Effect of grain size distribution on thermal decay in perpendicular recording with double layered media and single pole head by micromagnetic modeling

Abstract

In this work, micromagnetic simulations of the read/write process for perpendicular systems have been performed. In higher recording densities, grain size distribution is more important due to the dependency of thermal decay and SNR on grain size distribution. Therefore the magnetic layer was simulated by a Voronoi cell with different standard deviation of grain sizes. The effect of a soft under layer (SUL) on read/write was calculated by using a cubic cell. For a realistic writing head field, we used the single pole head field calculated by micromagnetics. Width and thickness of the write pole was 60 nm and 160 nm, respectively. Head sweep velocity during the writing process was taken to be 40 m/s. SNR and thermal decay at a linear density of 1058 kfci were calculated as a function of the different standard deviations of grain sizes. Thermal decay over a long time scale was investigated by the Langevin equation and the time-temperature scaling method. SNR is calculated by the reciprocity principle in a shielded magnetoresistive head.