Jun Aoyama

Advantage of MAMR Read-Write Performance

Microwave-assisted magnetic recording (MAMR) is one of the promising candidate technologies for next-generation hard disk drives. In MAMR, the high-frequency field from a spin-torque oscillator (STO) in the recording head is utilized to reduce the magnetization switching field of the medium. Micromagnetic modeling has shown the potential of MAMR; however, in terms of experimental results with actual heads and media, only little evidence of media magnetization reversal and improvement on overwrite has been reported. In this paper, we focus upon the experimental results of MAMR gain defined as a difference in the read-write performance when the STO is activated compared with when not activated. In conclusion, we show clear bit error rate improvement by activating the STO, giving an areal density increase of around 5-10% after considering the penalty associated with the magnetic core width increase. We also confirm that the magnetization switching in the STO is fast enough up to 2.3 GHz, and that there is no negative impact on the adjacent track interference nor on the far track interference.

A Head Cleaning Procedure for Heat-Assisted Magnetic Recording

In the heat-assisted magnetic recording (HAMR), write-induced head contamination covering the near-field transducer (NFT) can affect the transmission efficiency of optical energy from the NFT to a recording medium. We have experimentally confirmed that write performances such as data track width and signal amplitude change as a function of elapsed write time due to accumulation of the write-induced head contamination. Unintended changes of write performances in a drive can lose the capability to perform magnetic recordings as requested by a host. Here, we introduce the head cleaning procedure which removes the contamination from the interfacing surface of the head by placing it in close proximity to a disk surface. Effectiveness of the cleaning operation for performance stabilization is demonstrated with integrated HAMR drives. Detrimental effects of the mechanical cleaning operation on both head and media reliabilities have not been observed.