With the emergence of Heat-Assisted Magnetic Recording and Microwave-Assisted Magnetic Recording, understanding nanoscale heat transfer at the head-media interface is crucial for developing reliable hard disk drives. There is a need to develop a methodology that uses a spacing-dependent nanoscale heat transfer coefficient, determined by using wave-based radiation and van der Waals force driven phonon conduction theories to predict head temperatures in hard disk drives. We present a numerical model to simulate the head temperature due to heat transfer across a closing nanoscale gap between the head and the media (nonrotating) and compare our results with static touchdown experiments performed with a head resting on three different media (Si, magnetic disks with AlMg, and glass substrates). The Thermal Fly-Height Control (TFC) heater in the head is powered to create a local protrusion, leading to contact of a resistive Embedded Contact Sensor (ECS) that is used to measure the temperature change. As the ECS approaches the media, enhanced phonon conduction heat transfer causes a drop in the ECS temperature vs TFC power curve. Our model shows that the introduction of van der Waals forces between the head and the media during computation of the head's thermal protrusion causes a steeper drop in the simulated ECS temperature curve, ensuring a good quantitative match with experiments for all of the media materials tested and different initial ECS-media spacings. We isolate the effect of air conduction on ECS cooling by comparing our simulations with experiments performed in air vs vacuum.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)