Effect of laser heating on carbon wear and lube depletion in heat assisted magnetic recording

Heat-assisted magnetic recording (HAMR) is a promising approach for enabling large increases in the storage density. In HAMR systems, the high temperature working condition brings challenges for head-media interface, where lubricant depletion and carbon graphitization may occur and cause failure. To explore the effect of laser heating on the change of lubricant and carbon overcoat layers, HAMR FID heads were used to heat the media with both CVD and sputtered carbon overcoat (COC) using different laser power. It is found that 90% of the optimized laser current is not enough to fully switch the magnetic medium or cause any visible thickness reduction in both media types. OSA Q-phase images and thickness profiles show increasing laser power induces greater thickness reduction, due to lubricant depletion or carbon wear. Compared with sputtered COC, CVD carbon is considered to be more stable, as lower conductivity was observed in PF TUNA AFM analysis.