Magnetic impedance element and magnetic detection circuit

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a magnetic impedance element and a magnetic detection circuit, and more particularly to a magnetic impedance element and a magnetic detection circuit for detecting minute magnetism.

【0002】

[Conventional technology]

Conventionally, a magnetic head for detecting minute magnetism has been known. There are roughly two types of magnetic heads: magnetic induction type and magnetoresistive (MR) type.

【0003】

The former magnetic induction type magnetic head guides the magnetic flux to the core around which the coil is wound, and applies an induced electromotive force e = -dφ / dt proportional to the temporal change of the magnetic flux φ interlinking with the coil at both ends of the coil. It happens. Since the magnitude of the induced electromotive force is proportional to the temporal change of the magnetic flux φ, the induced electromotive force is generated only when the magnetic recording medium and the magnetic induction type magnetic head have relative velocities, and the magnitude of the induced electromotive force is It increases in proportion to the relative speed and the signal frequency recorded on the magnetic recording medium.

【0004】

Therefore, in order to generate an induced electromotive force of a certain level or higher, it is necessary to run or rotate at least one of the magnetic recording medium and the magnetically induced magnetic head at a predetermined speed or higher.

【0005】

Further, in the magnetic induction type magnetic head, in order to increase the reproduction sensitivity, it is necessary to increase the number of times the coil is wound to increase the magnetic flux φ interlinking with the coil. However, since the impedance is increased by increasing the number of times the coil is wound, there is a problem that the impedance noise is increased and the S / N is decreased as well as being easily affected by disturbance noise.

【0006】

On the other hand, the latter magnetoresistive magnetic head is composed of an MR element made of permalloy NiFe whose resistance value changes according to a change in an external magnetic field, and the equivalent circuit of the MR element is a variable resistance R as shown in FIG._MRIt is represented by. As shown in the operating principle diagram of FIG. 12, the resistance R to the MR element 100₁₀₀Via voltage source E₁₀₀A constant DC current I in the longitudinal direction of the MR element 100 by connecting_DCAnd apply a constant bias magnetic field Hb of about 1600 to 3000 [A / m] in the width direction of the MR element 100.

【0007】

Then, when an external magnetic field is applied and these combined magnetic fields H change, the resistivity ρ of the MR element 100 changes with respect to the combined magnetic field H as shown in FIG. That is, when the combined magnetic field H = 0 applied to the MR element 100, the resistivity ρ shows a maximum value and decreases in inverse proportion to the magnitude of the combined magnetic field H.

【0008】

The relationship between the angle θ and the resistivity ρ formed by the sense current vector J flowing in the longitudinal direction of the MR element 100 and the magnetization vector M is ρ = ρ₀+ Δρ_mcos²θ Will be. Where Δρ_mIs the maximum resistivity change. Magnetic-electric conversion efficiency of MR element 100 Δρ_m/ ρ is generally as low as 2.5 ~ 3 [%]. Therefore, for example, by incorporating an MR element in a bridge circuit and detecting a change in the resistance value, the magnitude of the external magnetic field can be known.

【0009】

However, unlike the magnetic induction type magnetic head, the magnetoresistive magnetic head composed of MR elements does not require a relative speed above a certain level in order to obtain an output above a certain level, and has the advantage of having a low impedance and a wide frequency band. Therefore, it is used for high-density magnetic head applications.

【0010】

In this way, in the magnetic induction type magnetic head, it is necessary to give the magnetic recording medium and the head a relative speed of a certain level or more in order to obtain the output level, and there is a problem of S / N, so that it is used for high-density magnetic heads. As a magnetic resistance type magnetic head was used.

【0011】

[Problems to be Solved by the Invention]

However, the MR element used in the magnetoresistive magnetic head has a problem that the magnetic-electric conversion efficiency is not sufficient and the sensitivity is low, and a bridge circuit or the like is required. Therefore, it has been studied to change the MR element Permalloy NiFe to another material having high magnetic-electric conversion efficiency, but no material that can be put into practical use has been found yet.

【0012】

In recent years, a giant magnetoresistive effect (Great Magnetoresistive; GMR) due to a multilayer film in which FeNiCo, Cu, FeNiCo, etc. are laminated has been discovered, but the magnetic field detection sensitivity is 0.4, which is about 3 to 4 times that of conventional MR elements. It remains at about [%] / [Oe], and there is no significant improvement in sensitivity. Further, this multilayer film has a problem that hysteresis of the value of the resistivity ρ easily occurs with respect to the increase / decrease of the magnetic field.

