JPH01224910A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To eliminate magnetic saturation at both magnetic pole layer tip parts at the time of recording and to reduce the adverse effect of a negative peak waveform at the time of reproduction by providing a superconductive material to change the width of the tip parts of first and second magnetic pole layers between at the times of the recording and reproduction and a heat generating or cooling member. CONSTITUTION:At tip parts 32 and 33 of first and second magnetic pole layers, a superconductive material 37 to change the width of the tip parts between at the time of the recording and at the time of the reproduction and a heat generating or cooling member 38 are provided. At the time of the recording, since the superconductive material 37, which is made into a superconductive condition at <=a critical temperature to indicate a complete diamagnetism beforehand, is heated by the heat generating member 38 to be made into a normal conductive condition, and information is recorded at the original width of the first and second magnetic pole layer tip parts 32 and 33, the magnetic saturation at the both magnetic pole layer tip parts 32 and 33 can be evaded. At the time of the reproduction, by returning the superconductive material to the superconductive condition, the adverse effect due to the negative peak waveform for phase margin characteristics can be reduced.

Description

[Detailed Description of the Invention] [Summary] Regarding a thin film magnetic head used in a magnetic disk device, etc., and in particular a head structure with good phase margin during reproduction and recording/reproduction efficiency, the present invention relates to the first and second magnetic pole layers of the thin film magnetic head. By changing the thickness of the tips during recording and playback, there is no magnetic saturation at the tips of both magnetic pole layers during recording, and during playback, there is no adverse effect of unnecessary negative peak waveforms on isolated playback waveforms. In order to reduce the occurrence position of the negative peak waveform by making it smaller than the information bit interval, an interlayer is installed between the ring-shaped first magnetic pole layer and the second magnetic pole layer through the recording/reproducing gap. A magnetic head in which a thin film coil is disposed so as to be covered with an insulating layer, the first,
The tip of the second magnetic pole layer is provided with a superconducting material and a heat generating or cooling member for changing the thickness of the tip through which magnetic flux enters and exits during recording and reproduction.

[Industrial application field]

The present invention relates to a thin-film magnetic head used in magnetic disk drives and the like, and particularly to a head structure with good phase margin during reproduction and good recording/reproducing efficiency.

High-density recording and high efficiency are required in magnetic disk devices, etc., and the thin-film magnetic heads used in these devices have a negative peak waveform 1. in the isolated reproduction waveform when reproducing information. So-called negative edges tend to occur, the phase margin decreases, and the reproduction efficiency tends to decrease due to these.

Therefore, there is a need for a head structure that can easily reduce the occurrence of negative peak waveforms in such isolated reproduced waveforms and improve reproduction efficiency.

[Prior Art] A conventional thin-film magnetic head for recording and reproducing has a slider, for example, as shown in a plan view of main parts in FIG. 3(a) and a sectional view taken along line AA' in FIG. A thin film coil 16 whose upper and lower surfaces are covered with a first magnetic pole layer 13, a gap layer 14, and an interlayer insulating layer 15 and a second magnetic pole layer 17 are laminated in this order on a magnetic substrate 11 with an insulating layer 12 in between. A protective film 18 is coated.

Further, the opposing tips of the first magnetic pole layer 13 and the second magnetic pole layer 17, which are formed into a ring shape with the gap layer 14 directly sandwiched between them, are opposed to the surface of the magnetic substrate 11 on which the first magnetic pole layer 13 is provided. Each of the exposed surfaces is exposed in a rectangular shape on a surface orthogonal to each other, and this exposed surface is defined as a medium facing surface 19. Then, by applying a recording signal current to the thin film coil 16, the first and second magnetic pole layers 13.17 are magnetized, and for example, a recording layer of a medium (not shown) in which the magnetic flux is opposed from the tip of the first magnetic pole layer 13. Information is recorded by forming a magnetic path that returns to the second magnetic pole layer 17 via the By outputting the magnetic flux, an induced voltage proportional to the temporal change in the magnetic flux is generated at both ends of the thin film coil 16, and reproduction is performed by outputting this.

[Problems to be Solved by the Invention] However, in the conventional thin-film magnetic head as described above, when reproducing information already recorded on the magnetic disk medium 20 as shown in FIG. The change point 21 of the magnetization direction (magnetic domain) in the recording layer of the magnetic disk medium 20 that rotates in the direction corresponds to the tip edges a and b of the first and second magnetic pole layers 13 and 17 and the gear portion 1.
When passing the position 4a, a voltage is detected at the reproduction output terminal of the thin film magnetic head, and the isolated reproduction waveform at this time is a positive peak waveform at the temporal position corresponding to the gap part 14a, as shown in the figure. An isolated reproduction waveform 21 occurs, but
The first and second magnetic pole layers 13 on both sides of this reproduced waveform 21.
There is a drawback that negative peak waveforms 22a and 22b, which are noise signals also called negative edges, are generated at temporal positions corresponding to leading edges a and b of 17, respectively, and degrade the reproduced signal.

