2015 年 39 巻 4 号 p. 139-146
Media for heat-assisted magnetic recording (HAMR) are designed with a minimized anisotropy constant ratio Ku / Kbulk by using a model calculation. The design method is improved from the previous rough estimation approach to a statistical estimation of the thermal stability factor of media during writing and rewriting. A comparison is made between HAMR and HAMR combined with shingled magnetic recording. The many relationships between the design parameters and Ku / Kbulk are revealed. The parameters are the thickness of the recording layer, the thermal conductivity of interlayer 1, the light-spot diameter, the heat-spot diameter, the linear velocity, the writing temperature, the grain number per bit, and the standard deviation of the grain size. In certain cases, the limiting factor for obtaining the minimum Ku / Kbulk value is information stability during 10 years of archiving, which relates to improving media preparation to increase Ku / Kbulk. In other cases, the limiting factor is the information stability on the trailing side located 1 bit from the writing position during writing and in the adjacent tracks during rewriting, which relates to examining the media structure to increase the heat-transfer thermal gradients.
