High speed switching measurements in thin film disk media

Thermal switching has been recognized as a possible limit to archival storage in advanced high density recording media. Thinner films with more isolated grains suffer from large magnetic viscosities similar to 10%/decade. Previous work has shown that the observed remanent coercivity H-CR(tau) in high viscosity tapes can be predicted from Sharrock's Law down to 10(-9)s. Here we report high speed switching results on thin film media which show that the remanent coercivity at 10(-8)s is increased similar to 40% relative to the VSM value in these films. A quantitative relationship between the viscosity, irreversible susceptibility, and the increase in H-CR(tau) is demonstrated.