That is, when recording information on the magnetic disk medium 20, 2
A common method is to invert the phase of the recording current at the position of "1" in the signal data based on the base system.
The change point 21 of the magnetization direction (magnetic domain) recorded at 0 corresponds to 1° of the recorded data, and in the reproduced waveform, only the isolated reproduced waveform 21, which is a positive peak waveform, is effective.

FIG. 5 shows how unnecessary negative peak waveforms that are originally generated in such a reproduced waveform affect isolated reproduced waveforms that are positive peak waveforms at intervals of several bits. For example, at the left position (a) of the central isolated reproduction waveform C corresponding to the recorded data "1 pa", the isolated reproduction waveforms A on the left and right sides and the negative peak waveform of A2 overlap, and also at the right position (b) When the negative peak waveforms of the isolated reproduced waveforms B+ and B2 overlap, the temporal position of the central isolated reproduced waveform C moves to the right from its original fixed position, which causes a decrease in the phase margin. It becomes.

Therefore, in order to avoid the negative influence of the negative peak waveform on the isolated reproduction waveform, the thickness of the tips of the first and second magnetic pole layers is made sufficiently thin, so that the negative peak waveform on the isolated reproduction waveform, which is the positive peak waveform, is made sufficiently thin. It is possible to make the generation position of the peak waveform smaller than the information bit interval, but if the thickness of the tips of the first and second magnetic pole layers is made thin, that part will become magnetically saturated during recording. However, there was a problem in that it was difficult to sufficiently magnetize the opposing recording medium.

In view of the above-mentioned drawbacks of the conventional technology, the present invention has been developed by changing the thickness of the tips of the first and second magnetic pole layers of a thin-film magnetic head during recording and reproducing, so that the thickness of the tips of the first and second pole layers of the thin-film magnetic head is changed during recording. A new thin-film magnetic head that is free from magnetic saturation and that reduces the negative influence of unnecessary negative peak waveforms on isolated reproduced waveforms by making the generation position of the negative peak waveforms smaller than the information bit interval during reproduction. The purpose is to provide the following.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention includes a thin film coil disposed between a ring-shaped first magnetic pole layer and a second magnetic pole layer through a recording/reproducing gap so as to be covered with an interlayer insulating layer. The magnetic head is provided with a superconducting material and a heat generating or cooling member at the tips of the first and second magnetic pole layers to change the thickness of the tips through which magnetic flux enters and exits during recording and reproduction. The configuration is as follows.

[For production]

In the thin film magnetic head of the present invention, a superconducting material and, for example, a heat generating member are provided at the tips of the first and second magnetic pole layers that face each other across the recording/reproducing gap, and which change the thickness of the tips through which magnetic flux flows. Therefore, when recording information on a magnetic disk medium, for example, the superconducting material, which has been brought into a superconducting state below a critical temperature exhibiting complete diamagnetic property, is heated with a heat generating member to become a normal conducting state, and the first and second magnetic poles are heated. By recording information in the original thickness state of each thickness of the layer tip, magnetic saturation at the tips of both magnetic poles, which is conventional, can be avoided.

In addition, when reproducing the information written in the trunk of the medium by such recording, heating of the superconducting material by the heat generating member is stopped or cooling is performed to return the superconducting material to its original superconducting state, so that its complete diamagnetic state can be restored. Due to the magnetic shielding effect caused by this, the respective thicknesses of the tips of the first and second magnetic pole layers are equivalently reduced. Therefore, the track information that has already been written can be reproduced with a thickness thinner than the original thickness of the tip of each magnetic pole layer, and the position of the negative peak waveform relative to the isolated reproduced waveform at that time can be determined from the bit interval of the information. can also be made smaller.

As a result, the negative influence of the negative peak waveform on the phase margin characteristics is reduced.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1(a) and FIG. 1) are side cross-sectional views of main parts of the tips of the first and second pole layers, and the first and second pole layers as seen from the medium surface side, showing an embodiment of the thin-film magnetic head according to the present invention. FIG. 7 is a plan view showing the tip surface of the second magnetic pole layer.

In both of these figures, 31 is an insulating layer, 32 and 33 are the tips of the first and second magnetic pole layers facing each other with a gap layer 34 in between, and 35 is an encapsulation layer in which a thin film coil 36 is disposed. The interlayer insulating layer 39 is a protective film.

Inside the -1 second magnetic pole layer tip portion 32.33, a film 37 made of a superconducting material and a heating or cooling member that can be electrically controlled from the outside, such as a heating resistive film 38, are superimposed. interpose each in the thickness direction as shown in the figure,
As shown in FIG. 1(b), a portion thereof is provided so as to be exposed to the medium facing surface 40.

Note that it is preferable to use, for example, a YBaCuO-based superconducting material as the superconducting film 37.

In such a thin film magnetic head, during recording and reproduction, the superconducting film 37 in the first and second pole layer tip portions 32 and 33 is cooled to a low temperature, for example, to form a superconducting film below a critical temperature that exhibits complete diamagnetic property. state, and when information is recorded on the magnetic disk medium 41, the heat-generating resistive film 38 is electrically heated to heat the superconducting film 37, and the superconducting film 37 is brought into a normal conductive state, and the tips of the first and second magnetic pole layers are returned to their original state. 32.33 thickness W
Record address information.

