Abstract
In this study, we investigated the effect of ultraviolet (UV) irradiation on the thickness stability of molecularly thin lubricant films over magnetic disk surfaces. Step-shaped multilayer (3.5-nm-thick) and monolayer (2-nm-thick) perfluoropolyether AM3001 films were dip-coated on magnetic disk surfaces, respectively, and then exposed to 172-nm UV rays through a photomask. We measured the time-dependent thickness profiles of the lubricant films in the UV-irradiated and non-UV-irradiated regions, respectively. By comparing the profiles, we found that for non-UV-irradiated multilayer films, lubricant thickness decreased with time due to the relaxation process, whereas for UV-irradiated multilayer films, the relaxation process was suppressed because of the increased intermolecular interactions. For monolayer films, the relaxation process was not observed regardless of UV irradiation.
