JP6383079B2 - Magnetic head, magnetic recording / reproducing apparatus, and method of manufacturing magnetic head - Google Patents

Description

  Embodiments described herein relate generally to a magnetic head, a magnetic recording / reproducing apparatus, and a magnetic head manufacturing method.

  Magnetoresistive elements are used as reproducing elements such as HDDs (Hard Disk Drives). In the HDD, in order to improve the recording density, noise reduction is required in addition to the improvement of the reproduction resolution. For this reason, a multi-magnetic head (multi-read head) in which a plurality of magnetoresistive elements are mounted on one magnetic head has been studied.

  Such a multi-magnetic head makes it possible to integrate the same signal to be reproduced a plurality of times and reduce white noise components. As a result, a high signal noise ratio (SNR) can be obtained, and the recording density can be improved.

  Here, the multi-magnetic head may be off-track due to skew. That is, if the magnetic head has an angle with respect to the track, one of the pair of magnetoresistive elements may be disengaged from the target track to be reproduced. In this case, it is difficult to reduce white noise.

  Therefore, even when there is a skew, it is necessary to narrow the interval between the magnetoresistive elements so that the pair of magnetoresistive elements are placed on the same track. For this reason, it has been studied to make the magnetic shield electrode between the magnetoresistive elements thin.

  However, if the magnetic shield electrode is made thinner, the shielding performance is deteriorated and the magnetoresistive element is easily affected by external noise.

JP 2003-69109 A

  An embodiment of the present invention aims to provide a magnetic head, a magnetic recording / reproducing apparatus, and a method of manufacturing a magnetic head, in which a space between magnetoresistive elements is reduced.

  The magnetic head according to the embodiment includes first to fourth electrodes, an insulating layer, and first and second signal detection units. The first and fourth electrodes include a magnetic material. The second electrode is disposed between the second electrode and the fourth electrode. The third electrode is disposed between the second electrode and the fourth electrode. The first signal detector is disposed between the first electrode and the second electrode, and includes a differential output type magnetoresistive element. The insulating layer is disposed between the second electrode and the third electrode. The second signal detection unit is disposed between the third electrode and the fourth electrode, and includes a differential output type magnetoresistive element. The second electrode includes a magnetic metal, and the third electrode includes a nonmagnetic metal.

1 is a schematic diagram showing a magnetic head according to a first embodiment. 1 is a schematic diagram showing a magnetic head according to a first embodiment. It is a schematic diagram which shows an example of a differential output type magnetoresistive effect element. It is a schematic diagram which shows an example of a differential output type magnetoresistive effect element. It is a schematic diagram which shows an example of a differential output type magnetoresistive effect element. It is a schematic diagram which shows an example of a differential output type magnetoresistive effect element. It is a schematic diagram which shows an example of a differential output type magnetoresistive effect element. It is a schematic diagram which shows an example of a differential output type magnetoresistive effect element. It is a schematic diagram which shows the magnetic head which concerns on a comparative example. It is a schematic diagram which shows the skew of a magnetic head. It is a schematic diagram which shows the magnetic head which concerns on 2nd Embodiment. It is a schematic diagram which shows the magnetic head which concerns on 2nd Embodiment. It is a schematic diagram which shows the magnetic head which concerns on 3rd Embodiment. It is a schematic diagram which shows the magnetic head which concerns on 3rd Embodiment. It is a schematic diagram which shows the magnetic head which concerns on 4th Embodiment. It is a block diagram which shows an example of a signal calculating part. It is a schematic diagram which shows an example of a magnetic recording / reproducing apparatus. It is a flowchart which shows an example of the manufacturing method of a magnetic head. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture. It is a schematic cross section which shows an example of the magnetic head in manufacture.

Hereinafter, embodiments will be described in detail with reference to the drawings.
(First embodiment)
1A and 1B are schematic views illustrating an example of the multi-reproducing element 10 according to the first embodiment. 1A is a plan view of the multi-reproducing element (magnetic head) 10, and FIG. 1B is a cross-sectional view taken along line A1-A2 of FIG. 1A, showing the shape of the multi-reproducing element 10 in the depth direction of FIG.

Here, the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as the actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and the following drawings, the same reference numerals are given to the same elements as those described above with reference to the previous drawings, and detailed description thereof will be omitted as appropriate.

  The multi-reproducing element 10 is mounted on, for example, a magnetic head (a magnetic head 93 described later) of an HDD (a magnetic recording / reproducing apparatus 90 described later). Therefore, the plan view of FIG. 1A is a schematic view of a magnetic recording medium (a magnetic recording medium 91 described later) mounted on the HDD, for example, as viewed from the medium facing surface. The cross-sectional view of FIG. 1B is a schematic diagram when viewed from the direction perpendicular to the magnetic recording medium facing surface, for example.

  As shown in FIGS. 1A and 1B, the multi-reproducing element 10 includes a first reproducing element unit 20, an insulating layer 30, a second reproducing element unit 40, a first side shield 24, and a second side shield 44. The insulating layer 30 is provided between the first reproduction element unit 20 and the second reproduction element unit 40.

The first reproduction element unit 20 includes a first electrode 21, a first signal detection unit 23, and a second electrode 22. The first signal detection unit 23 is provided between the first electrode 21 and the second electrode 22.
The second reproduction element unit 40 includes a third electrode 41, a second signal detection unit 43, and a fourth electrode 42. The second signal detection unit 43 is provided between the third electrode 41 and the fourth electrode 42.

  The first signal detector 23 and the second signal detector 43 are differential output type magnetoresistive elements. The details of the differential output type magnetoresistive effect element will be described later.

  Here, if the direction from the first electrode 21 toward the fourth electrode 42 is the Y axis, the Y axis is the film forming direction. The direction crossing the Y-axis direction, from the first signal detection unit 23 and the second signal detection unit 43 toward the first side shield 24 and the second side shield 44 is defined as the X-axis direction, and intersects the Y-axis direction. The direction intersecting with the axial direction is taken as the Z-axis direction.

The first electrode 21, the second electrode 22, and the fourth electrode 42 are made of a magnetic material. For this magnetic material, for example, any one of NiFe, CoZrTa, CoZrNb, CoZrNbTa, CoZrTaCr, and CoZrFeCr (hereinafter referred to as “NiFe etc.”) can be used. For the first electrode 21, the second electrode 22, and the fourth electrode 42, a multilayer film containing any one of NiFe and the like may be used.
The first electrode 21, the second electrode 22, and the fourth electrode 42 may have different magnetic materials or different laminated structures.

