JP3132113B2 - High density magnetic recording / reproducing head - Google Patents

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 magnetic recording medium having a high coercive force has been developed in response to a 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, with respect to the recording / reproducing magnetic head, a thin film head has been developed in order to cope with a narrow track and a short wavelength, and the conventional so-called bulk head has been shifted to a thin film head.

[0004] Further, due to a decrease in the relative speed between the reproducing magnetic head and the recording medium due to the higher density of the magnetic recording, a magnetoresistive (MR) effect type thin film reproducing type independent of the relative speed with respect to the magnetic recording medium. The development of magnetic heads is remarkable. As the MR sensing part of this MR effect type magnetic head,
A permalloy thin film or the like is used, but 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 value R in a non-magnetic state, for example, has been developed. However, in the case of permalloy, there is a problem that the value is as small as about 2%.

Recently, as an active type head, a magnetic head utilizing a change in inductance of a coil due to an external magnetic field has been proposed (for example, 199).
Proceedings of the 2005 IEICE Spring National Convention 5-35
page).

[0006]

On the other hand, the applicant of the present invention has been able to reproduce a signal magnetic field by magnetic recording on a magnetic recording medium with high sensitivity by applying Japanese Patent Application No. 3-333687. The present invention has provided a microwave waveguide type magnetic detector which has been described above.

As shown in FIG. 6, an example of a reproducing magnetic head using this magnetism detecting device is a microwave waveguide 2 including a soft magnetic material 1 whose magnetic permeability changes at an end portion by the application of an external magnetic field. 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 a magnetic recording medium is applied to the soft magnetic material 1 so that the soft magnetic material 1
Using the phenomenon that the magnetic permeability changes due to the external magnetic field, the change in the magnetic permeability changes the impedance characteristic of the waveguide, and the change in the reflectivity of the high-frequency power supplied to the waveguide,
An external magnetic field is measured as a voltage change at a predetermined position of the microwave waveguide 2.

The principle of operation of the reproducing type magnetic head of the microwave waveguide type will be further described. In the case where a microwave waveguide not matched at the load end is excited by high frequency power through a microwave transmission line such as a coaxial cable. A reflected wave exists in addition to the traveling wave, and a standing wave is generated by superimposing them. In particular, the standing wave ratio becomes maximum in the microwave waveguide in which the load end is opened or short-circuited.

FIG. 7 shows the standing wave amplitude | V | on the microwave waveguide 2 when the load end is open.
In the example shown by the solid line curve, the standing wave amplitude at x = x ₀ | V |
Indicates a state where 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 a voltage standing wave ratio, and λ indicates an interval at which a peak or a valley of the standing wave is repeated.

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

The microwave waveguide 2 may have a microwave strip line type configuration. This microwave strip line has a configuration in which a ground conductor 5 and a line conductor 6 are provided, and for example, a dielectric 7 and a soft magnetic body 1 are interposed therebetween.

The soft magnetic material 1 has a magnetic permeability μ that exhibits a sharp magnetic field dependence. The magnetic permeability is gradually increased by applying a magnetic field in a predetermined direction. When the magnetic field is further increased, the magnetic permeability decreases.

Thus, for example, the load end 2a constitutes a microwave strip line which is open.

The high frequency oscillator 3 is connected between the conductor 6 and the ground conductor 5 on the opposite side of the load end 2a of the microwave strip line type microwave waveguide 2 by a transmission line 8 made of, for example, a coaxial cable. I do.

The frequency of the high-frequency oscillator 3 is, for example, 1 G
Hz, the microwave waveguide 2 is excited in a state where no signal magnetic field is applied, 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. I do. 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 configuration is shown in FIG.
As shown in FIG. 2, the load end (open end) 2a of the microwave waveguide 2 is made to approach and close to the magnetic recording medium 4, and a leakage magnetic field, that is, a signal magnetic field based on recording on the magnetic recording medium 4 is changed to an external magnetic field H.
_Ex is given to the soft magnetic material 1 as _ex . In this case, the magnetic permeability μ of the soft magnetic material 1 changes due to the external magnetic field _{Hex, and} accordingly, the voltage standing wave ratio and the standing wave interval λ change as shown by the broken line in FIG. Thus, a magnetic signal can be read as a voltage change.

At this time, if the frequency of the high-frequency power supply, that is, the carrier frequency f is, for example, 1 GHz, even if the frequency of the recording signal magnetic field _Hex is set to a sufficiently high frequency of about 100 MHz, which is one digit lower than that, the detection circuit 9 performs , Only the change in H _ex can be extracted as a voltage change.

