JP2005209263A - Magnetoresistance effect type magnetic head, and magnetic recording/reproducing device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a GMR head equipped with a spin valve film having high corrosion resistance. <P>SOLUTION: At least one selected from an antiferromagnetic layer constituting the spin valve film of a magnetoresistance effect type magnetic head, a magnetization fixed layer, a magnetization free layer, and a nonmagnetic layer is set such that a corrosive current density is 0.1 mA/cm<SP>2</SP>or less in a polarization curve (anode curve) using the NaCl solution of a concentration of 0.1 mol/L. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetoresistive head using a spin valve film as a magnetosensitive element that detects a magnetic signal while slidingly contacting a magnetic recording medium, and a magnetic recording / reproducing apparatus including the magnetoresistive head.

  As a magnetosensitive element for detecting a signal magnetic field from a magnetic recording medium, a magnetoresistive element using a so-called magnetoresistive effect (hereinafter referred to as an MR element) whose resistance value changes depending on the magnitude and direction of an external magnetic field is used. Yes. A magnetic head provided with such an MR element is generally called a magnetoresistive head (hereinafter referred to as an MR head).

  As such an MR element, an element utilizing an anisotropic magnetoresistance effect has been conventionally used. However, since an MR ratio (MR ratio) is small, an element exhibiting a larger MR ratio is desired. In recent years, giant magnetoresistive elements (hereinafter referred to as GMR elements) using a spin valve film have been proposed (see, for example, Non-Patent Document 1 and Patent Document 1).

A GMR element has a spin valve film in which a nonmagnetic layer is sandwiched between a pair of magnetic layers, and a so-called sense current conductance flowing in an in-plane direction with respect to the spin valve film has a magnetization of the pair of magnetic layers. This utilizes the so-called giant magnetoresistance effect that changes depending on the relative angle.
Specifically, the spin valve film includes an antiferromagnetic layer, a magnetization fixed layer whose magnetization is fixed in a predetermined direction by an exchange coupling magnetic field that works between the antiferromagnetic layer, and a magnetization direction according to an external magnetic field. And a nonmagnetic layer that magnetically isolates the magnetization fixed layer and the magnetization free layer from each other.

  In a GMR element using a spin valve film, when an external magnetic field is applied, the magnetization direction of the magnetization free layer changes according to the magnitude and direction of the external magnetic field. When the magnetization direction of the magnetization free layer is opposite (antiparallel) to the magnetization direction of the magnetization fixed layer, the resistance value of the sense current flowing through the spin valve film is maximized. On the other hand, when the magnetization direction of the magnetization free layer is the same direction (parallel) to the magnetization direction of the magnetization fixed layer, the resistance value of the sense current flowing through the spin valve film is minimized.

  Therefore, in a magnetic head (GMR head) including the GMR element as described above, when a constant sense current is supplied to the GMR element, the sense current flowing through the GMR element in accordance with the signal magnetic field from the magnetic recording medium. Thus, the magnetic signal from the magnetic recording medium can be read by detecting the change in the voltage value of the sense current.

Incidentally, Patent Document 1 below discloses an example in which a GMR head is used for a hard disk drive.
A hard disk drive, for example, has a structure in which a GMR head is mounted on a head slider attached to the tip of a suspension. The head slider moves over the signal recording surface of the magnetic disk in response to an air flow generated by the rotation of the magnetic disk. While flying, the GMR head mounted on the head slider reads the magnetic signal recorded on the magnetic disk, thereby reproducing the magnetic disk.

The GMR head is not limited to a magnetic disk device, and in recent years, the use of magnetic tape devices such as a tape streamer, a commercial camcorder, and a consumer camcorder has been studied.
For example, a magnetic tape device employing a helical scan system has a structure in which the GMR head is disposed on the outer peripheral surface of the rotating drum so as to be inclined according to the azimuth angle with respect to a direction substantially perpendicular to the traveling direction of the magnetic tape. doing.
In the magnetic tape device, the rotating drum is driven to rotate while the magnetic tape runs obliquely with respect to the rotating drum, and the GMR head mounted on the rotating drum is recorded on the magnetic tape while sliding on the magnetic tape. By reading the magnetic signal, the reproducing operation for the magnetic tape is performed.

  In the magnetic tape device, since it is preferable to reduce the distance between the GMR head and the magnetic tape, that is, so-called spacing, it is desirable to smooth the surface of the magnetic tape from this viewpoint.

However, as the surface of the magnetic tape becomes mirror-finished, the contact area between the magnetic tape and the outer peripheral surface of the rotating drum increases, and the frictional force acting between the magnetic tape and the rotating drum during running increases. Sticking with the rotating drum occurs, and smooth running of the magnetic tape becomes difficult.
Therefore, the surface area of the magnetic tape is usually provided with minute protrusions such as SiO ₂ filler or organic filler to reduce the contact area with the outer peripheral surface of the rotating drum, and the frictional force acting between the magnetic tape and the rotating drum. The device is made small.
In addition, a protective film such as a DLC (Diamond Like Carbon) film is formed on the surface of the magnetic tape to prevent the occurrence of scratches, corrosion, and the like.

  By the way, in the conventional hard disk drive, the reproducing operation is performed in a state where the GMR head is not in contact with the signal recording surface of the magnetic disk. Further, Cu is usually used for the nonmagnetic layer constituting the spin valve film, and a DLC (Diamond Like) for preventing corrosion of Cu is conventionally formed on the medium facing surface of the GMR head facing the magnetic disk. A protective film such as a carbon film is formed.

  On the other hand, with respect to magnetic tape media, with increasing demand for high-density recording, metallic magnetic materials such as Co—Ni, Co—Cr, and Co are plated or vacuum thin film forming means (vacuum deposition method, sputtering method, ion plating). And so on), so-called metal magnetic thin film type magnetic recording media directly deposited on a nonmagnetic support have been proposed and attracted attention.

  Such a metal magnetic thin film type magnetic recording medium has excellent coercive force, remanent magnetization, squareness ratio, etc., and not only excellent electromagnetic conversion characteristics at a short wavelength, but also the thickness of the magnetic layer can be made extremely thin. Since there is little thickness loss at the time of demagnetization and reproduction, and it is not necessary to mix a binder that is a non-magnetic material in the magnetic layer, the packing density of the magnetic material can be increased and a large magnetization can be obtained. Has advantages.

  Furthermore, in order to improve the electromagnetic conversion characteristics of such a magnetic recording medium and obtain a larger output, when forming the magnetic layer of the magnetic recording medium, the magnetic layer is deposited obliquely, so-called The oblique vapor deposition has been proposed and put into practical use as a magnetic tape for high-quality VTR and digital VTR.