  The first electrode 21, the second electrode 22, and the fourth electrode 42 have a shielding function. The second electrode 22 is shared as a shield between the first reproduction element unit 20 and the second reproduction element unit 40, and magnetically separates the first reproduction element unit 20 and the second reproduction element unit 40. Thereby, reproduction signal deterioration due to the interaction between the first reproduction element unit 20 and the second reproduction element unit 40 can be effectively prevented.

  As will be described later, the resolution in the Y-axis direction of the first signal detection unit 23 and the second signal detection unit 43, which are differential output type magnetoresistive effect elements, in addition to the distance between the shields, each of the two free It also depends greatly on the distance between the layers (first free layer 62 and second free layer 64 described later). Therefore, the shielding function of the second electrode 22 need not be equivalent to that of the first electrode 21 and the fourth electrode 42. The shield function of the second electrode 22 may be weaker than the shield function of the first electrode 21 and the fourth electrode 42. That is, the thickness of the second electrode 22 (the length of the second electrode 22 along the Y-axis direction) may be smaller than the thickness of the first electrode 21 and the fourth electrode 42.

  The thickness of the second electrode 22 is preferably 10 nm to 60 nm (more preferably 20 nm to 40 nm). Within these thickness ranges, the shielding function of the second electrode 22 felt by the first signal detector 23 and the second signal detector 43 can be optimized. In addition, the surface unevenness of the third electrode 41 stacked on the second electrode 22 via the insulating layer 30 can be reduced. For this reason, the crystallinity of the third electrode 41 is also improved. As a result, an increase in the specific resistance of the third electrode 41 due to external factors such as crystallinity and surface unevenness can be suppressed.

  Here, the film thickness of the second electrode 22 is defined by the distance from the interface of the region in contact with the first signal detector 23 to the interface in contact with the insulating layer 30 along the Y-axis direction. For example, the thickness of the second electrode 22 can be measured by observing the cross section of the second electrode 22 with a TEM (transmission electron microscope).

  Further, the magnetization directions of the first electrode 21, the second electrode 22, and the fourth electrode 42 are directed in the X-axis direction when there is no externally applied magnetic field, that is, in the initial state. Therefore, an antiferromagnetic layer such as IrMn may be present inside each electrode.

  The third electrode 41 is made of a material having a specific resistance smaller than that of the first electrode 21 and the fourth electrode 42. The third electrode 41 is made of a nonmagnetic metal. As this nonmagnetic metal, for example, Cu, Au, Ag, W, Mo, and Ru (hereinafter referred to as “Cu etc.”) can be used. For this nonmagnetic metal, an alloy such as Cu may be used. The third electrode 41 may be a multilayer film containing Cu or the like.

  By using these materials as the third electrode 41, the thickness of the third electrode 41 (the length along the Y-axis direction of the third electrode 41) can be reduced while suppressing electromigration. . As a result, it is easy to reduce the distance between the first reproduction element unit 20 and the second reproduction element unit 40.

  The film thickness of the third electrode 41 is preferably 3 nm to 20 nm (more preferably 5 nm to 10 nm). It is possible to maintain the flatness of the third electrode 41 and suppress electromigration due to an increase in specific resistance due to external factors such as surface irregularities.

  Note that, from the viewpoint of the crystallinity of the second reproducing element unit 40, a layer serving as a base layer of the second reproducing element unit 40 may be used for the third electrode 41. Further, as the third electrode 41, for example, the same material as that of the second electrode 22 may be stacked with a thickness of 10 nm or less. As an example, NiFe (5 nm) may be laminated. This layer may or may not have a shielding function. Further, for this layer, for example, a Ta / Ru two-layer film of 10 nm or less may be used.

The insulating layer 30 can be formed using at least one of silicon oxide (eg, SiO ₂ ), silicon nitride, silicon oxynitride, aluminum oxide (eg, Al ₂ O ₃ ), aluminum nitride, and aluminum oxynitride.

  The thickness of the insulating layer 30 (the length along the Y-axis direction of the insulating layer 30) is preferably 5 nm or more and 40 nm or less. Within these thickness ranges, good electrical insulation between the first reproduction element unit 20 and the second reproduction element unit 40 can be obtained. In addition, it is possible to suppress an increase in specific resistance due to external factors such as surface roughness of the third electrode 41 laminated thereon. Thereby, electromigration of the third electrode 41 can be suppressed.

The first side shield 24 and the second side shield 44 are made of a magnetic material. For this magnetic material, for example, any one of NiFe, CoZrTa, CoZrNb, CoZrNbTa, CoZrTaCr, and CoZrFeCr (hereinafter referred to as “NiFe etc.”) can be used. For the first side shield 24 and the second side shield 44, a multilayer film containing any one of NiFe and the like may be used.

  The first side shield 24 and the second side shield 44 are exchange-coupled to the second electrode 22 and the fourth electrode 42, respectively. Exchange coupling includes, for example, direct bonding between a magnetic layer and a magnetic layer. The exchange coupling includes, for example, magnetic coupling between a plurality of magnetic layers acting via an ultrathin nonmagnetic layer provided between the plurality of magnetic layers in the plurality of magnetic layers. Exchange coupling is an effect through the interface between the magnetic layer and the magnetic layer, or the interface between the magnetic layer and the nonmagnetic layer. In the case of passing through the interface between the magnetic layer and the nonmagnetic layer, the exchange coupling depends on the thickness of the nonmagnetic layer and acts when the thickness of the nonmagnetic layer is 2 nm or less.

  The exchange coupling is different from the static magnetic field coupling due to the leakage magnetic field from the end of the magnetic layer. In exchange coupling, it can be considered that a ferromagnetic coupling bias magnetic field (or antiferromagnetic coupling bias magnetic field) acts between magnetic layers. For example, when there is no externally applied magnetic field bias, the direction of magnetization between the magnetic layers is aligned in the same direction (ferromagnetic coupling state) or in the opposite direction (antiferromagnetic coupling state) due to this exchange coupling action. )be able to.

  When there is an externally applied magnetic field bias or the like, the magnetization is directed in a direction determined by the combination of an externally applied magnetic field bias magnetic field and a bias magnetic field by exchange coupling. Therefore, when there is an externally applied magnetic field bias or the like, a ferromagnetic coupling bias magnetic field component due to exchange coupling or an antiferromagnetic coupling magnetic field component acts. At this time, the direction of the bias magnetic field due to exchange coupling does not necessarily match the direction of magnetization between the magnetic layers.

  In this embodiment, the magnetization direction in the initial state of the first side shield 24 and the second side shield 44, that is, when there is no externally applied magnetic field, is in the X-axis direction. The first side shield 24 and the second side shield 44 can be omitted. However, if the first side shield 24 and the second side shield 44 are provided, the reproduction resolution in the X-axis direction can be improved.

