JPH1173614A - Thin film magnetic head using ferrum based metal glass alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic impedance effect element thin film comprising a Fe-based metal glass alloy which shows ferromagnetism at a room temp. and a magnetic impedance effect, by using a Fe-based metal glass alloy which has specified or larger temp. difference in a supercooled liquid state expressed by a specified formula. SOLUTION: The Fe-based metal glass alloy essentially consists of Fe and contains other metal elements and semimetal elements. The temp. interval in its supercooled liquid state is expressed by ΔTx=Tx-Tg (wherein Tx is the initiation temp. of crystallization and Tg is the glass transition temp.). As for the metals, one or more kinds of Al, Ga, In, Sn are used. As for semimetals, one or more kinds of P, C, B, Ge are used. The Fe-based metal glass alloy has >=20 K temp. interval ΔTx in its supercooled liquid state, and has 35 to 60 K or more depending on the compsn., and shows magnetism at a room temp. The alloy exhibits better magnetism by heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film magnetic head using a magneto-impedance effect element thin film made of metallic glass.

[0002]

2. Description of the Related Art In recent years, magnetic recording devices such as a hard disk, a digital audio tape recorder, and a digital video tape recorder, which are external storage devices of a computer, are required to be further miniaturized and have an improved recording density. ing. In order to respond to the above demands, it is essential to improve the performance of magnetic heads.
A magnetic head using a magnetoresistive element (hereinafter abbreviated as MR element) as a reproducing head has been developed. A magnetic head using an MR element has no dependency on the relative speed with respect to the recording medium and is suitable for reading a recording signal at a low relative speed, but has a low resistance change rate with respect to a change in the recording magnetization of the recording medium. However, since the sensitivity of the output signal is low, there is a problem that it is difficult to cope with further higher density in the future.

[0003] Recently, attention has been focused on a magneto-impedance effect (MI).
(Magnetic impedance effect element: M)
I effect element). The magnetic impedance effect (MI effect) means that when an alternating current in the MHz band is applied from a power supply to a wire-shaped or ribbon-shaped magnetic material and an external magnetic field is applied in the length direction of the magnetic material in this state, the external magnetic field becomes several Even with a weak magnetic field of the order of Gauss, a voltage is generated at both ends of the magnetic material due to the impedance inherent in the material, and the amplitude changes within a range of several tens of percent corresponding to the strength of the external magnetic field. A phenomenon. While the magnetic detection sensitivity of the conventional MR element is about 0.1 Oe, an element having a magnetic impedance effect (MI effect element)
Is capable of detecting about 10 ⁻⁵ Oe of magnetization, and is therefore expected to be applied as a high-sensitivity magnetic head.

The present inventors have been developing various alloys, and have been studying metallic glass as one of the themes of the alloy development. Conventionally, certain types of multi-element alloys have a wide temperature range in the supercooled liquid state prior to crystallization, and these are known to constitute metallic glassy alloys . It is also known that this kind of metallic glass alloy becomes a bulk alloy much thicker than a thin ribbon of an amorphous alloy manufactured by a conventionally known liquid quenching method.
For example, conventionally, as such a metallic glass alloy, Ln-
Al-TM, Mg-Ln-TM, Zr-Al-TM, Hf-A
Compositions such as l-TM and Ti-Zr-Be-TM (where Ln represents a rare earth element and TM represents a transition metal) are known.

[0005]

In THE INVENTION solve problems you try Here alloys various compositions, even showing a supercooled liquid state, the temperature interval [Delta] T _x of these supercooled liquid, i.e., a crystallization starting temperature (T _x), Difference from the glass transition temperature (T _g ), that is, (T _g
x −T _g ) is generally small, and in reality, has a wide supercooled liquid temperature range as described above, considering that it has poor metallic glass forming ability and is not practical.
The existence of an alloy capable of forming a metallic glass by cooling is of great interest in metallurgy since it can overcome the thickness limitation of a conventionally known amorphous alloy as a ribbon. Further, when the alloy has a large ΔT _x , it is possible to form a film under a wide range of film forming conditions when forming an alloy thin film by means such as sputtering, which is industrially useful. However, whether it can be developed as an industrial material depends on finding a metallic glass alloy that exhibits ferromagnetism at room temperature. However, none of these conventionally known metallic glass alloys has magnetism at room temperature, and in this regard, when viewed as a magnetic material, there is a great industrial limitation. Therefore, conventionally, research and development of a metallic glass alloy which has magnetism at room temperature and can obtain a thick bulk material has been promoted. As a result of conducting research based on such a background, the present inventors have found a metallic glass having ferromagnetic properties at room temperature and also exhibiting the MI effect, and have reached the present invention.

