JPS59168917A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PURPOSE:To constitute a titled head so that a shape demagnetizing field in the track width direction is small even in case when the track width is narrowed, and also the resistance value of a magneto-resistance effect element does not drop, by constituting so that a length of a ferromagnetic thin film is larger than a track width of a head, and also a width of a part of the ferromagnetic thin film opposed to a track is larger than a width except the track width. CONSTITUTION:A magneto-resistance element 11 consisting of a ferromagnetic thin film consists of a part 11a corresponding to a track and a part 11b which is not opposed to the track. A length l2 of the magneto-resistance element 11 is larger than a track width l1. Also, a width w2 of 11a is larger than a width w1 of 11b. A shape demagnetizing field is in inverse proportion to an element width; therefore, the demagnetizing field in the part which is not opposed to the track can be made much larger than the demagnetizing field in the part 11a opposed to the track, and it can be realized that the bias magnetic field is scarcely applied at the effective time to the element of the part which is not opposed to the track. A current (j) flows through the part of the width w1 of the part which is not opposed to the track, and a resistance value of the MR element does not drop even if w2 is set larger than w1 in the part 11a opposed to the track.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a magnetoresistive magnetic head, and particularly relates to a magnetoresistive magnetic head that can obtain a large reproduction output with a small bias magnetic field. It is related to the head.

(b) Prior Art and Problems As a conventional magnetoresistive magnetic head, a kite head having the structure shown in FIG. 1 is known.

According to FIG. 1, a magnetoresistive element (MR element) made of a ferromagnetic thin film such as NiFe-4-Malloy 1. A bias conductor or permanent magnet 2 made of aluminum or the like is deposited by evaporation and photolithography, and silicon dioxide (Sin
2) The MR element 1 is arranged with an insulating layer 3 made of alumina (At20. Shielding magnetic materials 5 and 6 to improve the resolution of
is located. Here, 7 indicates a recording medium such as a magnetic disk or a magnetic tape, and arrow A indicates the moving direction of the recording medium.

FIG. 2 is a schematic perspective view of the MR element used in FIG. 1. Here, t is the film Jll, w is the element width,
t is the core width, and a constant current j is supplied to the kite element from the current terminal 8. Usually, the film thickness t is selected to be several tens of micrometers, and the core width t is made sufficiently longer than the element width W to achieve shape anisotropy. is necessary. - In order to impart axial anisotropy, it is also common practice to utilize induced anisotropy by evaporation in a magnetic field or the like. The wind element 1 detects signals by utilizing the phenomenon that its resistance value changes due to an external magnetic field, but the relationship between the external magnetic field and the resistance value is nonlinear as it is. It is necessary to linearize the operation of the element by applying a bias magnetic field in the element width direction to the kite element using the bias conductor 2, which is a magnetic field generating means. FIG. 3 is a graph showing the resistivity change (Δρ) of the Hm element, and this characteristic is approximately represented by ρ−ρ0+Δρ′ma Kobo 2θ.

Here, ρ0 is the minimum value of resistivity, Δρmax #'i resistivity change, θ is the angle between the magnetization vector M of the kite element and the current vector J (see Figure 2), and H- is θ= The magnetic field required to form the system is approximately expressed by the sum of the anisotropic magnetic field of the dish film and the shape demagnetizing field H6. If a bias magnetic field is applied to the MR element so that θ=4, the operation of the MR element will be approximately linear, and the dynamic range will be maximized. In this case, the required para-shaped demagnetizing field H4 is inversely proportional to the element width W, so in the case of the conventional example shown in FIG. The disadvantage was that it was difficult to make the MR element perform linear operation.

Figure 4 shows the magnetic field HK of the atomization film at 50e1 saturation magnetization 4π
MII: 10000 Gauss, film Wt: 50 μm
The results obtained by numerical analysis of the relationship between each H and the element width W in the case where It can be seen from FIG. 4 that H- increases rapidly when the element width W becomes 10 μm or less.

In order to reduce the increase in the demagnetizing field, it is good to increase the element width W, but when the element width W is increased, there is a drawback that the reproduction output decreases due to a decrease in the element resistance value itself.

Furthermore, as the ratio νW between the track width t and the element width W becomes smaller, a discontinuous change in electrical and mechanical resistance called Barkhansen H sound occurs, resulting in defects that deteriorate the characteristics of the magnetic head.

(c) Purpose of the Invention In view of the above drawbacks, the present invention aims to improve the recording density by reducing the shape demagnetizing field in the track width direction even when the track width of the magnetic head is narrowed, and by reducing the resistance of the magnetoresistive element. An object of the present invention is to provide a magnetoresistive magnetic head whose value does not decrease.

B) Structure of the Invention The object of the present invention is to provide a magnetoresistive magnetic head comprising a ferromagnetic thin film formed via an insulating film on an I plate and a connecting conductor layer, in which the length of the ferromagnetic thin film is A magnetoresistive effect type head, characterized in that the track width of the head is larger, and the width of the portion of the ferromagnetic thin film facing the dead track is also larger than the width of a portion other than the track width. This is achieved by a magnetic head.

(E) Embodiments of the Invention Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 5 is a schematic plan view showing one embodiment of the magnetoresistive magnetic head according to the present invention.

As shown in FIG. 5, a magnetoresistive element 1 made of a ferromagnetic thin film
1 is a portion 11m corresponding to the track (track width z1)
and a portion 11b that does not face the truck. The length t2 of this magnetoresistive element 11 is the track width 1. bigger. Further, the width W2 of the portion 11& of the skeleton element facing the track is larger than the width W2 of the portion 11b not facing the track.

As already mentioned, since the shape demagnetizing field is inversely proportional to the element width, the portion 11 that does not face the track as in the above embodiment
The demagnetizing field at b can be made much larger than the demagnetizing field at the portion 11m facing the track. Therefore, it is possible to apply almost no bias magnetic field to the elements in the portion not facing the track during effective operation. In this case, as will be discussed later in FIG. 7, the change in element resistance in the portion not facing the track is small and can be ignored. On the other hand, in the portion facing the track, the demagnetizing field is small and a sufficient bias magnetic field can be applied to the element 11.

FIG. 6 is a schematic diagram showing the current path of the element 11a in the part facing the track. It is assumed that the current j flows in the part having the width Wl of the element in the part not facing the track. In the part 11m where w2
Even if Wl is set larger than Wl, the resistance value of the MR element does not decrease.

FIG. 7 is a diagram showing the resistance change of the MR element in the portion 11a facing the track and the portion 11b not facing the track. The vertical axis is the resistivity ρ, and the horizontal axis is the external magnetic field in the direction of the hard magnetization axis.With respect to the HB /S ias magnetic field, the operating point of the portion 11a facing the track is Pl, and the operating point of the portion 11b not facing the track is This indicates that the risk of operation is P2. It will be understood that since the slope of the song @C at the operating point P2 is sufficiently smaller than the slope of the curve at the operating point P2, the reproduction output is also very small.

As a preferred embodiment of the child head according to the present invention, considering the case where a head with a track width of 10 μm is realized, the accuracy of the photomask and the portion 11a facing the track and the portion 11b not facing the track as described above are By considering the value of HK, t+=10 μm, t
! =3oμm, Wl =5μff! + W2 = 3
It is preferable to set it to about 0 μm.

(f) As described in detail, the magnetoresistive magnetic head according to the present invention has a small geometric demagnetizing field even when the track width is narrowed.
Moreover, the resistance value of the magnetoresistive element does not decrease and is 7! −
You can get playback output.

In addition, in the above embodiment, using an example in which one magnetoresistive element is formed on a substrate, Peta Tsuji also forms two magnetoresistive elements in parallel with an insulating layer interposed therebetween. The present invention can also be used in a shunt bias type magnetic head, which is a type of magnetic head in which a bias magnetic field is applied to each element by a current flowing through each element.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a magnetic @resistance effect type magnetic head for explaining the prior art, and FIG. 2 is a schematic perspective view of the magnetoresistive element (MR multilayer element) used in FIG. Figure 3 is a graph showing the resistivity change of the wind element, and Figure 4 shows the result of numerical analysis of the relationship between H- of the MR film and kite element width W. 5 is a schematic plan view showing an embodiment of the magnetoresistive magnetic head according to the present invention, and FIG. 6 shows a current path of the kite element in the portion facing the track according to the present invention. This is a schematic diagram, and FIG. 7 is a diagram showing resistance changes of an MR element in an embodiment according to the present invention. 2. 11... Magnetoresistive element, 2... Bias conductor or permanent magnet, 3... Insulating layer, 4... Substrate, 5.
6... Shield magnetic material, 7... Recording medium, 8...
Current terminal, 11a...portion facing the track, 11
b...The part that does not face the truck. Patent Applicant: Fujitsu Limited Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate 1) Yukio Patent Attorney Akiyuki Yamaguchi 3 Figure 11' Rest 40 Element Width w (Pm) Figure 5 JP-A-59-IG8917 (4) Subaru 6th edition, page 7

Claims (1)

[Claims] 1. In a magnetoresistive magnetic head comprising a ferromagnetic thin film formed via an insulating film on a substrate and a connecting conductor layer, the length of the ferromagnetic thin film is the length of the head. A magnetoresistive magnetic head characterized in that the track width is also large, and the width of a portion of the ferromagnetic thin film facing one track is larger than the width of a portion other than the track width.