Effect of intergranular exchange coupling on transition irregularity in coupled granular/continuous perpendicular media

Abstract

Recent simulations of coupled granular/continuous (CGC) perpendicular media are reviewed, and mechanisms previously shown to reduce bit transition irregularity are clarified using three-dimensional micromagnetic model that includes a simple representation of grain shape irregularity. Increasing intergranular exchange coupling is found to resolve magnetic clusters at the bit transition into smaller switching units. This is shown to reduce the amplitude and cross-track correlation length of the transition irregularity. The signal-to-noise ratio (SNR) of high-density granular media and CGC media is optimized with respect to intergranular exchange coupling. Depending on the media parameters used, the recording properties of granular and CGC media are found to differ, with CGC providing greater SNR. Preliminary experimental data are presented and found to support the results obtained from simulations.