JP2001134908A - Magnetic head and magnetic recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head for both recording and reproducing, by using a magnetic impedance effect. SOLUTION: A closed magnetic path is formed by first, second and third magnetic films, a conductive metallic film winding 23 is arranged between a return path yokes 6 butted on these films via gaps, and a means is provided for supplying a DC current to the conductive metallic film winding 23. During reproducing, a DC current is supplied to the conductive metallic film winding 23 and, during recording, a signal current is supplied to the conductive metallic film winding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing head utilizing the magnetic impedance effect, in which the impedance of a detection conductor changes according to an applied magnetic field, and a magnetic recording / reproducing apparatus using the magnetic recording / reproducing head.

[0002]

2. Description of the Related Art FIG. 5 is an IEICE technical report MR95-80.
Is a perspective view of a conventional reproducing magnetic head (hereinafter, referred to as MI head) 61 utilizing a magneto-impedance effect (MI effect) substantially similar to that reported in J. Am.
In FIG. 5A, the MI head 61 includes a detection conductor thin film 42 made of a conductive metal thin film and a pair of soft magnetic cores 4 having a width 43 substantially equal to the track width of the magnetic recording medium 53.
6 and 47 form a part for detecting the magneto-impedance effect. The pair of soft magnetic cores 46, 47
As shown in (b) of the partially enlarged view, each is formed of a laminated film in which permalloy films 44 and SiO ₂ films 45 are alternately laminated.

When reproducing the signal magnetization 54 recorded on the magnetic recording medium by the MI head 61, the high frequency oscillator 4
8, a high-frequency carrier signal in the UHF band is applied to the detection conductor thin film 42 via the resistor 49, and a high-frequency current 50 flows. Then, a voltage change occurring between the terminals 51 and 52 connected to both ends of the detection conductor thin film 42 is detected by the magnetic impedance effect. The directions of the axes of easy magnetization of the soft magnetic cores 46 and 47 are oriented in advance in the width direction of the recording track of the magnetic recording medium 53. Signal magnetization 5 in the magnetic recording medium 53
4, the high-frequency current 50 and both terminals 51 of the detection conductor thin film 42 are provided between the terminals 51 and 52.
A voltage of the high frequency carrier signal equal to the product of the impedance between 52 is generated. Signal magnetization 5 in the magnetic recording medium 53
When 4 exists, the axes of easy magnetization of the soft magnetic cores 46 and 47 are deviated from the previously oriented directions by the signal magnetization 54. As a result, the impedance between the terminals 51 and 52 of the detection conductor thin film 42 decreases due to the magnetic impedance effect.

The high-frequency carrier signal is AM-modulated by the signal magnetization 54 of the magnetic recording medium 53 and detected by the change in the impedance of the detection conductor thin film 42. The signal magnetization 54 of the magnetic recording medium 53 can be read by AM detection of this signal. The detection sensitivity of the signal magnetization 54 of the magnetic recording medium 53 by the magnetic impedance effect is much higher than the detection sensitivity by the magnetoresistance effect. The MI head utilizing the magneto-impedance effect may provide about ten times as much output as a giant MR head using a magnetic bubble which is currently under development.

FIG. 6 is a graph showing a change in a high-frequency carrier signal level (vertical axis) with respect to a magnetic field (horizontal axis) applied to the MI head 61. 6, a characteristic curve 56 is obtained by setting the frequency of the high-frequency carrier signal to 1 GHz, placing the MI head 61 in the center of the Helmholtz coil, and changing the intensity of the applied DC magnetic field. According to the characteristic curve 56, when the applied magnetic field intensity is near zero, the high-frequency carrier signal level gradually changes. In order to modulate a high-frequency carrier signal with a high degree of modulation with respect to a change in magnetic field strength and obtain a high-frequency carrier signal with little distortion, it is necessary to apply a DC bias magnetic field 55 so as to use a linear portion of the characteristic curve 56. desirable. In the above-mentioned MI head, a DC current is superimposed on a high-frequency carrier signal current by a DC power supply 58 in order to generate a DC bias magnetic field 55. By passing this DC current through the detection conductor thin film 42, a DC magnetic field is generated to be a bias magnetic field. There is also a method of applying a DC magnetic field with a permanent magnet (not shown).

