Adjacent and far track erasure dependence on media SUL permeability in shielded PMR head recording

Adjacent or far track erasure (ATE or FTE) in PMR recording can limit the recording track density. In a typical PMR head design, a shield is added near to the write pole to increase the write field gradient. The shield, however, leads to an additional flux path during writing, resulting in the erasure of neighboring tracks and bit error rate (BER) degradation. The media soft underlayer (SUL) is a part of the flux return path and its magnetic properties can also affect the ATE performance [1]. In this study, we report on systematic experimental and modelling results of ATE and FTE behavior of a PMR head with a wrapped-around shield (WAS) as a function of the SUL permeability and thickness.