R&D: Utilization of THMap for Laser and Write Current Optimization in HAMR

IEEE Transactions on Magnetics has published an article written by Aiko Sakoguchi, Western Digital Technologies GK, Fujisawa, Japan, and Graduate School of Science and Technology, University of Tsukuba, Tsukuba, Japan, Daniel Park, and Jay Lee, Western Digital Technologies, Irvine, CA, USA.

Abstract: “Both laser and write current influences write-ability and areal density capability (ADC) in heat-assisted magnetic recording (HAMR). Sufficiently high laser and write current is required to achieve a high proportion of magnetization switching of media grains, as measured by THMap, and obtain low bit error rate. However, increasing these currents also lead to a wider write width, resulting in a loss of ADC. This study compares these conditions necessary to achieve saturation of magnetization switching and those for maximizing ADC. ADC increases with write current up to the level required for saturation of magnetization switching. In contrast, higher laser current than that necessary for saturation of magnetization switching is required to maximize ADC. This is because increasing the laser current enhances the down-track thermal gradient and reduces bit-to-bit transition jitter. This finding suggests that achieving saturation of magnetization switching is a necessary condition for maximizing ADC. Furthermore, optimizing the laser current to reduce jitter plays a significant role in improving ADC.“