JPH026490Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is a ferromagnetic magnetoresistive element (hereinafter referred to as "magnetoresistance effect element") that reads magnetic information written on a magnetic storage medium by using the so-called magnetoresistive effect. A magnetoresistive head (hereinafter referred to as MR element) equipped with
(referred to as MR head).

(Prior art and its problems) As is well known, when an MR element is used as a highly efficient reproduction head that exhibits a linear response to magnetic information written on a magnetic storage medium, the MR element
A bias means must be provided for setting the angle θ _B (hereinafter referred to as bias angle) formed by the sense current I flowing through the element and the magnetization M of the MR element to a predetermined value (preferably 45 degrees).

Conventionally, a so-called shunt bias method shown in FIG. 1 has been disclosed as a bias method for an MR element. In FIG. 1, a non-magnetic conductor layer 2 (for example, Ti, Mo, etc.) is placed in contact with an MR element 1,
A magnetic field generated when a part of the sense current I supplied to the MR element 1 is also shunted to the conductor layer 2.
The configuration is such that the magnetization M of the MR element 1 is deflected with respect to the sense current I using H _B.

However, this method requires a relatively large current to flow through the nonmagnetic conductor layer 2 in order to obtain a predetermined bias angle θ _B , and therefore the electrical resistance of the MR element 1 may cause thermal drift. , and also caused thermal noise. Furthermore, in order to shunt a relatively large current to the conductor layer 2, it is necessary to select the film thickness and material of the non-magnetic conductor layer 2 so that it has an electrical resistance equal to or less than the electrical resistance of the MR element 1. This ends up being
This reduces the net resistance change of the MR head to an external signal magnetic field, and therefore also reduces the reproduction output of the MR head.

On the other hand, another bias method is disclosed in Japanese Patent Publication No. 53-37205. This biasing method is achieved by successively stacking an MR element 1, a nonmagnetic conductor layer 2, an insulating layer 3, and a magnetic bias layer 4, as shown in FIG. The sense current I, which is adjusted to a constant value and flows through the MR element 1 and the nonmagnetic conductor layer 2, is
A magnetic field is generated within the magnetic bias layer 4. This magnetic field alternately rotates the magnetic field M in the MR element 1 so as to form a predetermined bias angle θ _B with respect to the sense current I by magnetostatic coupling.

However, in this method, in order to obtain sufficient magnetostatic coupling between the MR element 1 and the magnetic bias layer 4, it is necessary to set the thickness of the nonmagnetic conductor layer 2 and the insulating layer 3 to be as thin as possible. In order to obtain sufficient magnetostatic coupling, if the insulating layer 3 is made thin, the MR
A local short circuit occurred between the element 1 and the magnetic bias layer 4, resulting in variations in the characteristics of the MR head.

(Object of the invention) An object of the invention is to provide a magnetoresistive head that overcomes the above-mentioned conventional drawbacks and realizes a good bias state.

(Structure of the invention) According to the invention, there is provided a magnetoresistive head having a structure in which a ferromagnetic magnetoresistive element, a nonmagnetic conductor layer, and an amorphous soft magnetic material layer are laminated in this order. Can be provided.

(Detailed Description of Configuration) The present invention will be described in detail below with reference to drawings showing embodiments.

FIG. 3 is an embodiment showing the MR element portion which is the main component of the MR head of the present invention.

An MR element 1 made of a ferromagnetic material (for example, Fe-Ni alloy, Ni-Co alloy) is placed on an insulating substrate material (not shown) with a smooth surface made of glass, ferrite, ceramics, etc. with a thickness of approximately 200 to 500 Å. A non-magnetic conductor layer 2 is formed on the MR element 1 by a method such as sputtering or vapor deposition to have a film thickness within a range.
(For example, Ti, Mo, Cr, Ta) are formed using a similar method, and further, an amorphous soft magnetic layer 5 is laminated on the nonmagnetic conductor layer 2. The thickness of the nonmagnetic conductor layer 2 is the same as that of the MR element 1 and the amorphous soft magnetic layer 5.
is selected within a range (for example, about 100 to 2000 Å) that can provide sufficient magnetostatic coupling. Materials for the amorphous soft magnetic layer 5 include Co-Zr, Co-Ti,
Amorphous alloys such as These materials have a resistivity higher than that of MR element 1, a saturation magnetization equal to or higher than that of MR element 1, and more importantly, a change in resistance due to an external magnetic field (magnetoresistive effect) is either zero or higher than that of MR element 1. A composition having a value one order of magnitude smaller can be selected. For example, in a Co-Ti based amorphous soft magnetic material, the magnetoresistive effect becomes zero at a Co composition of 83%, and the specific resistance is approximately 140 μΩ·cm. Also, Co-Zr
Regarding amorphous soft magnetic materials, the Journal of Magnetism and Magnetic Materials
Materials) 1983, Volumes 31-34, 1475-
In the paper by Yamagata et al. on page 1476,
As disclosed, with 13% Zr, zero magnetoresistive effect and a specific resistance of approximately 110 μΩ·cm are obtained.

A terminal 6 is provided in the laminated body of the MR element 1, the non-magnetic conductor layer 2, and the amorphous soft magnetic material 5, and the sense current I supplied from the terminal 6 is applied not only to the MR element 1 but also to the non-magnetic The current is also divided into the magnetic conductor layer 2 and the amorphous soft magnetic material 5 . In such a configuration, the sense current I divided into the MR element 1 and the nonmagnetic conductor layer 2
generates a magnetic field that passes within the plane of the amorphous soft magnetic material 5 and is perpendicular to the sense current, thereby rotating the magnetization of the amorphous soft magnetic material 5. The magnetization in the amorphous soft magnetic material 5 generates a magnetic field around the amorphous soft magnetic material 5 in a direction opposite to the direction of the magnetization, a part of which is applied to the MR element 1. On the other hand, the sense current I divided into the amorphous soft magnetic material 5 and the nonmagnetic conductor layer 2 is MR
A magnetic field passing through the plane of the element 1 and perpendicular to the sense current I is generated. The direction of this magnetic field matches the direction of the magnetic field generated by magnetization of the amorphous soft magnetic material 5. That is, the magnetic field generated by the magnetization of the amorphous soft magnetic material 5 and the magnetic field generated by the sense current I are
A bias magnetic field H _B is applied to the MR element 1 .
The bias magnetic field H _B rotates the magnetization M of the MR element 1 with respect to the sense current I to obtain a predetermined bias angle θ _B.

As is clear from the above description, the bias magnetic field H _B (that is, the bias angle θ _B ) applied to the MR element 1 can be arbitrarily set by the sense current I. Also, MR
The magnitude of the bias magnetic field H _B can also be changed depending on the distance between the element 1 and the amorphous soft magnetic material 5, that is, the thickness of the nonmagnetic conductor layer 2 and the magnetic properties of the amorphous soft magnetic material 5.
For example, if the thickness of the nonmagnetic conductor layer 2 is set thin, the magnetostatic coupling between the MR element 1 and the amorphous soft magnetic material 5 will increase, and the bias magnetic field H _B will be increased accordingly even if the sense current I is small. Can be set.

The operation and principle of the present invention has been described above using FIG. 3. However, in an MR head, the MR element is often used alone, and as shown in FIG. 4, in order to improve the reproduction resolution, A magnetic shield is provided.

FIG. 4 is a schematic cross-sectional view of the magnetically shielded MR head. The MR head shown in FIG. 4 has a structure in which an MR element 1, a nonmagnetic conductor layer 2, and an amorphous soft magnetic layer 5 are sandwiched from both sides by magnetic shields 8 and 7 made of a high magnetic permeability magnetic material. By adopting such a configuration, as is well known, the reproducing resolution can be greatly improved with respect to the signal magnetic field H _S from the magnetization 10 in the magnetic storage medium 9, and reproduction during high-density recording is also possible. The reproducing resolution is determined by the interval G between the two magnetic shields 7 and 8, and the smaller the interval G, the higher the reproducing ability during high-density recording. However, in the past, the MR element 1 and the means for biasing the MR element 1 (for example, the prior art shown in FIG. 2) occupied a relatively large area, so the spacing G was greatly limited. In this invention, as described above, the MR element including the bias means can be designed extremely compactly, so the interval G can be set small.