【0013】

The demand for high-density magnetic recording / playback heads is that higher performance is required to meet the higher density and larger capacity of video tape recorders, hard disk devices, and floppy disk devices. As the thin film head and the reproduction head formed in the above, a hybrid head of the MR head composed of the MR element is attracting attention, but a significant improvement in the sensitivity of the reproduction magnetic flux detection element is required.

【0014】

However, the conventional magnetoresistive magnetic head using the MR element has not achieved a significant improvement in sensitivity during reproduction as described above.

【0015】

Therefore, one of the applicants of the present application (Mori) first proposed a magnetic impedance element according to Japanese Patent Application No. 5-323816, and realized a significant improvement in sensitivity during reproduction. This magnetoresistive element consists of an amorphous wire (wire that has been tension-annealed after drawing) with a diameter of almost zero magnetic strain, and even a wire with a minute length of about 1 [mm] has a high frequency of about 1 [MHz]. When a current is applied, the voltage amplitude between both ends of the wire changes with a high sensitivity of about 10 [%] / [Oe], which is 100 times or more that of the MR element.

【0016】

However, since this high-sensitivity magnetic impedance element is made of an amorphous wire having a diameter of 30 [μm], it is not suitable for microfabrication, and it is difficult to construct an ultra-small magnetic detection circuit.

【0017】

Therefore, the present invention has been made in view of the above points, and an object of the present invention is to provide a magnetic impedance element capable of fine processing with high sensitivity and an ultra-small magnetic detection circuit.

【0018】

[Means for solving problems]

In order to solve the above problem, the present invention is configured as follows.

【0019】

That is, in the invention according to claim 1, it is composed of a substrate made of a non-magnetic material, a magnetic thin film formed on the substrate, and first and second electrodes arranged at both ends in the longitudinal direction of the magnetic thin film. ..

【0020】

Further, in the invention according to claim 9, high frequency currents are applied to the first magnetic impedance element having one magnetic thin film, the second magnetic impedance element having another magnetic thin film, and the first and second magnetic impedance elements. It was composed of an energizing means for energizing and a signal generating means for generating first and second signals which change according to the direction of the magnetic field applied to the first and second magnetic impedance elements, respectively.

【0021】

[Action]

According to the invention according to claim 1 having the above configuration, since the magnetic thin film has high magnetic-electric conversion efficiency, it works so that it can be optimally used for high-density regenerated magnetic head applications.

【0022】

Further, according to the invention of claim 9 of the above configuration, the external magnetism is detected based on the first and second signals that change according to the direction of the magnetic field applied to the magnetic impedance element having the magnetic thin film. It works.

【0023】

[Example]

Next, examples of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention.

【0024】

The magnetic impedance element 1 shown in FIG. 1 is an amorphous sputter magnetic thin film composed of a strip-shaped glass substrate 2 which is a non-magnetic material and a CoFeB material formed on the glass substrate 2 in a strip shape which is one size smaller than the glass substrate 2. It is composed of 3 and electrodes 4 and 5 for external connection arranged at both ends in the longitudinal direction of the amorphous sputter magnetic thin film 3. Conductive materials such as copper and aluminum are used for the electrodes 4 and 5. A non-magnetic ceramic substrate may be used instead of the glass substrate 2.

【0025】

Amorphous sputtering magnetic thin film 3 uses a normal high-frequency bipolar sputtering device (vacuum degree is 10).^-7[Torr]) It is formed on the glass substrate 2 with a film thickness of 4 [μm]. The amorphous sputtered magnetic thin film having a film thickness of about 1 [μm] may be formed into a multilayer film to have a film thickness of 4 [μm]. Further, it is etched into an elongated strip shape having a length of 10 [mm] and a width of 0.3 [mm] using ferric chloride.

【0026】

The amorphous sputter magnetic thin film 3 has magnetic anisotropy in a direction different from the exciting current energized between the electrodes 4 and 5, that is, in a direction perpendicular to or diagonally to the exciting current.

【0027】

Further, the amorphous sputter magnetic thin film 3 is improved in magnetic-electric conversion efficiency as compared with the conventional MR element by forming the thin film shape, but further magnetic-electricity is further subjected to magnetic-field temperature annealing treatment. The conversion efficiency has been improved.

