Akimasa Kaizu

Feasibility of discrete track perpendicular media for high track density recording

In conventional hard disk drive signal recording, the track pitch and the track density depend mainly on the write/read width of the magnetic head. In order to increase the track density, a narrow head is needed. We are developing a discrete track media with perpendicular anisotropy to evaluate the capability of high recording density. The tracks are separated physically by the groove. Then, the recording width and the track pitch are defined precisely by the tracks formed on the media. It is expected to have some features for high track density recording. The recording track fluctuation during the writing process and the magnetic interference from adjacent tracks are reduced. Also, the recording signal at the write-pole-edge is improved, and so on. We fabricated an actual discrete track perpendicular medium to evaluate the basic write/read properties. The measurements have been carried out on a spin-stand. The capability of this media at high track density are discussed.

Performance evaluation of discrete track perpendicular media for high recording density

In this paper, the evaluation results of the performance of discrete track perpendicular media is described. Discrete track patterns for data area and servo patterns such as address marks and burst patterns for each sector are formed by nano-imprint lithography and the dry etching process. Comparison of the error rate profile in both the discrete track media and conventional media is shown. Write and read operations are conducted by a perpendicular magnetic head which has MWW of 195 nm and MRW of 100 nm. In the conventional media, the error rate of the center-track is degraded due to the side-writing and cross talk. On the other hand, in the discrete track media, the error rate is kept unchangeable. This is because the grooves between the tracks prevent the side-writing and cross talk. In addition, higher SNR is observed at the narrower track pitch in the discrete track media.

Performance of Discrete Track Perpendicular Media on Off-Track-Capability at Higher Track Density

The off-track-capability (OTC) of the discrete track perpendicular medium is investigated by using Landau-Lifshitz-Gilbert micromagnetic simulation. The OTC is very important to design the system of the HDD. In this simulation, the OTC of the read head, the OTC of the write head and the OTC where both the read head and the write head have off-track are shown from the point of signal-to-noise ratio (SNR). The simulation results show that the discrete track medium has superior advantage on the OTC for both reading and writing process

Micromagnetic modeling of discrete patterned perpendicular media

In this paper, the benefit to separate each track and the feasibility to increase track density are investigated by using Landau-Lifshits-Gilbert micromagnetic model. A MFM image of the discrete patterned media recorded at 50 kFCL is shown. In the recording process, the single pole write head with a width, Pw, of 200 nm and a thickness, Pt, of 300 nm is used.