Damping Constant Influence on Spin Dynamics in Field Generating Layer of STO for MAMR Writing Head

For Microwave Assisted Magnetic Recording (MAMR), large amplitude of ac stray field and coherent motion of magnetization and also low driving power are necessary as a performance of spin torque oscillator for writing head. The damping constant is characterized by both the dynamical motion of magnetization and critical current for the precession-motion. The damping constants for FexCo1-x dot were investigated by a network analyzer-ferromagnetic resonance measurement. From these results, suitable material for the oscillator and the effect of finite magnetic element size are discussed.