Micromagnetic Simulation of Spin-Torque Oscillator for Microwave-Assisted Magnetic Recording—Interaction Between Write Head and STO and Optimum Injected Current.

The spin-torque oscillator (STO) is the most important component in microwave-assisted magnetic recording (MAMR). To realize MAMR, a small injected STO current is mandatory, as are large amplitude and stable oscillations. In this paper, an isolated STO element (without the write head) and an STO integrated into a write head were analyzed using micromagnetic analysis. First, the integrated STO was used and the optimum injected currents ( $J_{{\textrm {opt}}}\text{s} ) that excite high-frequency magnetic fields were derived for various Gilbert damping factors ( \alpha \texts ) and saturation magnetization ( 4\pi M_s ) in the field generating layer. Second, $J_{{\textrm {opt}}}\text{s}$ were derived for various isolated STO structures. The effect of the material characteristics on $J_{{\textrm {opt}}}$ was also investigated. [ABSTRACT FROM PUBLISHER]