JPH01201815A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To miniaturize a device and to make it light weight by heightening saturation magnetic flux density by providing an electrode to output a voltage generated by stress sensed by a piezoelectric thin film to an external circuit on a laminate body. CONSTITUTION:Since a superconductor layer 1 repulses so as to prevent a magnetic flux B from being inputted to its inside by a Meissner effect when the superconductor layer 1 passes through the magnetic field B from a magnetized magnetic tape 7, repulsion F is generated on the surface of the superconductor layer 1, and the repulsion F is applied as the stress on a piezoelectric layer 2, and electric charge Q is generated on the surface of the piezoelectric layer 2. Potential difference V between both sides of the piezoelectric layer 2 generated by the electrical charge Q is outputted from electrode layers 3 and 4 to the external circuit as a voltage signal. Since the outputted voltage V is proportional to the repulsion F that is the stress for the piezoelectric layer 2, and the repulsion f is proportional to the square of the magnetic strength of the magnetic flux B, the voltage V is proportionated to the square of the magnetic flux strength. Therefore, it is enough to perform a differential processing on a signal outputted as the voltage to detect the magnetic strength of the magnetic flux B. Thus, it is possible to miniaturize the device and to make it light weight.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic head for reading information from a magnetic recording medium.

[Conventional technology]

The technology for recording and reproducing information magnetically is applied to a wide range of fields such as audio, video, and computers, and it is easy to record, reproduce, and erase information, and recording media can be manufactured at low cost, and recording density is high. It has excellent features such as high viscosity, non-volatility, and the ability to easily form a recording medium into a tape.

Furthermore, as devices become smaller and recording becomes more dense, there is a need for smaller, lighter magnetic heads with higher saturation magnetic flux density.

In particular, the miniaturization of portable compact cassette tape recorders, which are rapidly becoming popular in the audio field, is remarkable.

Equipment with excellent dynamic range is required.

[Problem to be solved by the invention]

For example, in the compact cassette tape recorder mentioned above, the electronic circuitry has become thinner and smaller.

Although it contributes to weight reduction, because magnetic heads require coils, thinning of the film has not progressed, and the proportion of the head in the volume of the device is increasing.

However, compact cassette tape recorders and the like are mainly playback-only machines, and the magnetic head does not necessarily require a coil.

Furthermore, in order to be compatible with metal tapes with high coercivity, the magnetic head needs to be made of a material with a high saturation magnetic flux density of 10,000 Gauss or more.

However, materials with high saturation magnetic flux density are crystalline materials.
Considering practicality such as high magnetic permeability and wear resistance, it is limited to Sendust alloys, but Sendust alloys have a maximum saturation magnetic flux density of 10,000 Gauss, and nose quality materials include cobalt (Co). There are amorphous alloys, but they have the problem of low stability against temperature.

The present invention was made to solve these problems, and has a high saturation magnetic flux density and a small size.

The purpose is to provide a lightweight magnetic head.

[Means to solve the problem]

The magnetic head according to the present invention includes a superconductor thin film and a piezoelectric material *ny,= which senses the repulsion force to a magnetic field generated by the Meissner effect of the superconductor thin film as stress, and the piezoelectric thin film It is characterized by being equipped with an electrode that outputs the voltage generated by the stress sensed by the sensor to an external circuit.

[Effect]

In the magnetic head according to the present invention, the repulsion force against the magnetic field due to the Meissner effect of the superconductor thin film is applied to the piezoelectric thin film as stress, a potential difference corresponding to the applied stress is generated in the piezoelectric Wi film, and this potential difference is transferred to the electrodes. Output to external circuit via.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a schematic cross-sectional view showing the structure of a thin film magnetic helad according to the present invention, in which 1 is a superconductor layer made of a thin film of oxide such as Ba Y Cu O, etc., which responds to a magnetic field. be. The superconductor layer 1 is made of W.

The piezoelectric layer 2 is made of a thin film such as barium titanate, on which electrode layers 3.4 made of metals such as Ti and Cr are laminated on both sides, and the piezoelectric layer 2 is laminated with one electrode layer 4 interposed therebetween.
It is protected by a lower protective layer 5 made of an insulator of silicon oxide, and the upper surface of the lower protective layer 5 is laminated with an upper protective layer 6 made of a wear-resistant thin film such as titanium nitride or chromium nitride. Prevents wear.