The rate of change of the impedance of the detection conductor due to the magnetic impedance effect is proportional to the product of the frequency of the high-frequency carrier signal applied to the detection conductor and the rate of change of the permeability of the soft magnetic core. In order to increase the rate of change of the impedance of the detection conductor and increase the reproduction sensitivity, the conventional MI head uses a permalloy film 44 having a large change in magnetic permeability as a material of the soft magnetic cores 46 and 47, and uses a high frequency. In order to prevent the generation of eddy current due to the above, a laminated film in which permalloy films 44 and SiO ₂ films 45 as insulators are alternately laminated is used. Further, the frequency of the high-frequency carrier signal is set to a high value of several hundred MHz or more.

[0007]

The MI head 61 utilizing the magneto-impedance effect has high reproduction sensitivity and is suitable for high-density recording. However, since it is only for reproduction, it is necessary to use another recording head for recording. In particular, a recording / reproducing head having a recording function suitable for a magnetic recording medium having a weak local magnetic field and capable of reproducing with the same head is required.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording / reproducing head in which a recording function is further added to a reproducing head utilizing a magnetic impedance effect.

[0008]

According to the present invention, there is provided a magnetic head comprising:
A first magnetic film formed on a nonmagnetic substrate, a second magnetic film formed on the first magnetic film and partially having a concave portion, at least the concave portion of the second magnetic film A third magnetic film thinner than the thickness of the second magnetic film, a conductive metal film formed in the recess, and a third magnetic film formed so as to sandwich the conductive metal film together with the third magnetic film. 4, the magnetic film is formed so as to have a space at least on the surface of the conductive metal film, and one end is opposed to the fourth magnetic film while keeping a predetermined magnetic gap, and the other end is formed. A return path yoke in contact with the fourth magnetic film, a conductive metal film winding formed through the space, to which a recording signal is applied at the time of recording, and connected to both ends of the conductive metal film A high-frequency current generator that supplies a high-frequency current during reproduction, and Connected across the Shokumaku has a high frequency amplifier output by detecting a high-frequency signal during reproduction.
At the time of recording, the magnetic head works as a recording head by applying a recording signal to the conductive metal film winding. During reproduction, a high-frequency current is applied to both ends of the conductive metal film, whereby the recorded magnetization is detected as a change in impedance of the conductive metal film. Thus, the magnetic head of the present invention can perform recording and reproduction with the same head.

A magnetic recording / reproducing apparatus according to the present invention includes a first magnetic film formed on a non-magnetic substrate and a first magnetic film formed on the first magnetic film and having a concave portion (Z region) in a part thereof. A second magnetic film, a third magnetic film formed at least in the concave portion of the second magnetic film and having a thickness smaller than the thickness of the second magnetic film;
A conductive metal film formed in the concave portion, a fourth magnetic film formed so as to sandwich the conductive metal film together with the third magnetic material film, and a fourth magnetic film at least in a region where the conductive metal film is present One end is opposed to the fourth magnetic film while maintaining a predetermined magnetic gap, and the other end is formed so as to have a space on the surface of the magnetic film. A return path yoke that is in contact with a conductive metal film winding formed through the space, to which a recording signal is applied during recording, and connected to both ends of the conductive metal film to provide a high frequency current during reproduction A magnetic recording / reproducing head having a current generator, a high-frequency amplifier connected to both ends of the conductive metal film and detecting and outputting a high-frequency signal during reproduction, a recording medium for recording / reproducing by the magnetic recording / reproducing head, and the recording Characterized by comprising a positioning means for positioning the magnetic recording and reproducing head to the specified position on the body. Since the magnetic recording / reproducing head has a conductive metal film winding for applying a recording signal, recording and reproduction can be performed by the same head, and the configuration of the apparatus is simplified.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a cross-sectional view of a magnetic recording / reproducing head according to the present embodiment manufactured from a thin film using a photolithography technique.
As shown in FIG.
A first soft magnetic film 22 of CoNbZr amorphous having a thickness of μm is formed. On the first soft magnetic film 22, a second soft magnetic film 2 of FeTaN having a thickness of about 1 μm is further formed.
Is formed, a portion (hereinafter, referred to as a region Z) of the second soft magnetic film 2 between the horizontal lines (c) and (d) is removed by ion beam etching to form a concave portion. As a result, the second soft magnetic film 2 is divided, and the lower part of the divided figure is referred to as a soft magnetic film 5. Next, the second soft magnetic film 2
A third soft magnetic film 3 of FeTaN having a smaller thickness, for example, 50 nm is formed. The magnetic permeability of the second and third soft magnetic films 2 and 3 is higher than the magnetic permeability of the first soft magnetic film 22.

According to experiments conducted by the inventors, it is found that the magnetic permeability of the first soft magnetic film 22 is one tenth or less of the magnetic permeability of the second and third soft magnetic films 2 and 3. desirable. On the third soft magnetic film 3 in the region Z, a conductive metal film 1 made of copper (Cu) or the like is formed to a thickness similar to that of the second soft magnetic film 2.
After the surfaces of the third soft magnetic film 3 and the conductive metal film 1 are smoothed, a fourth soft magnetic film 4 of FeTaN is formed on the surfaces, and the conductive metal film 1 4 between the soft magnetic films 3 and 4. The conductive metal film 1 and the third and fourth soft magnetic films 3 and 4 form an MI sensor unit. By making the third soft magnetic film 3 extremely thin, the effects described in detail below can be obtained, and the surface can be smoothed efficiently, and the surface distortion when various films are formed in the subsequent steps can be reduced. can do. That is, the fourth soft magnetic film 4 and the return path yoke 6 which are formed sequentially next can be formed without deteriorating the magnetic characteristics.

Next, an insulating film of SiO ₂ is formed on the third soft magnetic film 3 in a portion to be the gap 8 of the magnetic head. A non-magnetic resist film 7A and a spiral conductive metal film winding 23 are formed in a space called a winding window 7 above the region Z on the fourth soft magnetic film 4. Finally, a soft magnetic film having a thickness of 1 μm to be a return path yoke 6 is formed on the resist film 7A and the fourth soft magnetic film 4. FIG. 2 is a left side view of FIG. In FIG. 2, both ends of a spiral conductive metal film winding 23 are connected to two common contacts of a changeover switch 31, respectively.
And a recording amplifier 33 for outputting a recording signal during recording. Electrodes 16 and 15 are provided at both ends of the conductive metal thin film 1, respectively. The electrode terminals 13 and 14 are connected to the electrodes 15 and 16 via connection lines, respectively.

The operation of the magnetic head of this embodiment will be described below. When recording with the magnetic head of this embodiment,
Switch the changeover switch 31 to the left to switch the conductive metal film winding 2
3 is connected to the recording amplifier 33. Switches 34, 3
5 is opened to separate the high-frequency oscillator 11 and the high-frequency amplifier 19 from the conductive metal film 1. When the recording signal current flowing through the conductive metal film winding 23 is small, the magnetic permeability of the first soft magnetic film 22 is smaller than the magnetic permeability of the second and third soft magnetic films 2, 3. The magnetic flux passes through the return path yoke 6 and the second and third soft magnetic films 2 and 3, and the gap portion 8 is formed.
Generates a magnetic field. When the recording signal current is large, the third soft magnetic film 3 saturates because the thickness is extremely small. As a result, the magnetic permeability of the third soft magnetic film 3 is greatly reduced, and the magnetic flux passes through the first soft magnetic film 22 that is not saturated without passing through the third soft magnetic film 3. Thus, the first soft magnetic film 2
2 is much thicker than the second and third soft magnetic films 2 and 3, so that the magnetic head does not saturate even when the recording signal current is large.

When reproducing with this magnetic head, the switches 34 and 35 are closed, the high frequency amplifier 19 is connected to the electrode terminals 13 and 14, and the high frequency oscillator 11 is
2 through which high-frequency current flows. Further, the switch 31 is switched to the right, and a DC current is caused to flow through the conductive metal film winding 23 by the DC power supply 20 to apply a DC bias. When the magnetic head faces the magnetic recording medium 10 in this state, the magnetic flux generated from the signal magnetization 9 of the magnetic recording medium 10 flows into the magnetic head from the gap 8.
The magnetic flux is applied to the third and fourth layers sandwiching the conductive metal film 1.
A closed loop is formed which passes through the soft magnetic films 3 and 4 and returns from the upper end to the signal magnetization 9 of the magnetic recording medium 10 through the return path yoke 6. Due to the magnetic flux, the third and fourth soft magnetic films 3 around the conductive metal film 1 mainly,
4, the magnetic permeability at high frequencies changes, and the impedance of the conductive metal film 1 changes due to the magnetic impedance effect. As a result, the waveform of the high-frequency voltage applied to the conductive metal film 1 changes according to the intensity of the signal magnetic field generated from the magnetization 9 of the magnetic recording medium 10, and becomes an AM modulated wave. This A
The M-modulated wave is detected by a high-frequency amplifier 19 that amplifies and detects the AM-modulated signal connected to the electrode terminals 13 and 14. The soft magnetic film 5 at the lower end of the magnetic head serves as a shield core for shielding a magnetic field generated from magnetization other than the signal magnetization to be detected, and is made of a soft magnetic film having a thickness of 1 to 3 μm. It is desirable that the reluctance be as small as possible.

FIG. 3 shows preferred dimensions of each part of the specific example of the magnetic head of the present invention. The thickness T1 of the conductive metal film 1 is 1 μm.
m and the width W1 are 5 μm. The thickness T2 of the third soft magnetic film 3 sandwiching the conductive metal film 1 is 50 nm, and the thickness T3 of the fourth soft magnetic film 4 is 35 nm. The thickness T5 of the soft magnetic film 5 is 1 μm, the thickness T7 of the resist film filling the winding window 7 is 2 μm, and the thickness T of the return path yoke 6.
6 is 2 μm. As the magnetic recording medium 10, a CoCrPt-based magnetic material having an areal recording density of 20 Gbits per square inch is used, and the distance between the head and the magnetic recording medium 10 is set to 10 nm. The relationship between the signal magnetization and the magnetic flux density in the magnetic head was examined.

FIG. 4 is a graph showing the magnetic flux density B of the magnetic head of the above-described specific example by the DC power supply 20 shown in FIG.
Shows the result of examining the relationship between the intensity H of the signal magnetization when a bias magnetic field is applied so that the magnetic field becomes Bb and the magnetic flux density B in the magnetic head caused by the signal magnetization. In FIG.
The horizontal axis represents the intensity H of the signal magnetization 9 and the vertical axis represents the magnetic flux density B of the third soft magnetic film 3 of the magnetic head. In the curve (hereinafter referred to as BH curve) in the figure, the intensity H of the signal magnetic field is H
When the magnetic flux density changes to about 2, the magnetic flux density B also increases like B2, but when it changes more than 2, the rate of increase of the magnetic flux density B decreases.
In this state, when the signal magnetic field changes between H1 and H2,
The input voltage of the high-frequency amplifier 19 changes between V1 and V2 to become an AM modulation signal. That is, the signal magnetic fields H1 to H2
, The magnetic flux density in the magnetic head changes like the magnetic flux densities B1 and B2.