Furthermore, when reproducing the information recorded in this way, the heat generation of the heat generating resistive film 38 is stopped, and the superconducting film 37 is stopped.
By returning to the original superconducting state, the thickness effective for reproduction of the first and second magnetic pole layer tips 32 and 33 due to the magnetic shielding effect due to its complete diamagnetic property becomes the original magnetic pole tip at the time of recording. Thickness W.

The thickness changes to a thickness Wb that is equivalently thinner than the thickness Wb.

Therefore, the original first and second magnetic pole layer tip portions 32°33
By reproducing track information that has already been written with a thickness W smaller than , it is possible to reduce the negative influence of the negative peak waveform in the isolated reproduction waveform on the margin characteristics.

FIGS. 2(a) and 2(b) are side sectional views of main parts of the tips of the first and second pole layers, showing another embodiment of the thin-film magnetic head according to the present invention, and FIGS. FIG. 2 is a plan view showing the tip end surface of the second magnetic pole layer, in which the same parts as in FIGS. 1(a) and 1(b) are given the same reference numerals.

The embodiment shown in these two figures is shown in FIGS. 1(a) and (b) above.
The difference from that is that the tips of the first and second pole layers are 32°3
A film 51 made of a YBaCuO superconducting material, for example, and a heating or cooling member that can be electrically controlled from the outside, such as a heating resistor, are arranged on each medium facing surface 40 of No. 3 so as to regulate the thickness direction as shown in the figure. The structure is such that the film 52 and the film 52 are overlapped with each other.

The configuration of this embodiment also allows the above-mentioned FIGS.
) When recording information on the magnetic disk medium 41, information is recorded with each thickness of the first and second pole layer tips 32 and 33 being the original thickness W, and then When reproducing information, similar effects can be obtained, such as being able to reproduce information with a thickness W that is thinner than the original thickness Wa of the tips of each of the magnetic pole layers.

Further, in this embodiment, the variable magnetic shield structure in which the superconducting film 51 and the heat generating resistive film 52 are superimposed is not provided in the first and second pole layer tips 32 and 33, and both C1' is placed in the pole layer tips. Since the structure is provided on the medium facing surface 40 of the portions 32 and 33, there is an advantage that manufacturing is easier than in the embodiment structure shown in FIGS. 1(a) and 1(b).

In addition, in the above embodiment, an example was explained in which a heat generating resistive film was used as a means for changing the temperature of a superconducting film, but depending on the material of the superconducting film to be applied, a thin film thermoelectric conversion element that utilizes the Peltier effect may also be used. In this way, the superconducting film may be cooled to a superconducting state below a critical temperature exhibiting complete diamagnetism, or the superconducting film in this superconducting state may be heated to a normal conducting state.

〔Effect of the invention〕

As is clear from the above description, according to the thin film magnetic head according to the present invention, there is no magnetic saturation at the tips of the first and second magnetic pole layers when information is recorded, and sufficient magnetization is recorded on the medium. It becomes possible, and during playback, the original first,
It can be reproduced with a thickness thinner than the thickness of the tip of the second magnetic pole layer, and the generation position of the negative peak waveform with respect to the isolated reproduced waveform can be made smaller than the information bit interval, and the phase margin characteristics This has an excellent effect of improving reproduction efficiency, such as reducing the negative influence of negative peak waveforms on the data.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are side sectional views of the main parts of the tips of the first and second magnetic pole layers, showing an embodiment of the thin-film magnetic head according to the present invention, and FIGS. 2(a) and 2(b) are side cross-sectional views of main parts of the first and second magnetic pole layer tips showing other embodiments of the thin-film magnetic head according to the present invention. 3(a) and 3(b) are plan views of essential parts for explaining a conventional thin-film magnetic head, and A-A. ' Cross-sectional view, Figure 4 is a diagram showing the relationship between the magnetic pole tip and isolated reproduced waveform during reproduction by a conventional thin-film magnetic head, and Figure 5 explains the interference of a negative peak waveform with the conventional isolated reproduced waveform. It is a diagram. 1(a) and Φ) to FIG. 2(a) and (b), 31 is an insulating layer, 32 is a first magnetic pole layer tip, 33 is a second magnetic pole tip, 34 is a gap layer, 35 is an interlayer insulation layer,
36 is a thin film coil, 37.51 is a superconducting film, 38.52
39 is a protective film; 40 is a medium facing surface; 41
indicate magnetic disk media, respectively. Figure 1 [Ql Figure 1 (1)) Figure 2 (Q)
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Claims (1)

[Claims] A thin film coil (36) is provided between the ring-shaped first magnetic pole layer and the second magnetic pole layer through a recording/reproducing gap (34) so as to be covered with an interlayer insulating layer (35). A magnetic head is provided with a superconductor at the tips (32, 33) of the first and second pole layers for changing the thickness of the tips through which magnetic flux enters and exits between recording and reproduction. material (37) and a heat generating or cooling member (
38) A thin film magnetic head characterized by comprising: