JPH0540902A - Magnetic recording and reproducing head of high density - Google Patents

Abstract

PURPOSE:To enable high densification with a simple configuration by providing a soft magnetic fine needle whose magnetic permeability varies in accordance with a magnetic field and providing the needle with an energizing means to magnetize it. CONSTITUTION:For recording, a magnet sensitive part, i.e., the tip of the soft magnetic fine needle 31 is brought into contact with a magnetic recording medium, and the fine needle 31 and the recording medium 4 are relatively transferred. Then, the input of a recording signal is amplified by means of an amplifier to the exciting means 32, i.e., an exciting coil and energized. By means of a leakage magnetic field from the tip of the fine needle 31, the recording medium 4 is magnetized in accordance with the recording signal, and recording is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high density magnetic recording / reproducing head.

[0002]

2. Description of the Related Art A high coercive force magnetic recording medium has been developed in response to the demand for high density recording in magnetic recording, and a perpendicular magnetic recording system using a magnetic recording medium having perpendicular magnetic anisotropy has been proposed.

On the other hand, regarding the recording / reproducing magnetic head, a thin film head has been developed in order to cope with a narrower track and a shorter wavelength, and the conventional so-called bulk head has been changed to a thin film head.

Further, due to the decrease in the relative speed between the reproducing magnetic head and the recording medium accompanying the higher density of the magnetic recording, a magnetoresistive (MR) effect type thin film reproducing exclusive use which does not depend on the relative speed with the magnetic recording medium is used. The development of magnetic heads is remarkable. As the MR magnetic sensing section of this MR effect type magnetic head,
Although a permalloy thin film or the like is used, a material having a remarkable MR effect, that is, a material having a sufficiently large ratio ΔR / R of a resistance change ΔR when a magnetic field is applied to a resistance R in a non-magnetic state has been developed. However, in the case of permalloy, there is a problem in that it is a small value of about 2%.

Recently, as an active head, a magnetic head has been proposed which utilizes a change in the inductance of a coil due to an external magnetic field (for example, 199).
Proceedings of the Annual Conference of IEICE Spring National Congress 5-35
page).

[0006]

On the other hand, the applicant of the present invention intends to further reproduce the signal magnetic field by the magnetic recording on the magnetic recording medium with high sensitivity according to the application of Japanese Patent Application No. 3-333687. To provide a microwave waveguide type magnetic detection device.

A reproducing magnetic head using this magnetic detection device has a microwave waveguide 2 including a soft magnetic material 1 whose magnetic permeability is changed by application of an external magnetic field at the terminal end, as shown in the configuration diagram of FIG. And a high frequency oscillator 3 for exciting the microwave waveguide 2.

Then, a magnetic field to be detected, that is, a recording signal magnetic field from the magnetic recording medium is applied to the soft magnetic material 1 to make it
Utilizing the phenomenon that the magnetic permeability changes due to the external magnetic field of, the change of the magnetic permeability changes the impedance characteristic of the waveguide, and from the change of the reflectance of the high frequency power supplied to the waveguide,
The external magnetic field is measured as a voltage change at a predetermined position of the microwave waveguide 2.

The operation principle of this microwave waveguide type reproducing magnetic head will be further explained. When a microwave waveguide which is not matched at the load end is excited by high frequency power through a microwave transmission line such as a coaxial cable. , In addition to traveling waves, there are reflected waves, and standing waves are created by superimposing them. In particular, the standing wave ratio becomes maximum in the microwave waveguide in which the load end is released or short-circuited.

FIG. 7 shows the standing wave amplitude | V | on the microwave waveguide 2 when the load end is released.
In the example shown by the solid line curve, the standing wave amplitude at x = x ₀ | V |
Indicates that a standing wave with a minimum is standing. In FIG. 7, the ratio between the minimum value and the maximum value of the standing wave amplitude is called the voltage standing wave ratio, and λ indicates the interval at which the peaks or valleys of the standing wave are repeated.

The standing wave ratio and λ depend on the magnetic permeability μ in the waveguide, and when the magnetic permeability μ changes with the external magnetic field H _ex ,
The voltage standing wave ratio and λ also change, whereby the standing wave standing manner changes as shown by the broken line in FIG. 7, and x = x
_The standing wave amplitude | V | at ₀ becomes the voltage V _ex . Therefore, the external magnetic field H _ex can be detected by this voltage V _ex .

