JPS6032244B2 - magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a readout device equipped with a magnetoresistive element that reads out magnetic information written on a magnetic recording medium using the so-called magnetoresistive effect, in which electrical resistance changes depending on an applied magnetic field. It relates to a dedicated magnetic head and a read/write magnetic head.

In recent years, there has been a strong demand for improved recording density in magnetic recording, and magnetoresistive heads have been attracting attention as heads for high-density recording and reproduction.

In order for a magnetoresistive head to work effectively as a high-density recording/reproducing head, both a means for applying a DC bias magnetic field to the magnetoresistive element and a means for magnetically shielding the magnetoresistive element are required. There is.

The DC bias magnetic field is necessary to bring the signal from the medium closer to a linear response and increase the sensitivity.As shown in Figure 1a, the DC bias magnetic field is generated using a ferromagnetic material such as permalloy. Gold for the magnetoresistive element 1,
The conductor layer 2 made of copper or aluminum is made of Si○, S
Spacing SP formed by insulator layers such as i02 and AI203
A method (conductor bias method) in which the magnetization M in the magnetoresistive element is set in a desired direction by a magnetic field generated by a current IB flowing through the magnetoresistive element (conductor bias method);
As shown in FIG. 2, a method (permanent magnet bias method) is known in which a permanent magnet thin film 4 that has been magnetized in a specific direction in advance is placed adjacent to the magnetoresistive element 1 and a leakage magnetic field generated from this magnetization is utilized. Next, a magnetic shield is necessary to block leakage magnetic flux from adjacent bits and obtain a high resolution reproduction output, and a magnetoresistive element is installed in accordance with the resolution required for the high magnetic permeability magnetic material. A method is known in which the material is held from both sides through a gap of a predetermined size.

Therefore, conventionally, as shown in FIG. 2, the magnetoresistive element 1 equipped with the above-mentioned DC bias magnetic field applying means 7 is made of a shielding magnetic material made of high magnetic permeability magnetic materials 5 and 6 such as ferrite or permalloy. A structure has been adopted in which it is supported from both sides via a gap g formed by an insulating layer or the like.

However, with this configuration, it is necessary to secure the space necessary for the DC bias magnetic field application means in the gap between the shielding magnetic materials, so the size of the shield gap g cannot be reduced to a certain level. In addition, in the conductor bias method, the temperature of the magnetoresistive element changes due to the heat generated by the current flowing through the conductor, which may cause fluctuations in the output level or damage the magnetoresistive element. If the thickness SP of the insulating layer that separates the conductor from the conductor is small, problems such as short-circuiting with the magnetoresistive element due to pinholes, polishing sag, etc. are likely to occur. The purpose of the present invention is to
Solving these shortcomings, the resolution, output level stability,
Furthermore, it is an object of the present invention to provide a magnetic head equipped with a magnetoresistive element having good electrical insulation properties.

According to the present invention, two shields made of a high magnetic permeability magnetic material are provided in the magnetoresistive element so as to be insulated from the magnetoresistive element and sandwich both sides thereof, and furthermore, a conductor layer is provided on the outside of one of the shields. A read-only magnetic head is constructed by providing a read-only magnetic head.

Then, by passing a current through this conductive layer, the one high permeability magnetic layer is magnetized, and a leakage magnetic field from the magnetized magnetic layer applies a DC bias magnetic field to the magnetoresistive element. Furthermore, according to the present invention, a second high magnetic permeability magnetic layer is further provided on the conductive layer of the read-only magnetic head with an insulating layer interposed therebetween.

In this case, this conductive layer not only serves as a means for applying a bias magnetic field to the magnetoresistive element as described above, but also
Together with the high permeability magnetic layer sandwiching the conductive layer, the write head is configured. Next, the present invention will be explained based on the drawings. As shown in FIG.
Two magnetic shield plates 9 and 10 are formed on the substrate so as to sandwich the magnetoresistive element 1 therebetween.

g is a gap that insulates the high permeability magnetic layers 9 and 10 and the magnetoresistive element 1, and is made of an insulator. Further, a conductor layer 2 is formed outside the gap formed by the two magnetic shield slopes so as to be adjacent to each other with an insulating layer (thickness SP) in between, for example, one of the magnetic shield plates 10'. The head configured in this manner is placed vertically close to the magnetic recording medium 3. (b) By passing a bias current 18 through the conductor layer 2 through the terminal 13, the adjacent high permeability magnetic material 10 is magnetized, and the leakage magnetic field generated by this magnetization is used as a DC bias magnetic field to drive the magnetoresistive element. magnetize.

