Experimental study of the head/medium magneto dynamics in perpendicular recording

A study has been conducted on the characteristics of the reversal dynamics for a perpendicular recording system consisting of a pole head, a recording layer, and a soft under layer (SUL) using time-resolved Kerr microscopy. It was found that the local step response as well as the 2-D magnetization distribution of the SUL in the pole area during reversal depend on the initial magnetization state of the recording layer. This phenomenon can cause pattern-dependent nonlinear timing shifts of the write process. The precessional frequency of the SUL response also differs for the two initial states. In the 2-D time-slices of the magnetization reversal we find evidence for the generation of spin wave modes which can limit the achievable data rate.