The reason why the input voltage changes between V1 and V2 is as follows. Due to the change in the magnetic flux density B, the magnetizations of the third and fourth soft magnetic films 3 and 4 are deviated from the direction of the easy axis of magnetization that is previously oriented. As a result the third
And the magnetic permeability of the fourth soft magnetic films 3 and 4 changes,
In addition, the impedance of the conductive metal film 1 sandwiched between the fourth soft magnetic films 3 and 4 changes, and the high-frequency voltage applied by the constant-current high-frequency oscillator 11 changes. As a result of various experiments by the inventors using a magnetic recording medium, FIG.
In order to make the operation represented by the BH curve
It is desirable that the thickness of the fourth soft magnetic films 3 and 4 be 50 nm or less. In particular, the thickness of the third soft magnetic film 3 is set to 50 nm or less and the thickness of the fourth soft magnetic film 4 is set to 35 nm or less, so that the third soft magnetic film 3 is thicker than the fourth soft magnetic film 4. Then, a suitable impedance change rate was obtained. In the BH curve, the rate of change of the amplitude of the input voltages V1 and V2, that is, the rate of change of the impedance, is desirably 10% or more, and the thicknesses of the third and fourth soft magnetic films 3 and 4 are each set to the above 50 nm. In the following, the change rate of the amplitude becomes 10% or more.

As the soft magnetic film, films having different magnetic permeability can be easily produced by performing heat treatment in a magnetic field while changing the strength and temperature of the magnetic field. Although the CoNbZr-based amorphous material is used as the material of the first soft magnetic film 22, other amorphous materials may be used. Further, as the third soft magnetic film 3 and the fourth soft magnetic film 4, Fe
Although TaN was used, any of Fe-based and Co-based metal magnetic films and oxide magnetic films having excellent effective magnetic permeability at a high frequency can be used. Although copper is used as the conductive metal film, a metal film such as Au or Ag having a small specific resistance can be used. In this embodiment, SiO ₂ is used as a dielectric material for forming the gap 8, but an inorganic dielectric film such as alumina or glass can be used. The substrate 21 is made of Ni
Although a TiMg ceramic substrate was used, other ceramics such as AlTiC, glass-based materials, and carbon substrates can also be used. Copper was used as the conductive metal film.
It is desirable to use a metal having good thermal conductivity such as u, Ag or other brass. By mounting the recording / reproducing head of this embodiment on a known head positioning means and facing a known magnetic recording medium such as a magnetic disk, it is possible to realize a magnetic recording / reproducing apparatus capable of recording and reproducing with the same head. Since recording and reproduction can be performed with the same head, the configuration of the apparatus is simplified and the cost of the apparatus is reduced.

[0019]

As has been described in detail in the embodiments, the present invention reduces the thickness of the soft magnetic film formed so as to sandwich the conductive metal thin film of the magneto-impedance effect head by the magnetic material forming the other magnetic paths. The function of the reproducing head having excellent reproduction sensitivity due to the thickness being smaller than the film thickness, and recording on the recording medium by applying a recording signal to the conductive metal film winding formed on the fourth soft magnetic film. A recording / reproducing head having a function of a recording head capable of performing the above-described operation and a magnetic recording / reproducing apparatus using the same can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic head according to an embodiment of the present invention.

FIG. 2 is a left side view of the magnetic head of FIG. 1;

FIG. 3 is a sectional view showing dimensions of each part of the magnetic head according to the embodiment of the present invention;

FIG. 4 shows the intensity H of the signal magnetization and the magnetic flux density B in the magnetic head.
Graph showing the relationship

FIG. 5 is a perspective view showing a use state of a conventional magnetic impedance head.