The present invention has been made in view of the above circumstances, and has as its object to provide a thin film magnetic head using a thin film made of a metallic glass alloy which exhibits ferromagnetism at room temperature and exhibits the MI effect for detecting an external magnetic field. And

[0007]

According to the present invention, in order to solve the above-mentioned problems, ΔT _x = T _x -T _g (where T _x indicates a crystallization start temperature and T _g indicates a glass transition temperature). The temperature interval ΔT _x of the supercooled liquid represented by the formula is mainly composed of an Fe-based metallic glass alloy having a temperature of 20 K or more, and a magneto-impedance effect element thin film that changes impedance by an external magnetic field is provided for detecting an external magnetic field. Features.
According to the present invention, a write head and a read head are provided on a slider that relatively moves toward a medium facing surface toward a magnetic medium, and the write head is a thin film-shaped upper core and lower core and a magnetic head interposed therebetween. The magnetic head has a magnetic induction type structure including a gap and a coil conductor, and the read head includes a magneto-impedance effect element thin film and an electrode film connected to the impedance effect element thin film.

The present invention is characterized in that in the above structure, a bias applying means is provided on the magneto-impedance effect element thin film. In the present invention, the bias applying means may be composed of a permanent magnet connected to the magneto-impedance effect element thin film. Further, in the present invention, the bias applying means comprises a ferromagnetic thin film laminated on the magneto-impedance effect element thin film, and an antiferromagnetic thin film laminated on the ferromagnetic thin film, A bias may be applied by an exchange coupling magnetic field induced in the ferromagnetic thin film by the antiferromagnetic thin film.

In the present invention, the Fe-based soft magnetic metallic glass alloy preferably contains a metal element other than Fe and a metalloid element. In the present invention, it is preferable that at least one of P, C, B and Ge is contained as a metalloid element. In the present invention, it is preferable that at least one of P, C, B and Ge and Si and the metalloid element are contained.
In the present invention, it is preferable that the other metal element is at least one or more of metal elements belonging to Groups IIIB and IVB of the periodic table. In the present invention, the other metal element is preferably at least one of Al, Ga, In, and Sn. Therefore, the present invention
The base metal glass alloy contains a metal element other than Fe and a metalloid element, and the other metal elements include Al, G
a, In, or Sn, one or more of P, C, B, and Ge as the metalloid element.
It is characterized by comprising at least one species or two or more species.

Further, in the present invention, the composition of the Fe-based metallic glass alloy is atomic%, Al: 1 to 10%, Ga:
0.5-4%, P: 0-15%, C: 2-7%, B: 2
-10%, Fe: the balance of the composition.
In the present invention, the composition of the Fe-based metallic glass alloy is atomic%, Al: 1 to 10%, Ga: 0.5 to 4%, P:
9 to 15%, C: 5 to 7%, B: 2 to 10%, Si: 0
~ 15%, Fe: balance may be used.

In the present invention, the composition of the Fe-based soft magnetic metallic glass alloy preferably further contains 0 to 4% of Ge in atomic%. In the present invention, in the composition of the Fe-based soft magnetic metallic glass alloy, Nb, Mo,
It is preferable that at least one of Hf, Ta, W, Zr, and Cr is contained in an amount of 7% or less. In the present invention, the composition of the Fe-based soft magnetic metallic glass alloy may be such that the atomic percentage of Ni is 10% or less and the atomic percentage of C is 30% or less.
It is preferable that at least one of o is contained.
Next, in the present invention, the X-ray diffraction image of the Fe-based soft magnetic metal glass alloy preferably has a halo pattern.
It is preferable that a heat treatment in a temperature range of 00 ° C. is performed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A thin film magnetic head according to one embodiment of the present invention will be described below with reference to the drawings. The thin-film magnetic head HA of this example is of a floating type mounted on a hard disk device or the like.
The side shown in FIG. 1A is the leading side facing the upstream side in the moving direction of the disk surface, and the side shown in FIG. 1B is the trailing side. On the surface of the slider 51 facing the disk, rail-shaped rail surfaces 51a, 51a, 51a are provided.
b, and air grooves 51c, 51c are formed. The thin-film magnetic head core 50 is provided on the trailing end surface 51d of the slider 51.

