JP2012128899A - Magnetic sensor and magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor and a magnetic head which are suitable for mass production and can raise output in such a structure that a magnetic flux from a minute area can be detected.SOLUTION: A magnetic sensor 1 includes: a main channel layer 7a which has a first area 71, a second area 72, and a third area 73 and extends in a first direction; a first ferromagnetic layer 12A laminated on the first area 71; a second ferromagnetic layer 12B laminated on the second area 72; a projection channel layer 7b which projects in the direction perpendicular to the thickness direction of the main channel layer 7a from the side of the third area 73 between the first area 71 and the second area 72 in the main channel layer 7a; and a magnetic shield S which covers both sides in the thickness direction of the projection channel layer 7b and both sides in the first direction of the projection channel layer 7b, and exposes an end surface 7c in the projection direction of the projection channel layer 7b. The magnetization direction of the first ferromagnetic layer 12A is in antiparallel with the magnetization direction of the second ferromagnetic layer 12B.

Description

  The present invention relates to a magnetic sensor and a magnetic head.

  Conventionally, various elements for detecting an external magnetic field are known (see, for example, Patent Document 1 below). For example, magnetic heads and magnetic sensors used in HDDs and the like are desired to detect magnetic fields from minute regions and to have high output characteristics. A conventional TMR element has a spin valve type structure and has a relatively large output characteristic. In order to detect a magnetic field from a minute region, a method of miniaturizing the element is taken, but the element resistance increases when the element is miniaturized. For example, in the recording density region of 1 Tbit / inch or higher, there is a limit to improvement in characteristics, and another structure or method is required.

JP 2007-299467 A

  Thus, for example, the structure of the magnetic sensor P1 as shown in FIG. In the magnetic sensor P1, a channel 7e is stacked on the substrate SB, and the first ferromagnetic layer 12A and the second ferromagnetic layer 12B, the first reference electrode 20A and the second reference electrode 20B are formed on the channel 7e. Are stacked. A portion of the channel 7e between the first ferromagnetic layer 12A and the second ferromagnetic layer 12B is covered with the magnetic shield layer S11. A through hole H extending toward the channel 7e is formed in the magnetic shield layer S11. In this structure, the magnetization direction G11 of the first ferromagnetic layer 12A and the magnetization direction G12 of the second ferromagnetic layer 12B are set to the Y-axis direction, and an external magnetic field is applied to the channel 7e from the Z-axis direction through the through hole H. Can be considered. The direction of the spin conducted in the channel 7e rotates around the axis of the applied magnetic field, and the spin diffuses with this rotation (so-called Hanle effect). In such a structure of the magnetic sensor P1, the resolution of detection of the external magnetic field is determined by the size of the through hole H provided in the magnetic shield layer S11. Therefore, the magnetic flux from the minute region corresponding to the size of the through hole H can be detected. At this time, since the magnetic flux can be detected without reducing the size of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B, the element by miniaturizing the first ferromagnetic layer 12A and the second ferromagnetic layer 12B. It is possible to suppress an increase in resistance.

  However, in the structure shown in FIG. 7, the axial direction of the through hole H into which the external magnetic field penetrates is the same as the stacking direction of the channel 7e on the substrate SB. That is, when such a magnetic sensor P1 is applied to a read head portion of a magnetic head, a lamination process parallel to ABS (Air Bearing Surface) is performed. On the other hand, the recording head portion for writing of the magnetic head is usually produced by a lamination process perpendicular to the ABS surface. Therefore, it is difficult to continuously manufacture the reading head unit and the recording head unit, which is not suitable for mass production.

  Further, as in the magnetic sensor P2 shown in FIG. 8, a structure in which the through hole H is formed in the magnetic shield layer S12 covering the side portion of the channel 7e is also conceivable. In this structure, it is conceivable that the magnetization direction G13 of the first ferromagnetic layer 12A and the magnetization direction G14 of the second ferromagnetic layer 12B are Z-axis directions and an external magnetic field from the Y-axis direction is detected. The through hole H is disposed to face the side surface of the channel 7 existing between the first ferromagnetic layer 12A and the second ferromagnetic layer 12B. With this arrangement, the external magnetic field from the minute region can be read from the side surface of the channel 7 through the through hole H. In FIG. 8, 81A, 81B, 7f, and 7g denote insulating films, and 8 denotes a permanent magnet.

  However, when the magnetic sensor P2 having the structure shown in FIG. 8 is manufactured, the substrate is cut and processed after the lamination process for forming the channel 7e, the first ferromagnetic layer 12A, the second ferromagnetic layer 12B, and the like on the substrate. . And after processing, it is necessary to laminate | stack again the magnetic shielding layer S12 on the side part of the channel 7e, and to form the micro through-hole H by photo processing. Such a manufacturing method is not suitable for mass production.

  Further, in the structure of the magnetic sensor P1 shown in FIG. 7, since the magnetic shield layer S11 covering the channel 7e is formed and then the alignment is made and the through hole H is opened, the width of the channel 7e through which spin is conducted (Y in FIG. 7) The width of the through hole H (the length in the Y-axis direction in FIG. 7) must be made smaller than the length in the axial direction. For this reason, the external magnetic field applied from the through hole H reaches only a part of the width of the channel 7e through which the spin flows, and it is difficult to improve the output. Similarly, in the structure of the magnetic sensor P2 shown in FIG. 8, after the magnetic shield layer S12 covering the channel 7e is formed, alignment is performed and the through hole H is opened, so that the thickness of the channel 7e through which spin is conducted (in FIG. 8) The height of the through hole H (the length in the Z-axis direction in FIG. 8) must be reduced with respect to the length in the Z-axis direction. For this reason, the external magnetic field applied from the through hole H reaches only a part of the thickness of the channel 7e through which the spin flows, and it is difficult to improve the output.

Further, in the magnetic sensor P1 shown in FIG. 7 and the magnetic sensor P2 shown in FIG. 8, spins are injected from the first ferromagnetic layer 12A or the second ferromagnetic layer 12B into the channel 7e. In this spin injection method, the flow of charge is Not accompanied (so-called nonlocal spin injection method). The spin conduction distance in this non-local spin injection method is the length d _NL shown in FIG. This length d _NL is equal to the length of the first ferromagnetic layer 12A (the length in the X-axis direction shown in FIGS. 7 to 9) at a distance from the first ferromagnetic layer 12A to the second ferromagnetic layer 12B. Half and the half of the length of the second ferromagnetic layer 12B (the length in the X-axis direction shown in FIGS. 7 to 9) are added. Therefore, the magnetic sensor using the non-local spin injection method has an advantage that the magnetic field from a minute region can be detected even if the first ferromagnetic layer 12A or the second ferromagnetic layer 12B is enlarged, but it is effective. There is a demerit that the spin conduction distance d _NL becomes longer.

  The present invention has been made to solve the above problems, and provides a magnetic sensor and a magnetic head that are suitable for mass production and can improve output in a structure capable of detecting magnetic flux from a minute region. For the purpose.

  In order to solve the above-described problem, the magnetic sensor of the present invention has a first region, a second region, and a third region, a main channel layer extending in the first direction, and a first layer stacked on the first region. A direction perpendicular to the thickness direction of the main channel layer from the side surface of the third region between the first region and the second region in the ferromagnetic layer, the second ferromagnetic layer stacked on the second region, and the main channel layer A projecting channel layer projecting in the direction of thickness, both sides of the projecting channel layer in the thickness direction, and both sides of the projecting channel layer in the first direction, and exposing a projecting direction end surface of the projecting channel layer. The magnetization direction of the magnetic layer is antiparallel to the magnetization direction of the second ferromagnetic layer.

