Information stability in three-dimensional heat-assisted magnetic recording

The anisotropy constant ratio Ku / Kbulk necessary for information stability in three-dimensional heat-assisted magnetic recording (3D HAMR) of 2 Tbpsi (total density of 4 Tbpsi) is evaluated by employing a bit error rate calculation using grain error probability. The minimum Ku / Kbulk value of a high Curie temperature (HC) layer is limited by the information stability in the HC layer while writing in a low Curie temperature (LC) layer, and a high Ku / Kbulk is necessary for the HC layer. The minimum Ku / Kbulk value of the LC layer is limited by the information stability in the LC layer for 10 years of archiving, and a high Ku / Kbulk is also necessary for the LC layer since the anisotropy constant of the LC layer is intrinsically low at the storage temperature due to its low Curie temperature. At 9 grains/bit, the Ku / Kbulk values required for 3D HAMR are 0.85 and 0.86 for the HC and LC layers, respectively, taking account of certain variations, namely, standard deviations of 2 % for the Curie temperature and 15 % for the grain size. © 2020, Magnetics Society of Japan. All rights reserved.