  For the first signal detector 23 and the second signal detector 43, differential output type magnetoresistive elements are used. The differential output type magnetoresistive effect element is a magnetoresistive effect element that outputs in response to a change in spatial magnetic field distribution. For example, in the case of a perpendicular magnetic recording type HDD, an ordinary TMR (tunnel magnetoresistance) element generates an output according to the magnetization direction of each recording bit, and a maximum output is obtained at the position of the recording bit. On the other hand, in the case of a differential output type magnetoresistive effect element, it is output in response to a transition region in which the magnetization direction of the recording bit changes, and the maximum output is obtained at the position of the bit transition region.

  2A to 4B are examples of a signal detection unit used in this embodiment, and show three types of differential output type magnetoresistive effect elements.

  FIG. 2A shows an example of a differential output type magnetoresistive effect element. 2B is a cross-sectional view taken along line A1-A2 of FIG. 2A and shows the shape in the depth direction of FIG. 2A. This magnetoresistive effect element includes an underlayer 51, a first antiferromagnetic layer 52, a first pinned layer 53, a first insulating layer 61, a first free layer 62, a nonmagnetic layer 63, a second free layer 64, a second layer. It has an insulating layer 65, a second pinned layer 71, a second antiferromagnetic layer 72, a Cap layer 73, and a hard bias HB (HB1, HB2).

  The underlayer 51 is for reducing the influence of contamination (contamination) from the deposition surface of the MR element and for improving the crystal orientation of the film formed thereon. For the base layer 51, for example, Ta, NiCr, FeNi, Ta / NiCr, or the like can be used. The film thickness of the foundation layer 51 can be set to 1 to 4 m, for example.

  The first antiferromagnetic layer 52 and the second antiferromagnetic layer 72 are made of an antiferromagnetic material. For example, IrMn, PtMn, or the like can be used as the antiferromagnetic material. The film thickness of the first antiferromagnetic layer 52 and the second antiferromagnetic layer 72 can be set to, for example, 5 to 15 nm.

  The first pinned layer (first magnetic pinned layer) 53 and the second pinned layer (second magnetic pinned layer) 71 are made of a ferromagnetic material. As this ferromagnetic material, for example, a CoFe, CoFeB, NiFe, or a laminated structure in which Ru is sandwiched between two combinations thereof (for example, CoFe / Ru / CoFe) can be used. The film thicknesses of the first pinned layer 53 and the second pinned layer 71 can be set to 1 to 10 nm, for example.

  For example, MgO, AlO (Al oxide layer), and TiO (Ti oxide layer) can be used for the first insulating layer 61. The film thickness of the first insulating layer 61 can be set to 1 to 2 nm, for example.

  For the first free layer (first magnetic free layer) 62 and the second free layer (second magnetic free layer) 64, for example, CoFe, CoFeB, NiFe or the like can be used. The film thicknesses of the first free layer (first magnetic free layer) 62 and the second free layer (second magnetic free layer) 64 can be set to 2 to 6 nm, for example.

  The nonmagnetic layer 63 can use, for example, Cu, Ru, or the like. The film thickness of the nonmagnetic layer 63 can be set to 0.3 to 10 nm, for example.

  The Cap layer 73 can use, for example, Cu, Ru, Ta, or the like. The film thickness of the Cap layer 73 can be set to 1 to 5 nm, for example.

  The hard biases HB1 and HB2 correspond to the first free layer (first magnetic free layer) 62 and the second free layer (second magnetic free layer) 64, respectively. For example, CoPt can be used as the hard biases HB1 and HB2. The magnetization directions of the hard biases HB1 and HB2 are the X-axis direction. The film thicknesses of the hard biases HB1 and HB2 are appropriately adjusted according to the magnitude of the magnetic field applied to the first free layer (first magnetic free layer) 62 and the second free layer (second magnetic free layer) 64. The film thicknesses of the hard biases HB1 and HB2 can be set to 5 to 15 nm, for example.

A thin non-magnetic metal (for example, 1 nm of Ru or Pt) may be inserted between the hard biases HB1 and HB2 for antiferromagnetic coupling. Alternatively, a thin insulating layer (for example, 2 nm Al ₂ O ₃ ) may be inserted between the hard biases HB1 and HB2. Alternatively, the hard biases HB1 and HB2 may be directly joined. Hard biases HB1 and HB2 and a laminate (underlayer 51, first antiferromagnetic layer 52, first pinned layer 53, first insulating layer 61, first free layer 62, nonmagnetic layer 63, second free layer 64, A thin insulating layer (for example, 2 nm of Al ₂ O ₃ ) is inserted between the second insulating layer 65, the second pinned layer 71, the second antiferromagnetic layer 72, and the Cap layer 73) to be insulated.

  FIG. 3A shows another example of the differential output type magnetoresistive effect element. 3B is a cross-sectional view taken along line A1-A2 of FIG. 3A and shows the shape in the depth direction of FIG. 3A. This magnetoresistive element has a base layer 51, a first free layer 62, a nonmagnetic layer 63, a second free layer 64, a Cap layer 73, and a hard bias HB.

Constituent materials and film thicknesses of the first free layer 62, the nonmagnetic layer 63, and the second free layer 64 can be the same as those shown in FIGS. 2A and 2B. Furthermore, for the first free layer 62 and the second free layer 64, for example, CoFeMnSi, CoMnSi, CoFeMnGe, CoMnGe, CoFeAlSi, CoFeGeGa, or the like can be used. The film thickness of the first free layer 62 and the second free layer 64 may be 2 to 6 nm, for example.
For the nonmagnetic layer 63, for example, Cu, Ag, MgO, AlO, TiO, or the like can be used. The film thickness of the nonmagnetic layer 63 can be set to 1 to 10 nm, for example.

  The constituent materials and film thicknesses of the base layer 51, the Cap layer 73, and the hard bias HB shown in FIGS. 3A and 3B are the same as those in FIGS.

  FIG. 4A shows another example of the differential output type magnetoresistive effect element. 4B is a cross-sectional view taken along line A1-A2 of FIG. 4A and shows the shape in the depth direction of FIG. 4A. The magnetoresistive element includes an underlayer 51, a first antiferromagnetic layer 52, a first pinned layer 53, a first insulating layer 61, a first free layer 62, a nonmagnetic layer 63, a second free layer 64, and a Cap layer. 73, and hard bias HB.

  The nonmagnetic layer 63 can also use the same material and thickness as in FIGS. 2A and 2B. However, for example, a laminated structure of an extremely thin Ru and a magnetic layer (for example, [Ru (0.4 nm) / CoFe (1 nm)] n (n is the number of times of lamination)) can be used. By doing in this way, adjustment of the distance between the 1st free layer 62 and the 2nd free layer 64, ie, adjustment of resolution, is possible.