【0028】

That is, the amorphous sputtered magnetic thin film 3 is annealed at a temperature of 250 [° C] for 1 hour in a DC magnetic field of 70 [Oe], and the magnetic-electric conversion efficiency is greatly improved before and after the annealing treatment. ing. The details of the magnetic-electric conversion characteristics will be described later.

【0029】

FIG. 2 is a circuit diagram showing a circuit used by the magnetic impedance element 1. In FIG. 2, the electrodes 4 and 5 at both ends of the magnetic impedance element 1 have a resistor R and a high-frequency signal source e._ACA series circuit consisting of is connected. High frequency signal source e_ACIs capable of varying the frequency f, and a constant level high-frequency exciting current i is applied to the magnetic impedance element 1 via the resistor R._ACIs energized.

【0030】

Since the magneto-electrical conversion efficiency of the magnetic impedance element 1 using the amorphous sputtered magnetic thin film 3 is significantly improved, it is the simplest because it is not necessary to compensate the sensitivity by using a bridge circuit or the like unlike the conventional MR element. It becomes a circuit configuration. Further, the magnetic impedance element 1 has an external magnetic field H in the longitudinal direction of the amorphous sputtered magnetic thin film 3._exIs applied. The external magnetic field H_exThe method of applying the above will be described later.

【0031】

FIG. 3 is a circuit diagram showing an equivalent circuit of the magnetic impedance element 1. The magnetic impedance element 1 has a fixed impedance Z.₀When the amorphous sputter magnetic thin film 3 has the above-mentioned dimensions, it is represented by a series circuit of variable impedance ΔZ.₀= 9.6 [Ω]. The variable impedance ΔZ is the exciting current i energized between the electrodes 4 and 5._ACIt changes according to the frequency f of and the external magnetic field H_exIt changes according to.

【0032】

FIG. 4 is a diagram showing the experimental results of the magnetic impedance element 1 using the annealed amorphous sputtered magnetic thin film 3, and the exciting current i in the circuit of FIG._AC= 30 [mA_PP]. In FIG. 4, the horizontal axis is the alternating current excitation current i._ACFrequency f [MHz], vertical axis is the voltage between electrodes 4 and 5, that is, the voltage drop E [V] that occurs in the amorphous sputter magnetic thin film 3._PP] Is represented. The solid line I in the figure is the external magnetic field H_exWhen = 0, the dashed line II is the external magnetic field H_exRepresents the case of = 1000 [A / m].

【0033】

External magnetic field H_exWhen = 0, the impedance of the amorphous sputtered magnetic thin film 3 is constant up to a frequency f of 20 [MHz], and the voltage drop E is also constant. Then, when f = 20 [MHz] or higher, an increase in the voltage drop E (that is, an increase in impedance), which is considered to be due to the skin effect, is observed. The rate of increase in the voltage drop E is remarkable when f = 80 [MHz] or higher.

【0034】

The voltage drop E rises more remarkably when a magnetic field is applied (broken line II), and the voltage drop E rises from f = 10 [MHz]. This phenomenon is caused by the magnetic field strength H_exWhen = 0 [A / m], the magnetic domain wall of the amorphous sputtered magnetic thin film 3 can hardly move and the impedance is small, but the magnetic field strength H_exIt is considered that when the amount increases, the magnetization vector of the amorphous sputtered magnetic thin film 3 rotates, the magnetic permeability in the width direction increases, and the impedance rises.

【0035】

The increase in voltage drop E (that is, increase in impedance) due to the application of a magnetic field is H._exThe case of = 1000 [A / m] is the most prominent, and when a magnetic field higher than this is applied, the rate of increase of the voltage drop E decreases on the contrary. The impedance (voltage drop E) changes symmetrically regardless of the direction of the applied magnetic field in the width direction of the amorphous sputter magnetic thin film.

【0036】

Therefore, a graph showing the relationship between the impedance change rate of the amorphous sputtered magnetic thin film 3 and the external magnetic field is shown in FIG. In FIG. 5, the horizontal axis is the external magnetic field H._ex[Oe] (1 [Oe] = 10³/ 4π [A / m]), the vertical axis is the impedance change rate, that is, the external magnetic field H_exImpedance Z when = 0₀External magnetic field H shown on the horizontal axis with respect to_exPercentage of impedance change ΔZ when₀Represents [%]. In addition, f = 80 [MHz], i_AC= 30 [mA_PP].