  In the magnetic sensor of the present invention, the channel has a main channel layer and a protruding channel layer, and the magnetic shield surrounds the protruding direction of the protruding channel layer so as to expose the end face of the protruding channel layer. . Therefore, the external magnetic field can be selectively supplied to the channel from the exposed end face. In this configuration, if the magnetization directions of the first and second ferromagnetic layers are antiparallel, the spin injected into the channel is less likely to be absorbed by the other ferromagnetic layer and is likely to remain in the channel. it is conceivable that. The direction of the spin conducted in the channel rotates around the axis of the applied magnetic field, and the spin diffuses with this rotation (so-called Hanle effect). Due to this spin rotation, the electrical resistance changes (so-called magnetoresistance effect). On the other hand, when an external magnetic field is not applied to the channel, the spin direction in the channel does not change and diffuses as it is. Therefore, a power source and an output measuring device are provided between the first ferromagnetic layer and the second ferromagnetic layer, and the change in the output is monitored, depending on whether or not an external magnetic field is applied, depending on the degree of spin rotation. Output can be detected.

  If the magnetization directions of the first and second ferromagnetic layers are parallel, it is difficult to read the change in output. This is presumably because the spin injected into the channel quickly propagates through the channel and is less affected by the external magnetic field applied from the protruding channel layer. Further, in the magnetic sensor of the present invention using the magnetoresistance measurement method, the output can be remarkably increased as compared with the magnetic sensor using the conventional non-local measurement method as shown in FIGS.

  Further, as described above, in the magnetic sensor of the present invention, the magnetic shield surrounds the protruding direction of the protruding channel layer so as to expose the end face of the protruding channel layer. In such a structure, a part of the magnetic shield is formed in advance, a channel including the main channel layer and the protruding channel layer is formed thereon, and then the magnetic shield is formed on the side and above the protruding channel layer. By forming the other part, it can be formed easily and has high mass productivity. Further, for example, when the magnetic sensor of the present invention is applied to a magnetic head, it can be stacked perpendicularly to the ABS surface, so that it is also compatible with a method for manufacturing a recording head part formed by vertically stacking the ABS surface. Highly preferable.

  Furthermore, in the magnetic sensor of the present invention, since the magnetic shield does not require a process of making a through hole for supplying a magnetic field, it is easy to make the thickness of the end face of the protruding channel layer the same as the thickness of the main channel layer. . Therefore, the thickness of the intrusion region of the external magnetic field applied from the end face of the protruding channel layer can be made equal to the thickness of the main channel layer through which spin flows, so that the output can be increased. And the magnetic flux from the micro area | region corresponding to the magnitude | size of the exposed end surface of a channel is detectable.

  The magnetization direction of the first ferromagnetic layer and the magnetization direction of the second ferromagnetic layer are preferably perpendicular to the direction in which the protruding channel layer protrudes. As described above, when an external magnetic field is applied to the channel, the spin direction in the channel rotates around the axis of the applied magnetic field. If the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are parallel to the direction in which the protruding channel layer protrudes, the protruding channel layer can be injected from either ferromagnetic layer. Rotation does not occur in the spin direction due to the external magnetic field applied from the direction in which the magnetic field protrudes, and it is difficult to detect the magnetic flux. Therefore, if the direction of magnetization of the first ferromagnetic layer and the second ferromagnetic layer is a direction perpendicular to the direction in which the protruding channel layer protrudes, it is possible to suitably detect the magnetic flux as described above.

  In addition, the magnetization direction of the first ferromagnetic layer is preferably parallel to the first direction, and the magnetization direction of the second ferromagnetic layer is preferably antiparallel to the first direction. Alternatively, the magnetization direction of the first ferromagnetic layer is a direction parallel to the stacking direction of the first and second ferromagnetic layers with respect to the channel layer, and the magnetization direction of the second ferromagnetic layer is the channel layer. The direction is preferably antiparallel to the stacking direction of the first and second ferromagnetic layers. In any case, the detection of the magnetic flux as described above can be suitably performed due to the external magnetic field applied from the direction in which the protruding channel layer protrudes.

  At least one of the magnetization direction of the first ferromagnetic layer and the magnetization direction of the second ferromagnetic layer is caused by an antiferromagnetic layer disposed on the first ferromagnetic layer or the second ferromagnetic layer, respectively. It is preferably fixed. When the antiferromagnetic layer is exchange coupled with the first ferromagnetic layer or the second ferromagnetic layer, unidirectional anisotropy can be imparted to the magnetization direction of the first ferromagnetic layer or the second ferromagnetic layer. It becomes possible. In this case, a first ferromagnetic layer and a second ferromagnetic layer having a higher coercive force in one direction can be obtained than when no antiferromagnetic layer is provided.

  In addition, it is preferable that at least one of the magnetization direction of the first ferromagnetic layer and the magnetization direction of the second ferromagnetic layer has a magnetization direction fixed by shape anisotropy. In this case, the magnetization direction can be fixed by forming at least one of the first ferromagnetic layer and the second ferromagnetic layer so as to have an appropriate shape.

  Moreover, it is preferable that the surfaces of the main channel layer and the protruding channel layer are covered with an insulating film between the first ferromagnetic layer and the second ferromagnetic layer. In this case, spin outflow from the main channel layer and the protruding channel layer to the magnetic shield can be prevented, and the output measurement by the external magnetic field can be accurately performed. In addition, the main channel layer and the protruding channel layer are preferably electrically insulated from the magnetic shield between the first ferromagnetic layer and the second ferromagnetic layer. In this case, it is possible to suitably suppress the outflow of current and spin current from the main channel layer and the protruding channel layer to the magnetic shield.

  Moreover, it is preferable to further include a permanent magnet that supplies a magnetic field to the main channel layer through the end face of the protruding channel layer. When a magnetic field is not applied to a channel using a permanent magnet, an output peak appears when the external magnetic field to be detected is zero, but the peak position of the output is shifted by applying a magnetic field to the channel using a permanent magnet. It is possible to generate an output peak when the external magnetic field is not zero.

  The material of the first ferromagnetic layer and the second ferromagnetic layer is selected from a metal selected from the group consisting of Cr, Mn, Co, Fe, and Ni, an alloy containing one or more elements of the group, or a group. It is preferable that the compound includes at least one element selected from the group consisting of B, C, N, Si, and Ge. Since these materials are ferromagnetic materials having a high spin polarizability, the function as a spin injection electrode or a spin reception electrode can be suitably realized.

  Further, the material of the main channel layer and the protruding channel layer is preferably a semiconductor containing any one of Si, Ge, GaAs, C, and ZnO. Since these semiconductors have a relatively long spin diffusion length, spins can be suitably accumulated in the channel.

In addition, a barrier is preferably formed between at least one of the first ferromagnetic layer and the second ferromagnetic layer and the main channel layer. This makes it possible to inject a large amount of spin-polarized electrons from at least one of the first ferromagnetic layer and the second ferromagnetic layer into the main channel layer, and to increase the potential output of the magnetic sensor. As such a barrier, a tunnel barrier made of an MgO film, an Al ₂ O ₃ film, a TiO ₂ film, an MgAl ₂ O ₄ film, or a ZnO film is preferably applied. Alternatively, the barrier is preferably a Schottky barrier.