The thin-film magnetic head core 50 shown in this example has
This is a composite type magnetic head whose sectional structure is shown in FIG. 2 and FIG.
MI effect element head (read head) h ₁ and inductive head (magnetic induction type magnetic head: write head) h ₂
Are sequentially laminated.

[0014] MI effect element head h ₁ in this example detects the leakage flux from a recording medium such as a magnetic disk by utilizing an MI effect to read the magnetic signals. In MI effect element head h _1, as shown in FIG. 2, the slider 5
Sendust (Fe) formed at the trailing end of
Lower gap layer 53 made of a magnetic alloy such as -Al-Si)
An upper gap layer 54 made of a non-magnetic material such as alumina (Al ₂ O ₃ ) is laminated thereon. On the upper gap layer 54, a later-described MI effect element 10 having a sectional structure shown in FIG. 4 and the like is formed. Also,
Further, on the MI effect element 10, an upper gap layer 54 made of alumina or the like is continuously formed so as to cover the MI effect element 10, and an upper shield layer is formed thereon. the lower core 55 of the inductive head h ₂ provided above are also used.

[0015] Figure 4 shows an example of a MI effect elements 10 applied to the MI effect element head h _1, MI for this example
The effect element 10 is made of M made of metallic glass described below.
I effect element thin film 12, ferromagnetic thin film 13 laminated on MI effect element thin film 12, and ferromagnetic thin film 13
And a antiferromagnetic thin film 14, 14 with their antiferromagnetic thin film 14 laminated on an electrode layer 15 which are laminated at a gap T _w which corresponds to the track width on the both end portions of the .

Here, the metallic glass constituting the MI effect element thin film 12 used in the present invention will be described below. Conventionally, Fe-based alloys such as Fe-PC-based alloys and Fe-P-B
It is known that those having a composition such as a Fe-Ni-Si-B system cause a glass transition, but a region of a supercooled liquid of these alloys is not observed, and it is not possible to constitute a metallic glass alloy. Can not.

On the other hand, in the Fe-based soft magnetic metallic glass alloy according to the present invention, the temperature interval ΔT
_x has a remarkable temperature interval of 20K or more and 35 to 60K or more depending on the composition, which is completely unexpected from the Fe-based alloy known from the findings so far. In addition, the Fe-based soft magnetic metallic glass alloy according to the present invention, which has excellent soft magnetism at room temperature and also exhibits the MI effect, is a completely novel one not seen in the previous findings.

The composition of the Fe-based soft magnetic metallic glass alloy according to the present invention can be described as containing Fe as a main component and further containing other metals and metalloids. Of these, other metals are group IIA of the periodic table, II
Groups IA and IIIB, IVA and IVB, VA
The metal element can be selected from Group III, Group VIA, and Group VIIA, and among them, the metal elements of Group IIIB and Group IVB are shown as preferable ones. For example, Al, Ga, In, S
n. Further, Ti, Hf, Cu, Mn, Nb, Mo, and C are added to the Fe-based soft magnetic metallic glass alloy according to the present invention.
1 selected from among r, Ni, Co, Ta, W, and Zr
More than one kind of metal element can be blended. Examples of the metalloid element include P, C, B, Si, and Ge. More specifically, in the present invention, the composition is atomic%, Al: 1 to 10%, Ga: 0.5 to 4%,
P: 0 to 15%, C: 2 to 7%, B: 2 to 10%, F
e: Fe-based metallic glass alloy which is the remainder and may contain unavoidable impurities.

Further, by adding Si to the above composition, the temperature interval ΔT _x of the supercooled liquid can be improved, and the critical thickness of the amorphous single phase can be increased. As a result, it is possible to further increase the thickness of the Fe-based soft magnetic metallic glass alloy having excellent soft magnetic properties at room temperature. If the content of Si is too large, the supercooled liquid region Δ
Since T _x disappears, preferably 15% or less. More specifically, the Fe-based metallic glass alloy of the present invention has a composition of atomic%, Al: 1 to 10%, and Ga: 0.5 to 0.5%.
4%, P: 0 to 15%, C: 2 to 7%, B: 2 to 10
%, Si: 0 to 15%, Fe: balance, and may contain unavoidable impurities.

