Micromagnetic Model Analysis of Spin-Torque Oscillator (STO) Integrated Into Recording Head for Microwave-Assisted Magnetic Recording—Oscillation of STO Versus Rise Time of In-Gap Field

Stable oscillation is one of the most important factors for spin-torque oscillators (STOs) used in a microwave-assisted magnetic recording system. We use a micromagnetic, integrated STO model, in which the STO is inserted into the main pole-trailing shield (MP-TS) gap of a write head, and show that the rise time of the in-gap field acting on the STO is critical to stable STO oscillation. We also show that the combination of a tilted STO and a tilted MP-TS gap results in stable STO oscillation due to weaker magnetostatic interactions between the STO and the write head.