Dynamic Thermal Responses of Heat-Assisted Magnetic Recording Head in Data Writing Process

Abstract

In the data writing process of heat-assisted magnetic recording (HAMR), due to the existence of servo sectors in the magnetic recording media, the laser power has to be “off” when the near field optical transducer passes over the servo sectors so as to protect the servo sector from being erased. In this paper, HAMR head dynamic thermal responses to the laser source heating and transducer absorption in the data writing process are studied. The results show that the dynamic temperature response times of the laser source and air-bearing surface are around 1 s. The transducer temperature can almost follow the transducer heating change (caused by absorption) because of its very fast temperature response which is around 2 μs. However, the transducer protrusion response time to the transducer absorption is 2 ~ 3 ms. Owing to the long response times of the slider temperature to the laser source heating and the transducer protrusion to its laser absorption, the fly height changes caused by the slider temperature increase and the transducer protrusion may be compensated with the thermal fly height control technology.