In the above composition, Ge is further reduced to 0.
To 4%, preferably 0.5 to 4%. Furthermore, in order to obtain a wider supercooled liquid region [Delta] T _x, p the amount of P and C in atomic%: 6~15%, C: 5
More preferably, it is set to ７7%. The composition may further contain at least one of Nb, Mo, Cr, Hf, W, and Zr in an amount of 7% or less.
It may contain 0% or less and Co 30% or less. In the composition of any of these cases, in the present invention,
The temperature interval ΔT _x of the supercooled liquid is 20K or more, and 35 to 60K or more depending on the composition.

The Fe-based soft magnetic metallic glass alloys having these compositions have magnetism at room temperature.
Shows better magnetism. For this reason, the excellent Soft magneti
It can be used as a material having c characteristics (soft magnetic characteristics). Further, after forming a thin film of a metallic glass alloy of these composition systems, a heat treatment can be performed if necessary. The heat treatment temperature in this case is preferably from 300 to the crystallization temperature, more preferably from 300 to 400 ° C., as a temperature range at which the magnetic properties do not deteriorate.

The ferromagnetic thin film 13 is made of a Ni—Fe alloy, a Co—Fe alloy, a Ni—Co alloy, Co, Ni—Fe—
It is made of a thin film such as a Co alloy. The ferromagnetic thin film 13
Can be configured as a laminated structure of a Co thin film and a Ni—Fe alloy thin film. The antiferromagnetic thin film 14 is preferably made of, for example, FeMn, NiO, Cr-Al, or an X-Mn-based alloy having an irregular structure. Here, in the above composition formula, X is Ru, Rh, I
It is preferable to be composed of one or more of r, Pd, and Pt. If the antiferromagnetic thin film 14 is made of any of the above alloys, a bias due to the exchange coupling magnetic field can be applied to the MI effect element thin film 12 in contact with the ferromagnetic thin film 13.

On the other hand, the inductive head h ₂ of this embodiment, on the lower core 55, the gap layer 64 is formed, a coil layer 66 that is patterned such that the planar spiral thereon formed The coil layer 66 is surrounded by an insulating material layer 67. Further, the layered upper core 68 formed on the insulating material layer 67 has its tip 68a opposed to the layered lower core 55 on the rail surface 51b with a small gap therebetween to form a magnetic gap G. , The base end 68 b of the upper core 68 is magnetically connected to the lower core 55. Further, a protective layer 69 made of alumina or the like is provided on the upper core 68.

[0024] In the above-described inductive head h _2, the recording current is applied to the coil layer 66, a recording current is supplied from the coil layer 66 to the core layer. And the magnetic gap G
A magnetic signal can be recorded on a recording medium such as a hard disk by the leakage magnetic field from the distal ends of the lower core 55 and the upper core 68 at the portion. In the MI effect element head h _1, MI effect elements thin film 12 by the presence or absence of micro-leakage magnetic field from the magnetic recording medium such as a hard disk
Of the recording medium can be read by reading the impedance change.

FIG. 6 shows an example of a circuit system for measuring the MI effect of the MI effect element thin film 12.
In the circuit configuration shown in FIG. 2A, an alternating current Iac in the MHz band is applied from the power supply Eac to the MI effect element thin film 12, and in this state, an external magnetic field H is applied in the longitudinal direction of the MI effect element thin film 12.
When ex is applied, even when the external magnetic field Hex is a weak magnetic field of about several gauss, a voltage Emi due to the material-specific impedance is generated at both ends of the MI effect element thin film 12, and the amplitude thereof corresponds to the intensity of the external magnetic field Hex Since it changes at a large rate, a weak magnetic field can be detected.

Next, when actually constructing the thin film magnetic head HA using the MI effect element thin film 12, it is necessary to take care that the sensitivity is not unstable due to the floating impedance of the circuit because a high frequency current is used. There is. As one solution to this problem, in the MI head having the above-described configuration, it is preferable to employ a self-oscillation type magnetic field detection circuit in which the MI head and a high-frequency power supply are integrated. FIG. 6B shows an example of a magnetic field detection circuit having this self-oscillation circuit.

In the circuit shown in FIG. 6B, blocks a,
b and c are a high-frequency power supply unit, an external magnetic field detection unit, and an amplification output unit, respectively.
Are connected to each other. The high-frequency power supply unit a is a circuit for generating a high-frequency AC current and supplying the high-frequency AC current to the external magnetic field detection unit b, and the type thereof is not particularly limited. Here, an example employing a stabilized Colwitz oscillation circuit will be described as an example. In the self-oscillation system, the magnetic field sensing operation can be performed by applying amplitude modulation (AM), frequency modulation (FM), or phase modulation (PM) using magnetic modulation. External magnetic field detection unit b is composed of a MI effect elements thin film 12 provided to the MI effect element head h ₁ of the thin-film magnetic heads HA and demodulation circuit, a standby state by supplying high-frequency alternating current from the high-frequency power supply a The applied MI effect element thin film 12 has an external magnetic field (Hex).
Is demodulated by the demodulation circuit and transmitted to the amplification output section c. The amplification output section c has a differential amplifier circuit and an output terminal. This magnetic sensor circuit is provided with a negative feedback loop circuit (not shown), and by applying strong negative feedback, a weak magnetic sensor circuit with high accuracy, high sensitivity, high speed response, and high stability is formed.