【0037】

In the figure, the broken line III shows the characteristics when the amorphous sputtered magnetic thin film is annealed, and the solid line IV shows the characteristics when the amorphous sputtered magnetic thin film is annealed under the above-mentioned conditions. The amorphous sputtered magnetic thin film before annealing has an external magnetic field H._exΔZ / Z near 8 [Oe]₀Is about 11 [%] at the maximum, and the magnetic-electric conversion efficiency is improved about 4 times compared to the conventional MR element (2.5 to 3 [%]).

【0038】

On the other hand, in the case of the amorphous sputtered magnetic thin film 3 that has been annealed, the external magnetic field H_exΔZ / Z near 12.5 [Oe] (= 1000 [A / m])₀Is about 44 [%] at the maximum, and the magnetic-electric conversion efficiency is dramatically improved to 4 times compared to the case without annealing treatment. That is, it is improved about 16 times as compared with the conventional MR element. Also, the sensitivity is H, which is the steepest place._exIn the vicinity of = 6 [Oe] (= 480 [A / m]), it is as high as about 10 [%] / [Oe].

【0039】

From FIGS. 4 and 5, the annealed amorphous sputtered magnetic thin film 3 is 80 [MHz] and 30 [mA] when detecting minute magnetism._PP] High-frequency exciting current, and the external magnetic field H around 480 [A / m]_exIt can be seen that the maximum sensitivity of magnetic-electric conversion efficiency can be obtained by adding.

【0040】

Compared to the conventional MR element, which is a general magnetic-electric conversion element, that requires an external magnetic field of 1600 to 3000 [A / m], the magnetic impedance element of this example is about 1/3 to 1/1. Since the external magnetic field of 6 is sufficient, the optimum external magnetic field can be applied with a weak fixed magnet or a circumferential magnetic field with a smaller DC current. Therefore, it can be used for high-density reproduction magnetic head applications such as hard disk devices, floppy disk devices, and video tape recorders.

【0041】

Here, a configuration for applying an external magnetic field will be described. FIG. 6 is a diagram showing a modified example of the first embodiment of the present invention.

【0042】

The magnetic impedance element 6 shown in FIG. 6 is an amorphous sputter magnetic thin film composed of a strip-shaped glass substrate 7 which is a non-magnetic material and a CoFeB material formed on the glass substrate 7 in a strip shape which is one size smaller than the glass substrate 7. It is composed of 8 and electrodes 9 and 10 for external connection arranged at both ends in the longitudinal direction of the amorphous sputter magnetic thin film 8, and a hard magnetic thin film 11. Conductive materials such as copper and aluminum are used for the electrodes 9 and 10.

【0043】

The hard magnetic thin film 11 is a fixed magnet made of a normal magnetic material having magnetic poles S and N at both ends in a strip shape shorter than the amorphous sputter magnetic thin film 8 in the longitudinal direction. It is formed so as to apply the magnetic flux of the above and is fixed on the amorphous sputter magnetic thin film 8.

【0044】

As a result, an external magnetic field of about 480 [A / m] can be applied in the longitudinal direction of the amorphous sputtered magnetic thin film 8. By disposing the hard magnetic thin film 11 on the bottom surface of the glass substrate 7, it is conceivable to apply a magnetic flux in the longitudinal direction of the amorphous sputter magnetic thin film 8 to the amorphous sputter magnetic thin film 8.

【0045】

Next, FIG. 7 is a diagram showing another modification of the first embodiment of the present invention. The magnetic impedance element 12 shown in FIG. 6 is roughly composed of a first magnetic impedance element 13, a second magnetic impedance element 14, and a conductive thin film 15. Since the first magnetic impedance element 13 and the second magnetic impedance element 14 have the same configuration as the magnetic impedance element 1 of FIG. 1, detailed description thereof will be omitted, but the configuration has amorphous sputter magnetic thin films 13b and 14b, respectively. Has been done.

【0046】

The first magnetic impedance element 13 and the second magnetic impedance element 14 are arranged in the same direction with their respective substrates 13a and 14a facing each other. A conductive thin film 15 is interposed between the first magnetic impedance element 13 and the second magnetic impedance element 14 so as to be substantially orthogonal to each of the amorphous sputtered magnetic thin film 13b and the amorphous sputtered magnetic thin film 14b. .. At this time, the upper surface and the lower surface of the conductive thin film 15 are fixed to the substrate 13a and the substrate 14a.

