Micromagnetic studies of switching speed in longitudinal and perpendicular polycrystalline thin film recording media

Micromagnetic modeling is used to study the gyromagnetic switching process in longitudinal and perpendicular thin film media. Medium magnetization switching time under an applied uniform reverse field is studied by varying the damping constant α. The remanent coercivity dependence on the time duration of applied pulse field is studied for media with different inter-granular exchange coupling. At a constant recording density of 635 kfci, square wave recording is simulated with different bit cell time (0.4–4.0 ns) by varying the relative head medium linear speed from 10 to 100 m/s. The gyromagnetic switching limit on longitudinal and perpendicular media is examined at data rates from 500 MHz to 2.5 GHz with α=0.02 and 0.05. Incomplete magnetization reversal occurs for perpendicular media at a lower recording data rate than for longitudinal media.