  FIGS. 2A to 4A are all differential output type magnetoresistive effect elements, which respectively show similar output characteristics, but have structural features with respect to the number of antiferromagnetic layers contained therein. For example, the structure of FIG. 2A has two antiferromagnetic layers (a first antiferromagnetic layer 52 and a second antiferromagnetic layer 72) for one magnetoresistive element. The structure of FIG. 3A does not include any antiferromagnetic layer, and the structure of FIG. 4A includes one antiferromagnetic layer (antiferromagnetic layer 52). The smaller the number of antiferromagnetic layers that the magnetoresistive element has, the higher the manufacturability.

  4A and 4B, the underlayer 51, the first antiferromagnetic layer 52, the first pinned layer 53, the first insulating layer 61, the first free layer 62, the second free layer 64, the Cap layer 73, and The constituent materials and film thicknesses of the hard biases HB1 and HB2 are the same as those shown in FIGS.

  For example, at least one of the first signal detection unit 23 and the second signal detection unit 43 is used. The first signal detection unit 23 and the second signal detection unit 43 need not be magnetoresistive elements having the same structure as long as they are differential output types. A combination of magnetoresistive elements having different structures may be used.

  2A, 3A, and 4A show the hard bias HB (HB1, HB2), the presence or absence of the hard bias HB is selected depending on the presence or absence of the first side shield 24 and the second side shield 44. . That is, for example, when the first side shield 24 is omitted, the hard bias HB is used in the first signal detection unit 23 shown in any of FIGS. 2A, 3A, and 4A. For example, when the second side shield 44 is omitted, the second signal detection unit 43 shown in any of FIGS. 2A, 3A, and 4A has a hard bias HB. For example, when the first side shield 24 is provided, the hard bias HB is omitted in the first signal detection unit 23 shown in any of FIGS. 2A, 3A, and 4A.

  As shown in FIGS. 2A to 4B, the differential output type magnetoresistive effect element generally has a first free layer 62, a nonmagnetic layer 63, and a second free layer 64. The resolution depends on the distance between the magnetic shields sandwiching the differential output type magnetoresistive effect element between the top and bottom and the distance between the two free layers (the first free layer 62 and the second free layer 64). The resolution in the Y-axis direction of the differential output type magnetoresistive effect element depends largely on the distance between the first free layer 62 and the second free layer 64 in particular.

  Further, since a differential signal is generated between the first free layer 62 and the second free layer 64, a relatively low frequency external noise applied to both the first free layer 62 and the second free layer 64 is canceled. It is easy to be done. That is, the differential output type magnetoresistive element is relatively resistant to noise.

  According to the present embodiment, it is possible to reduce white noise up to a large skew angle θ while maintaining high reproduction resolution. That is, a high SNR can be obtained. This facilitates high recording density.

As described below, the third electrode 41 and the second electrode 22 can be made thin, and the distance between the first signal detection unit 23 and the second signal detection unit 43 can be reduced. Because it is small.
That is, the third electrode 41 is not scheduled to function as a shield, and a nonmagnetic metal having a thickness of 3 nm to 20 nm can be used.
The second electrode 22 preferably has a certain degree of shielding property, but a magnetic metal of 10 nm or more and 60 nm or less can be used.

  Since the first signal detector 23 and the second signal detector 43 are both differential, the resolution in the Y-axis direction depends largely on the distance between the first free layer 62 and the second free layer 64, in particular. To do. Further, it is easy to remove relatively low frequency noise. As a result, a strong magnetic shield between the first signal detector 23 and the second signal detector 43 is not required.

  As described above, since the first signal detection unit 23 and the second signal detection unit 43 are of the differential type, it is easy to make the third electrode 41 and the second electrode 22 thinner, and the influence of skew can be reduced. .

(Comparative example)
FIG. 5 is a schematic diagram showing a multi-reproducing element (magnetic head) 10x according to a comparative example. As shown in FIG. 5, the multi-reproducing element 10 x includes a first reproducing element unit 20 x, an insulating layer 30, a second reproducing element unit 40 x, a first side shield 24, and a second side shield 44.

The first reproduction element unit 20x includes a first electrode 21, a first signal detection unit 23x, and a second electrode 22x.
The second reproduction element unit 40x includes a third electrode 41x, a second signal detection unit 43x, and a fourth electrode 42.

Here, the first signal detection unit 23x and the second signal detection unit 43x are non-differential (eg, TMR type) magnetoresistive elements.
In addition, all of the first electrode 21, the second electrode 22x, the third electrode 41x, and the fourth electrode 42 are magnetic bodies and have a magnetic shield function. That is, since the first signal detector 23x and the second signal detector 43x are non-differential, they are easily affected by external noise, and both the second electrode 22x and the third electrode 41x have a magnetic shield function. Required.
For this reason, it is necessary to make both the second electrode 22x and the third electrode 41x thick, and the interval between the first signal detection unit 23x and the second signal detection unit 43x becomes large. As a result, the multi-reproducing element (magnetic head) 10x is easily affected by skew.

  As shown in FIG. 6, it is considered that the information of the track T on the magnetic recording medium 91 is read by the magnetic head 93. At this time, when the track T is positioned near the inner periphery or the outer periphery of the magnetic recording medium 91, the magnetic head 93 has an angle (skew angle) θ with respect to the track T (occurrence of skew).

  FIGS. 6A and 6B respectively show a case where there is no skew and a case where there is no skew. When there is a skew, if the distance d between the first signal detection unit 23x and the second signal detection unit 43x is large, the tracks T read by the first signal detection unit 23x and the second signal detection unit 43x do not match. At this time, it is difficult to reduce the white noise component by integrating the same reproduced signal a plurality of times.

  In contrast, in the first embodiment, the second electrode 22 and the third electrode 41 can be thinned. As a result, the distance between the first signal detection unit 23 and the second signal detection unit 43 is reduced, and even if there is a skew, the possibility of being off-track is reduced. That is, the tracks read by the first signal detection unit 23 and the second signal detection unit 43 are easily matched. As a result, white noise components can be easily reduced by integrating the same reproduced signal multiple times.

(Second Embodiment)
7A and 7B are schematic views showing an example of the multi-reproducing element 10a according to the second embodiment. 7A is a plan view, and FIG. 7B is a cross-sectional view taken along line A1-A2 of FIG. 7A and shows the shape in the depth direction of FIG. 7A. The multi reproducing element 10a is mounted on a magnetic head of an HDD, for example. Therefore, the plan view of FIG. 7A is a schematic diagram viewed from the medium facing surface of a magnetic recording medium mounted on an HDD, for example. The cross-sectional view of FIG. 7B is a schematic diagram of the shape perpendicular to the magnetic recording medium facing surface, for example.