【0047】

The conductive thin film 15 has a tape-like shape made of a conductive material such as copper or aluminum, and has a direct current I in the longitudinal direction thereof._DCIs energized. Therefore, the direct current I_DCBy generating a circumferential magnetic field around the conductive thin film 15 based on the ampere right-handed screw rule, an external magnetic field can be applied in the longitudinal direction of the amorphous sputter magnetic thin film 13b and the amorphous sputter magnetic thin film 14b. The amorphous sputtered magnetic thin film 13b and the amorphous sputtered magnetic thin film 14b have spiral magnetic anisotropy around the conductive thin film 15.

【0048】

In this case, DC current I_DCIf it is configured so that it can be adjusted, the magnitude of the external magnetic field can be freely changed, and the optimum magnetic field strength can be easily obtained. The external magnetic fields applied to the amorphous sputtered magnetic thin film 13b and the amorphous sputtered magnetic thin film 14b are opposite to each other.

【0049】

By the way, since the amorphous sputtered magnetic thin film can be easily microfabricated by etching technology, it has an advantage that various microcells can be formed, and it is also possible to integrate a sensor module into one chip.

【0050】

FIG. 8 is a diagram showing a second embodiment of the present invention. The magnetic detector circuit 20 shown in FIG. 8 is roughly a magnetic impedance element MI having an amorphous sputtered magnetic thin film having high magnetic-electric conversion efficiency.₁And MI₂, An unstable multivibrator 21, and a differential amplifier circuit 22.

【0051】

Magnetic impedance element MI₁And magnetic impedance element MI₂Is connected in series between terminals 23 and 24. Also, the magnetic impedance element MI₁And magnetic impedance element MI₂Common connection terminal 25 is the power supply voltage V_CCIt is connected to the.

【0052】

Magnetic impedance element MI₁Is a fixed impedance Z₁And variable impedance ΔZ₁Is represented by an equivalent circuit connected in series, and the magnetic impedance element MI₂Is a fixed impedance Z₂And variable impedance ΔZ₂Is represented by an equivalent circuit connected in series.

【0053】

Magnetic impedance element MI₁And magnetic impedance element MI₂The series circuit of is formed by etching on a glass substrate in the shape shown in FIG. 9, for example. That is, the magnetic impedance element MI₁Is a shape that repeatedly folds back in parallel in the Y direction as shown in the figure, magnetic impedance element MI₂Is shaped to be repeatedly folded back in parallel with the X direction as shown in the figure. Both magnetic impedance elements have the same magnetic-electrical conversion characteristics, and Z₁= Z₂And ΔZ₁Variable range and ΔZ₂The variable ranges of are equal.

【0054】

Therefore, both magnetic impedance elements MI₁And MI₂When the direction of the magnetic field H applied to is the X direction (θ = 0,180 [°]), ΔZ₁Is the minimum value (ΔZ₁= 0), ΔZ₂Is the maximum value. ΔZ as θ increases₁While increasing ΔZ₂Decreases and ΔZ when θ = 45 [°]₁= ΔZ₂Will be. When θ further increases and the direction of the magnetic field H is the Y direction (θ = 90,270 [°]), ΔZ₁Is the maximum value, ΔZ₂Is the minimum value (ΔZ₂= 0). In FIG. 9, 23 and 24 indicate terminals, and 25 indicates a common connection terminal.

【0055】

Returning to FIG. 8, the unstable multivibrator 21 connected to the terminal 23 and the terminal 24 is a transistor Q.₁And Q₂And resistance R₁~ R₈And variable resistor VR and capacitor C₁~ C₄It is composed of and.

【0056】

Transistor Q₁Resistor R for collector load₁And magnetic impedance element MI₁The series circuit of is transistor Q₂Resistor R for collector load₂And magnetic impedance element MI₂Each series circuit of is connected, and both magnetic impedance elements MI₁And MI₂An oscillating current of several tens [MHz] is supplied to and excited as described later.

【0057】

Capacitor C₁Is a transistor Q₂It is a charge capacitor that turns on the capacitor C.₂Is a transistor Q₁It is a charge capacitor that turns on. Resistor R₃Is a transistor Q₂For limiting the base current of the resistor R₄Is a transistor Q₁For base current limiting. Resistor R₅And R₆Is the base ground resistance.