  According to another aspect of the present invention, there is provided a magnetic head comprising: a reading head unit comprising the above-described magnetic sensor; and a recording head unit for writing. Thereby, a novel magnetic head using the so-called Hanle effect and magnetoresistive effect can be provided.

  According to the present invention, it is possible to provide a magnetic sensor and a magnetic head that are suitable for mass production and capable of improving output in a structure capable of detecting magnetic flux from a minute region.

FIG. 1 is a schematic perspective view of a magnetic sensor according to the present embodiment. FIG. 2 is a schematic perspective view showing the shape of the channel. Fig.3 (a) is a side view which shows the shape of the end surface of the protrusion direction of a through-hole and a protrusion channel layer. FIG.3 (b) is a side view which shows the modification of the shape of the end surface of the protrusion direction of a through-hole and a protrusion channel layer. FIG.3 (c) is a side view which shows the modification of the shape of the end surface of the protrusion direction of a through-hole and a protrusion channel layer. FIG. 4A is a top view showing the shape of the channel. FIG. 4B is a top view showing a modification of the shape of the channel. FIG. 5 is a schematic diagram showing a thin film magnetic recording / reproducing head including a magnetic sensor. FIG. 6 is a graph showing the relationship between the external magnetic field and the resistance output in the magnetoresistance measurement method. FIG. 7 is a top view showing an example of a magnetic sensor. FIG. 8 is a side view showing an example of a magnetic sensor. FIG. 9 is a top view showing a comparison of effective distances for spin conduction between the non-local measurement method and the magnetoresistance measurement method. FIG. 10 is a graph showing the relationship between the external magnetic field and the resistance output in the non-local measurement method. FIG. 11 is a schematic perspective view showing a method of obtaining a desired number of graphene layers by a peeling method in the order of (a) to (c). FIG. 12 is a schematic perspective view illustrating a method of obtaining a desired number of graphene layers by a peeling method in the order of (a) to (d), following FIG. 11.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a magnetoresistive magnetic sensor according to the present invention will be described in detail with reference to the drawings. In the figure, an XYZ orthogonal coordinate axis system is shown.

  FIG. 1 is a schematic perspective view of a magnetic sensor 1 in the present embodiment. The magnetic sensor 1 mainly includes a substrate 21, a channel 7, a first ferromagnetic layer 12A, a second ferromagnetic layer 12B, and a magnetic shield S, and detects an external magnetic field B from the −Y-axis direction. It is. The substrate 21 is, for example, an AlTiC substrate. The substrate 21 has a first portion 21a and a second portion 21b. The first portion 21a and the second portion 21b extend in a predetermined axial direction (X-axis direction in this example) in the substrate 21 and are arranged in parallel to each other.

  The channel 7 includes a main channel layer 7a extending in the first direction (here, the X-axis direction) and a protruding channel layer 7b protruding in the Y-axis direction. As shown in FIG. 1, the main channel layer 7 a is disposed above the first portion 21 a of the substrate 21, and the protruding channel layer 7 b is disposed above the second portion 21 b of the substrate 21.

  FIG. 2 is a schematic perspective view showing the shape of the channel 7. The main channel layer 7a has a rectangular shape when viewed from the thickness direction of the channel 7 (Z-axis direction). The main channel layer 7 a has a first region 71, a second region 72, and a third region 73. Here, the third region 73 is disposed between the first region 71 and the second region 72.

  The protruding channel layer 7b protrudes from the side surface of the third region 73 in the main channel layer 7a in a direction (Y axis direction) perpendicular to the thickness direction (Z axis direction) of the main channel layer 7a. More specifically, the protruding channel layer 7b has a direction perpendicular to the first direction (X-axis direction) and a stacking direction of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B with respect to the channel 7 (Z-axis direction). Projecting in a direction perpendicular to (Y-axis direction).

An ion for imparting conductivity may be added to the channel 7. The ion concentration can be, for example, 1.0 × 10 ^{15 to} 1.0 × 10 ²² cm ⁻³ . The channel 7 is preferably made of a material having a long spin lifetime, and can be, for example, a semiconductor containing any one of Si, Ge, GaAs, C, and ZnO. The distance d _MR from the first ferromagnetic layer 12A to the second ferromagnetic layer 12B in the channel 7 is preferably equal to or less than the spin diffusion length in the channel 7.

  The first ferromagnetic layer 12 </ b> A and the second ferromagnetic layer 12 </ b> B function as an injection electrode for injecting spin into the channel 7 or a receiving electrode for detecting the spin conducted through the channel 7. The first ferromagnetic layer 12 </ b> A is stacked on the first region 71 of the channel 7. The second ferromagnetic layer 12 </ b> B is stacked on the second region 72 of the channel 7. Each of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B has a rectangular parallelepiped shape with the major axis in the Y-axis direction. The first ferromagnetic layer 12A and the second ferromagnetic layer 12B can have the same length in the X-axis direction.

  As shown in FIGS. 1 and 2, the magnetization direction G1 of the first ferromagnetic layer 12A (in this example, the direction parallel to the first direction, that is, the X-axis direction) is the magnetization direction G2 of the second ferromagnetic layer 12B. (In this example, the direction is antiparallel to the first direction, that is, the -X axis direction). The first ferromagnetic layer 12A and the second ferromagnetic layer 12B are made of a ferromagnetic material. The material of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B is, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe, Ni, an alloy containing one or more elements of the group, or the above The compound may include one or more elements selected from the group and one or more elements selected from the group consisting of B, C, N, Si, and Ge.

  As shown in FIG. 2, the magnetic shield S shields the external magnetic field from entering the channel 7, the first ferromagnetic layer 12A, and the second ferromagnetic layer 12B. The magnetic shield S covers both sides of the protruding channel layer 7b in the thickness direction (Z-axis direction) and both sides of the protruding channel layer 7b in the first direction (X-axis direction) via an insulating layer, and the protruding channel layer 7b. The end surface 7c in the protruding direction is exposed. Such a magnetic shield S is constituted by the first magnetic shield layer S1 and the second magnetic shield layer S2. The first magnetic shield layer S1 is disposed above the second portion 21b of the substrate 21. The second magnetic shield layer S2 is provided on the second portion 21b of the substrate 21. Examples of the material of the magnetic shield S (the first magnetic shield layer S1 and the second magnetic shield layer S2) include an alloy containing Ni and Fe, sendust, an alloy containing Fe and Co, an alloy containing Fe, Co, and Ni. Examples include soft magnetic materials. The thickness (length in the Z-axis direction) of S1 of the first magnetic shield layer is larger than the thickness (length in the Z-axis direction) of the main channel layer 7a and the protruding channel layer 7b, for example, 0.02 μm to 1 μm. . Moreover, the thickness (length in the Z-axis direction) of S2 of the second magnetic shield layer is, for example, 0.02 μm to 1 μm.

  The magnetic shield S has a through hole H that exposes the end face 7c in the protruding direction (Y-axis direction) of the protruding channel layer 7b. The through hole H is for applying an external magnetic field B to the main channel layer 7a via the protruding channel layer 7b. The external magnetic field B enters the channel 7 from the end face 7c of the protruding channel layer 7b exposed in the through hole H.

