Magnetoresistance effect element

Details Magnetoresistance effect element Magnetoresistance effect element

1992-01-21

1994-05-24

Lateef, Marvin M.

Electrical resistors

Resistance value responsive to a condition

Magnetic field or compass

32420721, H01L 4308

Patent

active

053152824

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a magnetoresistance effect element for reading a magnetic field intensity as a signal in a magnetic recording medium and the like.
A highly practical magnetoresistance effect element is required to have a large resistance change in a small external magnetic field. The magnetoresistance effect element of the present invention has a large resistance change in a small external magnetic field and can be practically used.


PRIOR ART

In these years, a sensitivity of a magnetic sensor and a density of magnetic recording have been increased. With such increase, a magnetoresistance effect magnetic sensor (hereinafter referred to as "MR sensor") and a magnetoresistance effect magnetic head (hereinafter referred to as "MR head") have been vigorously developed. The MR sensor and head read an external magnetic signal through the resistance change in a reading sensor part comprising a magnetic material. Since a relative speed of the MR sensor or head with a magnetic recording medium does not depend on a reproducing output, a high sensitivity is achieved by the MR sensor and a high output is obtained by the MR head even in case of a high density magnetic recording.
However, with a MR sensor which comprises a conventional magnetic substance utilizing anisotropic magnetoresistance effect such as Ni.sub.0.8 Fe.sub.0.2, the resistance change rate .DELTA.R/R (which will be defined below) is only about 2 to 5%. Then, a MR element having a larger resistance change rate is desired.
Recently, it was found that an artificial superlattice film in which directions of magnetization in adjacent magnetic layers are opposite such as [Fe/Cr].sub.N induces a large magnetoresistance effect (Phys. Rev. Lett., 61, 2472 (1988)). However, with this artificial superlattice film, an external magnetic field at which the maximum resistance change is achieved is very large, namely from ten several KOe to several ten KOe. Therefore, this artificial lattice film as such cannot be practically used.
That is, the conventional MR sensor and head have a small resistance change, and the conventional artificial superlattices such as Fe/Cr require too large external magnetic field to induce the resistance change.


SUMMARY OF THE INVENTION

As a result of extensive study to solve the above problems, the present inventors have succeeded in producing a highly practical magnetoresistance effect element.
The present invention provides a magnetoresistance effect element comprising a substrate and at least two magnetic thin layers which are laminated with interposing a non-magnetic thin layer therebetween on said substrate, wherein adjacent magnetic thin layers through the non-magnetic thin layer have different coercive forces and each of the magnetic thin layers and the non-magnetic layer has a thickness of not larger than 200 .ANG..


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly omitted cross section of a magnetoresistance effect element according to the present invention,
FIG. 2 is a schematic B-H curve which illustrates a function of the present invention,
FIG. 3 is B-H curve of [NiFe(25)/Cu(55)/Co(25)/Cu(55)].sub.5, and
FIG. 4 is a graph showing a relationship between the external magnetic field H and the resistance R of [NiFe(25)/Cu(55)/Co(25)/Cu(55)].sub.5.


DETAILED DESCRIPTION OF THE INVENTION

In the magnetoresistance effect element of the present invention, it is essential that the adjacent magnetic thin layers through the non-magnetic thin layer have different coercive forces, because the principle of the present invention is based on the fact that, when the directions of the magnetization in the adjacent magnetic layers are different, conduction electrons are scattered depending on spins so that the resistance increases, and when the directions of the magnetization are opposite, the element has the largest resistance. That is, in the present invention, as shown in FIG. 2, when an external field is between a coercoercive force Hc.sub.2 of one magnetic thin layer and a coercive force H

REFERENCES:
patent: 3813692 (1974-05-01), Brock et al.
patent: 3814863 (1974-06-01), O'Day et al.
patent: 4949039 (1990-08-01), Grunberg
patent: 5206590 (1993-04-01), Dieny et al.
patent: 5243316 (1993-09-01), Sakakima et al.

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