FIG. 7 shows the MI element thin film 12 used in the present invention.
FIG. 4 is a diagram showing the magnetic field sensitivity of FIG. As shown in FIG. 7, the MI effect element thin film 12 of the present invention shows similar parameter changes regardless of the polarity of the external magnetic field. Therefore, it is preferable to apply a DC magnetic field bias when configuring a linear detection type thin film magnetic head capable of linear response. Since the MI effect element thin film 12 of the present invention has high linearity in a weak magnetic field, the bias magnetic field may be small.

In order to apply the bias magnetic field, an exchange coupling magnetic field exerted by the antiferromagnetic thin film 14 shown in FIG. 4 is used. In the structure shown in FIG.
The bias is applied to the ferromagnetic thin film 13 by the exchange anisotropic coupling at the interface between both layers of the ferromagnetic thin film 3 and the antiferromagnetic thin film 14, and the region B in FIG. Thin film 14
Is in the X direction and is induced into a single magnetic domain, which induces the ferromagnetic thin film 13 in the region A within the track width Tw.
Are made into single magnetic domains in the X direction, and a bias is applied. The ferromagnetic thin film 13 thus magnetized by the bias magnetic field
When the leakage magnetic field from the magnetic recording medium is applied to the MI effect element thin film 12 adjacent to the element, the impedance change occurs in proportion to the magnitude of the leakage magnetic field, so that the leakage magnetic field can be detected.

The thin film magnetic head HA using the MI effect element thin film of the present invention is an MI effect element thin film 1 using metallic glass.
2 responds to a magnetic field change in the length direction (X direction in FIG. 4).
A highly sensitive thin-film magnetic head having an impedance change rate of several tens to 100% / Oe, a high resolution of 10 ^-6 Oe, and a cutoff frequency of several MHz can be configured. For example, even if the head length is extremely small, the magnetic field detection sensitivity does not deteriorate, and the minimum detection magnetic field for an AC magnetic field of 1 Hz or more reaches 10 ^-6 .

The thin-film magnetic head HA of this embodiment has the following features.
Since the magnetic flux change due to the rotation of the fast-response magnetization is used, high-speed response is achieved. In other words, when the passing current is set to a high frequency, the impedance changes sharply depending on the external magnetic field due to the skin effect and the sensitivity increases, and the movement of the domain wall is suppressed by strong overcurrent braking, and the movement of the magnetization vector generates a magnetic flux. Therefore, high-speed response is achieved. When a self-oscillation circuit such as a Colpitts oscillation circuit is formed using the MI effect element thin film 12 of the present invention to form an amplitude modulation type sensor, its cutoff frequency is about 1/10 of the oscillation frequency, and several tens of MHz. At oscillation frequency, several M from DC magnetic field
Up to a high frequency magnetic field of Hz, the resolution can be detected stably with high sensitivity of about 10 ^-6 Oe, and a thin film magnetic head capable of detecting even a small magnetic field from a magnetic recording medium with good sensitivity can be provided.

FIG. 5 shows another embodiment of the MI effect element thin film according to the present invention. The structure of this embodiment is such that a magnet layer (permanent magnet) 23 is provided on both sides of the MI effect element thin film 22 made of metallic glass. 23, and a structure in which an electrode film 25 is laminated on the magnet layers 23, 23, and a structure in which a bias is applied to the MI effect element thin film 23 by utilizing magnetic flux leakage from the magnet layer 23. I have. The magnet layer 23 used here is formed from a layer of a hard magnetic material (magnet material) such as Co-Pt or Co-Cr-Pt alloy. In the structure shown in FIG. 5, a bias can be applied in the same manner as in the previous embodiment, and magnetic information can be read from the magnetic recording medium using the MI effect in the same manner as in the structure in the previous embodiment. .