FIG. 4 is a diagram illustrating the operating principle of the thin-film magnetic head according to the present invention. When the superconductor layer 1 passes through the magnetic field B from the magnetized magnetic tape 7, the superconductor layer 1 is In order to repel the magnetic flux B so that it does not enter inside, a repulsive force F is generated on the surface of the superconductor layer 1, and this repulsive force F is applied as stress to the piezoelectric layer 2, causing the piezoelectric layer 2 to
A potential difference V between both sides of the piezoelectric layer 2 caused by the generated charge Q is output from the electrode layer 3.4 to an external circuit as a voltage signal.

The voltage V output to the external circuit is proportional to the repulsive force F, which is the stress on the piezoelectric layer 2, and the repulsive force F is proportional to the square of the magnetic intensity of the magnetic flux B. Therefore, the voltage V is the magnetic intensity of the magnetic flux B. is proportional to the square of Therefore, in order to detect the magnetic intensity of the magnetic flux B, it is sufficient to perform differential processing on the signal output as a voltage.

The size of the magnetic head is, assuming that the width is the width and the length is the length of the magnetic tape 7, the width is equal to or greater than the width of the magnetic tape, for example, 4 m or more for a cassette tape, and the length is equal to or greater than the superconductor layer 1. The superconductor layer 1 may be of any length as long as it can be in lubricious contact with the magnetic tape 7, and the width of the superconductor layer 1 should be 500 μm or less in correspondence with the track width of the magnetic tape 7.

FIG. 3 shows the radio frequency (radio frequency) used to form the superconductor layer 1.
y: RF) is a schematic cross-sectional view of a sputtering apparatus, in which reference numeral 30 denotes a reaction vessel; A heater 39 with electrodes and a heater 39 for heating the sample, a sample support stand 31 containing the heater 39 and supporting the sample, a target substrate 40 supported opposite the sample support stand 31, and a voltage applied thereto. One end of the reaction vessel 30 is opened to the outside, a gas introduction part 37 is connected to a mass flow controller (not shown), and the other end is opened to the outside, and an exhaust part 36 is not shown. Not connected to a diffusion pump. Further, the sample support stand 31 is supported by the reaction container 30 by an insulator 32.

Next, the manufacturing process of the thin film magnetic head according to the present invention will be explained based on the explanatory diagram of the manufacturing process shown in FIG. 2 and the schematic cross-sectional view of the RF sputtering apparatus shown in FIG. In this embodiment, the piezoelectric layer 2 is used as a substrate.

Piezoelectric layer 2 made of thoroughly cleaned barium titanate
Electrode layers 3.4 made of Ti are formed on both sides of the substrate to a thickness of 1 μm by electron beam evaporation (FIG. 2 (al)).

Next, the piezoelectric layer 2 on which the electrode layers 3 and 4 have been formed is placed on the sample support stand 31 in the reaction container 30 of the RF sputtering device, and the reaction container 30 is
At the same time as starting to reduce the pressure to within 0°C, power is supplied to the heater 39 to stabilize the temperature of the piezoelectric layer 2 at 650°C. When the pressure inside the reaction vessel 30 drops to 5 X 10-7 Torr or less, a mixed gas of argon (Ar) and oxygen (02) (Ar: 02!10: 7), and the pressure inside the reaction vessel 30 was increased to 2 x 10-2 Torr.
Keep r. After 5 minutes, while adjusting the matching unit 33, the high frequency power supply 34 was turned on to start supplying power with a voltage of 1.4 kV to the sample support stand 31, and the Ba Y placed on the sample support stand and the counter electrode 35 was turned on. Plasma is generated for 30 minutes between the target substrate 40 made of CuO, and BaYC with a thickness of l11m+ is formed on the piezoelectric layer 2.
A superconductor layer 1 made of uO is formed (Fig. 2 (bl
).

Further, after forming the superconductor layer 1, the high frequency power source 34 is turned off, the pulp of the gas introduction section 37 is closed, and the gas introduction is stopped. When the temperature of the piezoelectric layer 2 drops to 70° C., the reaction vessel 30 is opened and the piezoelectric layer 2 on which the electrode layer 3.4 and the superconductor layer 1 are laminated is taken out from the reaction vessel 30.