Although magnetic shields are arranged on both sides of the MR element 1 in FIG. 4, the magnetic shields may be provided only on one side. For example, only the magnetic shield 7 can be arranged. In this case, the amorphous soft magnetic layer 5
MR also functions as a magnetic shield.
The interval between the two magnetic shields, which determines the reproduction resolution of the head, is changed to G', making it possible to reproduce even higher recording densities.

(Example) In Fig. 3, a permalloy with a composition of 82% Ni-18% Fe (both by weight) is placed on a glass substrate with a smooth surface to a thickness of 400 Å as an MR element 1.
The film was formed with a thickness of 500 mm with Ti as the nonmagnetic conductor layer 2.
Å, and further as an amorphous soft magnetic layer 5,
Co-Zr (Co87%-Zr13%) amorphous alloy was deposited to a thickness of 400 Å, and these laminates were 50 μm long and wide.
It was processed into a strip shape of 5 μm, and terminals 6 were provided so as to supply a sense current I in the length direction. In the above configuration, when the sense current I is supplied in the range of 1 to 10 mA, the bias angle θ _B of the MR element 1 is 30 to 65
It was confirmed that it can be set within the range of Furthermore, an MR head exhibiting good linear response in this range was realized.

(Effects of the invention) As described above, in the present invention, a predetermined bias state can be achieved with an extremely small sense current I, so the thermal drift of the electrical resistance of the MR element due to heat generation and the thermal noise are extremely minimized. can. or,
A large current is passed through the non-magnetic conductor layer and the amorphous soft magnetic material 5.
Since there is no need to divide the current into two, the nonmagnetic conductor layer and the amorphous soft magnetic material can be made relatively thin or made of a material with a high specific resistance. As a result, the decrease in resistance change of the MR head against the external signal magnetic field can be suppressed to a minimum.

In addition, in the present invention, since the sense current I is constantly shunted to the amorphous soft magnetic material through the nonmagnetic conductor layer, the conventional technology as shown in FIG. 2, that is, the magnetic bias layer and the MR element Variations in characteristics due to local leakage of the sense current I, which occur when an insulating layer is interposed between the two, are eliminated. In addition, in the conventional technology shown in FIG. 2, when the sense current I is shunted to the magnetic bias layer, design considerations are taken such that the magnetic bias layer is always magnetically saturated so that it does not operate as a magnetoresistive element. (For example, optimization of the thickness of the magnetic bias layer, the distance to the MR element, the magnitude of the sense current I, and the characteristics of the magnetic storage medium, etc.) However, in the present invention, the magnetoresistive effect is zero. Alternatively, since an amorphous soft magnetic material that is sufficiently smaller than the MR element is used, such consideration becomes unnecessary, and the design margin is greatly expanded.

[Brief explanation of the drawing]

1 and 2 are schematic perspective views of the magnetoresistive element portion of a conventional magnetoresistive head, FIG. 3 is a schematic perspective view of the magnetoresistive element portion of the magnetoresistive head of the present invention, and FIG. 1 is a schematic cross-sectional view of a magnetically shielded magnetoresistive head showing an embodiment of the present invention. In the figure, 1...MR element, 2...Nonmagnetic conductor layer, 3...Insulating layer, 4...Magnetic bias layer, 5
...Amorphous soft magnetic layer, 6...Terminal, 7,8...
Magnetic shield, 9...magnetic storage medium, 10...indicates the direction of magnetization, respectively.

Claims (1)

[Scope of utility model registration request] A magnetoresistive head having a structure in which a ferromagnetic magnetoresistive element, a nonmagnetic conductor layer, and an amorphous soft magnetic layer are laminated in this order.