters D from 29 to 96 nm comprising of an in-plane magnetized field generation layer (FGL) Fe_(67)Co_(33) (7 nm) with high saturation magnetization, µ_0M_s ～ 2.3 T, and perpendicular FePt(10nm)/Co_2FeGa_(0.5)Ge_(0.5)(3nm) highly spin polarized spin injection layers. Out-of-plane high frequency,21-26 GHz, spin torque induced oscillation with a large cone angle in FGL was observed under nearly perpendicular external magnetic field µ_0H_(ext) of 1.1 T for the pillar D of 29 and 42 nm. Our micromagnetic simulation results indicated that ac magnetic fields of about 0.15 to 0.2 T are obtainable from the STOs having the same stacking structure and size as the experiment, which is large enough for the applications to microwave assisted magnetic recording technology.