Physical Review B, Vol. 43, No. 1, p1297-p1300 “Giant Magnetoresistance in Soft Ferromagnetic Multilayers” JP-A-8-111010

In a magnetic tape system in which application of a GMR head is currently being studied, the reproducing operation is performed with the GMR head in contact with the magnetic tape. When the protective film for preventing the occurrence of corrosion or the like is formed, the protective film is worn by contact with the minute protrusions or the protective film formed on the surface of the magnetic tape during the reproducing operation.
Furthermore, since the protective film formed on the medium sliding surface of the GMR head becomes a spacing with the magnetic tape, it causes deterioration of the short wavelength recording / reproducing characteristics of the GMR head.

Therefore, it was considered inappropriate to form a protective film on the medium sliding surface of the GMR head applied in the magnetic tape device.
For this reason, in the magnetic tape device, the medium sliding surface of the GMR head is in direct contact with the atmosphere, and corrosion is likely to occur under severe use conditions such as in a high temperature and high humidity or seawater atmosphere. was there.

  Further, the sensitivity of the GMR head is determined by the sense current flowing through the spin valve film, and the thickness of each layer constituting the spin valve film is formed in the order of nm. Even if slight corrosion occurs in each layer, The electrical resistance of each layer will change. Therefore, the occurrence of corrosion on the medium sliding surface of the GMR head greatly deteriorates the head characteristics of the GMR head.

In the above-mentioned Patent Document 1, studies have been made to improve the corrosion resistance of a magnetoresistive effect type magnetic head applied to a hard disk. However, in the hard disk device, the magnetic head does not slide directly on the medium. Therefore, it is clear that the damage amount due to the friction of the magnetic head is larger in the tape system.
In addition, in a hard disk device, since the medium is sealed by packaging without being exposed to the outside air, the tape system is also more serious with respect to the influence of damage to the magnetic head due to fine dust and the like. It is believed that there is. Therefore, it can be said that improving the corrosion resistance of the GMR head applied to the magnetic tape device is more important than the hard disk drive.

  In view of the above-described problems, particularly when a GMR element is used as a magnetosensitive element for detecting a magnetic signal while being in sliding contact with a magnetic recording medium, the corrosion resistance should be improved and a high rate of change in magnetoresistance should be maintained. is required.

  In addition, if a magnetic recording medium designed for a conventionally known inductive magnetic head is directly applied to a high-sensitivity magnetic head, the medium noise increases and the residual magnetization amount is large, so that the magnetic head is saturated. There was a problem that it would occur.

  In view of the above-described problems, in the present invention, investigation is performed from the viewpoint of the physical properties of the film of the magnetosensitive portion of the magnetoresistive effect type magnetic head, and the characteristics of the magnetic tape to be applied are limited, and high corrosion resistance It was decided to provide a magnetoresistive head with high sensitivity and a high performance magnetic recording / reproducing apparatus including the same.

In the present invention, as a magnetosensitive element for detecting a magnetic signal, an antiferromagnetic layer, a magnetization fixed layer whose magnetization is fixed in a predetermined direction by an exchange coupling magnetic field acting between the antiferromagnetic layer, A spin valve film having a configuration in which a magnetization free layer whose magnetization direction changes according to an external magnetic field and a nonmagnetic layer that magnetically isolates the magnetization fixed layer and the magnetization free layer are stacked; A polarization curve (anode curve) using a NaCl solution having a concentration of 0.1 mol / L for at least one of the antiferromagnetic layer, the magnetization fixed layer, the magnetization free layer, and the nonmagnetic layer constituting the spin valve film. ), A magnetoresistive head having a corrosion current density of 0.1 mA / cm ² or less is provided.

In the present invention, as a magnetosensitive element for detecting a magnetic signal, an antiferromagnetic layer, a magnetization fixed layer whose magnetization is fixed in a predetermined direction by an exchange coupling magnetic field acting between the antiferromagnetic layer, A magnetoresistor comprising a spin valve film having a structure in which a magnetization free layer whose magnetization direction changes according to an external magnetic field and a nonmagnetic layer that magnetically isolates the magnetization fixed layer and the magnetization free layer are stacked. An effect type magnetic head and a magnetic recording medium in which a metal magnetic thin film is formed on a tape-like nonmagnetic support, and the magnetoresistive effect type magnetic head detects a magnetic signal while being in sliding contact with the magnetic recording medium. A magnetic recording / reproducing apparatus for performing a magnetic recording / reproducing apparatus, wherein a single-layer film of at least one of an antiferromagnetic layer, a magnetization fixed layer, a magnetization free layer, and a nonmagnetic layer of a spin valve film constituting a magnetoresistive head N at a concentration of 0.1 mol / L In Cl solution polarization curves using (anode curve), the corrosion current density is intended to be 0.1 mA / cm ² or less, the product Mr between the residual magnetization Mr and the thickness t of the metallic magnetic film of the magnetic recording medium Provided is a magnetic recording / reproducing apparatus in which t is 4 mA to 20 mA and residual magnetization Mr is 160 kA / m to 400 kA / m.

  According to the magnetoresistive head of the present invention, high corrosion resistance of the spin valve film and each layer constituting the spin valve film is realized.

  According to the magnetoresistive head of the present invention, when applied to a magnetic tape device, high corrosion resistance is achieved without forming a protective film on the surface that is in sliding contact with the magnetic recording medium, and high temperature and high humidity. It was possible to maintain a high rate of change in magnetic resistance over a long period of time even under severe use conditions such as in the environment and in a seawater atmosphere.

  In addition, by specifying the product of the residual magnetization amount of the magnetic recording medium and the thickness of the magnetic layer, and the residual magnetization amount in the numerically optimal range, noise can be reduced and magnetic head saturation can be effectively achieved. Thus, there was no distortion of the reproduced waveform and a high SN could be realized.

  Hereinafter, a magnetoresistive head of the present invention and a magnetic recording / reproducing apparatus including the same will be described with reference to the drawings.

FIG. 1 shows a schematic configuration diagram of a magnetic recording / reproducing apparatus 1. The magnetic recording / reproducing apparatus 1 records and / or reproduces signals on the magnetic tape 2 by a helical scan method.
The magnetic recording / reproducing apparatus 1 includes a supply reel 3 for supplying a magnetic tape 2, a take-up reel 4 for taking up the magnetic tape supplied from the supply reel 3, and a magnetic tape between the supply reel 3 and the take-up reel 4. 2 and a plurality of guide rollers 5a to 5f for performing the routing of 2, and the magnetic tape 2 travels in the direction of arrow A in the figure.

Between the guide roller 5e and the guide roller 5f, as a tape running means, a pinch roller 5g on which the magnetic tape 2 is wound, a cap stun 6 sandwiching the magnetic tape 2 together with the pinch roller 5g, and the cap stun 6 A cap stun motor 6a that is rotationally driven is provided.
The magnetic tape 2 is sandwiched between the pinch roller 5g and the cap stun 6, and the cap stun 6 is rotated in the direction of arrow B in FIG. And it is made to run with tension.