  As shown in FIGS. 7A and 7B, the multi-reproducing element 10a includes a first reproducing element unit 20, an insulating layer 30, and a second reproducing element unit 40.

The first reproduction element unit 20 includes a first electrode 21, a first signal detection unit 23, and a second electrode 22a. The first signal detector 23 is provided between the first electrode 21 and the second electrode 22a.
The second reproduction element unit 40 includes a third electrode 41, a second signal detection unit 43, and a fourth electrode 42. The second signal detection unit 43 is provided between the third electrode 41 and the fourth electrode 42.

  Here, if the direction from the first electrode 21 toward the fourth electrode 42 is the Y axis, the Y axis is the film forming direction. In FIG. 7A, the direction that intersects the Y-axis direction and is parallel to the paper surface is defined as the X-axis direction, and the direction that intersects the Y-axis direction and also intersects the X-axis direction is defined as the Z-axis direction.

  In the first embodiment, the second electrode 22 is made of a magnetic material, whereas in the present embodiment, the second electrode 22a is made of a non-magnetic material. That is, in the present embodiment, both the second electrode 22a and the third electrode 41 are made of a nonmagnetic metal.

  The second electrode 22a is made of a material having a specific resistance smaller than that of the first electrode 21 and the fourth electrode 42. The second electrode 22a is made of a nonmagnetic metal. As this nonmagnetic metal, for example, Cu, Au, Ag, W, Mo, and Ru (hereinafter referred to as “Cu etc.”) can be used. For this nonmagnetic metal, an alloy such as Cu may be used. The second electrode 22a may be a multilayer film containing Cu or the like.

  By using these materials as the second electrode 22a, the thickness of the second electrode 22a (the length along the Y-axis direction of the second electrode 22a) can be reduced while suppressing electromigration. . As a result, the distance between the first reproduction element unit 20 and the second reproduction element unit 40 can be further reduced.

  The thickness of the second electrode 22a is preferably 3 nm to 20 nm (more preferably 5 nm to 10 nm). It is possible to maintain the flatness of the second electrode 22a and suppress electromigration due to an increase in specific resistance due to external factors such as surface irregularities.

  As the second electrode 22a, the same material as the first electrode 21 may be stacked with a thickness of 10 nm or less. For example, NiFe (10 nm) may be laminated. At this time, the second electrode 22a may or may not have a shielding function.

  Similar to the first embodiment, the first side shield 24 and the second side shield 44 may be omitted. When the first side shield 24 is provided, the non-magnetic metal and NiFe are stacked and used for the second electrode 22a, for example. At this time, NiFe is laminated on the first side shield 24 side.

The first signal detector 23 and the second signal detector 43 are differential output type magnetoresistive elements. The first signal detection unit 23 and the second signal detection unit 43 are, for example, any one of the differential output type magnetoresistive effect elements shown in FIGS. 2A, 2B, 3A, 3B, 4A, and 4B. Used.
Other material conditions (material, film thickness, shape) can be the same as those in the first embodiment.

  According to this embodiment, since the second electrode 22a can be made thinner, white noise can be reduced to a larger skew angle θ while maintaining high reproduction resolution. That is, it is possible to obtain a higher SNR. As a result, a higher recording density is possible.

(Third embodiment)
8A and 8B are schematic views illustrating an example of the multi-reproducing element 10b according to the third embodiment. 8A is a plan view, and FIG. 8B is a cross-sectional view taken along line A1-A2 of FIG. 8A, and shows the shape in the depth direction of FIG. 8A. The multi reproducing element 10b is mounted on a magnetic head of an HDD, for example. Therefore, the plan view of FIG. 8A is a schematic view seen from the medium facing surface of a magnetic recording medium mounted on, for example, an HDD. The cross-sectional view of FIG. 8B is a schematic diagram of the shape perpendicular to the magnetic recording medium facing surface, for example.

  As shown in FIGS. 8A and 8B, the multi-reproducing element 10b includes a first reproducing element unit 20, an insulating layer 30, and a second reproducing element unit 40.

The first reproduction element unit 20 includes a first electrode 21, a first signal detection unit 23, and a second electrode 22a. The first signal detector 23 is provided between the first electrode 21 and the second electrode 22a.
The second reproducing element unit 40 includes a third electrode 41 a, a second signal detection unit 43, and a fourth electrode 42. The second signal detection unit 43 is provided between the third electrode 41 a and the fourth electrode 42.

  Here, if the direction from the first electrode 21 toward the fourth electrode 42 is the Y axis, the Y axis is the film forming direction. In FIG. 8A, the direction that intersects the Y-axis direction and is parallel to the paper surface is defined as the X-axis direction, and the direction that intersects the Y-axis direction and intersects the X-axis direction is defined as the Z-axis direction.

  In the second embodiment, the third electrode 41 is made of a nonmagnetic material, whereas in the present embodiment, the third electrode 41a is made of a magnetic material. That is, in the present embodiment, the second electrode 22a is made of a nonmagnetic material, and the third electrode 41a is made of a magnetic material.

  The third electrode 41a is made of a magnetic material. For this magnetic material, for example, any one of NiFe, CoZrTa, CoZrNb, CoZrNbTa, CoZrTaCr, and CoZrFeCr (hereinafter referred to as “NiFe etc.”) can be used. For the third electrode 41a, a multilayer film containing any one of NiFe and the like may be used.

  The third electrode 41a has a shielding function. The third electrode 41a is shared as a shield between the first reproduction element unit 20 and the second reproduction element unit 40, and magnetically separates the first reproduction element unit 20 and the second reproduction element unit 40. Thereby, reproduction signal deterioration due to the interaction between the first reproduction element unit 20 and the second reproduction element unit 40 can be effectively prevented.

  As described above, the Y-axis direction resolution of the first signal detection unit 23 and the second signal detection unit 43 which are differential output type magnetoresistive effect elements, in addition to the distance between the shields, It also depends greatly on the distance between the free layers. Therefore, the shielding function of the third electrode 41 a is not necessarily the same as that of the first electrode 21 and the fourth electrode 42. The shield function of the third electrode 41 a may be weaker than the shield function of the first electrode 21 and the fourth electrode 42. That is, the thickness of the third electrode 41a (the length along the Y-axis direction of the third electrode 41a) may be smaller than the thickness of the first electrode 21 and the fourth electrode 42.

  The thickness of the third electrode 41a is preferably 10 nm to 60 nm (more preferably 20 nm to 40 nm). Within these film thickness ranges, the shield function of the third electrode 41a felt by the first signal detector 23 and the second signal detector 43 can be optimized.

  Here, the film thickness of the third electrode 41a is defined by the distance from the interface of the region in contact with the second signal detection unit 43 to the interface in contact with the insulating layer 30 along the Y-axis direction. For example, the film thickness can be measured by observing the cross section of the third electrode 41a with a TEM (transmission electron microscope).

