JPS59152521A - Magneto-resistance effect type multielement magnetic head - Google Patents

Abstract

PURPOSE:To obtain the structure of a magneto-resistance effect type reproduction head for current bias system multitrack having favorable reproduction sensitivity, head stability and a high S/N by bringing the 1st or the 3rd magnetic layers of magneto-resistance effect type reproduction heads into an electrically connected and magnetically unconnected state. CONSTITUTION:A ferrite substrate 6 is made of mechanochemically polished polycrystalline ferrite. A lower gap 7 and an upper gap 9 each made of a thin SiO2 film are formed by conventional RF sputtering. A thin film of ''Permalloy '' for a magneto-resistance effect element 8 and a thin film of ''Permalloy '' for a shield 10 are formed by vacuum deposition and DC confrontation sputtering, respectively, and a thin Ti film for a bias conductor 11 is formed by vacuum deposition. Patterning is carried out by conventional photoetching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the structure of a current bias type magnetoresistive reproducing head for a multi-track device.

[Prior art]

In the magnetoresistive reproducing head, in order to obtain the linearity of the magnetic field, it is necessary to tilt the direction of the current and the direction of the magnetization M at an angle of approximately 450 degrees.

As a conventionally known typical method (bias method) for tilting the magnetization M, there is a current bias method. The current bias method is further classified into a method using a shield as a bias conductor and a method using a new bias conductor.

Hereinafter, a current bias method using a shield as a nominal conductor will be explained in detail with reference to FIGS. 1 to 3.

Figures 1 and 2 schematically show the configuration of a multi-track magnetoresistive reproducing head using a conventional current bias method, with Figure 1 being a front view as seen from the tape sliding surface, and Figure 2 being The figure shows a side sectional view, in which the left side corresponds to the tape sliding surface. FIG. 6 shows the change in resistance of the magnetoresistive element with respect to the magnetic field, with the horizontal axis representing the magnetic field and the vertical axis representing the resistance value. In addition, 1 in the figure is Ni-Z
, a magnetic substrate such as n7 elite, a lower gap such as 2ba5i02, and 3 is a magnetoresistive element +! 4&”L 5i
The upper gap is 0.02%, and 5 is a shield made of a magnetic thin film such as permalloy. As the magnetoresistive element, a Parr alloy film having a film thickness of approximately 500 Å is used, and is generally formed so that its axis of easy magnetization is parallel to the tape sliding surface. In addition, the current L (~iR) for signal detection,
As shown in Figure 1, the tape is also flowing parallel to the sliding surface of the tape. Therefore, in an unbiased state,
The magnetization fvl and the current, t(MR), are parallel to each other.

That is, the operating point in the above-mentioned state corresponds to point A" in FIG. 3, and when the signal magnetic field from the tape is reproduced in this state,
As can be easily seen from Figure 3.

The strength of the reproduced signal is small, and the frequency of the reproduced signal is double the frequency of the signal recorded on the tape, making it impossible to faithfully reproduce the tape signal. Therefore, in the generally used reproducing head of the output resistance effect type, it is necessary to bias the operating point (B; Br in FIG. 6) where the highest output can be obtained and the least distortion can be obtained.
In the l++ current bias method, a current is passed through a conductor other than the magnetoresistive element, i(f3ias), and the magnetic field generated by the current changes the direction of magnetization of the magnetoresistive element, and the optimum operating point (Fig. 6) is determined. It is intended to bias towards middle B, B・). For this reason, the magnetic field required for the magnetoresistive element is approximately ±o, assuming that Hk is the anisotropic magnetic field of the magnetoresistive element.
, 7Hk. More specifically, the current bias method will be explained using FIG. 2. When a current, L(B・ias), is passed in the direction shown in Figure 2, 1(Bi
Due to the magnetic field generated by as), @resistance-effect 6
The magnetization M of is directed toward the sliding surface of take 1, and the optimum operating point B
, B.

However, as shown in FIG. 1, when the shield 5 is formed so as to be common between each track (between each reproducing head) (when it is formed in a state where it is magnetically connected) There are problems described below.

That is, when the above-mentioned magnetoresistive read head is operated at operating points B and B, noise similar to Barkhausen noise (hereinafter referred to as Barkhausen noise 2.) is generated, resulting in a decrease in mirror ratio. , and the head stability also deteriorates considerably. This noise is reduced by shifting the operating point from B, B' to C, Ct, and at the same time, the noise is reduced.

Stability is also improved. Therefore, the conventional current bias type magnetoresistive constraint head operates at an operating point of .c and Ct. It is clear from Figure 6 that when the operating point is biased to c or c, the reproduction sensitivity is degraded compared to when biased to the optimal operating point B or B.
There is no need to explain it again.