This microwave waveguide type magnetic head can also be constituted by a thin film technique.

However, in any of the thin-film magnetic heads, the track width is naturally limited due to limitations on processing, magnetic characteristics, and the like. It is only necessary to deal with this.

Further, an MR type magnetic head as described above,
Since the microwave waveguide type magnetic head is a read-only head, when combined with a recording head, there are also problems in manufacturing such as setting of the positional relationship and complication of the structure.

According to the present invention, there is provided a microwave waveguide type reproducing head based on a new principle capable of securely reading out even in the above-mentioned high density by adopting a simple structure. Provided is a high-density magnetic recording / reproducing head which also includes a recording head capable of high-density recording.

[0023]

FIG. 2 is a perspective view of a main part of an embodiment of a high-density magnetic recording / reproducing head according to the present invention. As shown in FIG. have a magnetic sensitive sections made of needle 31 and exciting means 32,
A dielectric 33 is provided on the outer periphery of the magnetic sensing portion composed of the soft magnetic fine needle 31.
A cylindrical conductor 5 is arranged through the
The soft magnetic fine needle 31 and the cylindrical conductor 5 are oscillated at a high frequency.
The soft magnetic fine needle 31 is magnetized by the exciting means 32 at the time of recording on the magnetic recording medium 4 composed of a perpendicular magnetization film, which is connected to the magnetic recording medium 4. High-frequency power is applied to the magnetically sensitive portion, that is, the soft magnetic fine needle 31, and the reflected wave of the soft magnetic fine needle 31 is changed by an external magnetic field to detect a leakage magnetic field from the recording portion of the magnetic recording medium and read out the recording.

[0024]

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

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment 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 using a perpendicular magnetization film is used. As the reproducing head, the basic configuration is the microwave waveguide type reproducing head described with reference to FIGS.

First, the high-density magnetic recording / reproducing
Before explaining the disk, the basics of the high-density magnetic recording / reproducing head
The configuration will be described with reference to the drawings. As shown in FIG. 1, a tapered needle-like dielectric 33 formed by, for example, melting and drawing a glass rod is formed, and a slit 34 is formed on the dielectric in the axial direction, and the soft magnetic material is divided into two. The body layer 35 is formed by electroless plating and electroplating, or evaporation,
The soft magnetic fine needle 31, that is, the magnetic field sensing part is formed by being formed by sputtering or the like.

The soft magnetic material whose magnetic permeability changes due to the external magnetic field
The magnetic layer 35 is made of, for example, Co.₇₅Ta ₁₁Zr₁₄Amorph
It can be composed of a soft magnetic material.

In this way, the slit 34
A microwave waveguide is constituted by the paired soft magnetic material layers 35. In other words, the pair of soft magnetic layers 35 are the conductors 5 and 6 of the microwave waveguide whose load ends are short-circuited.

The magnetic field sensing part, that is, the soft magnetic fine needle 3
1 is provided with exciting means 32 around which an exciting coil is wound.

In recording, as shown in FIG. 3, the tip of the magnetically sensitive portion, that is, the soft magnetic fine needle 31 is attached to the magnetic recording medium 4.
The fine needle 31 and the magnetic recording medium 4 are relatively moved. Then, the recording signal input is amplified by the amplifier 40 and supplied to the excitation means 32, that is, the excitation coil. In this manner, the magnetic recording medium 4 is magnetized, that is, magnetically recorded, in accordance with the recording signal by the leakage magnetic field from the tip of the soft magnetic fine needle 31 of the magnetic sensing portion.

In this case, if necessary, the magnetic recording medium 4
Although not shown, opposed magnetic poles are arranged opposite to the magnetically sensitive portion, that is, the soft magnetic fine needle 31, and the magnetic recording medium 4 is disposed on the back surface of the magnetic film opposite to the side facing the needle-shaped magnetically sensitive portion. By using a magnetic recording medium on which a high magnetic permeability film is formed, perpendicular recording can be performed satisfactorily on the magnetic recording medium 4.

Then, when reading the recorded information from the magnetic recording medium 4, the tip of the magnetically sensitive portion, that is, the soft magnetic fine needle 31, is brought into contact or close proximity. In this way, the magnetic permeability due to the leakage magnetic field due to the recording magnetization on the magnetic recording medium 4 being applied to the magnetic sensing portion, that is, to the soft magnetic fine needle 31, is changed. On the other hand,
At the same time, high-frequency power is supplied from the high-frequency oscillator 3 to the soft magnetic layer 35 of FIG. 1 through, for example, a transmission line 8 of a coaxial cable type.

