R&D: Information Degradation During Archiving in HAMR

Journal of the Magnetics Society of Japan has published an article written by T. Kobayashi,Graduate School of Engineering, Mie University, Japan, Y. Nakatani, Graduate School of Informatics and Engineering, Univ. of Electro-Communications, Japan, and Y. Fujiwara, Graduate School of Engineering, Mie University, Japan.

Abstract: “We examine the dependence of information stability on certain medium parameters, namely mean Curie temperature, grain height, and anisotropy constant ratio in 4Tbpsi heat-assisted magnetic recording, for 10 years of archiving. We introduce a minimum normalized readout field H₀ after 10 years of archiving and an information degradation rate R₀ during 10 years of archiving. To interpret the results, we investigate whether there is a correlation between H₀ or R₀ 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 H₀ and R₀ 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.“