Low resistance magnetic tunnel junctions and their interface structures

Effects of interface structure and oxidation state were studied in stacked magnetic tunnel junction (MTJ) structures with top and bottom antiferromagnetic layers to obtain optimum resistance and high tunneling magnetoresistance (TMR) ratios for read heads. The roughness of the NiFe surface and the A...

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Bibliographic Details
Published in:Journal of applied physics 2001-06, Vol.89 (11), p.7558-7560
Main Authors: Fujikata, J., Ishi, T., Mori, S., Matsuda, K., Mori, K., Yokota, H., Hayashi, K., Nakada, M., Kamijo, A., Ohashi, K.
Format: Article
Language:English
Subjects:
AVOIDANCE
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
MAGNETIC MATERIALS
MAGNETORESISTANCE
OXIDATION
PHYSICS
ROUGHNESS
SURFACTANTS
TUNNELING
VALENCE
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Summary:Effects of interface structure and oxidation state were studied in stacked magnetic tunnel junction (MTJ) structures with top and bottom antiferromagnetic layers to obtain optimum resistance and high tunneling magnetoresistance (TMR) ratios for read heads. The roughness of the NiFe surface and the Al coverage were significantly improved by introduction of O2 surfactant gas on the Ta-seed-layer surface, which increased TMR ratios of the MTJ with low resistance area (RA) products of less than 10 Ω μm2. Furthermore, it was found that avoidance of Ni oxidation and Co oxidation at the tunnel barrier interface is essential to obtaining high TMR ratios, and that a good Al coverage and Fe–oxide formation may enhance TMR ratios when Fe-rich magnetic materials are used. For the top-type and bottom-type structures, a TMR ratio of 12%–17% with RA products of 6–7 Ω μm2 was obtained, which provides sufficient performance for read heads.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.1361054