JP2001101621A - Magnetic head and magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic head which detects highly accurately an impedance change at the input of high frequency carrier signal, thereby, detects a signal magnetic field of a magnetic recording medium with high accuracy and has excellent resolution, and a magnetic recording and reproducing device having such a magnetic head. SOLUTION: This magnetic head has a pair of soft magnetic materials for shielding which are disposed so as to hold a magnetic thin film through dielectric films and is constituted in such a manner that the high frequency carrier signal is impressed on a pair of electrodes which are connected with both ends of the magnetic thin films and the impedance change of the magnetic thin film in accordance with the inner inductance change due to the signal magnetic field from the magnetic recording medium is detected. Further, this magnetic recording and reproducing device is formed by disposing the magnetic head on a reproducing circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head utilizing a change in impedance due to magnetism of a soft magnetic material to which a high-frequency carrier signal is applied, and a magnetic recording / reproducing apparatus using the same.

[0002]

2. Description of the Related Art When a magnetic field is applied from the outside to a magnetic circuit formed by a pair of soft magnetic materials having an easy axis of magnetization with a conductor interposed therebetween and a high-frequency current flows through the conductor, the intensity of the applied magnetic field , The impedance of the conductor changes. This change in impedance is caused by the magnetoresistance effect (MR
Unlike the above effect, the back electromotive force can be detected by measuring the back electromotive voltage generated by the product of the high frequency current flowing through the conductor and the impedance of the conductor caused by a change in the magnetic properties of the magnetic material. Therefore, a magnetic head (MI head) having high detection sensitivity by utilizing the change in impedance that can be detected in this manner.
Can be obtained. Hereinafter, such a conventional magnetic head (MI head) will be described with reference to the accompanying drawings.

FIG. 7A is a technical report of the Institute of Electronics, Information and Communication Engineers MR95.
FIG. 9B is a diagram schematically illustrating a magnetic head using a change in impedance due to magnetism, reported at −80, and FIG.
FIG. 3A is an enlarged cross-sectional view of a portion surrounded by a dashed line circle in FIG. As shown in FIG. 7A, the detection conductor film 37, which is a ribbon-shaped conductive metal thin film, has a pair of soft magnetic cores 41 and 42 having a width W substantially equal to the track width of the magnetic recording medium 48. Sandwiched by Each of the soft magnetic cores 41 and 42 is composed of a laminate of a permalloy film 39 and a SiO ₂ film 40 as shown in the enlarged sectional view of FIG.

[0006] A constant high-frequency carrier signal in the UHF band is applied from a high-frequency transmitter 43 to the electrode terminals 51 and 52 formed at both ends of the detection conductor film 37 via a resistor 44. By applying the high-frequency carrier signal to the electrode terminals 51 and 52 in this manner, a high-frequency current, which is indicated by the arrow A in FIG. As a result, a high-frequency voltage change occurs between the electrode terminals 51 and 52 connected to both ends of the detection conductor film 37 based on a change in impedance due to magnetism in the detection conductor film 37.

When a signal magnetic field does not exist in the magnetic recording medium 48, the detection conductor film 37 is provided between the electrode terminals 51 and 52.
Carrier signal (hereinafter referred to as UHF) corresponding to the product of the current A flowing through the
(Referred to as a carrier signal). On the other hand, when a signal magnetic field due to the magnetization indicated by the arrow M in FIG. 7 is present in the magnetic recording medium 48, the direction of the easy axis of the soft magnetic cores 41 and 42 is oriented in the direction of the track width. The magnetization directions of 41 and 42 are tilted from the orientation direction by the signal magnetic field. As a result, the magnetic permeability of the soft magnetic cores 41 and 42 decreases, and the impedance of the detection conductor film 37 decreases.

As described above, when a signal magnetic field is present in the magnetic recording medium 48, the impedance of the detection conductor film 37 changes, so that the UHF carrier signal is
8 is AM-modulated by the signal magnetic field of FIG. The AM-modulated UHF carrier signal (hereinafter referred to as AM-modulated signal) is detected between the detection terminals 46 and 47. By performing AM detection on the detected AM modulated signal, a signal recorded by the magnetization M of the magnetic recording medium 48 can be reproduced.

FIG. 8 is a graph showing the operation of the conventional magnetic head shown in FIG. 7, in which the horizontal axis represents the direction and intensity of the signal magnetic field, and the vertical axis represents A obtained from the detection terminals 46 and 47.
Indicates the level of the M-modulated signal. The curve 53 shown in FIG.
This is obtained by applying a DC magnetic field (DC magnetic field) to the center of a Helmholtz coil in a conventional magnetic head with the frequency of a UHF carrier signal being 1.0 GHz. The soft magnetic cores 41 and 42 shown in FIG.
A DC bias magnetic field (hereinafter, referred to as a bias magnetic field 50) having a magnetic field strength indicated by. As can be understood from FIG. 8, in order to detect a signal magnetic field with high sensitivity and obtain a waveform of an AM modulation signal with little distortion, the value of the bias magnetic field 50 is set so that the carrier signal level largely changes due to a change in magnetic field strength. Must be set to the optimal value. In the conventional magnetic head shown in FIG. 7, a UHF carrier signal and a DC current from a DC power supply (not shown) are supplied to the detection conductor film 37 to generate a DC magnetic field, which is used as the bias magnetic field 50.