  FIG. 3A is a side view showing an example of the shape of the end face 7c in the protruding direction of the through hole H and the protruding channel layer 7b. The end surface 7c exposed through the through hole H is a flat surface, and the end surface 7c has a rectangular shape. The shape of the through hole H corresponds to the shape of the end face 7c, and can take various shapes when viewed from the axial direction (−Y axis direction) of the through hole H. In this example, the shape is rectangular. ing. The length of one side (length in the X-axis direction) D1 of the through hole H is, for example, 0.01 μm to 0.1 μm, and the length of the other side (length in the Z-axis direction) D2 is, for example, 0.001 μm to 0.00. It can be 1 μm. The length of the other side of the through hole H (the length in the Z-axis direction) D2 is the same as the thickness of the main channel layer 7a and the protruding channel layer 7b.

The magnetic sensor 1 preferably further includes a barrier. The barrier is provided between the main channel layer 7a and at least one of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B. As a result, it is possible to inject many spin-polarized electrons from at least one of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B into the main channel layer 7a, and to increase the potential output of the magnetic sensor. Become. In the example shown in FIGS. 1 and 2, the barrier is a tunnel barrier made of insulating films 81A and 81B. The insulating film 81A is provided between the first region 71 of the main channel layer 7a and the first ferromagnetic layer 12A. The insulating film 81B is provided between the second region 72 of the main channel layer 7a and the second ferromagnetic layer 12B. Although this example shows a case where the insulating films 81A and 81B are formed of a single layer, the insulating films 81A and 81B may have a stacked structure including a plurality of layers. As the insulating films 81A and 81B, for example, an MgO film, an Al ₂ O ₃ film, a TiO ₂ film, a ZnO film, or a MgAl ₂ O ₄ film having a spinel structure can be used. From the viewpoint of suppressing an increase in resistance and functioning as a tunnel insulating layer, the thickness of the insulating films 81A and 81B is preferably 3 nm or less. The film thickness of the insulating films 81A and 81B is preferably 0.4 nm or more in consideration of the thickness of one atomic layer.

  The magnetic sensor 1 further includes a lower insulating layer 22 and an intermediate insulating layer 23. The lower insulating layer 22 and the intermediate insulating layer 23 function as a base of the channel 7. The lower insulating layer 22 is provided on the first portion 21 a of the substrate 21. The intermediate insulating layer 23 is provided on the lower insulating layer 22 and the second magnetic shield layer S2. That is, the intermediate insulating layer 23 is disposed above the first portion 21 a and the second portion 21 b of the substrate 21. Therefore, the main channel layer 7 a is laminated on the intermediate insulating layer 23 disposed above the first portion 21 a of the substrate 21. Further, the protruding channel layer 7 b is laminated on the intermediate insulating layer 23 disposed above the second portion 21 b of the substrate 21.

  The lower insulating layer 22 and the intermediate insulating layer 23 are made of an insulating material, for example, an oxide film such as alumina. The thickness (length in the Z-axis direction) of the lower insulating layer 22 is, for example, 0.02 μm to 1 μm. Moreover, the thickness (length in the Z-axis direction) of the intermediate insulating layer 23 is, for example, 0.003 μm to 0.03 μm. Thus, by making the lower insulating layer 22 and the intermediate insulating layer 23 that are the base of the channel 7 relatively thick, it is possible to suppress the leakage of spin current and current from the channel 7.

The magnetic sensor 1 further includes a channel-magnetic shield insulating layer 24. The channel-magnetic shield insulating layer 24 is provided between the channel 7 (the main channel layer 7a and the protruding channel layer 7b) and the first magnetic shield layer S1. The intermediate insulating layer 23 provided on the lower surface of the protruding channel layer 7b, and the channel-magnetic shield insulating layer 24 provided on the upper surface and side surfaces of the protruding channel layer 7b and further on one side surface of the main channel layer 7a in the Y-axis direction. Thus, the channel 7 is insulated from the first magnetic shield layer S1 and the second magnetic shield layer S2. The channel-magnetic shield insulating layer 24 is made of an insulating material, and is an oxide film such as SiO ₂ .

  Hereinafter, an example of a method for manufacturing the magnetoresistive magnetic sensor 1 according to the present embodiment will be described. First, alignment marks are formed on a substrate 21 prepared in advance. Using the alignment mark as a mark, a magnetic shield film to be the second magnetic shield layer S2 is formed on the substrate 21. Next, a resist mask is formed by photolithography, and an excess magnetic shield film is removed by milling or RIE. Thus, the second magnetic shield layer S2 is formed on the second portion 21b of the substrate 21.

Subsequently, an insulating film to be the lower insulating layer 22 is formed on the entire surface of the substrate 21 and polished by CMP until the second magnetic shield layer S2 is exposed. As a result, the lower insulating layer 22 is formed on the first portion 21 a of the substrate 21. Next, an insulating layer to be the intermediate insulating layer 23 is formed on the entire surface of the substrate 21, that is, on the first portion 21a and the second portion 21b by MBE. Examples of the insulating layer to be the intermediate insulating layer 23 include an HfO ₂ film, an SiO ₂ film, an Al ₂ O ₃ film, an MgO film, an SiC film, or an MgAl ₂ O ₄ film, and the thickness is, for example, 3 to 30 nm. And

  Thereafter, a semiconductor layer to be the channel 7 is formed on the insulating layer to be the intermediate insulating layer 23 by MBE. An example of this semiconductor layer is a 50 nm Si layer. This semiconductor layer is crystallized by laser annealing.

  After crystallization of the semiconductor layer, the surface of the semiconductor layer is cleaned by RCA cleaning and hydrofluoric acid. Subsequently, for example, an MgO layer having a thickness of 1 nm, a first ferromagnetic layer 12A and a second ferromagnetic layer 12B having a thickness of, for example, 5 nm, and a protective layer having a thickness of 3 nm are formed on the semiconductor layer by MBE. Thereafter, the protective film is removed by an ion milling method, and a part of the Fe layer that becomes the first ferromagnetic layer 12A and the second ferromagnetic layer 12B is removed to form, for example, a 3 nm Fe layer.

  Further, a synthetic composite film made of, for example, CoFe, Ru, CoFe, IrMn, Ru, and Ta in this order is formed on the Fe layer to be the first ferromagnetic layer 12A and the second ferromagnetic layer 12B by sputtering. With this structure, the Fe layer is fixed by the antiferromagnetic layer.

  Subsequently, annealing is performed under a magnetic field, thereby improving the coupling between the Fe layer and the CoFe layer that become the first ferromagnetic layer 12A and the second ferromagnetic layer 12B, and the first ferromagnetic layer 12A by the antiferromagnetic layer. The magnetization direction of the second ferromagnetic layer 12B is fixed. At this time, the magnetization direction is fixed so that the magnetization direction G1 (for example, the X-axis direction) of the first ferromagnetic layer 12A is antiparallel to the magnetization direction G2 (for example, the -X-axis direction) of the second ferromagnetic layer 12B. To do.

  After annealing, a resist mask is formed by photolithography, and the entire device is processed by etching and ion milling. At this time, by processing the semiconductor layer, the channel 7 including the main channel layer 7a and the protruding channel layer 7b as shown in FIG. 2 is formed.

  Thereafter, an insulating layer of, eg, 50 nm is formed on the exposed side surface of the channel 7. Then, a mask for processing the Fe layer to be the first ferromagnetic layer 12A and the second ferromagnetic layer 12B and the synthetic composite film into, for example, a rectangular shape is formed by an EB method or a photolithography method. Using this mask, unnecessary barrier layers and ferromagnetic layers on the channel 7 and a part of the channel 7 are removed by ion milling. As a result, the first ferromagnetic layer 12A is formed on the first region 71 of the channel 7 via the insulating film 81A, and the second ferromagnetic layer 12B is formed on the second region 72 of the channel 7 via the insulating film 81B. It is formed.

  Further, an insulating layer of 20 nm, for example, is formed on the exposed surface of the channel 7, the side surfaces of the insulating films 81A and 81B, and the side surfaces of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B. Subsequently, the upper portion of the first portion 21a of the substrate 21 is covered with a resist mask by photolithography, and the first magnetic shield layer S1 is formed above the second portion 21b of the substrate 21. Thereby, the protruding channel layer 7b is covered with the first magnetic shield layer S1 via the insulating layer (channel-magnetic shield insulating layer 24). The first magnetic shield layer S1 is formed on the second magnetic shield layer S2 via the intermediate insulating layer 23. Thus, the magnetic shield S covers both sides of the protruding channel layer 7b in the thickness direction (Z-axis direction) and both sides of the protruding channel layer 7b in the first direction (X-axis direction) via the insulating layer, and The end surface 7c in the protruding direction of the protruding channel layer 7b is exposed.

  Further, a plurality of electrode pads are formed on the substrate 21, and wiring is provided between the first ferromagnetic layer 12A and the second ferromagnetic layer 12B using the plurality of electrode pads. By the above method, the magnetic sensor 1 shown in FIGS. 1, 2, and 3 is manufactured.

  Hereinafter, the operation and effect of the magnetoresistive magnetic sensor 1 according to the present embodiment will be described. Before operating the magnetic sensor 1, for example, as shown in FIGS. 1, 2, and 4A, the magnetization direction G1 of the first ferromagnetic layer 12A (here, a direction parallel to the first direction, That is, the magnetization direction is fixed so that the X-axis direction is antiparallel to the magnetization direction G2 of the second ferromagnetic layer 12B (here, the direction antiparallel to the first direction, that is, the −X axis direction).

  In this magnetic sensor 1, the channel 7 has a main channel layer 7a and a protruding channel layer 7b, and the magnetic shield S in the protruding direction of the protruding channel layer 7b so that the end surface 7c of the protruding channel layer 7b is exposed. Surrounds. Therefore, the magnetic field B from the outside can be selectively supplied to the channel 7 from the exposed end surface 7c.

  As shown in FIG. 1, the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are connected to a current source 70, and a detection current is passed between the first ferromagnetic layer 12A and the second ferromagnetic layer 12B. For example, when a current flows from the first ferromagnetic layer 12A, which is a ferromagnetic material, to the nonmagnetic main channel layer 7a via the insulating film 81A, the direction corresponding to the magnetization direction G1 of the first ferromagnetic layer 12A is obtained. Electrons having a spin are injected into the channel 7. The injected spin is diffused along with the electric charge toward the second ferromagnetic layer 12B. In this way, the current and spin current flowing through the channel 7 can be configured to flow mainly in the first direction (X-axis direction). In this configuration, when the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are antiparallel, the spin injected into the channel 7 is difficult to be absorbed by the other ferromagnetic layer, It is thought that it becomes easy to stay in.

  Here, when the external magnetic field B is not applied to the channel 7, that is, when the external magnetic field B is zero, the direction of the spin that diffuses in the third region 73 between the first region 71 and the second region 72 of the channel 7 is Does not rotate. Therefore, spins in the same direction as the magnetization direction G 2 of the second ferromagnetic layer 12 B set in advance diffuse to the second region 72. Therefore, when the external magnetic field B is zero, the resistance output or voltage output becomes the maximum value. The output can be evaluated by an output measuring device such as a voltage measuring device 80 connected to the first ferromagnetic layer 12A and the second ferromagnetic layer 12B.

  On the other hand, consider a case where an external magnetic field B is applied to the channel 7. The external magnetic field B is applied to the channel 7 from the end face 7c of the protruding channel layer 7b exposed at the through hole H. In the example of FIG. 1, the external magnetic field B is perpendicular to the magnetization direction G1 (X-axis direction) of the first ferromagnetic layer 12A and the magnetization direction G2 (−X-axis direction) of the second ferromagnetic layer 12B ( -Apply from (Y axis direction). When the external magnetic field B is applied, the direction of the spin that has propagated through the region corresponding to the through hole H in the channel 7 rotates around the axial direction (−Y axis direction) of the external magnetic field B (so-called Hanle effect). ). Due to this spin rotation, the electrical resistance changes (so-called magnetoresistance effect). That is, when the external magnetic field B is applied, the direction of the spin injected from the first ferromagnetic layer 12A and propagating through the channel 7 is rotated, so that it is deviated from the magnetization direction in the first ferromagnetic layer 12A. Therefore, when the maximum value is obtained when the external magnetic field B is zero, the output is decreased from the maximum value by applying the external magnetic field B. Therefore, an output corresponding to the degree of spin rotation can be detected depending on whether or not an external magnetic field is applied. Further, it is possible to detect a magnetic flux from a minute region corresponding to the size of the exposed end face of the channel.

  In addition, when the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are parallel, it is difficult to read the change in output. This is presumably because the spin injected into the channel 7 quickly propagates through the channel and is less affected by the external magnetic field applied from the protruding channel layer 7b.

  FIG. 6 is a graph showing the relationship between the external magnetic field and the resistance output by the magnetoresistance measurement method in the magnetic sensor 1. As indicated by R1 in FIG. 6, when the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are antiparallel, the maximum value when the external magnetic field is zero is 0.00008 (V). It is about. On the other hand, as indicated by R2 in FIG. 6, when the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are parallel, no peak is observed when the external magnetic field is zero. This is because when the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are antiparallel, the spin injected into the channel 7 is not easily absorbed by the other ferromagnetic layer. When the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are parallel, the spin injected into the channel 7 quickly propagates through the channel 7 and is less affected by the external magnetic field B. Conceivable.

  Further, in the magnetic sensor of the present invention using the magnetoresistance measurement method, the output can be remarkably increased as compared with the magnetic sensor using the conventional non-local measurement method as shown in FIGS. As a comparison, FIG. 10 shows the relationship between the external magnetic field and the resistance output in a non-local measurement method such as the magnetic sensors P1 and P2 shown in FIGS. As indicated by R3 in FIG. 10, when the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are parallel, the maximum value when the external magnetic field is zero is about 0.00002 (V). It has become. Further, when the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are antiparallel as indicated by R4 in FIG. 10, the minimum value when the external magnetic field is zero is −0.00002 ( V) grade. As described above, in the magnetic sensor 1 using the magnetoresistance measurement method in which the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are antiparallel, the magnetic sensors P1 and P2 using the nonlocal measurement method are used. A remarkably high output can be obtained.

