R&D: Two Strategies to Mitigate Thermally-Induced Material Buildup in HAMR

Tribology Letters has published an article written by Qilong Cheng, Roshan Mathew Tom, and David B. Bogy, University of California at Berkeley, Berkeley, CA, 94720, USA.

Abstract: “Heat-assisted magnetic recording (HAMR), one of the promising hard disk drive technologies to achieve areal density > 10 Tb/in2, integrates a laser across its head-disk interface to assist data writing. However, the laser brings a disk-to-head material transfer problem due to the temperature difference. The thermally-induced material buildup on the head, also known as smear, has been a crucial reliability issue in HAMR, which needs to be addressed before HAMR hard disk drive’s commercialization. In this paper, two mitigation strategies for the material buildup issue are presented: a mechanical approach and a thermal approach. The mechanical approach utilizes the thermal fly-height control heater protrusions to accomplish light head-disk contact to burnish the buildup away due to frictional interactions. The atomic force microscopy images show that the upstream/downstream buildup can be removed by use of dual heaters respectively only within several revolutions. In the thermal approach, the direction of the temperature difference across the head-disk interface is reversed compared to that during the data writing. The results show that the material buildup breaks down into small dots from traces and is mitigated by 91% after a relatively long duration ∼ 40 min. Additionally, it is found that a pulsed laser operating at a higher frequency can produce less upstream buildup. This study contributes to the material buildup management in the HAMR head-disk interface, and hence, it is important for the next generation HAMR technology. “