JPH03280208A - Magneto-resistance effect head - Google Patents

Abstract

PURPOSE:To improve a resolving power by specifying the thicknesses of upper and lower magnetic shields and the gaps between the upper and lower magnetic shields and a magneto-resistance effect element with respect to the shortest reading out wavelength. CONSTITUTION:The shielding type MR head is so set that the thickness T1 of the lower magnetic shield 2, the thickness T2 of the upper magnetic shield 6, the gap G1 between the lower magnetic shield 2 and the MR element 3 and the gap G2 between the upper magnetic shield 6 and the MR element 3 satisfy equation I with respect to the shortest reading out wavelength lambda. The shielding type MR head having the high resolving power is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetoresistive head used in a magnetic disk device, a magnetic tape device, and a floppy disk device.

[Conventional technology]

In a magnetoresistive head, in a ferromagnetic metal such as NiFe or NiCo, the resistance value R is expressed by the following formula, %, with respect to the angle θ between magnetization and current. , ΔR: A read-only magnetic head that utilizes the property of changing according to the resistance that changes with the magnetic field. In a magnetoresistive head (hereinafter referred to as an MR head), a sense current is supplied to detect a signal voltage generated across a magnetoresistance effect element (hereinafter referred to as an MR element), that is, a reproduction output. Therefore, the reproduction output does not depend on the relative speed between the magnetic recording medium and the magnetic head, and
By applying an appropriate bias, it is possible to extract a reproduction output proportional to the signal magnetic field. The magnitude of this reproduction output is determined by the use of materials with a large resistance change rate, such as N1aoC.
If O2o or pe61N1+e is used, the head will be much larger than the conventionally used inductive head, so the MR head is a promising magnetic head for increasing the recording density of magnetic recording devices.

When using an MR element alone, the resolution depends on the width of the MR element in the signal magnetic field detection direction (hereinafter referred to as the MR element height).
In order to improve the resolution of the MR head, magnetic shields made of soft magnetic material may be provided adjacent to the upper and lower portions of the MR element.

An MR head equipped with a magnetic shield in this manner is called a shield type MR head. In this shield type MR head, it has conventionally been thought that the resolution is defined by the distance between the magnetic shield and the MR element, that is, the gap between the shields.

[Problem to be solved by the invention]

In order to increase the resolution of a shielded MR head, it is sufficient to shorten the gap between the shields. However, shield type M
There are limits to reducing the inter-shield gap in order to improve the resolution of the R head for the following two reasons.

First, if the inter-shield gap is made small, it may become impossible to ensure electrical insulation between the MR element and the magnetic shield. If the sense current to be supplied to the MR element is shunted to the magnetic shield, the reproduction output will be reduced by that amount, which is not preferable.

Secondly, it is effective to provide a means for applying a bias to the MR element close to the MR element, and the inter-shield gap cannot be made smaller than this bias applying means.

As mentioned above, the high resolution of the shielded MR head is
There is a limit to what can be achieved only by reducing the inter-shield gap, and therefore there is a limit to the recording density that can be read using a shielded MR head.

An object of the present invention is to provide a high-resolution shielded MR head that solves the above problems.

[Means to solve the problem]

In the shielded MR head of the present invention, the thickness T1 of the upper magnetic shield, the thickness T2 of the lower magnetic shield, the gap G1 between the upper magnetic shield and the MR element, and the gap G2 between the lower magnetic shield and the MR element have the shortest readout wavelength. For λ, 2T1+2・G,=72+2・G2=λ is satisfied.

[Effect]

In the present invention, by optimizing the sum of the thickness of the magnetic shield and the gap between the shields for the shortest readout wavelength,
Achieved high resolution of the shield type MR head.

FIG. 2 is a graph showing the relationship between the magnetic shield thickness and the reproduction output when the gap between the shields is 0.2 μm and the spacing is 0.2 μm. Except for the recording wavelength lOμ■, the reproduction output peaks at a specific magnetic shield thickness. That is, when the recording wavelength is 2 μm, the magnetic shield thickness is 1.6 μm, and when the M recording wavelength is 1.4 μm, the magnetic shield thickness is ! μm, and in the case of a recording wavelength of 1 μm, the reproduction output becomes maximum when the magnetic shield thickness is 0.6 μm. When this relationship is expressed as inter-shield gap G, magnetic shield thickness T, and recording wavelength λ, it becomes λ=20+T. Further, in the case of the recording wavelength [OAtm], the reproduction output reaches its lowest value when the magnetic shield thickness is 0.3 μm, increases gradually above this value, and rapidly increases below this value. The reason why the reproduction rate increases rapidly when the magnetic shield thickness is 0.3 μm or less is as follows.
This is thought to be because the shielding effect becomes /J) smaller.

As described above, when the inter-shield gap, magnetic shield thickness, and recording wavelength satisfy the above formula, a high-resolution shielded MR head can be obtained.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an MR head according to a first embodiment of the present invention.