Further, the effective distance d _MR for spin conduction in the magnetoresistance measurement method is the distance from the first ferromagnetic layer 12A to the second ferromagnetic layer 12B in the channel 7, and the non-local measurement method shown in FIG. Shorter than the effective distance d _NL for spin conduction at. Therefore, the influence of output attenuation due to the spin conduction distance is reduced, and high output can be realized. Actually, as shown by R1 in FIG. 6, when the magnetoresistance measurement method is used and the magnetization direction of the first ferromagnetic layer 12A is antiparallel to the magnetization direction of the second ferromagnetic layer 12B, the output is 0. 00008V. On the other hand, as shown by R3 in FIG. 10, the output when the magnetization direction of the first ferromagnetic layer 12A is parallel to the magnetization direction of the second ferromagnetic layer 12B using the non-local measurement method is 0. 00002V. Therefore, the output in the magnetoresistance measurement method can be four times the output in the non-local measurement method. This is because an increase in output of about 2 times can be obtained by shortening the effective spin conduction distance, and it is further reduced by 2 due to the difference in the principle observation method between the non-local measurement method and the magnetoresistance measurement method. This is considered to indicate that an output increase of about double is obtained. Moreover, it is considered that the change in output with respect to temperature can be suppressed by shortening the effective spin conduction distance.

  Further, in the magnetoresistive magnetic sensor 1 according to the present embodiment, a two-terminal structure using the first ferromagnetic layer 12A and the second ferromagnetic layer 12B as electrodes can be used, and therefore, as shown in FIG. 7 and FIG. The first reference electrode 20A and the second reference electrode 20B in a four-terminal structure such as the conventional non-local type magnetic sensors P1 and P2 can be eliminated.

  As described above, in the magnetic sensor 1 according to this embodiment, the peak of the maximum output appears when the external magnetic field B is zero, and when the external magnetic field B is increased or decreased, the output decreases. That is, since the output varies depending on the presence or absence of the external magnetic field B, the magnetic sensor 1 according to the present embodiment can be used as a magnetic detection element. Therefore, for example, when the magnetic sensor 1 according to the present embodiment is applied to a magnetic head or the like and the positive / negative timing of the external magnetic field is read, an output peak appears at the zero where the magnetic field of the domain wall cancels. Judgment can be made. Further, this magnetic sensor 1 has no hysteresis.

  Further, by using the end face 7c of the protruding channel layer 7b exposed from the magnetic shield S, a minute magnetic flux corresponding to the size of the end face 7c can be detected. At this time, since the resolution of detection of the external magnetic field is determined by the size of the end face 7c, the size (for example, the area of the XY plane) of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B is not reduced. Magnetic flux can be detected from a minute region. Therefore, it is also possible to suppress an increase in element resistance due to the miniaturization of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B.

  In the magnetic sensor 1, as described above, the magnetic shield S surrounds the protruding direction (Y-axis direction) of the protruding channel layer 7b so that the end surface 7c of the protruding channel layer 7b is exposed. In such a structure, a part of the magnetic shield S (second magnetic shield layer S2) is previously formed on the substrate 21, and the channel 7 including the main channel layer 7a and the protruding channel layer 7b is formed thereon. Furthermore, after that, by forming another part (first magnetic shield layer S1) of the magnetic shield S on the side and on the protruding channel layer 7b, it can be easily formed and the mass productivity is high. Further, for example, when the magnetic sensor 1 is applied to a magnetic head, the magnetic sensor 1 can be stacked perpendicularly to the ABS surface. High compatibility and preferable.

  Furthermore, in the magnetic sensor 1 according to the present embodiment, a process for forming a through hole for supplying a magnetic field in the magnetic shield using alignment is required as in the magnetic sensor P1 shown in FIG. 7 and the magnetic sensor P2 shown in FIG. And not. Therefore, it is easy to make the thickness (length in the Z-axis direction) of the end face 7c of the protruding channel layer 7b the same as the thickness (length in the Z-axis direction) of the main channel layer 7a. Therefore, the thickness (length in the Z-axis direction) of the penetration region of the external magnetic field B applied from the end face 7c of the protruding channel layer 7b is equal to the thickness (length in the Z-axis direction) of the main channel layer 7a through which spin flows. Therefore, the output can be increased.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment. The shape of the end surface 7c in the protruding direction of the protruding channel layer 7b is not limited to the above-described rectangle, and may be, for example, a triangle, a trapezoid, or a circle. In any shape, the external magnetic field B can be suitably detected. For example, in the example shown in FIG. 3B, the shape of the end surface 7c is a trapezoid in which the length of the upper base is shorter than the length of the lower base. In the example shown in FIG. 3C, the shape of the end surface 7c is a trapezoid in which the length of the upper base is longer than the length of the lower base.

  Moreover, in the said embodiment, as shown to Fig.4 (a), the main channel layer 7a of the channel 7 showed the example which is a rectangle seeing from the thickness direction. However, as shown in FIG. 4B, the side surface of the main channel layer 7a opposite to the protruding channel layer 7b is preferably recessed. That is, the channel 7 in the third region 73 has a meandering shape in the protruding channel layer 7b. With such a shape, the spin current in the channel 7 can be suitably passed to the protruding channel layer 7b, that is, the through hole H side. Therefore, the sensitivity of the magnetic sensor 1 with respect to the external magnetic field B can be increased, and the output characteristics can be further improved.

  4A and 4B, the protruding channel layer 7b has a trapezoidal shape having an inclined portion when viewed from the thickness direction of the channel 7 (Z-axis direction). That is, in the examples of FIGS. 4A and 4B, the shape of the protruding channel layer 7b when viewed from the thickness direction (Z-axis direction) of the channel 7 is the width on the tip side in the protruding direction (Y-axis direction). The main channel layer 7a side has a wider width (length in the X-axis direction) than (length in the X-axis direction). However, the shape of the protruding channel layer 7b is not limited to this. For example, the width (length in the X-axis direction) on the front end side in the protruding direction (Y-axis direction) of the protruding channel layer 7b may be the same as the width (length in the X-axis direction) on the main channel layer 7a side. However, the exposed end surface 7c of the protruding channel layer 7b is preferably a flat surface.

  In the above embodiment, the magnetization direction of the first ferromagnetic layer 12A is a direction parallel to the first direction (X-axis direction), and the magnetization direction of the second ferromagnetic layer 12B is antiparallel to the first direction. In this case, the direction is a negative direction (−X axis direction). As described above, when the external magnetic field B is applied to the channel 7, the spin direction in the channel 7 rotates around the axis of the applied magnetic field B (around the Y axis). If the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are parallel to the protruding direction of the protruding channel layer 7b, the external magnetic field B can be generated regardless of which ferromagnetic layer the spin is injected. Rotation does not occur in the spin direction due to the application of magnetic flux, and it is difficult to detect the magnetic flux. Therefore, in order to detect the magnetic field appropriately, the magnetization directions of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B are perpendicular to the direction in which the protruding channel layer 7b protrudes (Y-axis direction). Good.

  For example, the magnetization direction of the first ferromagnetic layer 12A is a direction parallel to the stacking direction of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B with respect to the channel layer 7 (for example, the Z-axis direction), and the second strong layer The direction of magnetization of the magnetic layer 12B may be a direction (eg, −Z axis direction) antiparallel to the stacking direction of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B with respect to the channel layer 7. Also in this case, the magnetization direction of the spin injected from the ferromagnetic layer and conducted in the channel 7 is rotated by the external magnetic field B applied from the end face 7c of the protruding channel layer 7b. Therefore, it is possible to suitably detect the magnetic flux as described above.

