JPH01214077A - Magnetoresistance element - Google Patents

Abstract

PURPOSE:To obtain an element in which Barkhausen noise which has seriously harmful influence upon the operation of a magnetic head and a magnetic sensor does not appear by a method wherein the projected length L to the easy-to-magnetize axis direction and the projected length W to the difficult-to-magnetize axis direction of a magnetoresistance effect film whose basic pattern is a parallelogram conform to a specific inequality. CONSTITUTION:The projected length L to the easy-to-magnetize axis direction and the projected length W to the difficult-to-magnetize axis direction of a magnetoresistance effect film whose basic pattern is a parallelogram conform to an inequality 0<W<1.2XL<0.45>. For instance, an Ni-Fe film 4 with a thickness of 0.04 mum is formed by vacuum evaporation on a substrate 3 obtained by oxidizing the surface of an Si chip to form a rectangular magnetoresistance effect film and Au films 5-1 and 5-2 are provided on both the ends of the rectangular film as electrodes. The magnetoresistance effect films with various long side lengths L and short side lengths W are experimentally produced and relations to the number of magnetic domains which are shown in the diagram are obtained. Therefore, if the shape of the magnetoresistance effect film conforms to the inequality 0<W<1.2XL<0.45>, a magnetic wall does not exist so that the Barkhausen noise of the magnetoresistance effect film can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetoresistive element used as a magnetic head or a magnetic sensor.

[Conventional technology]

A magnetoresistive element is a magnetic field detection element that utilizes the fact that the resistance value of a ferromagnetic material is magnetized depending on the angle formed by the direction of magnetization and the direction of flow of the first current69, and has high sensitivity.
- It is used as a magnetic disk device, a magnetic head for a magnetic tape device, and a magnetic sensor. Materials for the magnetoresistive element include N1-F spring thin film, Ni-
A ferromagnetic material with a thickness of several hundred nanometers, such as thin Co, is used, and its shape is often rectangular in order to increase the resistance value.

(Problems to be Solved by the Invention) In general, adO magnetic domains are included in the thin ferromagnetic material used in magnetoresistive elements in order to suppress the increase in static energy due to the generation of charges on the film end faces. In the magnetization process of the existing zero ferromagnetic material m film, if a magnetic domain exists,
Changes in magnetization are mainly caused by movement of domain walls that form the boundaries of magnetic domains. This movement of the ferromagnetic material is trapped at various locations due to defects in the ferromagnetic thin film or nonuniform magnetic properties, so that magnetization changes often occur discontinuously.

When such discontinuous magnetization changes occur in the morale resistance effect element, it becomes impossible to obtain a continuous response of resistance changes to changes in the magnetic field, resulting in inconvenience in operation as a magnetic head or a magnetic sensor. Noise associated with such discontinuous magnetization changes is called pulcium noise, and suppression of this noise has been an essential condition for maintaining stable operation tm of the magnetoresistive effect system. However, there has been no definitive method for suppressing this Barkhausen noise. Nowadays, when 1@ of a narrow signal detection section is required, such as in a magnetic head, if the shape of the magnetoresistive element is made smaller, the a-wall is more likely to appear, which has become a big problem.

An object of the present invention is to provide a magnetoresistive element in which Barkhausen noise, which has an adverse effect on the operation of the morale head and magnetic sensor, does not appear.

[Means for Solving the Problem] The magnetoresistive element of the present invention has a parallelogram as a basic pattern (projection of the magnetoresistive film in the 6B easy axis direction and in the S difficult axis direction). It is assumed that the projection length W satisfies the following inequality.

0 <W< 1.2 A magnetoresistive film pattern using a magnetic thin film, 2 is a domain wall.

In the figure, the axis of easy magnetization of the ferromagnetic thin film is oriented horizontally, a! The wall is easily formed in the axial direction with both ends joined together. When the ratio of the length of the side in the hard axis direction to the length of the side in the easy axis direction is large, many domain walls are formed as shown in Figure 2 (a3), but the length of the side in the easy axis direction When the ratio of the length of the side in the direction of the hard axis to the length of the side in the direction of the easy axis decreases, the number of domain walls decreases as shown in Figure 2(b) because the domain wall energy decreases.In addition, the length of the side in the direction of the easy axis When the ratio of the length of the side in the difficult axis direction to
Since the a-wall energy is larger, Fig. 2(c)
The domain wall disappears as shown in .

The parallelogram-based basic pattern is the coiled resistance effect. There is a relationship between the projection length W of the pancreas in the direction of the easy magnetization axis and the projection length W in the direction of the hard magnetization axis. If this holds true, the inventor Kim has found that, as shown in FIG. 1, there will be no Mi wall in this magnetoresistive film.

