Multiscale modeling of organic molecules contamination in head-disk interface under high thermal stress

Heat assisted magnetic recording (HAMR) which locally reduces coercivity with a laser pulse, is currently the most promising technology to achieve areal density beyond 10 Tbit/in2. However, due to the extreme operating condition of HAMR, the head-disk interface (HDI) suffers from extensive depletion and contamination of organic molecules. Our previous studies indicate that the conventional linear perfluoropolyether (PFPE) lubricants/grease molecules are not suitable for the severe thermal stress especially when coupled with external fields as the lubricant layer can be depleted and damaged. To simulate the molecular evaporation phenomena, we introduced novel multiscale modeling scheme, “Collection Of Spheres” model, which can predict mesoscale phenomena based on the atomistic/molecular level details via reduced order method. We have examined how the molecular architect affects evaporation under various degree of thermal stress (e.g., peak temperature and duration). Specifically, we examined several PFPEs (e.g., Z, Zdol, and Ztetraol) to study the effect of back-bone and end group properties on evaporation. Our multiscale model can provide holistic simulation of the HDI and provide molecular design criteria for HAMR device.