Simulation of Lubricant Recovery After Heat-Assisted Magnetic Recording Writing

The lubricant in a heat-assisted magnetic recording (HAMR) hard disk drive must be able to withstand the writing process in which the disk is locally heated a few hundred degrees Celsius within a few nanoseconds and be able to sufficiently recover the lubricant depletion and accumulation zones so as to allow for stable flying heights and reliable read/write performance. In a previous publication, we simulated the distortion of thin Zdol films due to a thermal spot during HAMR writing and predicted several Angstroms of depletion. In this paper, we continue these simulations into recovery. Our simulation results indicate that lubricant deformation caused by small thermal spots of 20-nm full-width half-maximum (FWHM) recover on the order of 100–1,000 times faster than larger 1-μm FWHM spots. However, the lubricant is unable to recover from sufficiently high writing temperatures. An optimal thickness at which HAMR writing deformation recovers fastest is apparent for sub-100-nm FWHM thermal spots. Our simulations show that simple scaling of experimental observations using optical laser spots of diameters close to 1 μm to predict lubricant phenomena induced by thermal spots close to 20-nm FWHM may not be valid. Researchers should be aware of the possibility of different lubricant behavior at small scales when designing and developing the HAMR head-disk interface.