Thermal decay of signal and noise in high-density thin-film media

Abstract

A combined experimental and theoretical study of signal and noise decay in a thin-film longitudinal medium is described. The experimental results show that medium noise power increases with time while signal power decreases, resulting in a degradation of signal-to-noise ratio (SNR). A medium noise model is developed. Ry utilizing this model in combination with a previous model of magnetization decay, noise power and SNR decays are calculated. Good agreement between calculations and experimental results is obtained. Theoretical estimates of the dependence of the thermal decay of SNR with temperature and average grain size are given for a high-density system.Iiidex Terms-Magnetic disk recording, signal-to-noise ratio, stability.

Micromagnetics of exchange spring media: Optimization and limits

“…where H c (y) is the Stoner-Wohlfarth switching field at an angle y to the anisotropy axis [36]. The exponent n is 2 for the special case that the external field H is applied parallel to the easy axis.…”

Effect of grain size distribution on recording performance in longitudinal thin film media

“…The total noise power is the sum of DC noise power and transition noise power [15]. To calculate SNR, the signal is obtained from the playback peak voltage of the isolated transition [9].…”

“…We have expanded this result to include effects of DC noise and nonuniform grain size distribution. Following [15], [16], the results are: The results from (5) are compared with the simulation data at 100 kfci in Table VI. Good agreement is found, even though the dibit SNR is slightly different from square wave recording.…”

“…The basic assumption leading to (5) is that the total magnetization can be simply decomposed into a spatially varying part and a uniform DC part [15]. The analysis for transition noise is applied to the spatially varying part and analysis of DC noise is applied to DC part.…”