| Co-Investigator(Kenkyū-buntansha) |
KUMAGAI Seiji Sony Corporation, Device Division, Chief Researcher, 主任研究員
KUBOTA Hitoshi Tohoku University, Graduate School of Engineering, Research Assistant, 大学院・工学研究科, 助手 (30261605)
ANDO Yasuo Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (60250726)
NAKATANI Isao National Institute for Materials Science, Section Chief, 機能特種性研究部第3研究室, 研究室長
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| Research Abstract |
In order to fabricate a read head using tunnel magnetoresistive junction, optimization of the tunnel junction (layered structure, stacking sequence, optimal annealing condition, thickness of barrier layer) and micro-fabricating process have been studied. Two kinds of read head were successfully demonstrated. The main results are summarized as follows.
1. The Ta30(Å)/Ni_<80>Fe_<20>(30Å)/Cu(200Å)/IrMn(100Å)CoFe(40Å)/Al-oxide/CoFe(40Å)/Ni_<80>Fe_<20>(200Å)/Ta(50Å) junction annealed at 250 ℃ for 1 h exhibited that the values of resistance times cross section and tunnel magnetoresistance ratio were 78 Ω・μm^2 and 33 %, respectively.
2. Using the photolisography and Ar ion milling process, we fabricated a small junction with 3x3 μm^2. On the other hand, small junction with 0.5x0.5 μm^2 was obtained by using electron beam lithography and no damage was confirmed for the junction by comparing the transport property measured before and after micro fabrication.
3. Feasibility of tunnel magnetoresistive read head with flux-guide layers was investigated for helical-scan tape storage applications. A long-range exchange coupling bias scheme, with a Cu layer and an antiferromagnet were deposited on top of free layer in the tunnel-valve element, was employed. In order to stabilize domain structures in the free layer, the long range exchange coupling biasing was combined with conventional permanent magnet bias method. The maximum output voltage of the flux guide type reader was 1.75 mV_<p-p> which was corresponding to +1.5 dB of a conventional anisotropic magnetoresistive reader. Furthermore, a tunnel magnetoresistive read head for HDD application was fabricated and an out put voltage corresponding to 10 Gb/inch^2 was realized.
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