Effect of Humidity on the Nanoscale Heat Transfer at the Head-Media Interface

Abstract

Abstract In hard disk drives (HDD), the head-media spacing has decreased to less than 10 nm. Across this nanoscale gap, the heat transfer between the head and media may affect the air-bearing design, lubricant transfer and contact issues. Thus, understanding the heat transfer mechanism is very important to magnetic recording, especially for Heat Assisted Magnetic Recording (HAMR). In this paper, the heat transfer between a head and a static media is studied. In particular, the effect of humidity on the nanoscale heat transfer between a head and a static media is studied experimentally. From the transient and steady data of the experiments, it is proposed that the dynamic response of head protrusion is faster than heat dissipation. Also, a layer of water is assumed to form between the head and the media under high humidity. The water-layer affects the spacing and the heat transfer coefficient across the interface. In the near-contact regime, namely when the clearance is less than 2 nm or so, the protrusion interacts with the water-layer on the media, resulting in a lower rate of change of cooling.