[0033]

The present invention will be described in more detail with reference to the following examples. (Example 1) Using a high-frequency magnetron sputtering apparatus,
Al ₂ O ₃ -TiC (Altic) coated with an Al ₂ O ₃ film
Substrate (substrate commonly used for sliders in magnetic heads)
A plurality of targets were sputtered using a plurality of targets so as to have the following structure to form a laminate, which was processed by etching to produce an MI effect element having a structure shown in FIG. At this time, an MI element thin film having a composition of Fe ₇₂ Al ₅ Ga ₂ P ₁₁ C ₆ B _{4 having} a thickness of 1000 ° and a ferromagnetic thin film having a thickness of 100 ° made of a Ni ₈₀ Fe ₂₀ alloy are laminated, and further thereon. An antiferromagnetic layer (Pt ₅₀ Mn ₅₀ ) having a thickness of 200 ° and an electrode layer having a thickness of 1000 ° are laminated by sputtering, and the electrode film corresponding to the track width (Tw = 2 μm) is removed by photolithography and ion milling. The MI effect element thin film having the structure shown in FIG. 4 was obtained by removing the ferromagnetic thin film.

The above-mentioned MI effect element thin film is inserted into the magnetic field detecting circuit shown in FIG. 6 (B), and an external magnetic field is applied in the length direction of the MI effect element thin film (the direction of FIG. 4) while an AC current of 3 MHz is applied. Hex was applied, and the relationship between the external magnetic field Hex (Oe) and the generated output voltage (mV) was plotted. The external magnetic field Hex starts from 0 Oe, 5 Oe,
e, −5 Oe, and 0 Oe were continuously changed back and forth. The amplification magnification was set to 10 times. FIG. 8 shows the measurement results. From these results, the MI effect element of this example has a value of -2 Oe to +2.
It can be seen that even in a weak magnetic field band of about Oe, high sensitivity and good quantitativeness are exhibited.

(Embodiment 2) Instead of the MI element thin film, F
to obtain a laminated body shown in FIG. 4 with a thin film of _{e 72 Al 5 Ga 2 P 10} C 6 B 4 Si 1 having a composition. As in the case of the first embodiment, the MI effect element of this example is inserted into the magnetic field detection circuit shown in FIG. 6B, and an external magnetic field Hex is applied in the longitudinal direction of the sample in a state where an alternating current of 3 MHz is applied. And an external magnetic field Hex (O
The relationship between e) and the generated output voltage (mV) was plotted. The external magnetic field Hex starts from 0 Oe and
e, 0 Oe, −5 Oe, and 0 Oe were continuously changed back and forth. The amplification magnification was set to 10 times. Figure 9 shows the measurement results.
Shown in From this result, the MI effect element of Example 2 was -2.
It can be seen that high sensitivity and good quantitativeness are exhibited even in a weak magnetic field band of about Oe to +2 Oe.

Next, FIG. 7 compares the magnetic field sensitivity of the laminate using the MI effect element thin film according to the present invention described above with the magnetic field sensitivity of the conventionally known MI effect element thin film. Indicated. As an MI effect element thin film exhibiting the MI effect, a conventionally known Fe—Si—B-based (Fe ₇₈ Si ₉ B ₁₃
Thin film), a Fe—Co—Si—B system ((Fe ₆
Co ₉₄ ) _72.5 Si _12.5 B ₁₅ amorphous thin film).

As is clear from the results shown in FIG. 7, the Fe--Si--B system shown by the curve and the Fe--Co--
When using the Si-B based MI effect element thin film, it is found that the following problems occur. That is, as shown in FIG. 7, when the output voltage Emi (mV) with respect to the positive and negative applied magnetic fields (Oe) is measured, the Fe-
Si-B based thin films have low magnetic field detection sensitivity and have an amplification factor of 1
When the amplification magnification is increased, it is difficult to obtain a high-sensitivity magnetic field detecting element due to the incorporation of noise and the like. In addition, Fe-Co-
Although the sensitivity of the Si-B thin film is sufficiently high as shown in FIG. 7, the sensitivity rises very sharply when the applied magnetic field is within a weak magnetic field of, for example, about -2 Oe to +2 Oe. And it is difficult to use it as a weak magnetic field detecting element. In a magnetic field band exceeding an absolute value of 2 Oe, the curve can be used because the slope of the curve is smooth. However, in order to use the curve of this portion, a bias magnetic field of about 2 Oe, which is about the same as the detection magnetic field, is required. Had to be applied. In contrast, when the MI effect element thin film of the metallic glass alloy according to the present invention is used,
It is clear that a weak magnetic field can be detected with high sensitivity because a positive / negative symmetrical gradient having an appropriate magnitude for detection can be obtained within the range of a weak magnetic field of about −2 Oe to +2 Oe.

