Experimental study of lubricant depletion induced by pulsed laser irradiation heating in heat-assisted magnetic recording

In this study, we experimentally investigate the lubricant depletion as well as the temperature distribution caused by pulsed laser irradiation heating and discuss the fundamental characteristics. It was determined that the maximum temperature increased as the duty ratio increased. However, the rate of the maximum temperature change due to the duty ratio was comparatively small. Therefore, it was suggested that the maximum temperature was almost constant when the duty ratio was more than 50% under experimental conditions. The thermal distribution or the thermal gradient also depended on the duty ratio and increased as this ratio decreased. It was also determined that the depletion of the lubricant film due to pulsed laser heating was smaller than that due to continuous laser heating. Moreover, it depended on the duty ratio and increased as the duty ratio increased. In addition, it depended on the full width at half maximum (FWHM) of the temperature distribution due to pulsed laser irradiation heating and increased as the FWHM is increased. Therefore, it is also suggested that the lubricant depletion issue will not be as critical in actual heat-assisted magnetic recording system because the FWHM would be very small under practical circumstances.