In the conventional magnetic head, in which the AM modulation signal is detected to detect a change in the impedance of the detection conductor film 37, the resistance value of the detection conductor film 37 becomes extremely large if the cross-sectional area is reduced. Further, if the soft magnetic cores 41 and 42 around the detection conductor film 37 are made thinner, the inductance of the magnetic circuit, that is, the impedance becomes smaller, and there is a problem that the signal magnetic field cannot be detected with high accuracy.

[0009]

The magnetic head constructed as described above is applied to a shield type magnetic head for improving the linear recording density, thereby realizing a high-sensitivity magnetic head realizing high density recording. Was desired. In order to realize such a magnetic head, it has been an important issue in this technical field to clarify a method for accurately detecting an impedance change at the input of a high-frequency carrier signal and an operation characteristic. The present invention detects a signal magnetic field of a magnetic recording medium with high accuracy by detecting a change in impedance at the input of a high-frequency carrier signal with high accuracy, and provides a magnetic head having excellent resolution and a magnetic recording / reproducing method having the magnetic head. It is intended to provide a device.

[0010]

In order to achieve the above object, a magnetic head according to the present invention comprises: a conductive magnetic thin film;
An inorganic dielectric film covering both surfaces of the magnetic thin film and serving as a magnetic gap; a pair of shielding soft magnetic materials arranged so as to sandwich the magnetic thin film via the dielectric film; DC bias applying means for applying a DC magnetic field to the magnetic thin film, a pair of electrodes connected to both ends of the magnetic thin film, and a high frequency carrier signal applying means for applying a high frequency carrier signal to the pair of electrodes. Detecting means for detecting an AM-modulated high-frequency carrier signal output from the pair of electrodes. The magnetic head of the present invention configured as described above can detect a change in impedance in an input high-frequency carrier signal with high accuracy.

Further, the magnetic head according to the present invention is characterized in that
A first electrode terminal connected to the pair of electrodes to which a high-frequency carrier signal is applied, and a second electrode terminal connected to the pair of electrodes and outputting an AM-modulated high-frequency carrier signal; An internal inductance of the magnetic thin film changes due to a signal magnetic field of the medium, and a high-frequency carrier signal that is AM-modulated due to the change of the internal inductance is detected from the second electrode terminal and recorded by the signal magnetic field of the magnetic recording medium. Is output. The magnetic head of the present invention thus configured can detect a signal magnetic field of a magnetic recording medium with high accuracy by efficiently detecting a change in impedance by a high-impedance magnetic circuit.

A magnetic recording / reproducing apparatus according to the present invention comprises a magnetic head having the above configuration, a magnetic head reproducing circuit for reproducing a signal recorded on a magnetic recording medium by the magnetic head, and a designated position on the magnetic recording medium. And a positioning mechanism for positioning the magnetic head. The magnetic recording / reproducing apparatus thus configured detects a signal magnetic field of a magnetic recording medium with high accuracy by efficiently detecting a change in impedance with a high-impedance magnetic circuit. Become.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic head according to the present invention will be described below with reference to the accompanying drawings. First,
The principle of the present invention will be described. It is self-evident electromagnetically that the inductance is determined by the current flowing through the conductor and the number of linkages between the magnetic flux generated at this time and the current. Regarding the inductance at this time, the inductance determined by the current flowing inside the conductor and the magnetic flux generated inside the conductor is defined as the internal inductance, and the inductance determined by the current flowing inside the conductor and the magnetic flux generated outside the conductor is separately considered as the external inductance. For example, an inductance when a non-magnetic conductor wire is wound around a magnetic material or an inductance when a soft magnetic material is formed around a non-magnetic conductor may be regarded as an external inductance. A magnetic head according to the present invention detects a change in the internal inductance of a conductive magnetic thin film due to a signal magnetic field of a magnetic recording medium, and reproduces a signal recorded on the magnetic recording medium.
The principle of detecting a signal magnetic field by the magnetic head of the present invention utilizes the principle of inductance in a ribbon-shaped conductive magnetic thin film. Regarding the principle of this inductance, see the literature IEEE Transsaction on Parts, Hybride, an
It is expressed by the following equation (1) as described in d Packaging, Vol-PHP10, No. 2, pp. 101 (1974).

L = 0.002W {ln [2W / (h + t)] + 0.25049 + [(h + t) / 3W] + (μeff / 4)} --- (1)

In the formula (1), L is the inductance of the ribbon-shaped conductive magnetic thin film, W is the length of the conductive magnetic thin film, h is the width of the conductive magnetic thin film, and t is the thickness of the conductive magnetic thin film. is there. Μeff is the effective magnetic permeability of the magnetic thin film. Further, when the impedance Z of the magnetic thin film is obtained based on the equation (1), it is expressed by the following equation (2).

