JPH02285274A - Magnetoresistance effect element - Google Patents

Abstract

PURPOSE:To reduce not only hysteresis but also the disturbance of an output signal waveform by forming dimples on a stripe to stabilize a magnetic domain structure. CONSTITUTION:A ferromagnetic membrane is formed on a glass substrate and a reluctance effect element is formed by a wet etching method. Then, dimples 5 are formed on a stripe-shaped ferromagnetic membrane at a position where a magnetic wall is generated so as to provide an interval l4 and the shape of each dimple 5 is made circular or oval. Since the position where the magnetic wall is generated is present at a place 1/20 - 1/5 a width Ws3, the distance Wd6 of the dimples 5 from the end part of the membrane in the pattern width direction thereof is set to about 1/20 - 1/5 the width Ws3 and the interval l4 is set to the width Ws3 or less and the size of each dimple 5 is set to about 10mum or less. By this method, the turbulence of a signal waveform caused by hysteresis can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to magnetoresistive elements such as magnetic encoders and magnetic heads that detect magnetic signals using the magnetoresistive effect of a ferromagnetic thin film. .

[Conventional technology]

Magnetoresistive elements have extremely high magnetic detection sensitivity to magnetic signals, and are therefore used as highly accurate rotation detection or position detection sensors. -Generally, the sensor pattern formed by the ferromagnetic thin film that is the magnetic sensing part is striped, and the change in resistance when a signal magnetic field is applied perpendicular to the stripe is measured by the change in voltage. It is read as.

[Problem that the invention seeks to solve]

However, when using a magnetoresistive effect element using the above-mentioned striped pattern, the paths shown by double-sided lines A and B in the magnetic field history curve (MR curve) of resistance change shown in Fig. 3 are different. There is a problem in that the detected signal waveform is disturbed due to the presence of hysteresis.

The present inventor observed magnetic domains in magnetic thin films, and found that in striped n-type thin films, magnetic walls 2 are formed at both ends of the stripe l in the width direction due to the influence of the demagnetizing field, resulting in a three-domain structure, as shown in Figure 4. It was thought that hysteresis was caused by this domain wall disappearing as the signal magnetic field changed, resulting in a single domain structure.

An object of the present invention is to stabilize the magnetic domain structure of a striped magnetic thin film and provide a magnetoresistive element with less hysteresis.

[Means for solving problems]

In order to achieve the above object, the present invention is characterized in that changes in the magnetic domain structure are suppressed by forming dimples at positions where domain walls occur on a striped magnetic thin film pattern.

For example, as shown in FIG. 1, dimples 5 are formed at a certain interval β4 at positions where domain walls are generated at both ends in the width direction on a striped magnetic thin film having a width Ws3. The shape of this dimple is preferably circular or oval. In addition, the position where the domain wall occurs is 1/20 to 115 of the stripe width,
Position-4 where dimples are formed from the edge in the pattern width direction
6 is desirably L/20 to L15, and the interval i is preferably narrow, preferably -1 or less.

The size of the dimples to be formed is preferably 10 μm or less.

〔Example〕

Embodiments of the magnetoresistive element of the present invention A permalloy thin film made of a ferromagnetic material having a thickness of 400 mm was formed on a glass substrate, and a stripe width of 30 μm was formed using the sea urchin dot etching method, and dimple formation positions were When a magnetoresistive element with stripes of 6:5 μm and dimple spacing l:15 μm was prepared and an MR convex curve was measured, almost no hysteresis was observed as shown in FIG.

In addition, when magnetic domains were observed, it was confirmed that the structure had a three-domain structure when the detected magnetic field strength was ±Hk or less.

For this reason, using a striped magnetic thin film with the above shape,
When a magnetoresistive element is manufactured, it becomes possible to reduce disturbances in signal waveforms caused by hysteresis, and a magnetoresistive element with excellent characteristics can be manufactured.

〔Effect of the invention〕

The magnetoresistive element of the present invention stabilizes the magnetic domain structure, which was unstable in the conventional stripe shape, by forming dimples on the stripe, and can reduce hysteresis, thereby reducing disturbances in the output signal waveform. detection accuracy can be improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the shape of the striped magnetic thin film in the present invention, and FIG. 2 is an MR diagram of the magnetoresistive element of the present invention.
A convex curve in FIG. 3 is an MR convex curve of a conventional magnetoresistive element. FIG. 4 is an explanatory diagram showing a magnetic domain structure in a conventional striped magnetic thin film.

Claims (3)

[Claims] (1) A magnetoresistive element characterized by having dimples in a magnetically sensitive part pattern made of a ferromagnetic thin film having a magnetoresistive effect. (2) The magnetoresistive element according to claim 1, wherein the dimple has a circular or elliptical shape. (3) A magnetoresistive element according to claim 1 or 2, characterized in that the size of the dimples is 10 μm or less.