Monte Carlo simulation of thermal fluctuation in magnetization of longitudinal and perpendicular magnetic recording media

Abstract

Thermal fluctuation in magnetization of longitudinal and perpendicular magnetic recording media was calculated using a Monte Carlo simulation method. Perpendicular recording is superior to longitudinal recording when the thickness is larger than the grain size. Longitudinal recording is superior to perpendicular recording when the grain size is larger than the thickness. Distribution of grain size increases thermal fluctuation of output signal of longitudinal and perpendicular recording media. In longitudinal recording, thermal fluctuation of the output signal increases with increasing recording density, but in perpendicular recording, it decreases with increasing recording density. In longitudinal recording, the reversal of magnetic moments begins near the transition region and then spreads to the other region, but in perpendicular recording the reversal of magnetic moments begins from the saturation region. In longitudinal recording media with well-oriented easy direction or in perpendicular recording media, the residual ratio of the output signal increases with increasing exchange interaction between adjacent grains. In longitudinal recording media in which the easy directions are in the plane of the media, but not well oriented, the residual ratio of the output signal decreases with increasing exchange interaction between adjacent grains when the interaction is not large ( A < 0.4 × 10 −6 erg/cm), and increases with increase in the exchange interaction when it is large ( A > 0.6 × 10 −6 erg/cm).