On the other hand, according to experiments by the present inventors, if the metallic glass alloy has an atomic composition ratio of Fe ₇₃ Al ₅ Ga ₂ P ₁₁ C ₅ B ₄ , the crystallization start temperature T _x is about 506 ° C. , and the the glass transition temperature the T _g is confirmed to be 458 ° C., the temperature interval of the supercooled liquid of the metallic glass alloy of this _{composition, ΔT x = T x -T g} = 506-458 = 48
° C.

Next, the magnetic properties of the thin film (thickness: 35 μm) of the metallic glass alloy having the above composition, “magnetic permeability μ ′ (1 kHz)
z): coercive force (Hc): saturation magnetization (σs) ”
The dependence of the heat treatment was measured. The result is shown in FIG.
FIG. 10 shows that the magnetic permeability is improved from the processing temperature exceeding 300 ° C., has a peak at around 350 ° C., and shows a tendency to increase as compared with the case where no heat treatment is performed up to about 400 ° C. Showed a tendency that the magnetic permeability was significantly reduced. It is considered that the change in the soft magnetic properties due to these heat treatments is because the internal stress existing in the sample without heat treatment is alleviated by performing the heat treatment. In addition, it can be said that the optimum heat treatment temperature is around 350 ° C. in the test composition in this case. In the heat treatment at the Curie temperature _Tc or lower, there is a possibility that the characteristics may be degraded due to the magnetic domain sticking. Therefore, it is considered that the heat treatment temperature is preferably at least 300 ° C or higher. Also,
Since the heat treatment at 450 ° C. tends to deteriorate from the value of the sample without heat treatment, the temperature is close to the crystallization temperature of this system (about 500 ° C.), and the onset of crystal nucleation (structural short-range ordering) or It is thought that it deteriorates due to the domain wall pinning due to the start of precipitation. Therefore, the temperature at which the thin film of the metallic glass alloy according to the present invention is heat-treated is 300
To 500 ° C, in other words, preferably from 300 ° C to the crystallization onset temperature, more preferably from 300 to 450 ° C.

[0040]

As described above, in the thin-film magnetic head of the present invention, the temperature difference ΔT _x of the supercooled liquid is 35K or more.
It is made of e-base metallic glass alloy, and has a magneto-impedance effect element thin film for generating an impedance change due to an external magnetic field for detecting an external magnetic field. It is possible to obtain a thin-film magnetic head capable of obtaining high-sensitivity read performance in a linear response to a minute magnetic field from a recording medium. In addition, the metal glass alloy of the present invention
Since the I effect element thin film has good symmetry of impedance change with respect to positive and negative magnetic fields and good quantification in a weak magnetic field region, it is possible to obtain a thin film magnetic head capable of obtaining high-sensitivity read performance. it can.

Next, a write head and a read head are provided on the slider, the write head has a magnetic induction type structure, and the read head is composed of a magneto-impedance effect element thin film and an electrode film. And a thin film magnetic head capable of reading out a leakage magnetic field from a magnetic recording medium with high sensitivity.

Next, in the present invention, the magneto-impedance effect element thin film provided with a bias applying means utilizes the fact that the symmetry of the impedance change of the metallic glass MI effect element thin film with respect to the positive and negative magnetic fields is good. By matching the linearly changing portion of the impedance change with the magnetic field detection region, good linear response can be used, so that a thin film magnetic head exhibiting high sensitivity and accurate reading performance can be obtained. As the bias applying means,
A structure using a permanent magnet connected to the magneto-impedance effect element thin film, or using a ferromagnetic thin film and an anti-ferromagnetic thin film partially laminated on the magneto-impedance effect element thin film to form a ferromagnetic thin film Any of the structures utilizing the induced exchange coupling magnetic field can be used.

Next, as the metallic glass alloy, an Fe-based metallic glass alloy contains a metal element other than Fe and a metalloid element, and Al, Ga, I
One or more of n and Sn may be contained, and one or more of P, C, B and Ge as metalloid elements may be used. Further, in the present invention, as the Fe-based metallic glass alloy, in atomic%, Al: 1 to 10%, Ga: 0.5 to 4%, P: 0
１５15%, C: 2７7%, B: 2〜１０10%, Fe: the remaining composition can be used. In addition to the above composition, Si added in the range of 0１５15% is used. Can be used. By using metallic glass alloys of these compositions, it is possible to reliably obtain a large MI effect with good linearity even in a weak magnetic field. You can get a head.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of a thin-film magnetic head including a magneto-impedance effect element thin film according to the present invention.

