Information Degradation during Archiving in Heat-Assisted Magnetic Recording

We examine the dependence of information stability on certain medium parameters, namely mean Curie temperature, grain height, and anisotropy constant ratio in 4 Tbpsi heat-assisted magnetic recording, for 10 years of archiving. We introduce a minimum normalized readout field H 0 after 10 years of archiving and an information degradation rate R 0 during 10 years of archiving. To interpret the results, we investigate whether there is a correlation between H 0 or R 0 and an effective thermal stability factor for 9 and 6 grains/bit. We find that there is a strong correlation since the anisotropy constant is much larger than the shape anisotropy. The H 0 and R 0 values are functions of the effective thermal stability factor and grain number, and are independent of grain number per bit. The effective thermal stability factor necessary for no information degradation is more than about 120. Furthermore, there is a weak correlation between the initial readout field or minimum readout field after 10 years of archiving and the effective thermal stability factor.