It goes without saying that the leakage magnetic field and the magnetic field generated by IB at this time are of a magnitude that does not affect the magnetization of the medium. Furthermore, since the two magnetic layers 9 and 10 are made of high permeability magnetic material, they block leakage magnetic flux from adjacent bits, and further reduce the attenuation of the signal magnetic flux in the y-axis direction that has entered the magnetoresistive element 1. It also has the function of In this case, the high permeability magnetic layers 9 and 10 are, for example, permalloy films (
(thickness of several thousand A to several rm), and magnetoresistive element 1
Examples include ferromagnetic materials such as permalloy (thickness of several hundred amps), insulators such as Si0, SiQ, or AI203 (thickness of several thousand amps), and conductors such as gold, copper, or aluminum (thickness of several thousand amps). A material having a thickness of A to several rm) formed using thin film technology is suitable. Note that the other magnetic shield plate may be a ferrite substrate that also serves as a base. The resolution is determined by the distance g between the magnetic shield plates 9 and 10 and the magnetoresistive element 1, but this g can be adjusted by placing the bias magnetic field applying means within the gap, as in the conventional head shown in FIG. It is much easier because there is no need to set it up.

This is particularly effective when obtaining a high-resolution image because the gap g can be made small without being subject to any restrictions from the bias magnetic field applying means. In addition, since the conductive layer 2 and the magnetoresistive element 1 are separated from each other, short circuits due to pinholes or polishing sag are reduced, and the yield rate is improved.
Further, the temperature of the magnetoresistive element 1 rises due to the heat generated by the current IB flowing through the bias conductor, but since it is separated from the heat source, fluctuations in output caused by temperature changes can be reduced. In this embodiment, the conductive layer 2 and the magnetic shield plate 10 are insulated, but the conductive layer 2 only needs to magnetize the magnetic shield plate 10, so insulation is not necessarily required.

However, when insulated in this way, a decrease in effective magnetic permeability due to eddy currents can be prevented. Further expanding the above invention,
As shown in FIG. 4, a high magnetic permeability magnetic material 11 is further provided on the conductor layer 2 shown in FIG. 3 via an SP (space) formed from an insulating layer to provide a writing function as well. You can also do that.

That is, during reproduction, in exactly the same manner as the configuration shown in FIG. Magnetic information is read from the medium as a playback gap. On the other hand, during writing, the high magnetic permeability magnetic bodies 10 and 11
The gap G formed by the magnetic material 10,
11 is passed through the conductor layer 2 through the terminal 13 as a write current. As explained above, according to the present invention, a conductive layer for applying a DC bias magnetic field is provided outside the read gap, which not only improves read resolution and increases the rate of non-defective products, but also constitutes a write head. A magnetic head having the characteristics obtained is achieved.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing a secondary method of applying a DC bias magnetic field to a magnetoresistive element, in which a is a conductor bias method, b is a permanent magnet bias method, and Fig. 2 is a conventional DC bias magnetic field applying means. A schematic perspective view showing a magnetoresistive head and a magnetic recording medium including a magnetic shield and a magnetic shield;
FIG. 3 is a schematic perspective view showing an embodiment of the magnetic head according to the first invention and a magnetic recording medium, and FIG. 4 is a schematic perspective view showing an embodiment of the magnetic head and magnetic recording medium according to the second invention of the invention. FIG. 2 is a schematic perspective view showing a medium. DESCRIPTION OF SYMBOLS 1... Magnetoresistive element, 2... Conductor layer, 3... Magnetic recording medium, 4... Permanent magnet thin film, 5, 6, 9 , 10, 1 1... High permeability magnetic layer, 7... DC bias applying means, 8... Substrate, 12... Magnetoresistive head Read terminal, 13... Current supply v supply terminal. Murasaki'zu, 3rd figure, Buddha with hair

Claims (1)

[Claims] 1. A magnetoresistive element, two shields made of a high magnetic permeability magnetic material sandwiching both sides of the magnetoresistive element, which are insulated, and a shield provided on the outside of one of the shields. 1. A magnetic head comprising a conductive layer, and the conductive layer and the one shield constitute means for applying a bias magnetic field to the magnetoresistive element. 2. The magnetic head according to claim 1, wherein an insulating layer is provided between the conductive layer and one of the shields. 3. A magnetoresistive element, two shields made of a high magnetic permeability magnetic material sandwiching both sides of the magnetoresistive element, and an insulating layer provided on the outside of one of the shields. Consisting of a conductive layer and a second high permeability magnetic layer provided on the conductive layer via an insulating layer,
The conductive layer constitutes a bias magnetic field applying means for the magnetoresistive element together with the one shield, and constitutes a write head together with the one shield and the second high permeability magnetic layer. A magnetic head featuring: