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Heat-assisted magnetic recording (HAMR) is a technique for overcoming the superparamagnetic limit and enabling large increases in the storage density of hard disk drives. A tiny area of the magnetic recording media has to be heated up to a high temperature with a laser to lower the coercivity temporarily before information can be written on the area. The possible degradation of the ultrathin media carbon overcoat induced by the laser heating is a concern. In this paper, the laser heating-induced degradation of ultrathin a-C:Nx, a-C:Hx, and a-C overcoats on HAMR media is studied. Surface topography changes induced by the laser heating are evaluated with atomic force microscopy and structure changes with the visible Raman spectrum and X-ray photoelectron spectroscopy (XPS). Laser heating areas are analyzed with time-of-flight secondary ion mass spectrometry and XPS to reveal the underlying mechanism of the degradations. It is found that at a proper HAMR writing temperature and for a total laser heating duration corresponding to a five-year drive life, the surface topography, structure, and composition of the a-C:Nx overcoat are changed by the laser heating. However, the surface topographies of the a-C:Hx and a-C overcoats are not changed. The structure and composition of the a-C:Hx and a-C overcoats are also not changed much. Interlayer diffusion between the carbon overcoat and the underlying magnetic layer is confirmed in the laser heating area for all the three overcoats.

In contrast to conventional hard disk drives that work in an ambient condition, Heat-Assisted Magnetic Recording (HAMR) technology works by applying a highly focused laser beam to heat hard disk media up to around 400 °C. Under the HAMR condition, relevant hard disk components, including lubricant film, need to be extremely thermally stable. This paper studied the HAMR laser effect on the damage of our synthesized lubricant film together with a commercial lubricant Z-Tetraol for comparison by using an x-ray photoelectron spectroscopy and a time of flight secondary ion mass spectroscopy. The results revealed that our lubricant showed better laser resistance and thermal stability than the commercial lubricant.