FIG. 6 is a graph showing the relationship between the magnetic field strength and the carrier signal level, showing the operation of the conventional magnetic impedance head.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive metal film 2 second soft magnetic film 3 third soft magnetic film 4 fourth soft magnetic film 5 soft magnetic film 6 return path yoke 7 winding window 8 gap 9 signal magnetization 10 magnetic recording Medium 11 High-frequency oscillator 12 Resistance 13 Electrode terminal 14 Electrode terminal 15 Electrode 16 Electrode 19 High-frequency amplifier 20 DC power supply 21 Substrate 22 First soft magnetic film 23 Conductive metal film winding 31 Changeover switch 33 Recording amplifier 34 Switch 35 Switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Fuyasu 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. F term (reference) 2G017 AC01 AC09 AD04 AD51 AD63 AD65 BA03 BA16 5D033 BB43 5D091 BB01 CC01 DD03 FF20 5E049 AA01 AA04 AA09 AC05 BA12

Claims (8)

[Claims] A first magnetic film formed on a non-magnetic substrate; a second magnetic film formed on the first magnetic film and partially having a concave portion; Formed in at least the concave portion of the body membrane,
A third magnetic film having a thickness smaller than a thickness of the second magnetic film, a conductive metal film formed in the concave portion, a fourth magnetic film formed so as to sandwich the conductive metal film together with the third magnetic film; A body film, which is formed so as to have a space on at least a surface of the fourth magnetic film in a region where the conductive metal film exists, and one end of the fourth magnetic material having a predetermined magnetic gap. A return path yoke facing the film and having the other end in contact with the fourth magnetic film; a conductive metal film winding formed through the space and applied with a recording signal during recording; Magnetic recording / reproducing having a high-frequency current generator connected to both ends of a conductive metal film and supplying a high-frequency current during reproduction, and a high-frequency amplifier connected to both ends of the conductive metal film and detecting and outputting a high-frequency signal during reproduction head. 2. The magnetic recording / reproducing head according to claim 1, wherein a DC current for direct current magnetic bias is applied to said conductive metal film winding during reproduction. 3. The magnetic recording / reproducing head according to claim 1, wherein the magnetic permeability of the first magnetic film is smaller than the magnetic permeability of the third magnetic film. 4. The thickness of the third magnetic film and the fourth magnetic film is not more than 50 nm, and the thickness of the third magnetic film is larger than the thickness of the fourth magnetic film. The magnetic recording / reproducing head according to claim 1, wherein: 5. A first magnetic film formed on a non-magnetic substrate, a second magnetic film formed on the first magnetic film and partially having a concave portion, the second magnetic film Formed in at least the concave portion of the body membrane,
A third magnetic film having a thickness smaller than a thickness of the second magnetic film, a conductive metal film formed in the concave portion, a fourth magnetic film formed so as to sandwich the conductive metal film together with the third magnetic film; A body film, which is formed so as to have a space on at least a surface of the fourth magnetic film in a region where the conductive metal film exists, and one end of the fourth magnetic material having a predetermined magnetic gap. A return path yoke facing the film and having the other end in contact with the fourth magnetic film; a conductive metal film winding formed through the space and applied with a recording signal during recording; Magnetic recording / reproducing having a high-frequency current generator connected to both ends of a conductive metal film and supplying a high-frequency current during reproduction, and a high-frequency amplifier connected to both ends of the conductive metal film and detecting and outputting a high-frequency signal during reproduction Head, the magnetic recording / reproducing Recording medium and recording and reproducing the head, magnetic recording and reproducing apparatus characterized by comprising positioning means for positioning the magnetic recording and reproducing head to a specified position on the recording medium. 6. The magnetic recording / reproducing apparatus according to claim 5, wherein a DC current for direct current magnetic bias is applied to said conductive metal film winding during reproduction. 7. The magnetic recording / reproducing apparatus according to claim 5, wherein the magnetic permeability of the first magnetic film is smaller than the magnetic permeability of the third magnetic film. 8. The thickness of the third magnetic film and the fourth magnetic film is not more than 50 nm, and the thickness of the third magnetic film is larger than the thickness of the fourth magnetic film. The magnetic recording / reproducing apparatus according to claim 5, wherein: