Thermal Response Time of Media in Heat-Assisted Magnetic Recording

Heat-assisted magnetic recording (HAMR) promises to deliver higher storage areal density than the current perpendicular magnetic recording product. A laser is introduced to the HAMR system to heat magnetic media to reduce the media coercivity. The thermal response of the media becomes very critical for the success of the magnetic writing process. The study of thermal response time in HAMR relies on the setup configurations, such as laser spot sizes, the way that laser energy is delivered to media and the media structures. In this paper, the thermal response time of HAMR media under three different heating methods is systematically investigated through experiments and numerical analysis. A lumped model is built to simplify the heat conduction problem to understand the difference in thermal responses under various experimental conditions. Dominant layers are identified under those experimental conditions. The transient thermal response is mainly determined by the dominant layers. Engineering the dominant layers helps the most in optimizing the thermal performance of the media. Our study clearly suggests that for HAMR systems, optimizing the thermal properties of the heat sink layer is the key to reducing variations in the transient thermal process resulting from changes in the linear speed.