In the magnetic recording / reproducing apparatus 1, a head drum 7 for performing a signal recording operation and a reproducing operation with respect to the magnetic tape 2 is provided between the guide rollers 5c and 5d.
A schematic perspective view of the head drum 7 is shown in FIG. The head drum 7 is fixed to a base (not shown) fixed to a rotating drum 9 that is driven to rotate in the direction of arrow A in FIG. And a drum 10.

The magnetic tape 2 is guided by the guide roller of FIG. 1 and travels while being helically wound around the outer peripheral surface portions 9a and 10a of the rotary drum 9 and the fixed drum 10 within an angle range of about 180 °. ing.
Further, a lead guide 10b for guiding the magnetic tape 2 is provided on the outer peripheral surface portion 10a of the fixed drum 10, and the magnetic tape 2 travels obliquely with respect to the rotation direction of the rotary drum 9 along the lead guide 10b. It is supposed to be.

A pair of magnetic recording heads 11 a and 11 b that perform a signal recording operation on the magnetic tape 2 and a pair of reproducing magnetic members that perform a signal reproduction operation on the magnetic tape 2 are disposed on the outer peripheral surface portion 9 a of the rotary drum 9. Heads 12a and 12b are attached.
The recording magnetic head 11a and the reproducing magnetic head 12a, and the recording magnetic head 11b and the reproducing magnetic head 12b are arranged opposite to the outer peripheral surface portion 9a of the rotary drum 9 with a phase difference of 180 °.
Further, the recording magnetic heads 11a and 11b and the reproducing magnetic heads 12a and 12b have their recording gap and reproducing gap inclined according to the azimuth angle with respect to the direction substantially perpendicular to the running direction of the magnetic tape 2. Is arranged.

  Therefore, in the head drum 7, the magnetic tape applied to the outer peripheral surface portions 9 a and 10 a of the rotary drum 9 and the fixed drum 10 travels in the direction of arrow A in FIG. By rotationally driving in the direction of arrow C, the signal recording operation is performed while the pair of recording magnetic heads 11a and 11b and the pair of reproducing magnetic heads 12a and 12b mounted on the rotating drum 9 slide on the magnetic tape 2. Alternatively, a reproduction operation is performed.

Specifically, at the time of recording, one recording magnetic head 11a forms a recording track with a predetermined track width while applying a magnetic field according to a recording signal to the magnetic tape 2, and the other recording magnetic head 11b The recording track is formed with a predetermined track width while applying a magnetic field corresponding to the recording signal adjacent to the recording track.
The recording magnetic heads 11 a and 11 b repeatedly form recording tracks on the magnetic tape 2 so that signals are continuously recorded on the magnetic tape 2.

On the other hand, at the time of reproduction, with respect to the magnetic tape 2, one reproducing magnetic head 12a detects a signal magnetic field from the recording track recorded by the recording magnetic head 11a, and the other reproducing magnetic head 12b is used for recording. A signal magnetic field is detected from the recording track recorded by the magnetic head 11b.
When the reproducing magnetic heads 12a and 12b repeatedly detect the signal magnetic field from the recording track, the signal recorded on the magnetic tape 2 is continuously reproduced.

  Next, FIG. 3 shows a schematic perspective view of the magnetoresistive head of the present invention corresponding to the reproducing magnetic heads 12a and 12b described above, and FIG. 4 shows the magnetoresistive effect. The schematic block diagram of the surface which is in sliding contact with the magnetic tape of the magnetic head is shown, and will be described in detail with reference to these.

  The magnetoresistive head 20 includes a so-called giant magnetism including a giant magnetoresistive element (hereinafter referred to as a GMR element) using a spin valve film as a magnetosensitive element for detecting a magnetic signal from a magnetic recording medium. This is a resistance effect type magnetic head (hereinafter referred to as GMR head).

  The GMR head 20 is more sensitive than an inductive magnetic head or an anisotropic magnetoresistive magnetic head that performs recording and reproduction using electromagnetic induction, and has a large reproduction output and is suitable for high-density recording. Therefore, in the above-described magnetic recording / reproducing apparatus 1, high density recording can be achieved by using the GMR head 20 for the pair of reproducing magnetic heads 12a and 12b.

In the magnetoresistive head 20, as shown in FIG. 4, a magnetic shield layer 24, a GMR element 27, a gap layer 26, and a shield layer 25 are sequentially formed on the first core member 21 by various thin film forming techniques. Thus, the second core member 23 is attached via the protective film 22.
Further, in the magnetoresistive head 20, the medium sliding surface 20 a with which the magnetic tape 2 is slidably contacted is a curved surface that is curved in a substantially arc shape along the traveling direction of the magnetic tape 2 indicated by arrow A in FIG. 3. Yes.
The reproducing gap that faces the outside from the medium sliding surface 20a is arranged so as to be inclined according to the azimuth angle θ with respect to the direction substantially orthogonal to the running direction of the magnetic tape 2.

  The pair of reproducing magnetic heads 12a and 12b have the same configuration except that their azimuth angles θ are in opposite phases. Accordingly, in the following description, the pair of reproducing magnetic heads 12a and 12b will be collectively described as the GMR head 20.

  The GMR head 20 has a structure in which a GMR element 27 is sandwiched between a pair of upper and lower magnetic shield layers 24 and 25 via a gap layer 26.

  The pair of magnetic shield layers 24 and 25 are made of a soft magnetic film having a sufficient width to magnetically shield the GMR element 27. By sandwiching the GMR element 27 via the gap layer 26, the magnetic shield layers 24 and 25 are separated from the magnetic tape 2. The signal magnetic field functions so as not to be drawn into the GMR element 27. That is, in the GMR head 20, a signal magnetic field that is not to be reproduced is guided to the pair of magnetic shield layers 24 and 25 with respect to the GMR element 27, and only the signal magnetic field to be reproduced is guided to the GMR element 27. Thereby, the frequency characteristics and reading resolution of the GMR element 27 are improved.

  The gap layer 26 is made of a nonmagnetic non-conductive film that magnetically isolates the GMR element 27 and the pair of magnetic shield layers 24 and 25, and the gap between the pair of magnetic shield layers 24 and 25 and the GMR element 27. Is the gap length.

  The GMR element 27 utilizes a so-called giant magnetoresistance effect in which the conductance of the sense current flowing in the in-plane direction with respect to the spin valve film 40 changes depending on the relative angle of magnetization of the pair of magnetic layers. .

  As the spin valve film 40, for example, as shown in FIG. 5, an underlayer 41, an antiferromagnetic layer 42, a magnetization fixed layer 43, a nonmagnetic layer 44, a magnetization free layer 45, and a protective layer 46 are sequentially stacked. As shown in FIG. 6, the bottom type spin valve film 40a having the above structure, the underlayer 41, the magnetization free layer 45, the nonmagnetic layer 44, the magnetization fixed layer 43, the antiferromagnetic layer 42, and the protective layer 46 are provided. As shown in FIG. 7, a top type spin valve film 40b having a sequentially stacked structure, an underlayer 41, an antiferromagnetic layer 42, a magnetization fixed layer 43, a nonmagnetic layer 44, a magnetization free layer 45, a non-magnetization layer 45, Examples include a dual type spin valve film 40c having a structure in which a magnetic layer 44, a magnetization fixed layer 43, an antiferromagnetic layer 42, and a protective layer 46 are sequentially stacked.

