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

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. By 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.