  At least one of the magnetization direction of the first ferromagnetic layer and the magnetization direction of the second ferromagnetic layer is caused by an antiferromagnetic layer disposed on the first ferromagnetic layer or the second ferromagnetic layer, respectively. It is preferably fixed. When the antiferromagnetic layer is exchange coupled with the first ferromagnetic layer or the second ferromagnetic layer, unidirectional anisotropy can be imparted to the magnetization direction of the first ferromagnetic layer or the second ferromagnetic layer. It becomes possible. In this case, a first ferromagnetic layer and a second ferromagnetic layer having a higher coercive force in one direction can be obtained than when no antiferromagnetic layer is provided.

  In addition, it is preferable that at least one of the magnetization direction of the first ferromagnetic layer and the magnetization direction of the second ferromagnetic layer has a magnetization direction fixed by shape anisotropy. In this case, the magnetization direction can be fixed by forming at least one of the first ferromagnetic layer and the second ferromagnetic layer so as to have an appropriate shape.

  In addition, it is preferable that at least one of the magnetization direction of the first ferromagnetic layer and the magnetization direction of the second ferromagnetic layer is fixed by the antiferromagnetic layer and the shape anisotropy. In this case, further higher output is possible.

  Moreover, it is preferable that the surfaces of the main channel layer 7a and the protruding channel layer 7b are covered with an insulating layer between the first ferromagnetic layer 12A and the second ferromagnetic layer 12B. Further, the end face 7c of the protruding channel layer 7b is not covered with the magnetic shield S but is exposed. In order to prevent the end surface 7c from coming into contact with the magnetic recording medium 20, a protective insulating film may be formed on the end surface 7c of the protruding channel layer 7b, or a lubricant may be applied to the end surface 7c. It may be applied.

  Further, it is preferable that the main channel layer 7a and the protruding channel layer 7b are electrically insulated from the magnetic shield S between the first ferromagnetic layer 12A and the second ferromagnetic layer 12B. In this case, it is possible to suppress the outflow of current and spin current from the main channel layer 7a and the protruding channel layer 7b to the magnetic shield.

  Further, as indicated by a dotted line in FIG. 1, it is preferable to further include a permanent magnet 90 for supplying a bias magnetic field to the main channel layer 7a via the end face 7c of the protruding channel layer 7b. When a magnetic field by a permanent magnet is not applied to the channel, an output peak appears when the detection-target external magnetic field is zero, but the output peak position is shifted by applying a magnetic field to the channel using the permanent magnet 90. It is possible to generate an output peak when the external magnetic field is not zero. 1 illustrates an example in which the magnetic sensor 1 includes two permanent magnets 90, the magnetic sensor 1 may include one or more permanent magnets 90.

  The material of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B is a metal selected from the group consisting of Cr, Mn, Co, Fe, Ni, an alloy containing one or more elements of the group, or a group. A compound containing one or more selected elements and one or more elements selected from the group consisting of B, C, N, Si, and Ge is preferable. Since these materials are ferromagnetic materials having a high spin polarizability, the function as a spin injection electrode or a spin reception electrode can be suitably realized.

  The material of the channel 7 (the main channel layer 7a and the protruding channel layer 7b) is preferably a semiconductor containing any one of Si, Ge, GaAs, C, and ZnO. Since these semiconductors have a relatively long spin diffusion length, spins can be suitably accumulated in the channel 7. Further, the half width of the peak of the voltage output or resistance output with respect to the external magnetic field is proportional to the reciprocal of the spin lifetime in the channel 7, so that the magnetic field sensitivity is improved if the spin lifetime is long. Examples of the material having a long spin life used for the channel 7 include Si and GaAs, and Si is particularly preferable. Moreover, although the magnetic field sensitivity becomes worse as the spin lifetime in the channel 7 is shorter, a wide range of magnetic fields can be detected.

In the manufacturing method of the magnetic sensor 1 described above, although an example of forming the MgO layer on the semiconductor layer as a barrier may be formed MgAl ₂ O ₄ layer on the semiconductor layer as a barrier. In this case, for example, the surface of the semiconductor layer (for example, Si) that becomes the channel 7 is cleaned. Next, an Mg film and an Al film are sequentially formed on the cleaned semiconductor layer, and then an oxidation process is performed in an oxidation chamber. This Mg film and Al film oxidation process is repeated until the barrier film thickness reaches a predetermined film thickness. However, in the last step in such a repetition step, the Mg film, the Al film, and the Mg film are formed in this order. Moreover, it implements so that ratio of Mg film | membrane and Al film | membrane may become a quantitative ratio. Subsequently, similarly to the method for manufacturing the magnetic sensor 1 described above, the first ferromagnetic layer 12A, the second ferromagnetic layer 12B, and the Cap layer (for example, the above-described synthetic composite film) are formed on the barrier. Thereafter, annealing is performed under a magnetic field (for example, 250 degrees, 3 hours, 3 kOe) to form a MgAl ₂ O ₄ layer crystal film.

  Further, an example in which a tunnel barrier made of an insulating film is applied as a barrier provided between the main channel layer 7a and at least one of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B has been shown. A Schottky barrier may be used. Such a Schottky barrier is formed, for example, when at least one of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B made of metal is in Schottky junction with the main channel layer 7a made of semiconductor. Alternatively, the Schottky barrier is configured such that the metal layer disposed between the main channel layer 7a and at least one of the first ferromagnetic layer 12A and the second ferromagnetic layer 12B has a Schottky junction with the main channel layer 7a made of a semiconductor. It may be formed by doing.

  FIG. 5 is a schematic diagram showing a thin film magnetic recording / reproducing head (magnetic head) 100A. The magnetic sensor 1 described above can be applied to the read head portion 100a of the thin film magnetic recording / reproducing head 100A. Specifically, the thin film magnetic recording / reproducing head 100 </ b> A performs magnetic information recording and reading operations at a position where its air bearing surface (air bearing surface) ABS is disposed opposite to the recording surface 20 a of the magnetic recording medium 20. I do. The end surface 7c of the protruding channel layer 7b exposed from the through hole H in the magnetic sensor 1 is disposed so as to correspond to the air bearing surface ABS.

  The magnetic recording medium 20 includes a recording layer 20b having a recording surface 20a and a soft magnetic backing layer 20c laminated on the recording layer 20b. A thin film is formed in the direction indicated by the Z-axis direction in FIG. Progress relative to the magnetic recording / reproducing head 100A. The thin-film magnetic recording / reproducing head 100 </ b> A includes a recording head unit 100 b that performs recording on the magnetic recording medium 20 in addition to the reading head unit 100 a that reads records from the magnetic recording medium 20. The read head unit 100a and the recording head unit 100b are provided on the substrate 21 and are covered with a nonmagnetic insulating layer such as alumina.

  As shown in FIG. 5, a recording head unit 100b for writing is provided on the reading head unit 100a. In the recording head portion 100b, a contact portion 32 and a main magnetic pole 33 are provided on the return yoke 30, and these form a magnetic flux path. A thin film coil 31 is provided so as to surround the contact portion 32. When a recording current is passed through the thin film coil 31, magnetic flux is emitted from the tip of the main magnetic pole 33, and information is recorded on the recording layer 20b of the magnetic recording medium 20 such as a hard disk. Can be recorded. As described above, the thin film magnetic recording / reproducing head 100A capable of detecting a magnetic flux from a minute region such as a recording medium can be provided by using the magnetic sensor 1 of the present invention.