The magnetization fixed layer 43 constituting the spin valve film is disposed adjacent to the antiferromagnetic layer 42, so that the magnetization is fixed in a predetermined direction by an exchange coupling magnetic field acting between the antiferromagnetic layer 42. It is in the state.
On the other hand, the magnetization free layer 45 is magnetically isolated from the magnetization fixed layer 43 via the nonmagnetic layer 44, so that the magnetization direction can be easily changed with respect to a weak external magnetic field. .

Therefore, in the spin valve film 40, when an external magnetic field is applied, the magnetization direction of the magnetization free layer 45 changes according to the magnitude and direction of the external magnetic field. When the magnetization direction of the magnetization free layer 45 is opposite (antiparallel) to the magnetization direction of the magnetization fixed layer 43, the resistance value of the current flowing through the spin valve film 40 is maximized.
On the other hand, when the magnetization direction of the magnetization free layer 45 is the same direction (parallel) to the magnetization direction of the magnetization fixed layer 43, the resistance value of the current flowing through the spin valve film 40 is minimized.

  Thus, the spin valve film 40 functions as a magnetosensitive element that detects a magnetic signal from the magnetic tape 2 by reading the resistance change because the electric resistance changes according to the applied external magnetic field. Yes.

  The underlayer 41 and the protective layer 46 are for suppressing an increase in specific resistance of the spin valve film 40, and are made of, for example, Ta.

Further, in order to stabilize the operation of the GMR element 27, a pair of electrodes for applying a bias magnetic field to the GMR element 27 is provided at both ends in the longitudinal direction of the spin valve film 40 as shown in FIGS. Permanent magnet films 28a and 28b are provided.
The width of the portion sandwiched between the pair of permanent magnet films 28 a and 28 b is the reproduction track width Tw of the GMR element 27.
Further, on the pair of permanent magnet films 28a and 28b, a pair of low resistance films 29a and 29b for reducing the resistance value of the GMR element 27 are provided.

Further, the GMR element 27 includes a pair of conductor portions 30a and 30b for supplying a sense current to the spin valve film, and a pair of permanent magnet films 28a and 28b and a low resistance film 29a on one end side, respectively. 29b is provided to be connected.
A pair of external connection terminals 31a and 31b connected to an external circuit are provided on the other end side of the conductor portions 30a and 30b.

  The protective film 22 covers the main surface of the first core member 21 on which the GMR head 20 is formed except for the portions where the external connection terminals 31a and 31b face the outside, and the first layer on which the GMR head 20 is formed. The first core member 21 and the second core member 23 are joined.

  The GMR head 20 shown in FIG. 3 and FIG. 4 is shown with the periphery of the GMR element 27 enlarged for easy understanding of the characteristics, but in practice, the first core member 21 and the second core member 21 are shown. Compared with the core member 23, the GMR element 27 is very fine, and the GMR head 20 faces the outside on the medium sliding surface 20a, almost the first core member 21 and the second core member. 23 is only the upper end face with which 23 is abutted.

The GMR head 20 configured as described above is attached to a chip base (not shown), and a pair of external connection terminals 31a and 31b are electrically connected to connection terminals provided on the chip base.
The GMR head 20 provided on the chip base is attached to the rotating drum 9 shown in FIG. 2 as a pair of reproducing magnetic heads 12a and 12b.

  By the way, in the magnetic recording / reproducing apparatus 1, since the reproducing operation is performed with the GMR head 20 in contact with the magnetic tape 2, the DLC (Diamond) is applied to the medium sliding surface 20a of the GMR head that is in sliding contact with the magnetic tape 2. A protective film such as a “Like Carbon” film cannot be formed. For this reason, in the conventional magnetic tape apparatus, the medium sliding surface of the GMR head is directly exposed to the atmosphere, and corrosion or the like is likely to occur under severe use conditions such as high temperature and high humidity or in a seawater atmosphere. There was a problem.

  In view of such points, in the present invention, even when a protective film is not formed on the medium sliding surface 20a, by applying a spin valve film that exhibits excellent corrosion resistance and can maintain a high magnetoresistance change rate, Appropriate reproducing operation for the magnetic tape 2 can be performed.

First, the material of the layers constituting the spin valve film 40 will be described.
The antiferromagnetic layer 42 is formed of a material exhibiting excellent corrosion resistance. For example, PtMn, NiO, IrMn, CrMnPt, α-Fe ₂ O ₃ , RhMn, NiMn, PdPtMn, or the like can be applied.

  The nonmagnetic layer 44 is formed of Au or a Cu alloy that exhibits excellent corrosion resistance and high conductivity. Examples of the Cu alloy include CuAu, CuPd, CuPt, CuNi, CuRu, and CuRh.

  The magnetization fixed layer 43 and the magnetization free layer 45 are formed of NiFe or CoNiFe which exhibits excellent corrosion resistance and excellent soft magnetic properties, and either one of them may be used or a combination thereof may be configured.

A corrosion resistance test was performed on the constituent films of the spin valve film 40 of the GMR head 20 according to the present invention.
Specifically, a corrosion test using an electrochemical method was performed, the change in electrical resistance before and after the corrosion test was measured, and the surface was observed after the corrosion test to examine whether or not corrosion occurred.
In this corrosion test, an Ag / AgCl electrode was used as a reference electrode, and a polarization curve measured when a sample was immersed in a NaCl solution having a concentration of 0.1 mol / L for a required time was referred to. . An example of the polarization curve at this time is shown in FIG.

Corrosion test samples include CuAu, Au, Cu corresponding to the nonmagnetic layer 44 of the spin valve film, CoNiFe corresponding to the magnetization free layer 43 and the magnetization fixed layer 45, and PtMn corresponding to the antiferromagnetic layer 42. An alloy film with an adjusted atomic composition was applied.
Pt was used for the measurement electrode, and it was performed at room temperature (about 20 ° C.). The potential increase rate during measurement was about 10 mV / sec. The thickness of the metal and alloy films of the sample was about 100 nm, and the pH of the NaCl solution was 7.

The corrosion of the metal or alloy film changes depending on the type and concentration of the solution, and particularly changes greatly depending on the presence or absence of reaction with Cl. In this corrosion test, we focus on the occurrence of corrosion under severe conditions such as high temperature and high humidity and in seawater atmosphere, and refer to the polarization curve when using a 0.1 mol / L NaCl solution to avoid this. It was decided to.
The ease of corrosion of metals and alloys is indicated by the current density shown on the horizontal axis of the polarization curve in FIG.
That is, if the current density in the anode curve of the polarization curve is higher, the corrosion reaction of the metal or alloy proceeds, and the metal or alloy is easily corroded.