Z = Rlead + jωL = Rlead + jω × 0.002W ｛ln [2W / (h + t)] + 0.25049 + [(h + t) / 3W] + (μeff / 4)} --- (2)

In the equation (2), Rlead is the resistance of the magnetic thin film, and Rlead = ρ · W / ht. ρ is the specific resistance of the magnetic thin film, and ω is the angular frequency. The following equation (3)
Is the effective magnetic permeability μeff of the magnetic thin film and its effective magnetic permeability μeff
Shows the relationship between the real part magnetic permeability μ ′ and the imaginary part magnetic permeability μ ″.

[0018]

(Equation 1)

Therefore, equation (2) is represented as equation (4) below.

Z = Rlead + jω × 0.002W ｛ln [2W / (h + t)] + 0.25049 + [(h + t) / 3W] + [(μ′-μ ″) / 4]｝ = {Rlead + 0.002Wω (μ ”) / 4) {+ jω × 0.002W} In [2W / (h + t)] + 0.25049+ [(h + t) / 3W] + (μ ′ / 4)} --- (4)

In the magnetic head of the present invention, the effective magnetic permeability μeff of the magnetic thin film changes according to the applied signal frequency, and the imaginary part magnetic permeability μ ″ increases as the frequency becomes higher.
The fact that a large percentage is used is used. As shown in equations (1) to (4), the inductance L of the magnetic thin film is related to its impedance Z, and the impedance Z greatly depends on the effective magnetic permeability μeff of the magnetic thin film. Therefore, a change in the signal magnetic field due to the magnetic recording medium appears as a change in the impedance Z of the magnetic thin film. Therefore, the magnetic head of the present invention detects a change in the internal inductance of the ribbon-shaped conductive magnetic thin film due to a signal magnetic field as a change in impedance using a high-frequency carrier signal of a predetermined frequency. The signal magnetic field detection method using the magnetic head of the present invention is a novel detection method not used in the conventional magnetic head. The internal inductance of the ribbon-shaped conductive magnetic thin film is irrelevant to its cross-sectional area, and is affected only by the length, as shown in the above-mentioned equation (1). Therefore, this detection method has a great advantage that the cross-sectional area of the conductive magnetic thin film can be reduced. That is, the magnetic head of the present invention is formed small and has a small gap in a narrow gap like a shield type magnetic head because the thickness t and the dimension h in the height direction of the conductive magnetic thin film do not greatly affect the impedance Z. It becomes possible to insert.

In conventional magnetic heads, when the MI effect using a high-frequency carrier signal is mainly considered, the internal inductance is often ignored and ignored. In conventional magnetic heads, when detecting using the MI effect, it is necessary to generate skin depth due to eddy currents and use the magnitude of the skin depth, so the conductive magnetic thin film must be dimensionally much thicker than skin depth. However, there is a limitation that the dimensions cannot be reduced. In a conventional magnetic head, a method of detecting a signal magnetic field using external impedance is largely affected by a cross-sectional area of a magnetic thin film and a cross-sectional area of a detection conductor film penetrating the magnetic thin film. . In particular, when the cross-sectional area of the nonmagnetic detection conductor film is reduced, the resistance component becomes extremely large, and there is a problem that a change in impedance is greatly restricted.

In the magnetic head and the magnetic recording / reproducing apparatus having the magnetic head according to the present invention, a high-frequency current is applied directly to the detection conductor film, which is a thin film having such a thickness that skin depth cannot be generated by eddy current. It detects a change in internal inductance caused by a magnetic permeability that changes due to a signal magnetic field applied by the recording medium, and detects the applied signal magnetic field. Such a method of detecting a signal magnetic field using an internal inductance is not used in a conventional magnetic head at all, and is a detection method not found in conventional magnetic heads. Further, the magnetic head of the present invention has a structure similar to that of a conventional MR head or giant MR head, but these magnetic heads pass a DC current. The magnetic head of the present invention uses a high-frequency carrier signal,
It differs greatly in that the magnetic permeability characteristics of the conductive magnetic thin film and the soft magnetic material for shielding are significantly changed. Therefore, even if a high-frequency current is applied to the conductive thin film of the magnetic head of the conventional MR head or giant MR head,
The magnetic head of the present invention is based on a technical idea completely different from that of the conventional magnetic head.

First Embodiment Next, the configuration of a magnetic head according to the present invention will be described in detail as a first embodiment. FIG. 1 is a sectional view schematically showing the structure of the magnetic head according to the first embodiment of the present invention. FIG. 2 is a front view of the magnetic head shown in FIG. As shown in FIG. 1, the conductive magnetic thin film 1 is sandwiched between two shielding soft magnetic bodies 2a and 2b via a non-magnetic dielectric film 3 from both sides. As shown in FIG. 2, electrodes 18 and 19 are connected to the coupling portions 1a and 1a at both ends of the ribbon-shaped conductive magnetic thin film 1, and the electrodes 18 and 19 are connected to electrode terminals 16a and 16a.
17a is provided. The electrode terminals 16a and 17a are connected to a high frequency oscillator 20 via a resistor 21 so that a high frequency carrier signal is applied.

In the first embodiment, the soft magnetic members 2 a and 2 b for shielding are set to have magnetic characteristics significantly different from the magnetic characteristics of the conductive magnetic thin film 1. Thereby, the soft magnetic members 2a and 2b for shielding and the conductive magnetic thin film 1
Are configured to share the frequency domain responsive to the applied signal magnetic field and the high frequency carrier signal. These will be described with reference to FIGS. 1, 2 and 3. FIG. The magnetic head according to the first embodiment is obtained by forming a thin film formed by sputtering deposition on a NiTiMg ceramic substrate by photolithography. The magnetic head shown in FIG. 1 is configured such that a conductive magnetic thin film 1 is sandwiched between soft magnetic members 2a and 2b for shielding via a nonmagnetic dielectric film 3. By disposing the magnetic recording medium 4 having a signal magnetic field close to the magnetic head,
The magnetic flux generated from the magnetization 12 on the magnetic recording medium 4 flows into the conductive magnetic thin film 1. The magnetic flux that has flowed into the conductive magnetic thin film 1 is diverted to the soft magnetic members 2 a and 2 b for shielding on both sides to form a magnetic closed circuit that returns to the magnetization 12 on the magnetic recording medium 4. At this time, the impedance between both ends of the conductive magnetic thin film 1 changes according to the signal magnetic field received from the magnetic recording medium 4.

In the first embodiment, electrodes 18 and 19 are provided at both ends of the conductive magnetic thin film 1. These electrodes 18 and 19 are connected to the electrode terminals 17 a and 16 a connected to the high-frequency oscillator 20 and to the impedance. Has the detection terminals 16b and 17b for measuring the measurement. Also,
In the first embodiment, the conductive magnetic thin film 1 is made of Fe
A TaN film was used. In the conductive magnetic thin film 1, the thickness (t) is 0.05 μm, the height (h) is 0.5 μm, and the track width (W) is 0.5 μm. The gap (Gm) between the soft magnetic members for shielding on both sides is 0.12 μm, the height (Hm) of the soft magnetic members 2a and 2b for shield is 100 μm, and the width (Wm) thereof is 1 μm. . The soft magnetic members 2a and 2b for shielding in the first embodiment are grounded. The magnetic head according to the first embodiment is set so as to have a flying height of 0.015 μm from the installation reference plane of the magnetic recording medium 4.

FIG. 2 is a diagram schematically showing a front view and a detection circuit diagram of the magnetic head of FIG. 1 viewed from the direction of arrow A. In FIG. 2, a high-frequency carrier signal from a high-frequency transmitter 20 is applied to electrodes 18, 1 formed at both ends of a conductive magnetic thin film 1.
9 are applied to the electrode terminals 16a and 17a. On the other hand, the DC bias magnetic field in the magnetic head of the first embodiment is configured to be applied by the permanent magnet 100. At this time, the level of the bias magnetic field with respect to the bell-bottom curve 53 as shown in FIG. 8 is set by changing the direction of the magnetic pole of the permanent magnet. The signal magnetic field of the magnetic recording medium 4 is applied to the detection terminals 16 b and 17 connected to the electrodes 18 and 19.
The high frequency carrier signal AM-modulated from b is output as a reproduction signal. Therefore, an AM detector and an amplifier are connected to the detection terminals 16b and 17b, and a reproduced signal is reproduced.

Next, the principle of the magnetic head reproducing method of the present invention will be described. In the magnetic head of the present invention, a high-frequency current is applied directly to the detection conductor film, which is a thin film having a thickness such that skin depth cannot be generated by eddy current, and the magnetic permeability changed by a signal magnetic field applied by the magnetic recording medium. The change in the internal inductance caused by the change is detected to detect the applied signal magnetic field.

In the above formula (1), L is the inductance of the conductive magnetic thin film 1, and W is the conductive magnetic thin film 1.
, H is the width of the conductive magnetic thin film 1, and t is the thickness of the conductive magnetic thin film 1. Μeff1 is the effective magnetic permeability of the conductive magnetic thin film 1. When the impedance Z between the electrodes 18 and 19 is obtained based on the equation (1), it is expressed by the following equation (5).