  Further, the magnetization directions of the first electrode 21, the third electrode 41a, and the fourth electrode 42 are directed in the X-axis direction when there is no externally applied magnetic field, that is, in an initial state. Therefore, an antiferromagnetic layer such as IrMn may be present inside each electrode.

  Other material conditions (material, film thickness, shape) are the same as those in the first embodiment and the second embodiment.

(Fourth embodiment)
FIG. 9 is a schematic diagram illustrating an example of the multi-reproducing element 10c according to the fourth embodiment. FIG. 9 is a plan view corresponding to FIG. 1A.

  As shown in FIG. 9, the multi-reproducing element 10c includes a first reproducing element unit 20, insulating layers 30, 31, a second reproducing element unit 40, and a third reproducing element unit 40a. Between the insulating layer 30 and the second reproducing element unit 40, the third reproducing element unit 40a and the insulating layer 31 are arranged. The third reproduction element unit 40a includes a fifth electrode 41a, a third signal detection unit 43a, and a sixth electrode 42a. The third signal detection unit 43a is provided between the fifth electrode 41a and the sixth electrode 42a.

  The multi-reproducing element 10c has three reproducing element units (first, second, and third reproducing element units 20, 40, and 40a), and can sequentially reproduce the same track by the three reproducing element units. By integrating the three reproduction signals, the white noise component can be further reduced as compared with the case where the two reproduction signals are integrated.

  Note that a reproducing element unit and an insulating layer may be further added between the insulating layer 30 and the second reproducing element unit 40 so that the multi reproducing element has four reproducing element units. By doing so, it is possible to integrate the four reproduction signals and further reduce the white noise component.

(Fifth embodiment)
FIG. 10 is a block diagram illustrating an example of a signal calculation unit included in the magnetic recording / reproducing apparatus according to the fifth embodiment. As shown in FIG. 10, the output signals of the first signal detector 23 and the second signal detector 43 of the multi-reproducing element 10 are amplified by head amplifiers 81 and 82, respectively. The output signal from the head amplifier 81 is input to the synchronization circuit 83. After being cached by the synchronization circuit 83, it is input to the data demodulator 84 at a predetermined timing, for example, as an in-phase combination signal with the output signal of the head amplifier 82, and the read signal S is obtained.
By doing in this way, the read signal S in which the white noise component is reduced can be obtained using the output signals of the first signal detector 23 and the second signal detector 43.

  In the magnetic recording / reproducing apparatus according to the fifth embodiment, the read signal S can be obtained by combining the output signals of the first signal detector 23 and the second signal detector 43 of the multi-reproducing element 10. . FIG. 10 is merely an example of a signal calculation unit. For example, the output signal of the first signal detector 23 is input to the synchronization circuit 83, combined with the output signal of the second signal detector 43, amplified by the head amplifier 81, and input to the data demodulator 84. May be.

(Sixth embodiment)
FIG. 11 shows a magnetic recording / reproducing apparatus (HDD apparatus) 90 according to the sixth embodiment. The magnetic recording / reproducing apparatus 90 includes a magnetic recording medium 91, a spindle motor 92, and a magnetic head 93. Any of the multiple reproducing elements 10 to 10c is used for the magnetic head 93. Also provided are head-ups 81 and 82, a synchronization circuit 83, and a data demodulator 84 shown in FIG.

  The magnetic recording / reproducing apparatus 90 is an apparatus using a rotary actuator. The magnetic recording medium 91 is mounted on a spindle motor 92 and is rotated by a motor (not shown) that responds to a control signal from a drive device control unit (not shown).

  When the magnetic recording medium 91 rotates, the pressing pressure by the suspension 94 and the pressure generated on the medium facing surface (also referred to as ABS) of the head slider are balanced. As a result, the medium facing surface (magnetic head 93) of the head slider is held with a predetermined flying height from the surface of the magnetic recording medium 91.

  The suspension 94 is connected to one end of an actuator arm 95 having a bobbin portion for holding a drive coil (not shown). A voice coil motor 97, which is a kind of linear motor, is provided at the other end of the actuator arm 95. The voice coil motor 97 is composed of a drive coil (not shown) wound around the bobbin portion of the actuator arm 95, and a magnetic circuit composed of a permanent magnet and a counter yoke arranged so as to sandwich the coil. be able to.

  The actuator arm 95 is held by ball bearings (not shown) provided at two positions above and below the bearing portion 96, and can be freely slid by a voice coil motor 97. As a result, the magnetic recording head can be moved to an arbitrary position on the magnetic recording medium 91.

  In the multiple reproducing elements according to the first to fourth embodiments and the multiple reproducing elements mounted in the fifth and sixth embodiments, between the first signal detection unit 23 and the second signal detection unit 43. The shift in the X-axis direction is preferably −10 nm to +10 nm (more preferably −5 nm to +5 nm). Within this range, white noise can be reduced up to a large skew angle θ.

(Production method)
A method for manufacturing the magnetic head will be described.
FIG. 12 is a flowchart showing a method for manufacturing a magnetic head. 13 to 25 are schematic cross-sectional views of an example of the magnetic head being manufactured. Here, the manufacturing method of the magnetic head of the first embodiment is shown. 13 to 18 correspond to FIG. 1A, and FIGS. 19 to 22 correspond to FIG. 1B.

(1) Formation of the first electrode 21 (see step S1, FIG. 13)
As shown in FIG. 13, the first electrode 21 (electrode layer) is formed on the substrate 11. For example, after a deposit (metal layer) of a material to be the first electrode 21 is formed on the substrate 11 by electroplating, the surface is polished. For example, the unevenness on the surface of the metal layer is planarized by a chemical mechanical polishing (CMP) method. The constituent material of the first electrode 21 is, for example, NiFe. The thickness of the first electrode 21 in the Y-axis direction is, for example, 1 μm.

  Thereafter, the substrate 11 is carried into a chamber (not shown). The inside of the chamber is decompressed (for example, vacuumed), and the upper surface of the first electrode 21 is etched with an ion beam. As a result, the oxide layer and the contamination layer formed on the upper surface of the first electrode 21 are removed. The oxide layer is attached, for example, during the manufacturing process.

(2) Formation of the first signal detector 23 (see step S2, FIGS. 14 to 22)
As illustrated in FIG. 14, the stacked film L <b> 1 that becomes the first signal detection unit 23 is formed on the first electrode 21 while the pressure inside the chamber is reduced, for example, by sputtering. The first signal detector 23 is, for example, a differential output type magnetoresistive effect element shown in FIGS. 4A and 4B, and includes a base layer 51, an antiferromagnetic layer 52, an insulating layer 61, a first free layer 62, a first free layer 62, 2 free layer 64, Cap layer (nonmagnetic layer) 73, and the like. The overall thickness of the multilayer film L1 (first signal detection unit 23) in the Y-axis direction is, for example, 26 nm.

