Ultra High Density Perpendicular Magnetic Recording

1991 Fiscal Year Final Research Report Summary

• Project/Area Number: 01420030
• Research Category: Grant-in-Aid for General Scientific Research (A)
• Allocation Type: Single-year Grants
• Research Field: 電子機器工学
• Research Institution: Tohoku University
• Principal Investigator: NAKAMURA Yoshihisa Tohoku University, Res. Inst. of Elec. Communi., Professor, 電気通信研究所, 教授 (50006235)
• Co-Investigator(Kenkyū-buntansha): YAMAMOTO Setsuo Tohoku University, Res. Inst. of Elec. Communi., Research Associate, 電気通信研究所, 助手 (30182629) ; OUCHI Kazuhiro Tohoku University, Res. Inst. of Elec. Communi., Professor, 電気通信研究所, 教授 (10006249) ; IWASAKI Shun-ichi Tohoku Institute of Technology, President, 学長 (80006212)
• Project Period (FY): 1989 – 1991
• Keywords: Perpendicular Magnetic Recording / High Density Recording / Perpendicular Magnetic Head / Perpendicular Magnetic Recording Medium / Perpendicular Magnetic Anisotropy / Sputtering / Sliding Contact Recording / Magnetic Domain

Research Abstract

The purpose of this study, was to achieve the ideal head/medium system and to pursue the feasibility of ultra high density recording in perpendicular magnetic recording. We developed the following three new technologies in this study :
(a) Magnetic domain control technique using the small notches fabricated at the edge of a main-pole film of a single-pole head. The reproduced voltage of 4OOnV_<o-p>/[mum^*turn^*(m/s)] was obtained using only 2mum trackwidth single-pole head. This reproduced voltage is higher than that of the highly sensitive ring head.
(b) New sputtering target was developed for high rate fabrication of high density perpendicular "magnetic recording media. The new sputtering target enables the confinement of the plasma and low gas pressure and low temperature sputtering. These are convenient features to fabricate magnetically soft enough Ni-Fe backlayer and Co-Cr layer with high perpendicular orientation, high crystallinity and narrower magnetic anisotropy field distribution. We proved that the fabrication of perpendicular magnetic recording tape media for high density recording is possible using this new sputtering target.
(c) Sliding contact recording technology combining the Co-Cr/Ni-Fe hard disk media with smooth surface and non-flying single-pole head supporting mechanism. Sliding contact recording excludes spacing loss, and derives the intrinsic high density recording performance of recording media. The pass wear durability and envelope of the reproduced voltage was drastically improved in this system.
In perpendicular magnetic recording using these new technologies, we achieved the highest -6dB recording density of 6, 700 bits/mm. The error rate of 10^<-9>, which guarantees the practical application as a hard disk drive, was realized at linear bit density of 4, 000 bits/mm and track density of 10 tracks/mm.