By doing so, 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, FIG. The change in the standing wave thus detected is detected by the detection circuit 9 and demodulated by the demodulator 41 to extract a reproduced output signal. As shown in FIG. 8, the change in the reproduced output with respect to the external magnetic field shows almost the same characteristics with respect to the positive and negative magnetic fields, and the change in the output with respect to the magnetic field is not monotonic. External magnetic field (signal magnetic field) to obtain an output whose polarity reverses depending on the polarity of
It is desirable to apply the bias magnetic field H _B1 or H _B2 to the magnetic sensing part 31 so that the operating point is at the position indicated by the point B ₁ or B ₂ in FIG. The bias magnetic field at the time of this reproduction can also be given by appropriately energizing the coil of the exciting means 32.

Embodiment 1 The following is an embodiment of the high-density magnetic recording / reproducing head of the present invention.
Will be described with reference to the drawings. As shown in FIG. 2, a soft magnetic fine needle 31 formed by stretching a glass rod and applying a soft magnetic material layer 35 to a tapered needle 36 as shown in FIG.
A coaxial type load terminal is provided, which is itself a conductor 6, that is, a so-called center conductor, and a conductive layer 37 is formed on the outer periphery thereof via a dielectric layer 33 and is used as an external conductor serving as the other conductor. However, an open-type microwave waveguide type configuration can be adopted. In this case, the excitation means 32 is
That is, the coil is wound.

Embodiment 2 As shown in FIG. 4, a partially cutaway perspective view shows CoFeS
The soft magnetic fine needle 31 is made of an iB amorphous.
This soft magnetic fine needle 31 was produced by the following method. That is, first, a diameter of about 1 was produced by a rapid quenching method in water flow.
A 00 μm CoFeSiB-based amorphous magnetic wire (made by Unitika) is electropolished in phosphoric acid to form a needle with a tip curvature radius of about 5 μm. Next, the wire having the sharpened tip was cut into about 5 mm to obtain a soft magnetic fine needle 31.

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

The chip having the soft magnetic fine needle 31 wound thereon is placed 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.

Then, the center conductor and the outer conductor of the coaxial cable 39 are connected to the soft magnetic fine needle 31 and the shield case 38, and the high frequency power of about 1 GHz or more from the high frequency oscillator 3 is connected by the coaxial cable 39. At the same time, a detection point, for example, a Schottky barrier diode D is connected to a connection point between the magnetic head and the coaxial cable 39, and is input to the oscilloscope Osc.

The characteristics of the magnetic head according to the second embodiment were determined as follows.

That is, in this case, as shown in FIG.
A magnetic layer 52 of a TbFe-based amorphous alloy film is sputtered to a thickness of about 0.2 μm on a mm-square slide glass 51, and the medium 4 is moved slightly along X and Y axes orthogonal to each other along the surface of the medium 4. 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)).

Then, the soft magnetic fine needle 31 of the magnetic head is
The XY stage was moved in the X direction while applying a direct current of 200 mA to the coil of the exciting means 32 while being in contact with the surface of the magnetic layer of the medium 4, and a linear magnetization pattern 53 was recorded on the medium 4.

Next, the power supply to the exciting means 32 is cut off, a high-frequency power of about 1 mW near 1 GHz is supplied from the high-frequency oscillator 3 to the coaxial cable 39, and the stage is moved across the recording magnetization pattern on the medium 4 as described above. 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-described recording / reproduction confirmation is performed on the medium 4
On the other hand, although the magnetization state in one direction was recorded by DC, it is possible to record the AC signal by changing the direction of the supplied current, and the reproduction is performed when the polarity of the recording magnetization pattern is reversed. A signal output according to the direction can be obtained.

Embodiment 3 Using the same magnetic head structure and magnetic recording medium 4 shown in FIG. 4 as in Embodiment 2 , the XY stage described in FIG. 5 is moved in the X direction at a speed of 1 mm per second. Then, a DC current whose polarity was alternately inverted was applied to the coil of the exciting means 32. The current reversal interval of energization is 1 second, and the current value is ± 200.
mA. Next, the magnetic head is returned to the origin position with X and Y, and while supplying high frequency power of about 1 GHz from the coaxial cable 39, the XY stage is moved at 1 m / s which is the same as during recording.
While moving at a speed of m, the detection output of the diode D was observed by the oscilloscope Osc. In this case,
A DC current of about 2 mA was applied to the exciting means 32 to apply a bias magnetic field to the magnetic sensing part, that is, the soft magnetic fine needle 31. At this time,
A signal output of about 1 mV was obtained in which the polarity was reversed every second in response to the magnetic reversal of the recording current.

