Media damping constant and performance characteristics in microwave assisted magnetic recording with circular ac field

Medium damping constant remains as one of the key concerns for microwave assisted magnetic recording (MAMR) since switching field reduction seems to be less evident for media with possible high damping constant. In this paper, the impact of medium damping constant on the recording performance is analyzed via dynamic micromagnetic modeling for MAMR with a polarized ac field. The analysis on isolated grains shows that when matching the precession chirality, switching field reduction is significantly greater with circular ac field than that with linear ac field, especially in high damping regime. Recording simulations show that an area density of 1.88 Tb/in.2 with a medium signal-to-noise ratio of 18.2 dB can be achieved on media with strong anisotropy of 31 kOe and a relatively high damping constant of 0.1.