The WRITE process in magnetic recording

An extension of an earlier model of the WRITE process in saturation recording that accounts for internal fields due to magnetization divergence in the recording medium is presented. It is shown that the initial condition of the medium determines the internal field distribution during WRITE and may lead to appreciable peak shift and WRITE over modulation. The special case of two successive reversals of magnetization for a dc biased recording medium is considered in detail. System design criteria for optimization of the recording medium parameters, the head pole gap, and the WRITE time constant are presented for a system where the remaining parameters are constrained. Calculation for the initial and quiescent magnetization and internal field and the expected signal trace, in addition to experimental data, are presented for an out-of-contact drum system employing a NiZn ferrite WRITE-READ head and a CoNiP plating.