Z = Rlead + jωL = Rlead1 + Rlead2 + jω × 0.002W ｛ln [2W / (h + t)] + 0.25049 + [(h + t) / 3W] + (μeff1 / 4)} = {Rlead1 + Rlead2 + 0.002Wω (μ1 ″ / 4) {+ Jω × 0.002W} In [2W / (h + t)] + 0.25049 + [(h + t) / 3W] + (μ1 ′ / 4)} --- (5)

In equation (5), Rlead1 is the electrode 18,
19, and Rlead2 is the resistance of the conductive magnetic thin film 1. Rlead1 = ρ1 · W / ht, Rlead2 = ρ2 ·
W / ht. ρ1 is the specific resistance of the electrodes 18 and 19, ρ2
Is the specific resistance of the conductive magnetic thin film 1, and ω is the angular frequency. Μ1 ′ is the real part magnetic permeability at the effective magnetic permeability μeff1 of the conductive magnetic thin film 1, and μ1 ″ is the effective magnetic permeability μeff.
is the imaginary part magnetic permeability μ ″ at eff.
Are the effective permeability μeff1 of the conductive magnetic thin film 1 and the real part permeability μ1 ′ and the imaginary part permeability μ of the effective permeability μeff1.
1 ".

[0032]

(Equation 2)

FIG. 3 is a diagram showing the magnetic permeability characteristics of the conductive magnetic thin film 1 and the soft magnetic members 2a and 2b for shielding. In FIG.
The horizontal axis is the frequency [MHz] of the high-frequency carrier signal,
The vertical axis is the magnetic permeability. FIG. 3 shows the effective magnetic permeability μeff1 of the conductive magnetic thin film 1 as the real part magnetic permeability μ1 ′ and the imaginary part magnetic permeability μeff.
1 ", and the shielding soft magnetic bodies 2a, 2
The effective magnetic permeability μeff2 (solid line) of b is converted to the real part magnetic permeability μ2 ′.
(Dashed line) and the imaginary part magnetic permeability μ2 ″ (dotted line). The effective magnetic permeability μeff of the conductive magnetic thin film 1 determined by the real part magnetic permeability μ1 ′ and the imaginary part magnetic permeability μ1 ″.
1 is the effective magnetic permeability μeff of the shielding soft magnetic bodies 2a and 2b determined by the real part magnetic permeability μ2 ′ and the imaginary part magnetic permeability μ2 ″.
The frequency of the high-frequency carrier signal is set to be larger than 2.

By setting as described above, in the structure of the magnetic head shown in FIG. 2, the inductance L is the internal inductance generated when the current of the high-frequency carrier signal flows inside the conductive magnetic thin film 1, and the inductance L The external inductance due to the soft magnetic members 2a and 2b for shielding outside the magnetic thin film 1 is added. But,
As shown in the magnetic permeability characteristic diagram of FIG. 3, when a high frequency carrier signal of 1 GHz is used, the soft magnetic material 2a for shielding is used.
The value of the effective magnetic permeability μeff2 of 2b approaches 1.0. Therefore, when the high-frequency carrier signal is 1 GHz, the impedance Z is represented only by the impedance between both ends of the conductive magnetic thin film 1 as shown in the above-mentioned equation (5). As can be seen from FIG. 3, as the frequency increases, the real part permeability μ1 ′ decreases and the imaginary part permeability μ1 ″ increases. In the effective magnetic permeability μeff1 in the high frequency region, the imaginary part permeability μ1 ″ is reduced. Most accounts for the proportion. Therefore, the frequency of the high-frequency carrier signal is 1 GHz
In the case of z, as shown in the equation (5) for calculating the impedance Z, the change in the impedance Z due to the change in the effective magnetic permeability μeff1 of the conductive magnetic thin film 1 due to the signal magnetic field is caused by the real part of the impedance Z (resistance Ingredients) account for a large proportion.

The specific structure of the magnetic head according to the first embodiment is as follows. The electrodes 18 and 19 are made of Cu
The electrodes 18 and 19 have a width of 10 μm,
The thickness is 1 μm and the length is 10 μm. Also, electrode 1
The resistance component Rlead1 of 8, 19 was 0.018 Ω / μm. Even when the length of the electrodes 18 and 19 is 100 μm, the resistance component Rlead1 is 0.18Ω, which is compared with the resistance component Rlead2 of the conductive magnetic thin film 1 and the resistance component generated from the internal inductance as described later. This resistance component Rlead1 is negligible. The conductive magnetic thin film 1 used in the first embodiment is made of FeTa.
It was an N film, and its specific resistance was 75 Ω · cm. The specific resistance of the Cu film of the electrodes 18 and 19 is 1.7 Ω · cm.
Met. The experimental results based on these figures are:
This is shown in the impedance characteristic diagram of FIG. 5 described later.

In the magnetic head of the first embodiment, the magnetic flux generated from the magnetization of the magnetic recording medium 4 at a position off the track facing the conductive magnetic thin film 1 is reliably short-circuited by the shielding soft magnetic members 2a and 2b. The configuration is such that the conductive magnetic thin film 1 is not affected. In the magnetic head of the first embodiment configured as described above,
When a signal magnetic field is received from the magnetic recording medium 4, a high-frequency carrier signal AM is transmitted from between the respective detection terminals 16b and 17b of the electrodes 18 and 19 provided at both ends of the conductive magnetic thin film 1.
The modulated signal is output. Thus, the detection terminal 16
b and 17b, so that the AM-modulated signal of the high-frequency carrier signal is output from between the shield soft magnetic bodies 2a and 2b.
For the effective magnetic permeability μeff2 of b, a magnetic material that does not respond to a high frequency carrier signal of 1 GHz in response to a signal frequency generated from the magnetic recording medium 4 is selected.

As shown in FIG. 3, as the effective magnetic permeability μeff2 of the shielding soft magnetic bodies 2a and 2b of the first embodiment, the frequency of the high-frequency carrier signal responds up to about 700 MHz, but does not respond at 1 GHz. Set. The magnetic head according to the first embodiment configured as described above can detect the impedance change at the input of the high-frequency carrier signal with high accuracy, and can reliably detect the signal magnetic field from the magnetic recording medium 4. it can. Further, by providing the magnetic head of the first embodiment in a magnetic recording / reproducing apparatus, it is possible to record and reproduce an image with excellent resolution.

Second Embodiment Next, a magnetic head according to a second embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 4 is a sectional view showing the magnetic head of the second embodiment. As shown in FIG. 4, in the magnetic head of the second embodiment, similarly to the first embodiment, the conductive magnetic thin film 1 is provided on the soft magnetic members 2a and 2b for shielding via the non-magnetic dielectric film 3. It is pinched. In the soft magnetic members 2a and 2b for shield according to the second embodiment, first soft magnetic members 29 and 30 for shield are provided at positions facing the conductive magnetic thin film 1. Therefore, the soft magnetic members 2a and 2b for shielding are
And the second soft magnetic members 31 and 32 for shielding.

In the second embodiment, the conductive magnetic thin film 1
And the effective magnetic permeability of the first shield soft magnetic bodies 29 and 30 is μeff1 in the magnetic permeability characteristic diagram shown in FIG.
The effective magnetic permeability of the second soft magnetic members 31 and 32 for shielding is μ
eff2. Since the magnetic head of the second embodiment is configured as described above, the conductive magnetic thin film 1
In response to the high-frequency carrier signal, it changes with the signal magnetic field of the magnetic recording medium 4. In addition, the first soft magnetic body 2 for the shield 2
Like the conductive magnetic thin film 1, the reference numerals 9 and 30 respond to a high-frequency carrier signal and change with the signal magnetic field of the magnetic recording medium 4. On the other hand, the second soft magnetic members 31 and 32 for shielding are
It is configured to respond to the signal frequency generated from the magnetic recording medium 4 but not to the high frequency carrier signal.

As described above, in the magnetic head of the second embodiment, the first shield soft magnetic members 29 and 30 are provided at positions facing the conductive magnetic thin film 1, and the first shield soft magnetic members 29 and 30 are provided. The bodies 29, 30 are configured to change with the signal magnetic field. As described above, since the external inductance is formed by the first shielding soft magnetic bodies 29 and 30 in the magnetic head of the second embodiment, the impedance of the magnetic head of the second embodiment is higher than that of the first embodiment. Z changes greatly, and a highly efficient magnetic circuit can be constructed.

As described above, in the magnetic head according to the second embodiment, the effective magnetic permeability related to the internal inductance of the conductive magnetic thin film 1 and the effective magnetic force of the first shielding soft magnetic bodies 29 and 30 forming the external inductance. It is configured such that the magnetic permeability changes according to the signal magnetic field. However, like the conductive magnetic thin film 1, the thickness of the first shield soft magnetic bodies 29, 30 is sufficiently thin so that eddy current does not occur at the frequency of the high-frequency carrier signal. , 0.05 μm. If the thickness of the first soft magnetic members 29 and 30 for shielding is configured to be thick so as to generate an eddy current, the inductance of the conductive magnetic thin film 1 is reduced by the signal magnetic field, whereas the first soft magnetic material is reduced. Body 2
In the portions 9 and 30, the skin depth changes in the increasing direction, so that the inductance of the first soft magnetic bodies 29 and 30 changes in the increasing direction. Therefore, the inductance of the first soft magnetic bodies 29 and 30 changes in a direction to offset the change in the inductance of the conductive magnetic thin film 1. Therefore, it is important to set the thickness of the first shielding soft magnetic bodies 29 and 30 to a thickness that does not cause eddy current at the frequency of the high-frequency carrier signal. In the magnetic head of the second embodiment, the thickness of the conductive magnetic thin film 1 is set to an appropriate level with respect to the bell-bottom curve 53 shown in FIG. It is necessary to make adjustments so that a weak signal magnetic field generated from the medium can be reliably detected.