【0058】

Resistor R₇Is a transistor Q₁Emitter resistance and resistance R₈Is a transistor Q₂Emitter resistance of. The variable terminal of the variable resistor VR is grounded, and one of the variable terminals of the variable resistor VR is a resistor R.₇Transistor Q connected to one end of₁Emitter resistance of, the other is resistance R₈Transistor Q connected to one end of₂It becomes the emitter resistance of.

【0059】

Variable resistance VR is a magnetic impedance element MI₁And MI₂Magnetic impedance element MI with no magnetic field applied to₁And MI₂, Transistor Q₁And Q₂, And the amplitude difference of the oscillation voltage of the unstable multivibrator 21 caused by the slight characteristic difference of each resistor (transistor Q).₁Emitter oscillation voltage V₁And transistor Q₂Emitter oscillation voltage V₂(Difference from) is to be corrected.

【0060】

The self-oscillation frequency of the unstable multivibrator 21 is the magnetic impedance element MI.₁And MI₂Impedance and resistance R₁And R₂And R₃And R₄And the capacitor C₁And C₂And the transistor Q₁Collector-emitter capacitance and transistor Q₂It depends on the collector-emitter capacitance of. This self-excited oscillation frequency is the magnetic impedance element MI in this embodiment.₁And MI₂The magnetic-electric conversion efficiency of is set to several tens [MHz], which is the maximum.

【0061】

By the way, one of the variable terminals of the variable resistor VR and the resistor R₇Series resistor with and capacitor C₃A low-pass filter is configured by the parallel circuit of. Also, the other and resistance R from the variable terminal of the variable resistor VR₈Series resistor with and capacitor C₄A low-pass filter is configured by the parallel circuit of. This allows the transistor Q₁Emitter oscillation voltage V₁And transistor Q₂Emitter oscillation voltage V₂Are attenuated in high frequency components to form sine waves that are 180 [°] out of phase with each other.

【0062】

The differential amplifier circuit 22 has a resistor R.₉And R₁₀And R₁₁And R₁₂And R₁₃And differential amplifiers 26 and 27. Transistor Q at the non-inverting input terminal of the differential amplifier 26₂Emitter oscillation voltage V₂However, the transistor Q is connected to the non-inverting input terminal of the differential amplifier 27.₁Emitter oscillation voltage V₁Is entered. As a result, the differential amplifier circuit 22 has a resistor R.₉~ R₁₃Each emitter oscillation voltage V with a predetermined amplification gain determined by the value of₁And V₂Output voltage E that stably and well amplified only the difference component of_OIs output to the output terminal 28.

【0063】

As mentioned above, the magnetic impedance element MI₁And MI₂Magnetic impedance element MI according to the direction of the magnetic field applied to₁And MI₂Variable impedance ΔZ₁And ΔZ₂Changes, this ΔZ₁And ΔZ₂Each emitter oscillation voltage V according to the change of₁And V₂Changes. Therefore, the output voltage E_OIs a magnetic impedance element MI₁And MI₂It is a magnetic field detection signal whose magnitude and polarity change according to the direction of the magnetic field applied to.

【0064】

According to this embodiment, ΔZ according to the change in the direction of the magnetic field.₁And ΔZ₂Magnetic impedance element MI so that one of them decreases and the other increases.₁And MI₂Pattern is formed. Therefore, the magnetic impedance element MI₁And MI₂The detection sensitivity can be improved in combination with the original high magnetic-electric conversion efficiency. Further, the magnetic impedance element can be microfabricated and the circuit can be made compact.

【0065】

FIG. 10 is a diagram showing a third embodiment of the present invention. The high-speed regenerative magnetic recording cell 30 shown in FIG. 10 has a magnetic impedance element 31 made of an amorphous sputter magnetic thin film having high magnetic-electric conversion efficiency, and functions as a magnetic flash memory capable of ultra-high-speed reading.

【0066】

In FIG. 10, a magnetic impedance element 31 is formed as a sputtered thin film on the glass substrate 32. A paramagnetic body 32 is fixed to one end of the magnetic impedance element 31, and a magnetic body 33 is fixed to the other end of the magnetic impedance element 31. The paramagnetic material 32 and the magnetic material 33 are both formed as a sputtered thin film in the same manner as the magnetic impedance element 31. Therefore, it is possible to microfabricate each width direction dimension to about 0.1 [μm].