In the present invention, the current density of the sample when a predetermined potential is applied is defined as the corrosion current density, which is defined.
The corrosion current density in the present invention is defined as follows.
That is, if the corrosion potential of the polarization curve shown in FIG. 8 (corrosion potential here is the potential when the current value in the polarization curve is zero) is Ecorr, the current density flowing through the sample when the additional potential E = Ecorr + 500 mV is the corrosion current. It is defined as density.
The definition of the corrosion current density is described in detail in the following document.
`` Applied Physics Letters Vol.81, No27, 5198-5200, 2002 Improved corrosion resistance of IrMn by Cr and Ru additions MJCarey et al ''

Further, the surface condition of the sample was observed after the corrosion test.
In consideration of the above-described test with the single layer film and the local battery effect, the test was performed with a laminated film in which each layer was laminated on a base film made of a metal having a high corrosion potential, for example, Au. This is because the laminated film in contact with Au tends to corrode more easily than the single layer film due to the local battery effect.

The corrosion current density measured as described above and the evaluation results of the corrosion resistance are shown in Table 1 below.
The evaluation of the corrosion resistance before and after the corrosion test was judged in consideration of both the change in the electrical resistance of the sample and the observation result of the surface state using an optical microscope.
In Table 1 below, ◯ indicates a case in which no change was observed in the electrical resistance and no change occurred on the surface, Δ indicates a case in which the electrical resistance hardly changed and a slight discoloration occurred on the surface, Indicates the case where the electrical resistance changes and corrosion occurs on the surface.

The corrosion resistance evaluation results of each film of Samples 1 to 12 shown in Table 1 above changed greatly with Samples 8 and 9 having a corrosion current density of 0.1 mA / cm ^{2 in} the polarization curve (anode curve) as a boundary.
That is, when the corrosion current density is 0.1 mA / cm ² or less, the sample surfaces of the nonmagnetic layer 44, the magnetization fixed layer 43, the magnetization free layer 45, and the antiferromagnetic layer 42 constituting the spin valve film 40 are corroded. It was found that there was almost no change in resistance before and after the corrosion test, and excellent corrosion resistance was realized.
On the other hand, when the corrosion current density is greater than 0.1 mA / cm ² , corrosion occurs on the sample surfaces of the nonmagnetic layer 44, the magnetization fixed layer 43, the magnetization free layer 45, and the antiferromagnetic layer 42, and the corrosion test. It was found that the resistance change before and after increased rapidly, and that practically sufficient corrosion resistance could not be obtained.

As is clear from the above, a NaCl solution having a concentration of 0.1 mol / L in the nonmagnetic layer 44, the magnetization fixed layer 43, the magnetization free layer 45, and the antiferromagnetic layer 42 constituting the spin valve film 40 was used. By specifying each film composition so that the corrosion current density is 0.1 mA / cm ² or less in the anode curve, excellent corrosion resistance is realized in each film, and high magnetoresistance change in the finally obtained GMR head It has been found that the rate can be maintained over a long period of time.
Note that, as long as at least one of the films constituting the spin valve film 40 satisfies the conditions regarding the corrosion current density, an effect of improving the corrosion resistance of the spin valve film 40 can be obtained, but all of the constituent films satisfy the above conditions. Thus, it was confirmed that a spin valve film having extremely high corrosion resistance can be obtained.

Next, the elemental composition of each film constituting the spin valve film 40 will be considered.
The material of the nonmagnetic layer 44 is preferably Au or CuAu, which exhibits excellent corrosion resistance and high conductivity. However, the composition ratios of Cu and Au are (100-a) and a (a is an atom, respectively). %.), It is preferable that 15 ≦ a <100.
As shown in Table 1 above, it is confirmed that when the ratio of Au to Cu is increased, the current density is decreased, and the progress of the corrosion reaction is slowed in the corrosion test environment. It is because the corrosion current density mentioned above will be 0.1 mA / cm < ² > or less by setting it as% or more.
The nonmagnetic layer 44 is at least selected from Au, Al, Ta, In, B, Nb, Hf, Mo, W, Re, Pt, Pd, Rh, Ga, Zr, Ir, Ag, Ni, and Ru. One or two or more elements may be optionally added.
In addition to CuAu, any of CuPd, CuPt, CuNi, CuRu, and CuRh as the nonmagnetic layer exhibits excellent corrosion resistance as in the case described above, such as in high temperature and high humidity or in a seawater atmosphere. It was confirmed that the occurrence of corrosion was avoided even under severe use conditions, and proper regeneration operation could be performed.

Next, the magnetization fixed layer 43 and the magnetization free layer 45 will be described.
The magnetization fixed layer 43 and the magnetization free layer 45 are formed of NiFe or CoNiFe as described above, and either one of them may be used or a combination thereof may be configured.
Moreover, the magnetization fixed layer 43 and the magnetization free layer 45 may have a laminated structure in which these alloys are laminated, or a laminated ferri structure in which these alloys and nonmagnetic films made of, for example, Ru are alternately laminated.

As for the magnetization fixed layer 43 and the magnetization free layer 45, when the samples 7, 8, and 10 in Table 1 are compared, the corrosion current density is 0.1 mA / in an anode curve using a NaCl solution having a concentration of 0.1 mol / L. It was found that excellent corrosion resistance evaluation can be obtained when it is less than cm ² .

Therefore, with respect to the magnetization fixed layer 43 and the magnetization free layer 45 constituting the spin valve film, the corrosion current density is 0.1 mA / cm ² or less in an anode curve using a NaCl solution having a concentration of 0.1 mol / L. Thus, it is preferable to adjust the composition ratio of the constituent elements.

The magnetization free layer 45 preferably has a small coercive force Hc, and the coercive force Hc is preferably smaller than 10 Oe (796 A / m). This is because when Hc> 10 Oe, the magnetoresistive effect deteriorates due to an increase in coercive force.
Further, both NiFe and CoNiFe have a higher magnetoresistive effect when they are in the fcc phase (face-centered cubic structure). On the other hand, in the case of another crystal structure (for example, a bcc structure (body-centered cubic structure)), lattice mismatch occurs at the interface and the magnetoresistive effect deteriorates, and the fcc phase and the bcc phase coexist. Also in this case, lattice mismatch occurs at the interface, and the magnetoresistive effect deteriorates.

  In the spin valve film 40 described above, the magnetization fixed layer 43 and the magnetization free layer 45 are at least one or two selected from NiFe, CoNiFe, Au, Ir, Pt, Al, Ru, Rh, Cr, and Pd. The above elements may be added.

  Further, when a plurality of magnetization fixed layers 43 and magnetization free layers 45 made of NiFe or CoNiFe are formed, they may have different compositions, or may be constituted by a plurality of combinations. .