1 is a substrate, 2 is a lower magnetic shield, 3 is an MR element, 4 is an intermediate layer, 5 is a bias application film, 6 is an upper magnetic shield,
7 is an electrode, T1 is a lower shield thickness, T2 is an upper shield thickness, G is a gap between lower shields, and G2 is a gap between upper shields. In FIG. 1, the lower magnetic shield thickness T1 is 0.8 μm, the lower inter-shield gap G1 is 0.4 μm, the upper magnetic shield thickness T2 is 0.6 μm, and the upper inter-shield cap G2 is 0.5 μm. The shield type MR head of this embodiment has a shortest readout wavelength of λ or 1.
When used in a magnetic recording device with a thickness of 6 μm, the structure satisfies the following formula.

Next, a method of manufacturing the shield type MR head of this embodiment will be explained with reference to FIG.

First, NiF with a thickness of 0.8 μm is placed on the ceramic substrate 1.
The e-film is formed by sputtering, and the lower magnetic shield 2 is formed using photolithography and ion etching. Next, after forming a 0.4 μm thick Sin insulating film (not shown) by sputtering,
NiFe film with a thickness of 0.04 μm, T with a thickness of 0.01 pm
A CoZrMo film with a thickness of 0.05 μm was successively formed by a sputtering method, and then a CoZrMo film with a thickness of 0.2 μm was formed.
A u film is formed by vacuum evaporation. Using photolithography, ion etching, and chemical etching, this laminated film is formed into a three-layer MR head consisting of an MR element 4, an intermediate layer 5, and a bias application film 6, and an electrode 7 connected to both ends of the MR head. It is formed. This three-layer structure MR
In the head, due to the magnetic coupling between the bias application film 6 and the MR element 4 and the bias magnetic field generated by the sense current,
A bias is applied to R element 4. A 5in2 insulating film (not shown) with a thickness of 0.44 μm was formed on this three-layer structure MR head by sputtering, and then
．． A 6 μm NiFe film is formed by sputtering, and the upper magnetic shield 6 is formed using photolithography and ion etching. Here, the gap G2 between the upper shields is made of a 0.44 μm thick Sin□ film,
It is defined by the total thickness of a Ti film with a thickness of 0.01 μm and a CoZrMo film with a thickness of 0.05 μm. After forming the upper magnetic shield 6, terminals (not shown) are formed, and a 30 μm thick Al2O3 protective film is further formed by sputtering to complete the transducer. The completed transducer is machined into a magnetic Rad slider.

When the reproduction characteristics of the shielded MR head fabricated according to this example were measured, it was found that the reading characteristics at the shortest readout wavelength of 1.6 μm were higher than that of other shielded MR heads with the same inter-shield gap and magnetic shield thickness of 3 μm. Playback output is 3D
B It was big. Furthermore, the reproduction output with respect to the read wavelength 10 μm was 1 dB smaller.

Next, as a second example, the lower magnetic shield thickness T is 0.2 μm, the upper magnetic shield thickness T2 is 0.2 μm, the lower inter-shield gap G1 is 0.7 μm, and the upper inter-shield gap G2 is 0.7 μm. A shield type MR head was manufactured. The configuration of the shielded MR head in this embodiment is the same as that of the shielded MR head in the first embodiment shown in FIG.
Same as head. When we measured the reproduction characteristics of this shield type MR head, we found that the reproduction output at the shortest recording wavelength of 1.6 μm was 3 dB higher than that of other shield type MR heads with the same gap between shields and magnetic shield thickness of 3 μm. . However, the reproduction output at the recording wavelength lOμ0 was 6 dB larger, resulting in lower resolution. Therefore, it was shown that when the magnetic shield thickness is extremely thin, the shielding effect for long recording wavelengths decreases.

〔Effect of the invention〕

As explained above, the present invention has the effect of significantly improving resolution by optimizing the sum of the magnetic shield thickness and the inter-shield gap with respect to the shortest read wavelength.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an MR head according to an embodiment of the present invention;
FIG. 2 is a graph of the dependence of the reproduction output on the thickness of the magnetic shield, showing the effect of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Lower magnetic shield, 3... MR element, 4... Intermediate layer, 5...
Bias application film, 6... Upper magnetic shield, 7...
Electrode, G, - Gap between lower shields, G2... Gap between upper shields, T1... Lower shield thickness, 2 - Upper shield thickness.

Claims (1)

[Claims] 1. A magnetoresistive head including a magnetoresistive element and magnetic shields adjacent to the upper and lower parts of the magnetoresistive element, wherein the upper magnetic shield has a thickness T_1, the lower magnetic shield has a thickness T_1, and a thickness T_1 of the upper magnetic shield; The thickness T_2, the gap G_1 between the upper magnetic shield and the magnetoresistive element, and the gap G_2 between the lower magnetic shield and the magnetoresistive element are expressed by the formula T_1+2・G_1=T_ with respect to the shortest read wavelength λ.
A magnetoresistive head characterized by satisfying 2+2・G_2=λ.