Lubricant Depletion Characteristics Induced by Rapid Laser Heating in Thermally Assisted Magnetic Recording

In this study, fundamental research was conducted on lubricant depletion due to rapid laser heating in thermally assisted magnetic recording (TAMR) systems. The effects of lubricant film thickness on lubricant depletion were investigated using a conventional lubricant, Zdol2000. The lubricant depletion characteristics resulting from laser heating were found to largely depend on the lubricant film thickness. Lubricant depletion mechanisms were also studied. In this study, it was found that lubricant depletion is predominantly due to lubricant evaporation for cases in which the lubricant film thickness is greater than one monolayer. In addition, the effect of laser irradiation duration on lubricant depletion was investigated using both continuous and 300-kHz pulsed laser irradiations, since actual TAMR systems require pulsed laser irradiation lasting a few nanoseconds. The differences between the fundamental lubricant depletion characteristics of continuous and pulsed laser irradiations were elucidated on the basis of the experimental results obtained in this study. Furthermore, it has been suggested that diamond-like-carbon (DLC) thin films on the disk surfaces are also affected by rapid laser heating, because the temperature of the films increases to more than 500 K upon laser heating. Therefore, we also studied the damage to DLC thin films due to rapid laser heating and found that the reflectivity of the DLC thin films changed; this change was presumably due to the decrease in the DLC density as well as the asperity in the laser-irradiated region.