Numerical study of thermal-induced lubricant depletion induced on an anisotropic multilayer disk in a heat assisted magnetic recording system

This paper presents a numerical investigation of heat transfer and lubricant depletion on the hard disk surface in a heat-assisted magnetic recording (HAMR) system. The disk consists of multilayer structures with anisotropic thermal properties on the top-recording layer and a thin layer of lubricant on the top surface. The heat generated by the laser results in the non-uniform temperature filed and subsequent lubricant depletion on the disk top surface. Two multilayer structures with different alloy materials on the top layer are studied. The results show that the top-layer alloy anisotropy does affect both temperature distribution and lubricant depletion, with the extent of the effect depending on the thermal diffusivity ratio (defined as the ratio of the thermal diffusivity along x–y direction to that along z direction on the top layer) as well as the alloy material of the top layer. For the top-layer alloy with inferior thermal properties, the effect of anisotropy is more significant at the range of thermal diffusivity ratio from 1 to 0.5. With a further reduction in this ratio, the anisotropy of the top-layer material does not show further noticeable effect.