Specifically, the spin valve film 40 that satisfies the above-described conditions is, for example, Ta as the underlayer 41, Ni ₈₀ Fe ₂₀ and Co ₅₀ Ni ₃₀ Fe ₂₀ as the magnetization free layer 45, and a nonmagnetic layer. When Cu ₇₀ Au ₃₀ , Co ₅₀ Ni ₃₀ Fe _{20 serving} as the magnetization fixed layer 43, PtMn serving as the antiferromagnetic layer 42, and Ta serving as the protective layer 46 are sequentially laminated, excellent corrosion resistance can be realized. In the finally obtained GMR head, even when a protective film is not formed on the sliding surface 20a with the magnetic tape, corrosion does not occur under severe conditions such as high temperature and high humidity or in a seawater atmosphere. Generation | occurrence | production can be avoided effectively and it has confirmed that appropriate reproduction | regeneration operation | movement was maintainable over a long term.

The present invention is not limited to the GMR head configured as described above, and can be applied to, for example, a composite magnetic head in which an inductive magnetic head using electromagnetic induction is stacked on a GMR head.
In the present invention, a pair of magnetic layers are stacked via an insulating layer, and the conductance of a tunnel current flowing from one magnetic layer to the other magnetic layer changes depending on the relative angle of magnetization of the pair of magnetic layers. The present invention is also applicable to a magnetic tunnel effect type magnetic head including a magnetic tunnel junction element.

Next, a magnetic recording medium (magnetic tape) to which the magnetoresistive effect magnetic head constituting the magnetic recording / reproducing apparatus 1 of the present invention is applied will be described.
As shown in FIG. 9, the magnetic recording medium (magnetic tape) is formed by sequentially laminating a metal magnetic thin film 62 and a protective layer 63 on a long nonmagnetic support 61, and on the metal magnetic thin film forming surface side. Has a configuration in which a back coat layer 64 is formed on the opposite main surface.

Any material conventionally used for the base film for magnetic tape can be applied to the nonmagnetic support 61. Examples thereof include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and plastics such as polyamide, aramid resin, and polycarbonate.
The nonmagnetic support 61 may have a single layer structure or a multilayer structure. The surface of the nonmagnetic support may be subjected to a surface treatment such as a corona discharge treatment, or an organic layer such as an easy adhesion layer.

The metal magnetic thin film 62 can be formed by using a conventionally known technique such as a vacuum evaporation method, a sputtering method, a CVD (Chemical Vapor Deposition) method, an ion plating method, etc., using a metal magnetic material such as a Co-based alloy. In particular, it is preferable to form a film by a vacuum deposition method.
The film thickness of the metal magnetic thin film 62 can be controlled by changing the line speed, and the residual magnetization amount can be controlled by changing the amount of oxygen introduced during vapor deposition.

  Further, an underlayer or an undercoat layer may be interposed between the nonmagnetic support 61 and the metal magnetic thin film 62 by using a predetermined material, for example. Examples of the underlayer include Cr film, CrTi, CrMo, CrV and the like, and examples of the undercoat layer include a water-soluble latex coating film mainly composed of acrylic ester.

Next, characteristics of the metal magnetic thin film of the magnetic recording medium 2 will be described.
The metal magnetic thin film 62 has a product Mr · t of a residual magnetization Mr and a film thickness t of 4 mA to 20 mA.
If Mr · t of the magnetic recording medium 2 is larger than 20 mA, the GMR head is saturated and the MR resistance change is out of the linear region, and the reproduction waveform is distorted. On the other hand, if Mr · t is smaller than 4 mA, This is because the reproduction output becomes small and a good C / N (signal / noise ratio) cannot be obtained.
Therefore, by defining Mr · t in the range of 4 mA to 20 mA, there is no distortion of the reproduction waveform, and the reproduction output is large and has a good C / N. Furthermore, the product Mr · t is preferably 6 mA to 20 mA, and Mr · t is preferably 6 mA to 17 mA.

  Mr and t can be controlled by the amount of oxygen introduced during vapor deposition, the feed speed of the nonmagnetic support 62, and the like. That is, if the amount of oxygen introduced during vapor deposition is reduced, Mr increases, and if the amount of oxygen introduced is increased, Mr decreases. Further, if the feed speed of the non-magnetic support 62 during vapor deposition is slowed, t becomes thick, and if the feed speed is slowed, t becomes thin. Further, Mr can also be adjusted by surface oxidation treatment after the magnetic layer 62 is formed.

The residual magnetization Mr is preferably 160 kA / m to 400 kA / m. When Mr is larger than 400 kA / m, magnetic particles cannot be separated and noise increases due to magnetic interaction. On the other hand, when Mr is smaller than 160 kA / m, oxidation of Co particles proceeds, This is because sufficient reproduction output cannot be obtained.
Therefore, by defining Mr in the range of 160 kA / m to 400 kA / m, noise can be reduced and sufficient reproduction output can be provided. And Mr is more preferably in the range of 200 kA / m to 360 kA / m.

The film thickness t of the metal magnetic thin film 62 is controlled so that the product Mr · t of the residual magnetization Mr and the film thickness t falls within the above numerical range.
The thickness t of the metal magnetic thin film 62 is preferably 15 nm to 100 nm, more preferably 20 nm to 75 nm, and further preferably 20 nm to 50 nm.

In the magnetic recording medium 2 of the present invention, the arithmetic average roughness Ra on the metal magnetic thin film forming surface side is preferably 1 nm to 5 nm, and the ten-point average roughness Rz is preferably 20 nm to 200 nm.
As for each surface roughness, Ra is an average value of absolute value deviation from an average line, and Rz is a reference length, as standardized by JIS roughness shape parameters (JIS B0601-1994). Choose 5 points from the highest mountain top and 5 points from the lowest valley bottom, and assume the average height.
The surface roughness Ra and Rz here were measured with an area of 50 μm × 50 μm using AFM.

  When Ra is less than 1 nm or Rz is less than 20 nm, the magnetic recording medium 2 sticks to the rotating drum 9 and the guide roller 5 during the tape running, and the running performance of the magnetic tape deteriorates. On the other hand, if Ra is larger than 5 nm or Rz is larger than 200 nm, the magnetoresistive head 12 is worn by sliding, and the magnetic recording medium 2 and the magnetoresistive head 12 are also worn. This increases the spacing and causes the output to deteriorate.

The magnetic recording medium (magnetic tape) preferably has a coercive force Hc in the in-plane direction of 100 kA / m to 160 kA / m.
This is because when the coercive force Hc is smaller than 100 kA / m, it is not possible to realize low noise and high SN ratio. On the other hand, if the coercive force Hc exceeds 160 kA / m, sufficient recording cannot be performed and the reproduction output is lowered.
Therefore, by defining the coercive force in the in-plane direction within the range of 100 kA / m to 160 kA / m, a low noise and a high SN ratio can be realized, and a high reproduction output can be obtained.

