Switching window analysis of a magnetic media grain in microwave assisted magnetic recording

In order to achieve the effective magnetic switching of a magnetic media grain in the media for microwave assisted magnetic recording, the effects of property distribution of the grain and applying time of the microwave on the switchable frequency window are studied by micromagnetic simulation. The simulation results show the grain dimension and damping constant distribution causes a slight change in switchable frequency window, while the anisotropy energy density and saturation magnetization variation (±10%) may cause the mismatch of the switchable microwave frequency. The switchable frequency window increases with the applying time of the microwave if the microwave duration is shorter than 0.2 ns. Further increase of applying time of the microwave does not further improve the switchable frequency window significantly in the simulation condition when it starts from time zero. These results indicate that it is critical to control the distribution of the anisotropy energy density and saturation magnetization variation to reduce the mismatch of frequency and achieve effective magnetic switching, and the microwave does not need to be on all the time, which can reduce the energy consumption of the microwave generator in the magnetic head.