Therefore, in the magnetoresistive element used in such a magnetoresistive film, since there is no domain wall, the change in magnetization is not caused by domain wall movement but by magnetization rotation, and Barkhausen noise does not occur and there is no magnetic field change. Continuous responses can be obtained.

In addition, if the part of the magnetoresistive element other than the signal detection part is covered with the electrode 4m111, the resistance change of the magnetoresistive element in the part connected by the electrode will not contribute to the output, thus impairing the single output state. It is possible to realize a morale head or a magnetic sensor having a signal detecting section smaller than the outer dimensions of the morale resistance effect element without having to do so.

〔Example〕

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

FIG. 3 is a plan view showing the main seat s of the first embodiment of the present invention.

In this example, a rectangular magnetoresistive film is formed by depositing a film with a thickness of 0.04 pm<DNi-F*m4'eX2 evaporation method on the surface t-oxidized substrate 3 of the S1 chip, and Au
A film 5-1, 5-2'i is provided to serve as an electrode.

Long side length L (equal to the projection length in the easy magnetization axis direction),
When we made all prototypes with various short side lengths W (equal to the projected length in the direction of the hard magnetization axis) and determined the relationship with the number of exposed areas, we found the results shown in Figure 1.

Note that the morale characteristics of N l −F @membrane 4 are determined by the coercive force He
is (I U 00/4 z ) A/m, anisotropic magnetic field H
k is (400G/4x)A/m.

In Fig. 1, the ○ mark indicates an element where the domain wall has disappeared, and the X mark indicates an element where the domain wall existed.If the solid line that forms the boundary between the O mark and the X mark is expressed using L and W, then W = L 2 X Lo
-" (1). Therefore, if the length W of the side of the rectangular magnetoresistive film in the direction of the hard axis of magnetization is smaller than the right side of equation (1), that is, 0<W<L2XL" (2) If the shape satisfies the following conditions, the Barkhausen noise of the magnetoresistive system can be eliminated.

FIG. 4(a) is a plan view showing the main parts of the second embodiment, FIG. 4(b) is a front view, and FIG. 4(c) is a top view of the main part of the second embodiment.
-Y'1M8j'r surface view.

This embodiment is a magnetoresistive element for a magnetoresistive head.

This example will be explained according to its manufacturing method.

5i (h
After forming a base layer 7 of 10 μm in thickness by sputtering, N1-Fep was formed as a lower shield layer 8 to a thickness of 1% by sputtering. Furthermore, the lower gap JfI4
9, a 5iOs film was deposited with α3, gm by sputtering.
After Ili, ll, Co-Zr-Mo amorphous film/T
Magnetoresistive effect t consisting of three-layer structure of id/N1-F@ film
illOa~10b to form fe, *Co-Z'
The -Mo amorphous film was formed to a thickness of 0.05 μm by sputtering, and the Ti film and N1-Fe film were each formed to a thickness of 0.048 m by vacuum evaporation. The easy axis of magnetization of the magnetoresistive element is set in the horizontal direction in Fig. 4(a), and the projected length in the easy width direction is 2002 m1! The projection length W to the axial gyrus is 1
0) tm. g107zm's maiden department (10m
The regions 10b and 10e other than ) were covered with a gold film 5-1.5-2 having a float of 0.2 Pm to form a penetrating surface. The Au film was formed by a vacuum evaporation method. In the magnetoresistive film, Co-Zr
-Mo amorphous film is a soft magnetic film for bias application, Ti film is N
The N1-Fe film, which is a film that gaseously separates the t-F@ exchange and the Co-Zr-Mo1 exchange effl, has a magnetoresistive effect, and the Co-Zr-Mo amorphous film and the N1-F@)[ A bias is applied to the N1-F@ film by magnetic coupling via the film end face. That is, the self-biasing means t-
We are prepared. Thereafter, as the upper gap layer 11, S i
A 0.3 μm thick film was formed by Ox llik sputtering, and a 1 μm thick Ni—Fe pattern was formed as the upper seal 112 by sputtering. On top of that, Al5os Hoen/
m13t20) Am film was formed to complete the transducer. The board with the completed transducer is
It was formed into a magnetic disk slider by machining.

The magnetoresistive film of this embodiment consists of a square part 10m and a parallelogram part 1tlb, IUe, and the projection in the direction of the easy axis of magnetization *Lr'12UO,um.

The projected length W in the direction of the hard magnetization axis is 10. In um, the inequality W
<1.2XL'°4s, and the filling area other than No. 16 detection part of the magnetoresistive film (magnetic head grinding part) is covered with electrodes and does not contribute to signal detection. ,
A narrow track magnetoresistive head with tracks + WA 10 and gm has been realized. When electromagnetic conversion characteristics were measured using this magnetoresistive head, a signal with no Barkhausen noise and a high signal-to-noise ratio was obtained.

FIG. 5 is a plan view showing the third embodiment.

This embodiment is a magnetoresistive element for a magnetic sensor.