The microwave waveguide 2 may have a microwave strip line type structure. The microwave strip line has a ground conductor 5 and a line conductor 6, and for example, a dielectric 7 and a soft magnetic body 1 are interposed between the two.

The soft magnetic material 1 is made so that its magnetic permeability μ exhibits a sharp magnetic field dependence. When the magnetic field is applied in a predetermined direction, its magnetic permeability gradually increases, and when the magnetic field is further increased, the magnetic permeability decreases.

In this way, for example, the load end 2a constitutes an open microwave strip line.

Then, a high-frequency oscillator 3 is connected between a conductor 6 and a ground conductor 5 on the side opposite to the load end 2a of the microwave stripline type microwave waveguide 2 by a transmission line 8 using, for example, a coaxial cable. To do.

The frequency of the high frequency oscillator 3 is set to, for example, 1G.
By adjusting the frequency to about Hz, the microwave waveguide 2 is excited without applying a signal magnetic field, and the excitation frequency is adjusted so that the node of the standing wave comes to x = x ₀ as shown by the solid curve in FIG. To do. Then, the standing wave voltage at x = x ₀ is detected by the detection circuit 9 and the voltage is detected by the voltmeter 10.

The magnetic head having such a structure is shown in FIG.
As shown in FIG. 2, the load end (open end) 2a of the microwave waveguide 2 is made to face the magnetic recording medium 4 closely, and a leakage magnetic field, that is, a signal magnetic field based on recording on the magnetic recording medium 4 is applied to the external magnetic field H.
_It is given to the soft magnetic body 1 as _ex . By doing so, the magnetic permeability μ of the soft magnetic body 1 is changed by the external magnetic field H _{ex, and} accordingly, the voltage standing wave ratio and the standing wave interval λ are changed as shown by the broken line in FIG. Therefore, the magnetic signal can be read as a voltage change.

At this time, if the frequency of the high-frequency power supply, so to speak, the carrier frequency f is, for example, 1 GHz, the frequency of the recording signal magnetic field H _ex is 100 GHz, which is one digit lower than that, that is, 100 MHz. However, only the change in H _ex can be extracted as a voltage change.

This microwave waveguide type magnetic head can also be constructed by thin film technology.

However, in any of the thin film magnetic heads, the track width is naturally limited due to restrictions in processing, magnetic characteristics, etc., and a short wavelength is required to improve the recording density. It is necessary to deal only with

Furthermore, the MR type magnetic head as described above,
Since the microwave waveguide type magnetic head is a read-only head, when it is combined with a recording head, manufacturing problems such as setting the positional relationship and complicating the structure also occur.

The present invention constitutes a microwave waveguide type reproducing head based on a new principle capable of surely performing the reading even with the above-mentioned high density by adopting a simple constitution, and further, integrally with this, Provided is a high-density magnetic recording / reproducing head which also constitutes a recording head capable of high-density recording.

[0023]

As shown in FIG. 1 which is a perspective view of an essential part of an embodiment of a high-density magnetic recording / reproducing head according to the present invention, a soft magnetic thin film whose magnetic permeability is changed by an external magnetic field is shown. A magnetic recording medium 4 having a magnetically sensitive portion composed of a needle 31 and an exciting means 32, and a magnetic recording medium 4 made of a perpendicularly magnetized film is magnetized at the time of recording by the exciting means 32 to thereby magnetically record the soft magnetic fine needle 31. When recording on the medium 4 and reproducing, a high frequency power is applied to the magnetic sensitive portion, that is, the soft magnetic fine needle 31, and the reflected wave of this is changed by an external magnetic field, so that the leakage magnetic field from the recording portion of the magnetic recording medium is changed. Detect and
Read the record.

[0024]

According to this structure, as described with reference to FIGS. 4 and 5, the reproduction is performed by the microwave waveguide type structure, so that the high-sensitivity short wavelength reproduction is performed and the magnetic sensitive portion has the soft magnetic fine needle. 31, that is, the tapered shape,
Higher resolution reading can be performed, and since the recording is also performed by the same needle-shaped magnetic sensing unit 30, high density recording can be performed.

[0025]

EXAMPLE An example of a high density magnetic recording / reproducing head according to the present invention will be described. In this case, as the magnetic recording medium 4, a magnetic recording medium having a perpendicular magnetization film is used. As the reproducing head, the microwave waveguide type reproducing head structure described in FIGS. 4 and 5 is used as a basic structure.

