Yoshikazu Soeno

Piezoelectric piggy-back microactuator for hard disk drive

A new piezoelectric piggy-back microactuator for high density hard disk drives was designed and fabricated to achieve more accurate positioning of the magnetic head and increasing servo bandwidth. The microactuator is made of stiff piezoelectric ceramic material to actuate the slider on which the head-element is formed. It is designed to amplify the actuating displacement. The basic mechanical performance of the microactuator was evaluated. The stroke of displacement was /spl plusmn/0.5 /spl mu/m with a drive voltage of /spl plusmn/lO V and a dc bias of +10 V. The resonant frequency of the microactuator was high at 34 kHz. The fundamental resonant frequency of an assembled head with microactuator was high at around 20 kHz. The head variation was suppressed to O.1 /spl mu/m by the microactuator with feedback control. These results suggest the feasibility of increasing servo bandwidth up to several kHz and positioning the head more precisely.

Fabrication of discrete track perpendicular media for high recording density

The feasibility of discrete track media with perpendicular anisotropy for high track density has been studied. The discrete tracks are separated physically and magnetically by grooves. The discrete track media were fabricated by using an e-beam lithography and dry etching process. In particular, the recording layer was etched using reactive ion etching with CO-NH3 mixed gas. With this process, we obtained a discrete track medium with a track pitch of 90 nm without causing damage to the magnetic recording film or degradation of its magnetic properties. To solve the flying instability issue due to the grooved surface roughness, a smooth surface like continuous layer media was obtained by using only dry processes. The surface roughness (Ra) was below 1 nm. Flying stability of a head-slider on the smooth surface of the discrete track media similar to the continuous layer media has been achieved.

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