  As shown in FIG. 15, a mask pattern M <b> 1 is formed on the laminated film L <b> 1 that becomes the first signal detection unit 23. As the mask pattern M1, for example, a resist mask or a metal mask containing Ta is used. For example, the mask pattern M1 is formed by using an optical lithography technique. The shape of the upper surface of the mask pattern M1 defines the width in the X-axis direction of the stacked film L1 that becomes the first signal detection unit 23. This width is, for example, 35 nm.

  As shown in FIG. 16, using the mask pattern M1 as a mask, the laminated film L1 that becomes the first signal detection unit 23 is etched by, for example, ion beam etching. As a result, a partial pattern of the laminated film L1 that becomes the first signal detection unit 23 is formed.

As shown in FIG. 17, after the insulating film I is laminated on the mask pattern M1 and the first electrode 21, a film L2 to be the first side shield 24 is laminated.
The insulating film I is for preventing the first side shield 24 from being energized, and is made of, for example, Al ₂ O ₃ . The thickness of the insulating film I in the Y-axis direction is 3 nm, for example. The material of the first side shield 24 film is, for example, NiFe. The thickness in the Y-axis direction of the film L2 to be the first side shield 24 is set so that, for example, the etched region is filled.

  In FIG. 17, the mask pattern M1 is actually undercut, although it is simplified for easy understanding. For this reason, the insulating film I and the film L2 are not formed on the side surface of the mask pattern M1.

  As shown in FIG. 18, the mask pattern M1, the insulating film I on the mask pattern M1, and the film L2 to be the first side shield 24 are removed by, for example, a lift-off method. Thereafter, planarization is performed by CMP or the like so that the film L2 to be the first side shield 24 and the upper surface of the multilayer film L1 to be the first signal detection unit 23 are aligned.

  Next, the shape as viewed from FIG. 1B is produced. As shown in FIG. 19, a mask pattern M2 is laminated on the laminated film L1 to be the first signal detection unit 23 patterned in the X-axis direction, as in FIG. The difference from FIG. 15 is that the upper surface shape of the mask pattern M2 defines the width in the Z-axis direction.

  As shown in FIG. 20, the first signal detector 23 is formed by ion beam etching or the like using the mask pattern M2 as a mask.

As shown in FIG. 21, an insulating film L3 made of, for example, Al ₂ O ₃ is stacked on the mask pattern M2 and the first electrode 21. The thickness of the insulating layer L3 in the Y-axis direction may be stacked so as to fill the etched region, or may be about 3 nm thick and a hard bias layer, that is, a magnetic layer may be stacked thereon. is there. FIG. 21 shows a case where the insulating film L3 is stacked so as to fill the etched region.

  As shown in FIG. 22, the mask pattern M2 and the insulating film L3 on the mask pattern M2 are removed by lift-off. Thereafter, planarization is performed by CMP or the like so that the upper surfaces of the insulating layer L3 and the first signal detection unit 23 are aligned.

(3) Formation of second electrode 22, insulating layer 30, and third electrode 41 (step S3, see FIG. 23)
As illustrated in FIG. 23, the second electrode 22, the insulating layer 30, and the third electrode 41 are sequentially stacked on the plane including the first signal detection unit 23 and the first side shield 24 by, for example, sputtering.

The constituent material of the second electrode 22 is, for example, NiFe. The thickness of the second electrode 22 in the Y-axis direction is, for example, 20 nm. The constituent material of the insulating layer 30 is, for example, Al ₂ O ₃ . The thickness of the insulating layer 30 in the Y-axis direction is, for example, 15 nm. The constituent material of the third electrode 41 is, for example, Cu. The thickness of the third electrode 41 in the Y-axis direction is, for example, 5 nm.

(4) Formation of second signal detector 43 (see step S4, FIG. 24)
As shown in FIG. 24, a laminated film to be the second signal detection unit 43 is laminated on the third electrode 41, and then a pattern is formed. Since these steps are the same as the steps of FIGS. 14 to 22, detailed description thereof is omitted.

(5) Formation of the fourth electrode 42 (see step S5, FIG. 25)
As shown in FIG. 25, the fourth electrode 42 is formed on the plane composed of the second signal detector 43 and the second side shield 44. For example, the fourth electrode 42 is formed by electroplating.

  The method of manufacturing the magnetic head according to the above embodiment is an example, and only points are shown. Actually, subsequent processes include a write head formation process, a wafer cutting process, and a magnetic recording medium facing surface formation by polishing. Conventional manufacturing methods can be applied to these steps. Description of these conventional manufacturing methods is omitted.

Hereinafter, examples will be described.
Example 1
The characteristics of the magnetic head according to Example 1 will be described. The layer structure of the magnetic head according to Example 1 is the same as that of the first embodiment. The layer structure of the magnetic head according to Example 1 is shown in Table 1.

  As the first signal detector 23 and the second signal detector 43, the differential output type magnetoresistive effect element shown in FIGS. 4A and 4B is used. The layer configurations of the first signal detection unit 23 and the second signal detection unit 43 are shown in Table 2.

  The positional deviation in the X-axis direction in FIG. 1A between the first signal detection unit 23 and the second signal detection unit 43 is approximately 0 nm. The sizes of the four free layers included in the first signal detection unit 23 and the second signal detection unit 43 are 35 nm × 35 nm.

  Using the magnetic head of Example 1, the dependency of SNR on the skew angle θ in a 1000 kfci magnetic recording pattern was measured with a spin stand. The applied voltage at the time of measurement was 100 mV for both the first signal detector 23 and the second signal detector 43. The reproduction signal was acquired by synchronizing the output waveforms of the first signal detection unit 23 and the second signal detection unit 43 in terms of software and performing combination processing.

(Comparative Example 1)
The characteristics of the magnetic head according to Comparative Example 1 will be described. As shown in FIG. 5, in the magnetic head according to Comparative Example 1, TMR elements sandwiched between upper and lower magnetic shields are stacked with an insulating layer interposed therebetween. The layer configuration of the magnetic head according to Comparative Example 1 is shown in Table 3.

  Here, the positional deviation of the two TMR elements in the X-axis direction in FIG. 5 is approximately 0 nm. Table 4 shows the layer structure of the TMR element.

  The size of the free layer included in the two TMR elements is 35 nm × 35 nm.

  As in Example 1, the dependency of SNR on the skew angle θ in a 1000 kfci magnetic recording pattern was measured with a spin stand. The applied voltage at the time of measurement is set to 100 mV as in Example 1. The reproduced signal in Comparative Example 1 was also obtained by performing signal processing in software as in Example 1.

