Lubricant depletion due to moving laser heating: A molecular dynamics simulation study

Heat-assisted magnetic recording has been perceived as an enabling technology of next generation hard disk drives. In this paper, molecular dynamics simulations of ultrathin polymeric lubricant film under moving laser heating are carried out. The effect of the laser spot size is examined and the surface morphologies show that the lubricant undergoes severe depletion through evaporation and thermodiffusion. Raised ridges due to non-equilibrium thermocapillary stress are formed around the depletion track towards the laser moving direction when ultra-small laser spot size is used. Lubricant depletion at different laser spot sizes results in thermodiffusion-related degradation. More intriguingly, a critical laser spot size is observed, at which the film exhibits maximum thermodiffusion.