【0067】

Further, the magnetic impedance element 31, the paramagnetic material 32, and the magnetic material 33 have conductivity, and electrodes 34 and 35 made of, for example, copper or aluminum are arranged at each end of the paramagnetic material 32 and the magnetic material 33. It is installed. Then, a recording current is energized between the electrodes 34 and 35 from the external circuit.

【0068】

The paramagnetic material 32 has magnetic poles on the magnetic impedance element 31 side and the electrode 34 side as shown in the drawing, and magnetically biases the magnetic impedance element 31. The orientation of the magnetic poles may be opposite to the orientation shown in the drawing.

【0069】

The magnetic material 33 is a magnetic material such as that used for magnetic recording materials (for example, CoNi, CoNiγ-Fe).₂O_3,(CoNiP, etc.), the magnetic impedance element 31 side is magnetized and held by a positive or negative pulse current for recording to a polarity corresponding to the direction of the current for recording.

【0070】

According to the high-speed regenerative magnetic recording cell 30 having the above configuration, when the magnetic material 33 is recorded and magnetized in a direction having a magnetization vector opposite to that of the paramagnetic material 32, the magnetic field of the magnetic impedance element 31 is canceled. The voltage across it is minimized. On the other hand, when the magnetic material 33 is recorded and magnetized in a direction having a magnetization vector in the same direction as the paramagnetic material 32, the voltage across the magnetic material 33 becomes maximum. Therefore, the recorded signal can be stored in the magnetic impedance element 31.

【0071】

Therefore, if a large number of high-speed reproduction magnetic recording cells 30 having the above configuration are arranged in an integrated structure, a magnetic flash memory that is electronically reproduced by a decoder can be manufactured, and ultra-high-speed reading becomes possible.

【0072】

[Effect of the invention]

According to the invention of claim 1 as described above, since the magnetic thin film has high magnetic-electric conversion efficiency, it can be used for high-density regenerated magnetic head applications, and can be finely processed with higher sensitivity than before. There are features that make it possible.

【0073】

Further, according to the invention of claim 9, since the external magnetism is detected based on the first and second signals that change according to the direction of the magnetic field applied to the magnetic impedance element having the magnetic thin film, as compared with the conventional case. The detection sensitivity can be improved, and the magnetic impedance element can be finely processed, so that the circuit can be made compact.

[Simple explanation of drawings]

[Figure 1]

It is a figure which shows the 1st Example of this invention.

[Figure 2]

It is a circuit diagram which shows the use circuit of a magnetic impedance element 1.

[Fig. 3]

It is a circuit diagram which shows the equivalent circuit of a magnetic impedance element 1.

[Fig. 4]

It is a figure which shows the experimental result of the magnetic impedance element 1 using the amorphous sputter magnetic thin film 3.

[Fig. 5]

It is a figure which shows the relationship of the impedance change rate of an amorphous sputtered magnetic thin film 3 | an external magnetic field.

[Fig. 6]

It is a figure which shows one modification of the 1st Example of this invention.

[Fig. 7]

It is a figure which shows the other modification of the 1st Example of this invention.

[Fig. 8]

It is a figure which shows the 2nd Example of this invention.

[Fig. 9]

Magnetic impedance element MI₁And magnetic impedance element MI₂It is a figure which shows the shape of.

[Fig. 10]

It is a figure which shows the 3rd Example of this invention.

[Fig. 11]

It is a circuit diagram which shows the equivalent circuit of an MR element.

[Fig. 12]

It is an operation principle diagram of an MR element.

[Fig. 13]

It is a figure which shows the change with respect to the synthetic magnetic field H of the resistivity ρ of MR element 100.

[Explanation of symbols]

1,31, MI_1,MI₂ Magnetic impedance element 2 Glass substrate 3 Amorphous sputter magnetic thin film 4,5,9,10,34,35 electrodes 20 Magnetic detector circuit 21 Unstable multivibrator 22 Differential amplifier circuit 30 High-speed playback magnetic recording cell 32 Paramagnetic material 33 Magnetic material 100 MR element Z_0,Z_1,Z₂ Fixed impedance ΔZ_0,ΔZ_1,ΔZ₂ Variable impedance