FIG. 5 shows the impedance characteristics of the magnetic head according to the first embodiment and the magnetic head according to the second embodiment. In FIG. 5, the horizontal axis represents the frequency [MHz] of the high-frequency carrier signal, and the vertical axis represents the impedance [Ω]. In FIG. 5, a curve 60 represents the impedance characteristic of the magnetic head of the first embodiment when no magnetic field is applied. In FIG. 5, a straight line 61 indicates the impedance characteristic when a magnetic field reaching saturation is applied to the magnetic head of the first embodiment from the outside. As shown in FIG.
Hz, the magnetic head of the first embodiment
It can be seen that an impedance change rate of 5% (43Ω−15Ω / 43Ω) is obtained. In FIG. 5, a curve 62 indicates the impedance characteristic of the magnetic head of the second embodiment. The impedance characteristic when a magnetic field reaching saturation is applied to the magnetic head of the second embodiment from the outside is the same as the straight line 61. Therefore, when the high frequency carrier signal is set to 1 GHz,
A 69% impedance change rate was obtained.

In the first and second embodiments, the magnetic head using the FeTaN film as the conductive magnetic thin film 1 has been described. However, the conductive magnetic thin film of the present invention may be a specific resistance such as permalloy. A magnetic material having a small size is more suitable. The specific resistance of the FeTaN film is 75 Ω · cm, while the specific resistance of the permalloy film is 20 Ω · cm. According to the experiment of the inventor, when a permalloy film was used, when a magnetic field reaching saturation was applied from the outside, FIG.
The level of the straight line 61 of the impedance characteristic shown in FIG.
Ω was reduced to about 4Ω. Therefore,
In the case of a magnetic head having a configuration using a permalloy film as the conductive magnetic thin film 1, 90% (43Ω−4Ω / 43Ω)
It was confirmed by experiments that the above-described impedance change rate was obtained.

Next, a method for manufacturing a magnetic head according to the present invention will be described with reference to specific examples. FIG. 6 is a sectional view of a specific embodiment of the magnetic head according to the present invention.
FIG. 6 illustrates a cross section taken along line AA ′ of FIG. 2 as viewed from a surface of the magnetic head facing the magnetic recording medium;
FIG. 3 is a sectional view of the magnetic head in FIG. 2 as viewed from below. The magnetic head shown in FIG. 6 is a magnetic head formed by lamination using a photolithography technique. In the magnetic head shown in FIG. 6, a Cu thin film 35 having good conductivity was formed on a NiTiMg ceramic substrate 34, and a first soft magnetic body 2a for a shield was formed thereon. After forming the first shield soft magnetic body 2a as described above, a nonmagnetic dielectric film 3, for example, an alumina film was formed.

Next, as shown in FIG. 6, a conductive magnetic thin film 1 of FeTaN having a predetermined length is formed above the first soft magnetic body 2a for shielding, and C
The electrodes 18 and 19 were formed by connecting u thin films. Permanent magnets 100 are formed at the coupling portions 1a at both ends.
Further, a non-magnetic dielectric film 3, for example, an alumina film is formed so as to cover the conductive magnetic thin film 1. Furthermore, after covering with a dielectric film 3 and smoothing, the second soft magnetic body 2b for shield is used.
Was formed. An overcoat layer 36 of an alumina film is formed so as to further cover the laminated body formed as described above, and is etched using an ion beam to form a Cu electrode terminal 1.
6, 17 were provided. The electrode terminal 16 is electrically connected to the electrode terminal 17 via the Cu thin film 35, the electrode 18, the conductive magnetic thin film 1, and the electrode 19. The electrode terminal 16 is used for grounding, and the electrode terminal 17 is used as a signal detection terminal.

As shown in FIG. 6, the conductive magnetic thin film 1 comprises a first shield magnetic body 2a and a second shield magnetic body 2a.
b, a microstrip line symmetrical about the conductive magnetic thin film 1 is formed. FIG.
In the embodiment shown in FIG. 2, the metal soft body of CoZrNb is used as the soft magnetic body 1 for shielding so that no eddy current is generated.
A laminated film with iO2 was used. The reason for using a metal amorphous material of CoZrNb as the material of the soft magnetic body 1 for shielding is that there is a characteristic that magnetic properties can be changed by using heat treatment in a magnetic field.

The magnetic head constructed as described above has
A high frequency carrier signal of GHz can be handled stably, and a signal magnetic field can be detected with high accuracy. The magnetic material used in the magnetic head of the present invention is Fe having excellent magnetic permeability at 1 GHz.
All of the system-based and Co-based metal magnetic film and oxide magnetic film are effective. Although alumina is used as a dielectric for forming the gap (Gm) in the magnetic head of the present invention in the above-described embodiment, an inorganic dielectric film such as glass or SiO2 is also effective.