The protective layer 63 may be any material as long as it is used as a protective film for a conventional magnetic tape. For example, diamond-like carbon _{(DLC), CrO 2, Al} 2 O 3, BN, Co _{oxide, MgO, SiO 2, Si 3} O 4, SiN x, SiC, SiN x -SiO 2, ZrO 2, TiO 2, TiC etc. are mentioned. The protective layer 63 may be a single layer film, a multilayer film or a composite film.

Note that the magnetic recording medium is not limited to the configuration shown in FIG. 9, and various material layers and functional layers are interposed as necessary, or a lubricant or rust prevention is provided on the metal magnetic thin film 62 or the protective layer 63. A top coat layer made of an agent or the like may be formed.
Moreover, what laminated | stacked two or more metal magnetic thin films may be used. Further, it may have vertical anisotropy or in-plane random orientation.

  As described above, according to the present invention, excellent corrosion resistance is realized by limiting the current density when a predetermined potential is applied to the spin valve film constituting the magnetoresistive head.

  In addition, regarding the magnetic recording medium applied to the apparatus of the present invention, the product of the residual magnetization amount and the film thickness of the metal magnetic thin film and the residual magnetization amount are specified in a numerically optimal range, thereby reducing noise. Therefore, the head saturation can be effectively avoided, the reproduction waveform is not distorted, and a high SN can be realized.

Next, the present invention will be described with specific examples.
In the following examples, specific material names, numerical values, and the like will be described, but the present invention is not limited to these.

(Experiment A)
[Example A1]
A sample magnetic tape was prepared as follows.
As a non-magnetic support, a polyethylene terephthalate film having a thickness of 10 μm and a width of 150 mm is prepared, and a water-soluble latex mainly composed of an acrylic ester is applied to the surface so that the density of fine irregularities becomes 10 million pieces / mm ^2. Thus, an undercoat layer was formed.

A Co—O-based metal magnetic thin film was formed on the undercoat layer to a thickness of 40 nm by vacuum deposition.
The film forming conditions are shown below.
(Deposition conditions)
Degree of vacuum during deposition: 7 × 10 ⁻² Pa
Ingot: Co
Incident angle: 45 ° to 90 °
Introduction gas: Oxygen gas

After forming the metal magnetic thin film, a protective layer made of a carbon film was formed to a thickness of about 10 nm by sputtering or CVD. Thereafter, a back coat layer made of carbon and urethane resin was formed to a thickness of 0.6 μm on the surface opposite to the metal magnetic thin film forming surface. Further, a lubricant made of perfluoropolyether was applied on the protective layer.
Then, it cut | judged to 8 mm width, the metal magnetic thin film surface was oxidized through the process hold | maintained in air | atmosphere and normal temperature for a predetermined period, and the magnetic tape was produced.

  The residual magnetization Mr of the magnetic tape manufactured as described above was 325 kA / m, the thickness t of the metal magnetic thin film was 40 nm, and the product Mr · t was 13 mA.

[Examples A2 to A6], [Comparative Examples A1 and A2]
By adjusting the amount of oxygen introduced during the deposition of the metal magnetic thin film and the holding process time in the atmosphere after the metal magnetic thin film is formed, the residual magnetization Mr is controlled, and the product Mr · t with the film thickness t is set to Control was performed so that the values shown in Table 2 below were obtained.
Other manufacturing conditions were the same as in Example A1, and a sample magnetic tape was produced.

The electromagnetic conversion characteristics of the magnetic tapes of [Examples A1 to A6] and [Comparative Examples A1 and A2] were measured.
Specifically, a modified 8 mm VTR is used to record an information signal at a recording wavelength of 0.4 μm on each sample magnetic tape, and then the reproduction output, noise level, and C / N are measured by the shield type GMR head 20. Went.

  The production conditions of the magnetic tapes of [Examples A1 to A6] and [Comparative Examples A1 and A2] and the measurement results of reproduction output, noise level, and C / N are shown in Table 2 below.

  As shown in Table 2 above, in Examples A1 to A6 in which the product Mr · t of the residual magnetization amount Mr and the film thickness t of the metal magnetic thin film was 4 mA to 20 mA, there was no distortion and a high reproduction output was obtained. Good C / N was obtained.

On the other hand, in Comparative Example A1 in which the product Mr · t of the residual magnetization Mr and the film thickness t of the metal magnetic thin film was less than 4 mA, the reproduction output was small and good C / N was not obtained.
Further, in Comparative Example A2 where Mr · t is larger than 20 mA, the GMR head was saturated, and the reproduction output was distorted.

[Examples A7 to A10], [Comparative Examples A3 and A4]
Next, the residual magnetization amount Mr of the metal magnetic thin film was changed to produce a magnetic tape, and the reproduction output, noise level, and C / N were measured and evaluated.
In these, the product Mr · t of the residual magnetization Mr and the film thickness t of the metal magnetic thin film is made constant at 13 mA by adjusting the holding process time in the atmosphere after the metal magnetic thin film is formed. The residual magnetization Mr was controlled as shown in Table 3 below. Other manufacturing conditions were the same as in Example A1.

  Table 3 below shows the measurement results of the residual magnetization amount Mr, reproduction output, noise level, and C / N of the magnetic tapes of [Examples A7 to A10] and [Comparative Examples A3 and A4] manufactured as described above.

  As shown in Table 3 above, in Examples A7 to A10 in which the residual magnetization amount Mr of the metal magnetic thin film is 160 to 400 kA / m, noise is reduced, high reproduction output is obtained, and good C / N was obtained. In particular, when the Mr was 200 to 360 kA / m, good magnetic properties were obtained.

On the other hand, in the comparative example A3 in which the residual magnetization amount Mr is less than 160 kA / m, a sufficient reproduction output cannot be obtained.
Further, in Comparative Example A4 where the residual magnetization amount Mr was larger than 400 kA / m, noise increased and a good C / N could not be obtained.

(Experiment B)
[Example B1]
A sample magnetic tape was prepared as follows.
As a non-magnetic support, a polyethylene terephthalate film having a thickness of 10 μm and a width of 150 mm is prepared, and a water-soluble latex mainly composed of an acrylic ester is applied to the surface so that the density of fine irregularities becomes 10 million pieces / mm ^2. Thus, an undercoat layer was formed.

Next, a Co—O-based metal magnetic thin film was formed on the undercoat layer to a thickness of 40 nm by vacuum deposition.
The film forming conditions are shown below.
(Deposition conditions)
Degree of vacuum during deposition: 7 × 10 ⁻² Pa
Ingot: Co
Incident angle: 45 ° to 90 °
Introduction gas: Oxygen gas

After forming the metal magnetic thin film, a protective layer made of a carbon film was formed to a thickness of about 10 nm by sputtering or CVD. Thereafter, a back coat layer made of carbon and urethane resin was formed to a thickness of 0.6 μm on the surface opposite to the metal magnetic thin film forming surface. Further, a lubricant made of perfluoropolyether was applied on the protective layer.
Then, it cut | judged to 8 mm width, the metal magnetic thin film surface was oxidized through the process hold | maintained in air | atmosphere and normal temperature for a predetermined period, and the magnetic tape was produced.