  For example, the graphene layer 70 a can be used as the channel 7, for example. The graphene layer 70a is a layer in which spins are accumulated by spin injection. Graphene is a sheet having a structure in which carbon atoms are planarly bonded in a hexagonal network. The graphene layer 70a may be a laminate of a plurality of graphene sheets, but is preferably a graphene sheet having three or less layers, more preferably two or less layers, and most preferably a single-layer graphene sheet. As a result, the thickness of the graphene layer 70a can be made as thin as possible, and the magnetic flux from an extremely small region can be selectively detected.

  Such a graphene layer 70a can be obtained by, for example, a peeling or decomposition method. In the peeling method, for example, as shown in FIG. 11A, highly oriented pyrolytic graphite (HOPG) 400 is prepared. This highly oriented pyrolytic graphite (HOPG) 400 is obtained by laminating a large number of single-layer graphene sheets 401. In addition, a release plate 500 in which a resist layer 503 is applied on a film substrate 501 that is soluble in an organic solvent is prepared.

  Subsequently, as shown in FIG. 11B, the resist layer 503 on the film substrate 501 is brought into contact with the HOPG 400 under normal pressure. As a result, the resist layer 50 and the HOPG 400 are attached. Subsequently, the HOPG 400 and the peeling plate 500 are placed under vacuum, and the peeling plate 500 is peeled from the HOPG 400 as shown in FIG. Thereby, a part of the graphene sheet, that is, one layer or a plurality of layers of the graphene sheet is peeled and attached from the first HOPG 400 on the resist layer 503 of the peeling plate 500.

  Further, as shown in FIG. 12 (a), another release plate 500 is prepared, and the resist is brought into contact with the peeled plural layers of graphene sheets 401 in a state where the vacuum is maintained. Peel off as shown. Such adhesion and peeling are repeated in vacuum while observing such an operation with an optical microscope or the like so that the adhered resist layer has a desired film thickness.

  After that, the graphene sheet 401 attached on the resist layer 503 of the peeling plate 500 is formed on the base material, for example, on the substrate 21 as shown in FIG. (2) By adhering in vacuum on the intermediate insulating layer 23 of the base material on which the magnetic shield layer S2 is laminated, and then returning to normal pressure, dissolving the film base material 501 with an organic solvent, dissolving and washing the resist, As illustrated in FIG. 12D, a graphene sheet 401 having a desired number of layers can be disposed on a desired base material from the release plate 500.

  Further, in the decomposition method, first, for example, after performing oxidation and hydrogen etching on the SiC layer formed by the CVD method or the like as necessary, the silicon atoms are desorbed by electron impact heating or the like, so that the SiC layer is desorbed. A graphene sheet can be formed on the layer.

  In addition, as shown in FIG. 4A, an example in which the main channel layer 7a extends along a straight line in the first direction between the first ferromagnetic layer 12A and the second ferromagnetic layer 12B is shown. The shape of the channel 7 is not limited to this. For example, when viewed from the stacking direction (Z-axis direction), the main channel layer 7a may be V-shaped, U-shaped, or arc-shaped between the first ferromagnetic layer 12A and the second ferromagnetic layer 12B. .

  DESCRIPTION OF SYMBOLS 1 ... Magnetic sensor, 7 ... Channel, 7a ... Main channel layer, 7b ... Projection channel layer, 7c ... End surface, 12A ... First ferromagnetic layer, 12B ... Second ferromagnetic layer, 21 ... Substrate, 22 ... Lower insulating layer 23 ... intermediate insulation layer, 24 ... channel-magnetic shield insulation layer, 81A ... insulation film, 81B ... insulation film, S ... magnetic shield, S1 ... first magnetic shield layer, S2 ... second magnetic shield layer, H ... Through hole.

Claims (15)

A main channel layer having a first region, a second region, and a third region and extending in a first direction;
A first ferromagnetic layer stacked on the first region;
A second ferromagnetic layer stacked on the second region;
A protruding channel layer protruding in a direction perpendicular to the thickness direction of the main channel layer from a side surface of the third region between the first region and the second region in the main channel layer;
A magnetic shield that covers both sides of the protruding channel layer in the thickness direction and both sides of the protruding channel layer in the first direction and exposes end surfaces of the protruding channel layer in the protruding direction;
A magnetoresistive magnetic sensor in which a magnetization direction of the first ferromagnetic layer is antiparallel to a magnetization direction of the second ferromagnetic layer.   2. The magnetic sensor according to claim 1, wherein the magnetization direction of the first ferromagnetic layer and the magnetization direction of the second ferromagnetic layer are perpendicular to a direction in which the protruding channel layer protrudes. The direction of the magnetization of the first ferromagnetic layer is a direction parallel to the first direction;
The magnetic sensor according to claim 1 or 2, wherein the magnetization direction of the second ferromagnetic layer is a direction antiparallel to the first direction. The magnetization direction of the first ferromagnetic layer is a direction parallel to the stacking direction of the first ferromagnetic layer and the second ferromagnetic layer with respect to the channel layer,
The direction of the magnetization of the second ferromagnetic layer is a direction antiparallel to the stacking direction of the first and second ferromagnetic layers with respect to the channel layer. Magnetic sensor.   At least one of the direction of the magnetization of the first ferromagnetic layer and the direction of the magnetization of the second ferromagnetic layer is an anti-reflection layer disposed on the first ferromagnetic layer or the second ferromagnetic layer, respectively. The magnetic sensor according to any one of claims 1 to 4, wherein the magnetic sensor is fixed by a ferromagnetic layer.   The magnetization direction of at least one of the magnetization direction of the first ferromagnetic layer and the magnetization direction of the second ferromagnetic layer is fixed by shape anisotropy. The magnetic sensor as described in any one.   7. The surface of the main channel layer and the protruding channel layer is covered with an insulating film between the first ferromagnetic layer and the second ferromagnetic layer, according to claim 1. Magnetic sensor.   The main channel layer and the protruding channel layer are electrically insulated from the magnetic shield between the first ferromagnetic layer and the second ferromagnetic layer, respectively. The magnetic sensor described.   The magnetic sensor according to claim 1, further comprising a permanent magnet that supplies a magnetic field to the main channel layer through the end face of the protruding channel layer.   The material of the first ferromagnetic layer and the second ferromagnetic layer is a metal selected from the group consisting of Cr, Mn, Co, Fe, Ni, an alloy containing one or more elements of the group, or from the group The compound according to any one of claims 1 to 9, which is a compound including one or more elements selected and one or more elements selected from the group consisting of B, C, N, Si, and Ge. Magnetic sensor.   11. The material according to claim 1, wherein a material of the main channel layer and the protruding channel layer is a semiconductor containing any one of Si, Ge, GaAs, C, and ZnO. Magnetic sensor.   The magnetic field according to any one of claims 1 to 11, wherein a barrier is formed between at least one of the first ferromagnetic layer and the second ferromagnetic layer and the main channel layer. Sensor. The magnetic sensor according to claim 12, wherein the barrier is a tunnel barrier made of an MgO film, an Al ₂ O ₃ film, a TiO ₂ film, an MgAl ₂ O ₄ film, or a ZnO film.   The magnetic sensor of claim 12, wherein the barrier is a Schottky barrier.   A magnetic head comprising: a read head unit comprising the magnetic sensor according to claim 1; and a recording head unit for writing.

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