As mentioned above, the conventional multi-track magnetoresistive reproducing head using the current bias method has the above-mentioned problems.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the drawbacks of the prior art and to provide a structure of a current bias type multi-track magnetoresistive read head which has good read sensitivity and head stability and has a high ratio. .

[Summary of the invention]

As a result of a series of systematic studies on our current bias multi-track magnetoresistive read head, we have found the following: ■ The cause of the pseudo-Barkhausen noise observed in conventional heads. This is due to the shape of the shield 5, and the fact that the above-mentioned noise is suppressed by about -20 dB by making the shield into an island-like structure separated for each track. It has become clear that head stability is also improved.

In other words, by using magnetically isolated island-shaped shields for each track, head stability, playback sensitivity,
It has been found that the head can be operated at the optimum operating points B and B' without damaging the φ ratio.

But in this case, the bias current, 1(f3ias)
.

It is necessary to electrically connect each shield to allow the current to flow.

[Embodiments of the invention]

The present invention will be described in more detail below using examples.

An embodiment of the present invention will be described using FIG. 4. Fourth
The figure is a schematic diagram of the configuration of a multi-track current bias type magnetoresistive reproducing head according to the present invention, as viewed from the tape sliding surface.・In the figure, 6 is a Nt-ZrL ferrite, 7 is a lower gap made of a Sin thin film (thickness: 0.6 μm), 8 is a magnetoresistive element made of an 81% Ni permalloy thin film (thickness: 500A), 9 is 5
in2 thin film (.

Upper gap consisting of film thickness: 0.3 μm), 10 is 81
%Ni permalloy thin film shield, 11 is TL:
It is a bias conductor made of a thin film (thickness: 0.5μ77+).

The ferrite substrate 6 is manufactured by Mechano Chemical Lab.

It is polished polycrystalline ferrite. Also, Sin, thin film 7
, 9 is made by the normal sputtering method, and the permalloy thin film for the fB low resistance effect element 10 is made by the vacuum evaporation method (.

Substrate temperature: 6so° C.), one permalloy thin film for the shield 10 <s DC facing sputtering method, and a Ti thin film for the bias conductor 11 by a vacuum evaporation method. Pattern of each part.

-Ning was carried out using a conventional photoetching method.

When the head formed by the method described above was operated at the optimum operating point, the pseudo-noise (Lukhausen noise) was reduced by approximately -20 dB, and the playback sensitivity was 6.dB compared to the conventional head.
BB degree improved. Rad stability has also been greatly improved.

In this embodiment, the bias conductor 11 is exposed to the sliding surface of the tape, but the same results can be obtained even if the bias conductor is not exposed to the sliding surface. It goes without saying that the same results can be obtained using materials other than Ti as the material for the piezoelectric conductor 11.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a stable multi-drag current bias type magnetoresistive rege head with high reproduction sensitivity and a good ψ ratio.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the configuration of a conventional current bias type magnetoresistive reproducing head as seen from the tape sliding surface, Figure 2 is a side sectional view of the same head, and Figure 3 shows the change in magnetoresistance of the magnetoresistive element. The characteristic diagram shown in FIG. 4 is a schematic view of a multi-track current bias type magnetoresistive reproducing head according to the present invention, as viewed from the tape sliding surface. DESCRIPTION OF SYMBOLS 1... High magnetic permeability substrate, 2... Lower gap, 3... Magnetoresistive element, 4... Upper gap, 5... Shield, 6... Ni-Zn ferrite, 7... - Lower gap made of 5 in2, 8... Magnetoresistive element made of permalloy, 9... Upper gap made of 5 in2, 10... Shield made of permalloy, 11... Bias conductor. Representative Patent Attorney Akira Takahashi - 1st / Must ■λ (I3 ridge 5) (2-th) 3rd layer (bore) 4 Figure

Claims (2)

[Claims] (1) A first magnetic layer with high magnetic permeability, a first non-magnetic insulating layer, a fourth magnetic layer having a magnetoresistive effect, a second non-magnetic insulating layer, a sixth magnetic layer with high magnetic permeability. In a multi-element magnetic head comprising a plurality of magnetoresistive read heads each having a plurality of magnetic layers laminated in sequence on the same magnetic or non-magnetic substrate, the first or third magnetoresistive read head of each magnetoresistive read head is A magnetoresistive multi-element magnetic head characterized in that at least one of the magnetic layers is electrically connected to each other and magnetically disconnected. (2) First non-magnetic insulating layer, 5 with magnetoresistive effect
A multi-element magnetic device comprising a plurality of magnetoresistive read heads on the same magnetic substrate, each of which has a plurality of magnetoresistive reproducing heads each comprising a second magnetic layer having high magnetic permeability, a second non-magnetic insulating layer, and a second magnetic layer having high magnetic permeability laminated in this order. In the head, each. The second magnetic layer of the magnetoresistive head of
A magnetoresistive multi-element magnetic head characterized by being electrically connected and magnetically disconnected.