The surface roughness Ra of the magnetic tape was 3.0 nm and Rz was 50 nm.
The residual magnetization Mr was 325 kA / m, the thickness t of the metal magnetic thin film was 40 nm, and the product Mr · t was 13 mA.

[Examples B2 to B6], [Comparative Examples B1 to B4]
By controlling the protrusion height and surface roughness of the nonmagnetic support 61 during the production of the magnetic recording medium 2 and providing an undercoat layer or undercoat layer between the nonmagnetic support 61 and the metal magnetic film 62, the following table is obtained. A magnetic tape having surface roughness Ra and Rz shown in 4 was produced.

The electromagnetic conversion characteristics of the magnetic tapes of [Examples B1 to B6] and [Comparative Examples B1 to B4] were measured.
Specifically, head wear measurement was performed by using a modified 8 mm VTR and changing resistance of the shield type GMR head 20 after running each sample magnetic tape. Table 4 below shows the results of evaluation of head wear and evaluation of runnability of the magnetic tape.
Regarding head wear, ◎ indicates that almost no wear has been observed, ○ indicates that the amount of head wear is 3% or less, × indicates that the head wear is 10% or more, and − indicates running of the magnetic tape. It was evaluated that it could not be measured due to the impossibility.
In addition, the running performance of the magnetic tape was evaluated as “◯” when practically good running performance was obtained, and “x” when sticking occurred and running was poor.

  As shown in Table 4, in Examples B1 to B6 in which Ra of the metal magnetic thin film is 1 to 5 nm and Rz is 20 to 200 nm, the magnetic head is not worn, has excellent durability, and further travels. Good evaluation was also obtained about the property.

On the other hand, in Comparative Example C1 in which Ra of the metal magnetic thin film was less than 1 nm and in Comparative Example C2 in which Rz was less than 20 nm, sticking occurred during traveling, and traveling performance deteriorated.
Further, in Comparative Example B3 in which Ra of the metal magnetic thin film is larger than 5 nm and Comparative Example B4 in which Rz is larger than 200 nm, the wear of the magnetoresistive effect type magnetic head is increased, and the resistance of the magnetoresistive effect type magnetic head is reduced. It became high and the output became unstable.

1 shows a schematic plan view of a recording / reproducing apparatus for magnetic tape. 1 is a schematic perspective view of a head drum constituting a recording / reproducing apparatus. 1 is a schematic perspective view of a magnetoresistive head of the present invention. The end view which looked at the GMR head from the medium sliding contact surface side is shown. A schematic cross-sectional view of a bottom-type spin valve film is shown. 1 is a schematic cross-sectional view of a top-type spin valve film. A schematic sectional view of a dual type spin valve film is shown. A polarization curve (anode curve) using a 0.1 mol / L NaCl solution is shown. 1 shows a schematic cross-sectional view of a magnetic recording medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnetic recording / reproducing apparatus, 2 ... Magnetic recording medium, 3 ... Supply reel, 4 ... Take-up reel, 5a-5f ... Guide roller, 5g ... Pinch roller, 6 ... Capstan, 6a ... ... Capstan motor, 7 ... head drum, 8 ... drive motor, 9 ... rotating drum, 10 ... fixed drum, 11a, 11b ... recording magnetic head, 12a, 12b ... reproducing magnetic head, 20 ...... GMR head, 21 ... first core member, 22 ... protective film, 23 ... second core member, 24,25 ... magnetic shield layer, 26 ... gap layer, 27 ... GMR element, 28a, 28b ... permanent magnet film, 29a, 29b ... low resistance film, 30a, 30b ... conductor part, 31a, 31b ... external connection terminal, 40, 40a, 40b, 40c ... spin valve film, 41 …… Base , 42... Antiferromagnetic layer, 43... Magnetized pinned layer, 44... Nonmagnetic layer, 45... Magnetized free layer, 46. 63 …… Protective layer, 64 …… Back coat layer

Claims (5)

As a magnetosensitive element for detecting a magnetic signal, an antiferromagnetic layer, a magnetization fixed layer whose magnetization is fixed in a predetermined direction by an exchange coupling magnetic field acting between the antiferromagnetic layer, and an external magnetic field A magnetoresistive head having a spin valve film having a configuration in which a magnetization free layer whose magnetization direction changes and a nonmagnetic layer that magnetically isolates the magnetization fixed layer and the magnetization free layer are stacked. There,
A single layer film of at least one of the antiferromagnetic layer, the magnetization fixed layer, the magnetization free layer, and the nonmagnetic layer constituting the spin valve film,
A magnetoresistive head having a corrosion current density of 0.1 mA / cm ² or less in a polarization curve (anode curve) using a NaCl solution having a concentration of 0.1 mol / L.   2. The magnetoresistive head according to claim 1, wherein the magnetic signal is detected while slidingly contacting a tape-like magnetic recording medium. It is mounted on a rotating drum that constitutes a helical scan magnetic recording / reproducing device,
3. The magnetoresistive head according to claim 2, wherein the magnetic signal is detected while slidingly contacting the tape-shaped magnetic recording medium sliding on the peripheral surface of the rotating drum. As a magnetosensitive element for detecting a magnetic signal, an antiferromagnetic layer, a magnetization fixed layer whose magnetization is fixed in a predetermined direction by an exchange coupling magnetic field acting between the antiferromagnetic layer, and an external magnetic field A magnetoresistive effect type magnetic head comprising a spin valve film having a configuration in which a magnetization free layer whose magnetization direction changes and a nonmagnetic layer that magnetically isolates the magnetization fixed layer and the magnetization free layer are laminated; ,
A magnetic recording medium in which a metal magnetic thin film is formed on a tape-like nonmagnetic support,
The magnetoresistive effect type magnetic head is a magnetic recording / reproducing apparatus that detects a magnetic signal while being in sliding contact with the magnetic recording medium,
A single layer film of at least one of the antiferromagnetic layer, the magnetization fixed layer, the magnetization free layer, and the nonmagnetic layer constituting the spin valve film,
In a polarization curve (anode curve) using a NaCl solution having a concentration of 0.1 mol / L,
The corrosion current density is 0.1 mA / cm ² or less,
The product Mr · t of the residual magnetization amount Mr and the film thickness t of the metal magnetic thin film is 4 mA to 20 mA,
A magnetic recording / reproducing apparatus having a residual magnetization Mr of 160 kA / m to 400 kA / m. A rotating drum on which the magnetoresistive effect type magnetic head is mounted;
The tape-shaped magnetic recording medium travels on the peripheral surface of the rotating drum,
5. The magnetic recording / reproducing apparatus according to claim 4, wherein a magnetic signal is detected while the magnetic recording medium and the magnetosensitive element are in sliding contact with each other by a helical scan method.

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