Next, a resist 10 is applied to the superconductor layer 1 (see FIG. 2).
C1), the resist 10 other than the part corresponding to the superconductor N1 that detects the magnetic field is removed by exposure and development.
d)) [The superconductor layer 1 other than the part that detects the magnetic field is removed by dry etching.
), and further remove the registration mark 0 (FIG. 2(f)). In this way, the superconductor layer 1 is formed to have a length of 5 μm and a width of 500 μm.
Process buttering leaving the clear part.

Plasma C is placed on the patterned superconductor layer 1.
A lower protective layer 5 made of a silicon nitride film with a thickness of 1 μm is formed by the VD method (FIG. 2 (81)).

Further, on the lower protective layer 5, a plasma CVD method is applied.

A wear-resistant upper protective layer 6 made of a titanium nitride film with a thickness of 1 μm is formed by an ion blating method or the like (
Figure 2 (h)).

Finally, the piezoelectric layer 2 is processed to the required dimensions.

In this embodiment, the electrode layers 3 and 4 are laminated in parallel to the piezoelectric layer 2, but they may be formed on the side surface of the piezoelectric layer 2.

The characteristics of the thin film magnetic head formed as described above will be described below with reference to numerical values. The critical temperature Tc of the superconductor layer l is 90K (Kelvin), and the critical magnetic field Hc is 30T.
(Tesla).

When the thickness of the piezoelectric layer 2 used as a substrate is 2 mm, the magnetic field is 100
The voltage signal output from the piezoelectric layer 2 at 0 Gauss is 6
0 μV, 6 mV at 10000 Gauss, 100
It showed good signal reproduction characteristics of 580+wV at 000 Gauss.

Further, in the case of a ceramic head in which the electrode layer 2 was formed on the side surface of the substrate 2, the voltage signal output from the piezoelectric layer 2 was 70 μV when the magnetic field was 10,000 Gauss. In this case, the thickness of the magnetic head is 2 mm, and the length is 10 m.

The magnetic head is significantly smaller and lighter than the magnetic head of a conventional compact cassette recorder, which has a width of 6n and a thickness of 5 to 100 ota.

In this example, the piezoelectric layer 2 was produced as a substrate, but a piezoelectric layer was formed on a substrate made of quartz or the like.

A superconductor layer and an electrode layer may be formed.

Furthermore, in this embodiment, one set of the piezoelectric layer 2 and the superconductor layer was formed at 111rti, but a plurality of sets of these may be laminated.

Furthermore, if Si is used as the substrate, the processing circuit for the voltage signal output from the piezoelectric layer 2 can also be fabricated on the same substrate as the magnetic head, and in this case, the size and weight of the signal processing circuit can be reduced.

〔Effect of the invention〕

The thin-film magnetic head according to the present invention has a superconductor layer and a piezoelectric layer formed into thin films, applies repulsive force to a magnetic field due to the Meissner effect of the superconductor layer as stress to the piezoelectric layer, and generates a magnetic field according to the applied stress. By extracting the voltage signal through the electrodes, the saturation magnetic flux density of the thin-film magnetic head is increased and the excellent effect of reducing the size and weight of the thin-film magnetic head is achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a thin film magnetic head according to the present invention;
FIG. 2 is a schematic diagram showing the manufacturing process, and FIG. 3 is a schematic cross-sectional view of the high frequency sputtering equipment used in the manufacturing.
FIG. 4 is a diagram explaining the principle. l...Superconductor layer 2...Piezoelectric layer 3.4...
Electrode Layer Xu Applicant Sumitomo Metal Industries Co., Ltd. Agent
Patent attorney Noboru Kono h) (b) (C) Yan 29 (e) (f) (g) (h) Funeral 4 Figure ↓ I 3 Figure

Claims (1)

[Claims] 1. A superconductor thin film and a piezoelectric thin film that senses the repulsion to the magnetic field generated by the Meissner effect of the superconductor thin film as stress are laminated, and a voltage generated by the stress sensed by the piezoelectric thin film is generated in this laminate. A thin film magnetic head characterized by being equipped with an electrode that outputs a signal to an external circuit.