  Table 5 compares the SNR dependence of the SNR of Example 1 and Comparative Example 1. As a result, it can be seen that Example 1 has an effect of reducing white noise, that is, a high SNR, up to a larger skew angle θ than Comparative Example 1, and it is easy to increase the recording density.

(Example 2: Material dependence of non-magnetic metal)
The characteristics of the magnetic head according to the second embodiment will be described. In Example 2, the constituent material (nonmagnetic metal) of the third electrode 41 is changed. Table 6 shows the constituent material of the third electrode 41.

The positional deviation in the X-axis direction in FIG. 1A between the first signal detection unit 23 and the second signal detection unit 43 is substantially 0 nm, as in the first embodiment. The size of the free layer included in the first signal detection unit 23 and the second signal detection unit 43 is also 35 nm × 35 nm as in the first embodiment.
In Example 2, as in Example 1, the dependency of SNR on the skew angle θ was measured.

(Comparative Example 2: When the nonmagnetic metal is NiFe (5 nm))
The characteristics of the magnetic head according to Comparative Example 2 will be described. In Comparative Example 2, the constituent material (nonmagnetic metal) of the third electrode 41 is NiFe (5 nm).
Also in Comparative Example 2, as in Example 2, the dependence of SNR on the skew angle θ was measured. However, in Comparative Example 2, when the applied voltage was 100 mV, disconnection occurred on the second signal detection unit 43 side, and the signal could not be acquired.

  Table 7 shows a comparison of the dependency of SNR on skew angle θ between Example 2 and Comparative Example 2. Thereby, the effectiveness of the third electrode 41 material of Example 2 is shown.

(Example 3: When both the 2nd electrode 22 and the 3rd electrode 41 are nonmagnetic metals)
The characteristics of the magnetic head according to the third embodiment will be described. The layer structure of the magnetic head according to Example 3 is the same as that of the second embodiment, and is shown in Table 8.

  The first signal detection unit 23 and the second signal detection unit 43 use the differential output type magnetoresistive effect element shown in the first embodiment. The layer configurations of the first signal detection unit 23 and the second signal detection unit 43 are shown in Table 2.

  The positional deviation in the X-axis direction in FIG. 7A between the first signal detection unit 23 and the second signal detection unit 43 is substantially 0 nm as in the second embodiment. The sizes of the four free layers included in the first signal detection unit 23 and the second signal detection unit 43 are 35 × 35 nm.

  Using the magnetic head of Example 3, the dependence of SNR on the skew angle θ in a 1000 kfci magnetic recording pattern was measured with a spin stand. The applied voltage at the time of measurement was 100 mV for both the first signal detector 23 and the second signal detector 43. The reproduced signal was acquired by synchronizing the output waveforms of the first signal detection unit 23 and the second signal detection unit 43 with software and performing combination processing.

  Table 9 compares the dependency of SNR on skew angle θ between Example 3 and Comparative Example 1. Thus, it can be seen that Example 3 has an effect of reducing white noise, that is, a high SNR, up to a larger skew angle θ than Comparative Example 1, and it is easy to increase the recording density.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Multi reproduction | regeneration element 20 1st reproduction | regeneration element part 21 1st electrode 22 2nd electrode 23 1st signal detection part 24 1st side shield 30 Insulating layer 40 2nd reproduction | regeneration element part 41 3rd electrode 42 4th electrode 43 2nd signal Detector 44 Second side shield 40a 3 Playback element 41a 5th electrode 42a 6th electrode 43a 3rd signal detector 51 Underlayer 52 Antiferromagnetic layer 53 1st pinned layer 61 1st insulating layer 62 1st free layer 63 Nonmagnetic layer 64 Second free layer 65 Second insulating layer 71 Second pinned layer 72 Antiferromagnetic layer 73 Cap layers 81, 82 Head amplifier 83 Synchronizing circuit 84 Data demodulator 90 Magnetic recording / reproducing apparatus 91 Magnetic recording medium 92 Spindle motor 93 Magnetic head 94 Suspension 95 Actuator arm 96 Bearing portion 97 Voice coil motor

Claims (10)

A first electrode including a magnetic material;
A fourth electrode including a magnetic material;
A second electrode disposed between the first electrode and the fourth electrode;
A third electrode disposed between the second electrode and the fourth electrode;
A first signal detector disposed between the first electrode and the second electrode and including a differential output type magnetoresistive element;
An insulating layer disposed between the second electrode and the third electrode;
A second signal detector disposed between the third electrode and the fourth electrode and including a differential output type magnetoresistive element;
The second electrode includes a magnetic metal, and the third electrode includes a nonmagnetic metal. The magnetic head according to claim 1, wherein a thickness of the second electrode is 3 nm or more and 20 nm or less. The magnetic head according to claim 1, wherein a thickness of the third electrode is 10 nm or more and 60 nm or less. 4. The device according to claim 1, wherein each of the first signal detection unit and the second signal detection unit includes a nonmagnetic layer and a first free layer and a second free layer disposed on both sides of the nonmagnetic layer. 2. A magnetic head according to claim 1. The first signal detection unit further includes a first hard bias and a second hard bias;
5. The nonmagnetic layer, the first free layer, and the second free layer of the first signal detection unit are disposed between the first hard bias and the second hard bias. The magnetic head described in 1. A fifth electrode disposed between the insulating layer and the third electrode;
A third signal detector disposed between the fifth electrode and the third electrode and including a differential output type magnetoresistive element;
A sixth electrode disposed between the third signal detector and the third electrode;
A second insulating layer disposed between the sixth electrode and the third electrode;
At least one of the fifth electrode and the sixth electrode includes a nonmagnetic metal;
The magnetic head according to claim 1. The magnetic head according to claim 6, wherein the other of the fifth electrode and the sixth electrode includes a magnetic material. A first side shield and a second side shield disposed between the first electrode and the second electrode;
8. The magnetic head according to claim 1, wherein the first signal detection unit is disposed between the first side shield and the second side shield. 9. A magnetic head according to claim 1;
A signal output unit for outputting a third signal based on the first signal and the second signal respectively output from the first signal detection unit and the second signal detection unit;
A magnetic recording / reproducing apparatus comprising: Forming a first signal detection unit including a differential output type magnetoresistive element on a first electrode including a magnetic material;
Forming a second electrode on the first signal detector;
Forming an insulating layer on the second electrode;
Forming a third electrode on the insulating layer;
Forming a second signal detector including a differential output type magnetoresistive element on the third electrode;
Forming a fourth electrode including a magnetic material on the second signal detection unit,
A method of manufacturing a magnetic head, wherein the second electrode includes a magnetic metal and the third electrode includes a nonmagnetic metal.

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