Embodiment 4 Using the same magnetic head structure and magnetic recording medium 4 shown in FIG. 4 as in Embodiment 2 , the XY stage explained in FIG. A sine wave current of 10 kHz was supplied to the coil to write a recording pattern on the medium. The maximum value of the exciting current was 200 mA. After that, return the magnetic head to the origin with X and Y, and execute
The detection output of the diode D was measured by the oscilloscope Osc while tracing the recording track under the same conditions as in Example 3 . At this time, as in the third embodiment , the exciting means 32,
That is, a DC current of about 2 mA was applied to the exciting coil, and a bias magnetic field was applied to the magnetic sensing 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 embodiments are for illustrating the principle of the present invention, and include the number of turns of the exciting coil, the wire diameter, the exciting current, and the frequency of the high-frequency power supplied during reproduction. , Relative movement speed between the magnetic head and the medium,
The frequency and the like of the recording signal are not limited to the above-mentioned numerical values, but can be adjusted to an arbitrary value according to the size of the magnetic head such as the soft magnetic fine needle 31 and the like.

The operating principle of the magnetic head of the present invention during reproduction is different from a so-called inductive head which responds to a temporal change of magnetic flux, 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 the reproduction of the recording signal of the stationary medium.

[0048]

According to the present invention described above, a recording head is provided with a magnetic material in a microwave waveguide, and a change in the standing wave caused by a change in the magnetic permeability of the microwave waveguide due to a magnetic field to be detected is utilized. Is detected as a voltage change at a predetermined position, so that the signal magnetic field based on the recording information from the magnetic recording medium can be reproduced with high sensitivity regardless of the relative speed with the magnetic recording medium as in the case of the MR effect type magnetic head. It can be performed.

Also, by adopting the microwave waveguide type configuration, the so-called carrier frequency can be reduced to several hundred MHz.
z or on the order of GHz, the frequency of the recording signal on the magnetic recording medium can also be made high, so that it does not depend on the relative speed with respect to the magnetic medium. Density recording can be achieved.

According to the present invention, the recording head is formed as a recording head for performing not only reproduction but also recording by providing an exciter means 32 in the needle shape of the magnetic sensing part having the soft magnetic material. Therefore, the whole structure is concise. In addition, the magnetic sensing part has a needle-like configuration, and since the needle-like tip can actually be on the order of submicron, it is possible to achieve high density during recording and high resolution during reproduction, Higher recording density can be achieved.

The structure of the magnetic sensing portion, that is, the soft magnetic fine needle 3
1 is wound with an exciting means 32, specifically, a coil.
A cylindrical conductor is provided on the outer periphery of the magnetic fine needle 31 via a dielectric 33.
Since the number 5 is arranged, it is possible to bring a great benefit in practical use, for example , the manufacturing is simplified.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of an example of a magnetic recording / reproducing head .

FIG. 2 is a perspective view in which a part of a main part of an embodiment of a magnetic recording / reproducing head according to the present invention is sectioned.

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, partially in section, of a main part of another embodiment of the magnetic recording / reproducing head according to the present invention.

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

FIG. 6 is a configuration diagram of an example of a microwave waveguide type magnetic detector used for describing 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]

 DESCRIPTION OF SYMBOLS 31 Soft magnetic fine needle 32 Excitation means 4 Magnetic recording medium

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-9005 (JP, A) JP-A-58-122601 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 5/02 G11B 5/127

Claims (1)

(57) [Claims] 1. A and the magnetic sensitive section formed of a soft magnetic fine needle, possess an excitation means, the outer periphery of the magnetically sensitive portion made of the soft magnetic thin needle, through the dielectric
A cylindrical waveguide is arranged to form a microwave waveguide
And, contact with the soft magnetic fine needle and the tubular conductor in the high-frequency oscillator
The magnetic recording medium consisting of a perpendicular magnetization film is magnetized by the exciting means at the time of recording, thereby recording on the magnetic recording medium. A high-frequency power is applied to the magnetic recording medium, and a reflected magnetic field is changed by an external magnetic field to detect a leakage magnetic field from a recording portion of the magnetic recording medium and read out the recording. Recording / playback head.