Computer simulation of SNR in longitudinal and perpendicular recording

Abstract

Magnetic properties, output signal, media noise and signal to noise ratio (SNR) in longitudinal and perpendicular magnetic recording at 350 K were investigated by solving the Langevin equation numerically and/or by using a Monte Carlo simulation. The exchange interaction between grains was assumed to be zero at first. The effect of thermal fluctuation on output signal of perpendicular media is smaller than that of longitudinal media when the thickness of the media is larger than the grain size, and it is opposite when the grain size is larger than the thickness. The maximum recording density was calculated assuming that SNR of 25 dB was necessary. For longitudinal recording, it is possible to attain the recording density of 30 Gb/in 2 after three years decay. For perpendicular recording, it is possible to attain the recording density of 50 Gb/in 2 after three years decay. The signal increases and media noise decreases with increasing the exchange interaction between adjacent grains of perpendicular recording.