Example 1 As shown in FIG. 1, a tapered needle-shaped dielectric 33 formed by, for example, melt-drawing a glass rod is formed, and a slit 34 is formed on it in the axial direction. The soft magnetic layer 35 divided into two is electroless plated and electroplated,
Alternatively, the soft magnetic fine needles 31, that is, the magnetic field sensitive portions are formed by deposition by vapor deposition, sputtering or the like.

A soft magnetic material whose permeability changes due to this external magnetic field
The magnetic layer 35 is, for example, Co₇₅Ta ₁₁Zr₁₄The amorph
Can be made of a soft magnetic material.

In this way, the slit 34 allows two
The divided pair of soft magnetic layers 35 constitutes a microwave waveguide. That is, the pair of soft magnetic layers 35 are the conductors 5 and 6 of the microwave waveguide whose load ends are short-circuited.

Further, the magnetic field sensitive portion, that is, the soft magnetic fine needle 3
1 is provided with an exciting means 32 around which an exciting coil is wound.

For recording, as shown in FIG. 3, the magnetic sensitive portion, that is, the tip of the soft magnetic fine needle 31, is attached to the magnetic recording medium 4.
And the thin needle 31 and the magnetic recording medium 4 are relatively moved. Then, the recording signal input is amplified by the amplifier 40 and is supplied to the exciting means 32, that is, the exciting coil. In this manner, the leakage magnetic field from the tip of the soft magnetic fine needle 31 of the magnetic sensing portion magnetizes the magnetic recording medium 4 according to the recording signal, that is, magnetic recording is performed.

In this case, if necessary, the magnetic recording medium 4
Although not shown, opposing magnetic poles are arranged so as to face the magnetic sensitive portion, that is, the soft magnetic fine needles 31 with the magnetic field sandwiched therebetween, or the magnetic recording medium 4 has a magnetic film on the back surface opposite to the side facing the needle magnetic sensitive portion. By using a magnetic recording medium on which a high magnetic permeability film is formed, good perpendicular recording can be performed on this magnetic recording medium 4.

In reading the recording from the magnetic recording medium 4 thus recorded, similarly, the magnetic sensitive portion, that is, the tip of the soft magnetic fine needle 31 is brought into contact with or close to each other. By doing so, the leakage magnetic field due to the recording magnetization on the magnetic recording medium 4 is applied to the magnetic sensitive portion, that is, the soft magnetic fine needles 31, so that the magnetic permeability thereof changes. On the other hand, at this time,
At the same time, high-frequency power is supplied from the high-frequency oscillator 3 to the soft magnetic material layer 35 of FIG. 1 through, for example, the coaxial cable type transmission line 8.

In this way, the external magnetic field, that is, the signal magnetic field from the magnetic recording medium 4, changes the reflected wave due to the change in the magnetic permeability of the soft magnetic fine needle 31, in this example the soft magnetic layer 35, that is, it will be described with reference to FIG. The detected change in the standing wave is detected by the detection circuit 9, demodulated by the demodulator 41, and a reproduction output signal is extracted. The change of the reproduction output with respect to the external magnetic field shows almost the same characteristics for the positive and negative magnetic fields as shown in FIG. 8, and the change of the output with respect to the magnetic field is not a monotonic increase, and therefore the linearity and the magnetic field are not increased. External magnetic field (signal magnetic field) in order to obtain positive and negative polarity inversion output depending on the polarity of
It is desirable to apply the bias magnetic field H _B1 or H _B2 to the magnetic sensing section 31 so that the operating point is at the position B ₁ or B ₂ in FIG. The bias magnetic field at the time of reproducing can also be applied by appropriately energizing the coil of the exciting means 32.

Example 2 As a magnetically sensitive portion, as shown in FIG. 2, a soft magnetic fine needle 31 is formed by applying a soft magnetic material layer 35 described above to a needle-like body 36 which is formed by drawing a glass rod and tapering it. A coaxial type load end in which the conductor 6 is used as one conductor 6, a so-called center conductor, and a conductive layer 37 is formed on the outer periphery of the conductor 6 via the dielectric layer 33 to serve as the other conductor. It is also possible to adopt an open microwave waveguide type configuration. In this case, the exciting means 32, that is, the coil is wound around the center conductor 6.