As the substrate 3, 5iOstl# and 5 are placed on the surface of the Si chip.
An isNi film was used to test, and N1-F
@8II All 8II gold method is used to form a film with a thickness of α04 μm, and the magnetoresistive effect F! II was formed. The magnetic anisotropy of the magnetoresistive film was set in the side direction of the easy axis direction.

Electrodes made of an Au film 5-1.5-2 with a thickness of 0.3 μm are connected to both ends of the magnetoresistive film 10, and an electrode with a thickness of 0.3 μm is connected thereto.
．． The film was formed by a sputtering method with a holding ratio of 5/1 m.

The electrode was formed by a vacuum evaporation method. Note that the connection electrode 14-
1.14-2.14-3 is also an Au film. In this magnetic sensor, the length of the magnetoresistive film in the easy axis direction is 50 μm, and the length W of the side in the hard axis direction is 5 μ weave.
When this sensor satisfying the inequality W<1.2x L% 4+1 was used as a position detection sensor, a good position signal without Barkhausen noise was obtained.

FIG. 6 is a plan view showing the main parts of the fourth embodiment.
Substrate 3, magnetoresistive effect 1 (4-1 to 4-4) and '#
The method of forming the lE electrodes (5-1, 5-2, 14-1-14-3) is the same as in the third embodiment. The difference from the third embodiment is that the shape of the air resistance effect film is a folded pattern, and the length L' of this folded back is 7.0.
μm, +@VV is 5 μm. The length L' of the fold and the length W are determined by the inequality W<1.2XL/(L4 % 2
Satisfied. In this $ air sensor 2, the - air resistance effect film is formed continuously and has a rectangular shape with a length of about 70μ in the easy axis direction and a side length W of the hard axis direction of 5μ. Compared to the pattern, fewer charges are generated at the edge of the pattern, making it easier to create a single magnetic domain. Further, since the folded portion of the magnetoresistive element is covered with an electrode, signal detection is performed only in the rectangular portion where the magnetoresistive film is atomized. Therefore, the signal detection area could be seen in one direction. When this magnetic sensor was used as a position detection sensor, a good 1st shift 100th dive with no Barkhausen noise was achieved.

In the above embodiment, only the magnetoresistive element using the Ni-Fe film was explained, but since the magnetic domain structure of the ferromagnetic material pattern is mainly determined by the shape effect, Ni-Co, etc. It goes without saying that the present invention can also be applied to other strong-amount thin films.

[Effects of the Invention] As described above, in the single-resistance effect element according to the present invention, an excellent signal with suppressed Barkhausen noise can be obtained. Since it can be set freely regardless of the dimensions, it is possible to improve the performance and reliability of the magnetic head, magnetic sensor, etc. used, and also reduce the cost of testing the characteristics of the magnetoresistive element. can do.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between the projected length W of the magnetoresistive film in the direction of the easy axis of magnetization, the projection length W in the direction of the hard axis of magnetization, and the number of sections; If the ratio of the length of the side in the direction of the axis of easy magnetization to the length of the side in the direction of the axis of easy magnetization of the magnetic thin film pattern is greater than 1, and if it is smaller than l, then l
Fig. 2 shows the shape of the magnetic domain when the height is small, the third figure is a half-view showing the main parts of the first embodiment, and Fig. 4 (-1 can)
4(e) is a plan view and a front view showing the main parts of the second embodiment, FIG. 4(e) is a Y-Y'Wr plane view of FIG. Figure 3 is a plan view showing the main components of the third embodiment and the fourth embodiment, respectively. l...Ferromagnetic thin film pattern, 2...
Domain wall, 3...Substrate, 4, 4-1 to 4-4 =
Ni-Fe film, 5-1゜5-2...Au1i
i, 6...ceramic substrate, 7...
Base layer, 8...Lower shield layer, 9...
Lower gap layer, 10 & 110b, lOc... Magnetoresistive film, 11... Upper gap layer, 12.
... Shield layer, 13 ... Protective layer, 14
-1.14-2.14-3... Connection electrode. Agent Patent Attorney Susumu Uchihara 0 Single Production Area
rikyokuku 20 SO 10 θ 2 θ θ Visit O Projection length l ≠ 1 no Tachibana 1 figure ¥ Z map 3 times 4-1 ¥]

Claims (3)

[Claims] (1) A magnetoresistive effect characterized in that the projected length L in the direction of the easy axis of magnetization and the projected length W in the direction of the hard axis of magnetization of a magnetoresistive film having a parallelogram basic pattern satisfy the following inequality: element. 0<W<1.2×L^0^. ^4^5 (2) The magnetoresistive element according to claim (1), further comprising a self-biasing means. (3) The magnetoresistive element according to claim 1 or 2, further comprising a conductive film that selectively covers the magnetoresistive film and defines a signal detection section.