Flying Height Control Using Dual Thermal Protrusions in Heat Assisted Magnetic Recording (HAMR)

Thermal flying height (TFC) control technology has been used in the past few years to achieve a lower flying height for higher storage areal density. In this paper, a slider with dual thermal protrusion, one produced by the laser used to heat the disk in HAMR and the other one used for TFC, is programmed with feedback control to reduce the flying height modulation (FHM) due to disk waviness and to attenuate the external disturbances. A numerical simulation is conducted to investigate the feasibility of the system. The results show that FHM of the dual protrusion slider is reduced significantly when the protrusion heights and locations are optimized. External disturbance induced FHM can be suppressed as well. This scheme can benefit HAMR because it will provide a more consistent flying height and more freedom to compensate external disturbances.