Example 3 As shown in a partially cutaway perspective view in FIG. 4, CoFeS
The soft magnetic fine needle 31 made of iB-based amorphous is constituted.
The soft magnetic fine needle 31 was manufactured by the following method. That is, first, the diameter of about 1
A CoFeSiB-based amorphous magnetic wire of 00 μm (manufactured by Unitika) is electrolytically polished in phosphoric acid to form a needle shape having a tip curvature radius of about 5 μm. Next, the wire whose tip was sharpened was cut into about 5 mm to obtain a soft magnetic fine needle 31.

Then, a formal-coated copper wire having an outer diameter of 0.03 mm was wound 30 times around the tip of the soft magnetic fine needle 31 as an exciting means 32.

The chip wound with the soft magnetic fine needle 31 is housed in a copper shield case 38 having an inner diameter of 0.5 mm, and the gap between the chip and the shield case is filled with a dielectric 33 made of epoxy resin.

The soft magnetic fine needle 31 and the shield case 38 are connected to the central conductor and the outer peripheral conductor of the coaxial cable 39, and the coaxial cable 39 allows the high frequency power from the high frequency oscillator 3 near 1 GHz or higher. Is supplied, a Schottky barrier diode D for detection is connected to the connection point between the magnetic head and the coaxial cable 39, and the result is input to the oscilloscope Osc.

The characteristics of the magnetic head according to the third embodiment were judged as follows.

That is, in this case, as shown in FIG.
A magnetic layer 52 made of a TbFe-based amorphous alloy film is sputtered on a slide glass 51 having a side of mm to a thickness of about 0.2 μm, and the medium 4 is finely moved along the plane of the medium 4 in X and Y axes orthogonal to each other. It was set on an XY stage having a fine movement device. At this time, the coercive force of the magnetic layer of the medium 4 was about 80 kA / m (1000 (Oe)).

The soft magnetic fine needle 31 of the magnetic head is
The linear magnetization pattern 53 was recorded on the medium 4 by bringing it into contact with the surface of the magnetic layer of the medium 4 and moving the XY stage in the X direction while applying a DC current of 200 mA to the coil of the exciting means 32.

Then, the excitation means 32 is de-energized, the coaxial cable 39 is supplied with high frequency power of about 1 mW in the vicinity of 1 GHz from the high frequency oscillator 3, and the stage is moved so as to cross the recording magnetization pattern on the medium 4. It was moved in the Y direction. At this time, each time the magnetic head, that is, the soft magnetic fine needle 31 crossed the recording pattern, a change in the signal voltage of about 1 mV was detected by the diode D and observed by the oscilloscope Osc. At this time, it was found from the amount of movement of the magnetic head that the width of the magnetization pattern 53 recorded on the medium 4 was about 10 μm.

It should be noted that the above-mentioned confirmation of recording / reproduction is performed by the medium 4
On the other hand, although a unidirectional magnetization state was recorded with direct current, it is possible to record an AC signal by changing the direction of the supply current, and the reproduction of this magnetization pattern is possible if the polarity of the recording magnetization pattern is reversed. A signal output according to the direction can be obtained.

Example 4 Using the same magnetic head structure and magnetic recording medium 4 shown in FIG. 4 as in Example 3, the XY stage described in FIG. 5 was moved in the X direction at a speed of 1 mm per second. A direct current whose polarity is alternately inverted was applied to the coil of the excitation means 32. The current reversal interval of energization is 1 second, and the current value is ± 200
It was set to mA. Next, the magnetic head is returned to the origin position of X and Y, the high frequency power of about 1 GHz is supplied from the coaxial cable 39, and the XY stage is 1 m / s, which is the same as when recording.
The detection output of the diode D was observed by the oscilloscope Osc while moving at a speed of m. At this time,
A direct current of about 2 mA was applied to the exciting means 32 to apply a bias magnetic field to the magnetically sensitive portion, that is, the soft magnetic fine needle 31. At this time,
A signal output of about 1 mV in which the polarity is inverted every second corresponding to the polarity inversion of the recording current was obtained.

