Current-perpendicular spin valves with partially oxidized magnetic layers for ultrahigh-density magnetic recording

Magnetoresistance (MR) of current-perpendicular spin valves with nano-oxide layers (NOLs) has been investigated. Insertion of a NOL in a spacer between free and pinned magnetic layers can increase both resistance and MR ratio of the spin valves to the level that satisfies the needs for over 150-Gb/i...

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Bibliographic Details
Published in:IEEE transactions on magnetics 2003-09, Vol.39 (5), p.2377-2380
Main Authors: Oshima, H., Nagasaka, K., Seyama, Y., Jogo, A., Shimizu, Y., Tanaka, A., Miura, Y.
Format: Article
Language:English
Subjects:
Applied sciences
Degradation
Electronics
Exact sciences and technology
Iron alloys
Magnetic devices
Magnetic field measurement
Magnetic materials
Magnetic moments
Magnetic recording
Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.)
domain-motion devices, etc
Magnetism
Magnetoresistance
Perpendicular magnetic recording
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Spin valves
Voltage
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Summary:Magnetoresistance (MR) of current-perpendicular spin valves with nano-oxide layers (NOLs) has been investigated. Insertion of a NOL in a spacer between free and pinned magnetic layers can increase both resistance and MR ratio of the spin valves to the level that satisfies the needs for over 150-Gb/in/sup 2/ recording density. It is shown that the MR enhancement is strongly NOL-material dependent; ferromagnetic CoFe(B) alloys are found to be quite effective in the improvement, while nonmagnetic composites such as TaCu and RuCu degrade the MR ratio. The NOL-thickness dependence of the MR ratio is also measured. It is presented that the CoFe(B) NOL thicker than 1 nm greatly enhances the MR ratio. Nominal-thickness dependence of residual magnetic moment of the NOLs shows that partially oxidized CoFe(B) layers are most effective for the MR enhancement. Little degradation of the free-layer response to an applied magnetic field by the NOL insertion has been observed. From the current-voltage (I-V) characteristic, the electronic transport is revealed to be dominated by metallic conduction rather than tunneling. It suggests that the enhancement stems from the conduction through pinholes.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2003.815455