FIG. 2 is a sectional view of a main part of the thin-film magnetic head shown in FIG. 1;

FIG. 3 is a perspective view showing a cross section of a part of a main part of the thin-film magnetic head shown in FIG. 1;

FIG. 4 is a sectional view showing an example of a magneto-impedance effect element thin film provided in FIG.

FIG. 5 is a sectional view showing another example of the magneto-impedance effect element thin film.

6A and 6B show a circuit for measuring a magnetic impedance characteristic. FIG. 6A is a circuit diagram showing an example of the circuit, and FIG.
Is a circuit diagram showing another example.

FIG. 7 is a graph showing magnetic field sensitivity in an example of the MI effect element of the present invention.

FIG. 8 is a graph showing magnetic field sensitivity in an example of the MI effect element according to the present invention.

FIG. 9 is a graph showing magnetic field sensitivity in another example of the MI effect element of the present invention.

FIG. 10 is a graph showing the heat treatment temperature dependence of the magnetic properties of a metallic glass alloy.

[Explanation of symbols]

HA · · · thin film magnetic head, h ₁ · · · MI effect element head (read head), h ₂ · · · inductive head (magnetic induction type magnetic head: write head), 10 · · · MI effect elements, 12 ... MI effect element thin film, 13 ... ferromagnetic thin film,
14: antiferromagnetic thin film, 15: electrode film, 22: MI
Effect element thin film, 23: magnet layer (permanent magnet) 25: electrode film, 50: magnetic head core, 51: slider.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akihiro Makino Alps Electric Co., Ltd., 1-7 Yukitani Otsuka-cho, Ota-ku, Tokyo (72) Inventor Akihisa Inoue 35 Kawamoto Moto Hasekura, Aoba-ku, Sendai, Miyagi Prefecture, Japan House 11-806

Claims (8)

[Claims] 1. A temperature interval ΔT _x of a supercooled liquid represented by an equation of ΔT _x = T _x −T _g (where T _x represents a crystallization start temperature and T _g represents a glass transition temperature) is 20K. A thin-film magnetic head comprising a magneto-impedance effect element thin film mainly composed of the above-mentioned Fe-based metallic glass alloy, the impedance of which changes due to an external magnetic field, for detecting an external magnetic field. 2. A write head and a read head are provided on a slider which moves relatively to a magnetic medium with the medium facing surface facing the magnetic medium, and the write head is interposed between a thin-film upper core and a lower core. A magnetic induction type structure having a magnetic gap and a coil conductor, wherein the read head includes a magneto-impedance effect element thin film and an electrode film connected to the impedance effect element thin film. Item 7. The thin film magnetic head according to Item 1. 3. The thin-film magnetic head according to claim 1, wherein a bias applying means is provided on the magneto-impedance effect element thin film. 4. The thin-film magnetic head according to claim 3, wherein said bias applying means comprises a permanent magnet connected to said magneto-impedance effect element thin film. 5. The bias applying means includes a ferromagnetic thin film laminated on the magneto-impedance effect element thin film and an antiferromagnetic thin film laminated on the ferromagnetic thin film. 4. The thin-film magnetic head according to claim 3, wherein the thin-film magnetic head is applied by an exchange coupling magnetic field induced in the ferromagnetic thin film by the antiferromagnetic thin film. 6. The Fe-based metallic glass alloy contains a metal element other than Fe and a metalloid element, and the other metal element is one or two of Al, Ga, In, and Sn. Containing the above, P, C, as the metalloid element
6. The thin-film magnetic head according to claim 1, wherein one or more of B and Ge are contained. 7. The composition of the Fe-based metallic glass alloy in atomic%: Al: 1 to 10% Ga: 0.5 to 4% P: 0 to 15% C: 2 to 7% B: 2 to 10% Fe The thin film magnetic head according to any one of claims 1 to 6, wherein: 8. The composition of the Fe-based metallic glass alloy in atomic%: Al: 1 to 10% Ga: 0.5 to 4% P: 0 to 15% C: 2 to 7% B: 2 to 10% Si The thin film magnetic head according to any one of claims 1 to 6, wherein: 0 to 15% Fe: balance.