Example 5 Using the same magnetic head structure and magnetic recording medium 4 shown in FIG. 4 as in Example 3, the XY stage described in FIG. 5 is moved at a speed of 1 mm / sec while the exciting means 32 is operated. A recording pattern was written on the medium by passing a 10 kHz sinusoidal current through the coil. The maximum value of the exciting current was 200 mA. After that, the magnetic head was returned to the origins of X and Y, and the detection output of the diode D was measured by the oscilloscope Osc while tracing on the recording track under the same conditions as in Example 4. At this time, as in the fourth embodiment, the exciting means 32,
That is, a direct current of about 2 mA was applied to the exciting coil to apply a bias magnetic field to the magnetically sensitive portion, that is, the soft magnetic fine needle 31. At this time, a substantially sinusoidal output voltage of 10 kHz and about 1 mV was observed.

The parameters described in the above embodiment are for showing the principle of the present invention, and are the number of windings of the exciting coil, the wire diameter, the exciting current, and the frequency of the high frequency power supplied during reproduction. , Relative movement speed of the magnetic head and the medium,
The frequency and the like of the recording signal are not limited to the above numerical values, and may be adjusted to any value according to the size of the magnetic head such as the soft magnetic fine needle 31 and the like.

The principle of operation of the magnetic head of the present invention during reproduction differs from that of a so-called induction type head which responds to a change in magnetic flux over time, and responds to the magnitude of the magnetic flux flowing into the magnetic sensing portion, that is, the soft magnetic fine needle 31. .. Therefore, the output voltage does not depend on the relative speed with respect to the medium, and enables reproduction of the recording signal of the stationary medium.

[0048]

As described above, according to the present invention, as a recording head, a microwave waveguide is provided with a magnetic material, and a change in the standing wave due to a change in magnetic permeability due to a magnetic field to be detected by the microwave waveguide is used. Since it is detected as a voltage change at a predetermined position of the magnetic recording medium, the signal magnetic field based on the recording information from the magnetic recording medium can be reproduced with high sensitivity regardless of the relative velocity with the magnetic recording medium, like the MR effect magnetic head. It can be performed.

Further, since the microwave waveguide type structure is adopted, the carrier frequency is, so to speak, several hundred MH.
Since it can be increased to z or GHz order, the recording signal frequency on the magnetic recording medium can be set to a high frequency, which is higher in combination with the fact that it does not depend on the relative speed with the magnetic medium. The density can be recorded.

Further, in the present invention, the magnetic sensitive portion having the soft magnetic material is needle-shaped, and the exciting means 32 is provided on the magnetic sensitive portion to be used as a recording head for not only reproduction but also recording as a recording head. So the whole structure is simple. Further, the magnetically sensitive portion has a needle-like configuration, and since the needle-like tip can actually be on the order of submicron, high density at the time of recording and high resolution at the time of reproducing can be achieved. Higher recording density can be achieved.

Further, the structure thereof is also the magnetic sensing portion, that is, the soft magnetic fine needle 3.
Since only the excitation means 32, specifically, the winding of the coil is performed in the first embodiment, it is possible to bring a great advantage in practical use such that the manufacturing thereof becomes simple.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of an embodiment of a magnetic recording / reproducing head according to the present invention.

FIG. 2 is a perspective view showing a part of a main portion of another embodiment of the magnetic recording / reproducing head according to the present invention in section.

FIG. 3 is a block diagram of a recording / reproducing system of a head according to the present invention.

FIG. 4 is a perspective view in which a part of a main portion of another embodiment of the magnetic recording / reproducing head according to the present invention is shown in section.

FIG. 5 is an explanatory diagram of recording / reproducing operation.

FIG. 6 is a configuration diagram of an example of a microwave waveguide type magnetic detection device used for explaining the present invention.

FIG. 7 is an explanatory diagram of a standing wave amplitude voltage for explaining the operation of the microwave waveguide type head.

FIG. 8 is a magnetic field-output voltage curve diagram of the microwave waveguide type head.

[Explanation of symbols]

 31 Soft Magnetic Fine Needle 32 Exciting Means 4 Magnetic Recording Medium

Claims (1)

[Claims] 1. A magnetic recording medium comprising a magnetically sensitive portion made of soft magnetic fine needles and an exciting means, wherein the soft magnetic fine needles are magnetized by the exciting means at the time of recording on a magnetic recording medium made of a perpendicular magnetization film. By doing so, recording on the magnetic recording medium is performed, and high frequency power is applied to the magnetic sensitive section during reproduction, and the reflected wave of the magnetic field is changed by an external magnetic field, so that the leakage magnetic field from the recording section of the magnetic recording medium is reduced. A high-density magnetic recording / reproducing head characterized by detecting and reading the recording.