In the magnetic head of the above-described embodiment, a laminated film of a CoZrNb metal magnetic material and SiO2 is used as the soft magnetic films 2a and 2b for shielding so as not to generate an eddy current. As the soft magnetic film for shielding in the above, Fe-based and Co-based metal magnetic materials, ferrite oxides and the like are effective as other metal magnetic materials. Although the magnetic head of the above-described embodiment is formed using a NiTiMg ceramic substrate, other ceramic materials such as AlTiC, glass-based materials, and carbon materials are also effective as the substrate in the magnetic head of the present invention.
The magnetic head of the above embodiment includes a magnetic head reproducing circuit for reproducing a signal recorded on a magnetic recording medium by the magnetic head, and a positioning mechanism for positioning the magnetic head at a designated position on the magnetic recording medium. It can be used for a provided recording / reproducing device. The magnetic recording / reproducing device having such a configuration can detect a signal magnetic field with high accuracy and provide a device having excellent resolution.

[0049]

As apparent from the detailed description of the embodiments, the present invention has the following effects.
According to the present invention, a magnetic head having an excellent resolution by detecting a signal magnetic field with high precision by efficiently detecting an impedance change due to a signal magnetic field at the input of a high frequency signal by a high impedance magnetic circuit, and It is possible to provide a magnetic recording / reproducing device having a head. In the magnetic head according to the present invention, the magnetic permeability of the conductive magnetic thin film and the magnetic permeability of the shielding magnetic thin film forming the shielded high-frequency impedance head are set to different values, and the conductive magnetic thin film Since the shielded magnetic thin film is configured to respond only to the frequency of the signal magnetic field, it responds to signals from the frequency up to the frequency of the high-frequency carrier signal. A magnetic circuit can be configured. Therefore, according to the present invention,
A signal magnetic field of a magnetic recording medium is detected with high accuracy, and a magnetic head having excellent resolution and a magnetic recording / reproducing apparatus having the magnetic head can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a configuration of a magnetic head according to a first embodiment of the present invention.

FIG. 2 is a side view schematically showing a side surface of the magnetic head according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram of the magnetic permeability of a magnetic material in the magnetic head according to the first embodiment of the present invention.

FIG. 4 is a sectional view schematically showing a configuration of a magnetic head according to a second embodiment of the present invention.

FIG. 5 is a characteristic diagram showing impedance changes in the magnetic head according to the present invention.

FIG. 6 is a bottom view showing the configuration of a specific example of the magnetic head according to the present invention.

FIG. 7 is a schematic diagram showing a schematic configuration of a conventional magnetic head.

FIG. 8 is a graph illustrating the operation principle of a conventional magnetic head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive magnetic thin film 2a Soft magnetic material for shielding 2b Soft magnetic material for shielding 3 Dielectric film 4 Magnetic recording medium 16a Electrode terminal 16b Electrode terminal 17a Detection terminal 17b Detection terminal 18 Electrode 19 Electrode 20 High frequency transmitter 21 Resistance 29 First Soft magnetic material 30 first soft magnetic material 31 second soft magnetic material 32 second soft magnetic material

Claims (7)

[Claims] 1. A pair of shields comprising a conductive magnetic thin film, an inorganic dielectric film covering both surfaces of the magnetic thin film and serving as a magnetic gap, and a magnetic thin film interposed therebetween with the dielectric film interposed therebetween. A soft magnetic material, DC bias applying means disposed near both ends of the magnetic thin film, and applying a DC magnetic field to the magnetic thin film; a pair of electrodes connected to both ends of the magnetic thin film; A magnetic head comprising: a high-frequency carrier signal applying unit that applies a high-frequency carrier signal; and a detecting unit that detects an AM-modulated high-frequency carrier signal output from the pair of electrodes. 2. A first electrode terminal connected to the pair of electrodes and to which a high-frequency carrier signal is applied, and a second electrode terminal connected to the pair of electrodes and outputting an AM-modulated high-frequency carrier signal. The internal magnetic field of the magnetic thin film changes due to the signal magnetic field of the magnetic recording medium, and a high-frequency carrier signal AM-modulated by the change of the internal inductance is detected from the second electrode terminal. 2. The magnetic head according to claim 1, wherein the magnetic head is configured to output a signal recorded by a signal magnetic field of the medium. 3. The magnetic head according to claim 1, wherein an effective magnetic permeability of the shielding soft magnetic material at a frequency of a high-frequency carrier signal is smaller than an effective magnetic permeability of the magnetic thin film. 4. The magnetic head according to claim 1, wherein the thickness of the magnetic thin film is equal to or less than the skin depth at the frequency of the high-frequency carrier signal. 5. A first magnetic body, wherein the pair of shielding soft magnetic bodies is disposed at a position facing the magnetic thin film,
3. The magnetic head according to claim 1, further comprising a second magnetic body having a magnetic permeability smaller than that of the first magnetic body. 4. 6. The magnetic head according to claim 1, wherein the soft magnetic material for shielding is arranged substantially symmetrically on both sides of the magnetic thin film to form a microstrip line. 7. A magnetic head according to claim 1, a magnetic head reproducing circuit for reproducing a signal recorded on a magnetic recording medium by said magnetic head, and a magnetic head reproducing circuit designated on the magnetic recording medium. And a positioning mechanism for positioning the magnetic head at a position where the magnetic head is positioned.