JPS6138524B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a magnetoresistive magnetic head.

As shown in FIG. 1, this type of magnetic head generally consists of a ferromagnetic thin film having uniaxial anisotropy such as permalloy deposited or sputtered on a substrate 1, which is a magnetoresistive element 2, covered with an insulating layer 3 and a bias magnetic field. It is constructed by laminating permanent magnet films 4 made of iron oxide or the like that give a magnetic field, but conventionally, the structure is such that the perpendicular component of the signal magnetic field from the magnetic recording medium 5 is applied in the direction of the easy axis of magnetization E _A of the magnetoresistive element 2. Therefore, if the original signal to the magnetic recording medium 5 is a rectangular wave signal with a long repetition period, the signal magnetic field H _S from the magnetic recording medium 5 has a vertical component with a large value only in the magnetization transition region. As a result, the waveform of the reproduced signal obtained from the lead-out conductor 6 becomes a short-width pulse (for example, as shown in FIG. 6A). For this reason, conventional magnetic heads have the drawback of requiring electrical processing to reproduce the original signal from the reproduced signal.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and the magnetoresistive element is
configured to receive a signal magnetic field from the magnetic recording medium in a direction parallel to the axis of easy magnetization,
By giving the magnetoresistive element a memory effect,
It is an object of the present invention to provide a magnetoresistive head capable of directly reproducing an original signal having a long repetition period in a form relatively approximating the original waveform.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, the magnetoresistive effect element 2 having uniaxial anisotropy is configured such that the direction of its easy axis of magnetization E _A is the same as the direction of the signal magnetic field H _S from the magnetic recording medium 5, and magnetization is A bias magnetic field H _B is applied by the permanent magnet film 4 in a direction perpendicular to the direction of the easy axis E _A . The other configuration is the same as that of the conventional example shown in FIG. Ru. The relationship between the current I and the direction of the easy axis E _A of the signal magnetic field perpendicular component H _S is shown in FIG.

In the above configuration, when a strong alternating magnetic field is applied to the magnetoresistive element 2 in a direction parallel to its axis of easy magnetization E _A , the direction of magnetization is θ) changes as shown in FIG. Point 7 in the same figure,
8, 9, 10, 11, and 12 correspond to points 10 to 12 on the magnetization characteristics of the magnetoresistive element 2 shown in FIG. 5, respectively. 13 in the same figure indicates 1 when the deviation angle between the easy magnetization axis E _A and the direction of the applied magnetic field is 90° or less.
4 shows the case where this deviation angle is 90°.

Therefore, when a pulsed magnetic field H _S having a waveform as shown in FIG. 6A is applied in a direction parallel to the axis of easy magnetization of the magnetoresistive element 2, a positive first It is magnetized in one direction (θ=0) in the same direction as the applied magnetic field H _S by the pulse 15, and maintains that direction until the negative second pulse 16 is applied. When the second pulse 16 is applied, the magnetization direction is rotated by 180°, and the magnetization direction (θ=180°) is maintained until the next positive third pulse 17 is applied. That is, the magnetoresistive element 2 exhibits a memory effect in that it maintains a constant magnetization state given by the previously applied magnetic field until the next magnetic field in the opposite direction is applied. Therefore, if the magnetization characteristics of the magnetoresistive element 2 are ideal, the generated magnetic field will be
From a magnetic recording medium having a pulse waveform as shown in FIG.

Practically speaking, it is preferable to apply a bias magnetic field H _B of an appropriate magnitude to the magnetoresistive element 2, and this is applied by the permanent magnet film 4 in the embodiment. When the bias magnetic field H _B is applied, the magnetization direction of the magnetoresistive element 2 rotates by an angle θ ₀ determined by its size and the characteristics of the magnetoresistive element 2, but the direction of the bias magnetic field H _B is the axis of easy magnetization E _A Since the rotation is perpendicular to the rotation direction, the above rotation is reversible, and as shown in FIG. Again θ=θ ₀ or θ=180°−θ
A magnetization direction of ₀ is given, and the bias effect due to the bias magnetic field H _B is maintained.

Therefore, a _{predetermined} angle ( ₀ <
<90°), the level is adjusted as shown in FIG. 6D, and a signal magnetic field H _S from the magnetic recording medium 5 as shown in FIG. 6 outputs a reproduction voltage having a waveform as shown in FIG. When the magnetization angle is zero-level corrected to give a switching characteristic and a signal magnetic field H _S from the magnetic recording medium 5 is applied as shown in FIG.
A reproduced voltage having a waveform as shown in FIG. 6E, which is approximately similar to the original signal waveform, is output.

As described above, according to the present invention, the ferromagnetic thin film of the magnetoresistive element is configured to receive a signal magnetic field in the direction of its axis of easy magnetization, thereby giving the magnetoresistive element the function of a storage element. Even if the signal magnetic field from the magnetic recording medium is a pulsed magnetic field, it is possible to reproduce the original rectangular wave signal with a long repetition period, and furthermore, it is possible to reproduce the original rectangular wave signal with a long repetition period. Since a bias magnetic field is applied in a perpendicular direction to provide a bias effect and an operating current is supplied to provide switching characteristics, the original signal waveform can be reproduced almost faithfully. It can also be used as a temporary storage element for pulsed magnetization.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional example of a magnetoresistive magnetic head, FIG. 2 is a diagram showing a magnetoresistive magnetic head according to the present invention, and FIG. 3 is a diagram showing a signal magnetic field and an operating current in the above embodiment. FIG. 4 is a diagram showing the applied magnetic field-magnetization angle characteristic, FIG. 5 is a hysteresis characteristic diagram, and FIG. 6 is a waveform diagram. 2 is a magnetoresistive element, 5 is a magnetic recording medium, E _A is an easy axis of magnetization, H _S is a signal magnetic field, and H _B is a bias magnetic field. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A magnetoresistive element having uniaxial anisotropy is applied with a signal magnetic field and a bias magnetic field from a magnetic recording medium in its easy axis direction and hard axis direction, respectively, and the application of both magnetic fields. A magnetoresistive magnetic head characterized by being supplied with an operating current in a direction different from the direction of the magnetic head and having hysteresis or memory operating characteristics. 2. The magnetoresistive magnetic head according to claim 1, wherein the direction of application of the bias magnetic field is perpendicular to the axis of easy magnetization of the magnetoresistive element. 3. The magnetoresistive magnetic head according to claim 1, wherein the magnetoresistive element is composed of a combination of a ferromagnetic thin film having uniaxial anisotropy and a permanent magnet film having high coercive force.