Magnetic multilayer film and magnetoresistance element

Details Magnetic multilayer film and magnetoresistance element Magnetic multilayer film and magnetoresistance element

1993-08-26

1996-05-07

Thibodeau, Paul J.

Stock material or miscellaneous articles

Structurally defined web or sheet

Including components having same physical characteristic in...

324252, 360110, 360113, 428216, 428692, 428693, 428694R, 428694T, 428694TM, 428900, G01R 3302, G11B 5127, G11B 566, B22B 702

Patent

active

055144527

ABSTRACT:
A magnetic multilayer film having magnetoresistance (MR) is prepared by depositing at least two magnetic thin films having different coercive forces while interposing a non-magnetic thin film therebetween. A first magnetic thin film having a lower coercive force has a squareness ratio SQ.sub.1 of 0.01-0.5, an anisotropic magnetic field Hk of 1-20 Oe, and a thickness t.sub.1, a second magnetic thin film having a higher coercive force has a squareness ratio SQ.sub.2 of 0.7-1.0 and a thickness t.sub.2 .ltoreq.t.sub.1, and the non-magnetic thin film has a thickness t.sub.3 .ltoreq.200 .ANG.. A first preferred form requires 4 .ANG..ltoreq.t.sub.2 <30 .ANG. and 6 .ANG..ltoreq.t.sub.1 .ltoreq.200 .ANG.. A second preferred form requires 4 .ANG..ltoreq.t.sub.2 <20 .ANG. and 10 .ANG..ltoreq.t.sub.1 <20 .ANG.. A third preferred form requires 4 .ANG..ltoreq.t.sub.2 <30 .ANG. and 6 .ANG..ltoreq.t.sub.1 .ltoreq.40 .ANG.. The magnetic multilayer film has a great MR ratio of more than several percents in a low external magnetic field, a sharp rise at zero magnetic field and high heat resistance. It also has improved hysteresis and MR slope in an applied magnetic field between -10 Oe and +10 Oe. It additionally has a high MR slope of at least 0.15%/Oe in an applied magnetic field between -50 Oe and +50 Oe, improved hysteresis of MR ratio, and a high MR slope in a high-frequency magnetic field. There are obtained high sensitivity MR sensors and MR heads capable of high density magnetic recording.

REFERENCES:
The Journal of Japanese Applied Magnetics Society, vol. 17, No. 2, 1993, D. Miyauchi, et al., pp. 365-368, "MR Properties and Thermal Stabilities of Cu/Co/Cu/NiFe Multilayers" (applicants explanation).
Physical Review Letters, vol. 61, No. 21, Nov. 21, 1988, M. N. Baibich, et al., "Giant Magnetoresistance of (001)Fe/(001) Cr Magnetic Superlattices", pp. 2472-2475.
Proceedings of Magnetics Research Meeting of the Japanese Electrical Society, MAG-91-161, Hoshino, et al., pp. 65-71 (Applicants discussion in specification).
Proceedings of Magnetics Research Meeting of the Japanese Electrical Society, MAG-91-242, T. Okuyama, et al., "Magnetoresistance of Maltilayers with Two Magnetic Layers", pp. 1-10 (Applicant's discussion in specification).
Journal of The Physical Society of Japan, vol. 59, No. 9, Sep. 1990, pp. 3061-3064, Teruya Shinjo, et al., "Large Magnetoresistance of Field-Induced Giant Ferrimagnetic Multilayers".
Journal of Magnetism and Magnetic Materials 99 (1991), pp. 243-252, H. Yamamoto, et al., "Magnetoresistance of Multilayers with Two Magnetic Components".
Journal of Magnetism and Magnetic Materials 121 (1993), pp. 339-343, R. Kergoat, et al., "Magnetization Reversal in Ni80Fe20/Cu/Co Spin-Valves".
Journal of Magnetism and Magnetic Materials 121 (1993), pp. 402-405, T. Valet, et al., "Correlation Between Giant Magnetoresistance and the Microstructure of Ni80Fe20/Cu/Co! Multilayers".
Appl. Phys. lett. 61 (26), Dec. 28, 1992, T. Valet, et al., "Interplay Between Oscillatory Exchange Coupling and Coercivities in Giant Magnetoresistive Ni80Fe20/Cu/Co/Cu! Multilayers", pp. 3187-3189.
Jpn. J. Appl. Phys., vol. 31, 1992, pp. L484-L486, No. 4B, Apr. 15, 1992, Hiroshi Sakakima, et al., "Low-Field Giant Magnetoresistance in Ni-Fe-Co/Cu/Co/Cu! Superlattices".

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