JP5338264B2 - Magnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic sensor capable of increasing a potential output. <P>SOLUTION: The magnetic sensor 100A includes: a channel layer 5; a magnetic free layer 6 disposed on a first part of the channel layer 5 to detect an external magnetic field; an upper inner pinned magnetic layer 18A disposed on a second part different from the first part of the channel layer 5; and a lower inner pinned magnetic layer 12 disposed opposite to the upper inner pinned magnetic layer 18A with the channel layer 5 between. The upper inner pinned magnetic layer 18A and the lower inner pinned magnetic layer 12 are fixed so that magnetization directions thereof are made parallel or anti-parallel to each other. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a magnetic sensor.

  A magnetoresistive element is known as a magnetic sensor used in a thin film magnetic recording / reproducing head. In general, in a magnetoresistive element, a high output is obtained because a current flows between the magnetization fixed layer and the magnetization free layer. However, in the magnetoresistive element, a signal unnecessary as a magnetic sensor is obtained due to the movement of the domain wall by the spin torque given by the current.

On the other hand, a spin accumulation (SA) magnetic sensor is known in which a magnetization free layer and a magnetization fixed layer are formed on the same horizontal plane (channel layer for accumulating spin) (for example, Patent Document 1, Patent) Reference 2). For example, when a spin accumulation type magnetic sensor is used for a thin film magnetic recording / reproducing head, it is not necessary to pass a current through a magnetization free layer that senses an external magnetic field such as a magnetic recording medium. That is, in the spin accumulation type magnetic sensor, it is possible to detect the magnetic state as the output voltage by using only the spin current. Therefore, an unnecessary signal that is observed by the magnetoresistive element is less likely to be observed by the spin accumulation type magnetic sensor.
JP 2007-299467 A Japanese Patent No. 4029772

  By the way, from the viewpoint of making a spin accumulation type magnetic sensor having a high output, a method of making the distance between the magnetization free layer and the magnetization fixed layer sufficiently shorter than the spin diffusion length and a two-dimensional flow of the spin current are considered. A method of arranging electrodes may be considered. Alternatively, in order to inject many spin-polarized electrons from the magnetization fixed layer to the channel layer, a method of providing an insulating layer between the magnetization free layer and the magnetization fixed layer and the channel layer can be considered. However, in the conventional spin accumulation type magnetic sensor, the potential output is not sufficient.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a magnetic sensor capable of increasing the potential output.

  In order to solve the above-described problem, a magnetic sensor of the present invention includes a channel layer, a magnetization free layer that is provided on the first portion of the channel layer, and detects an external magnetic field, and the first portion of the channel layer. An upper inner magnetization pinned layer provided on a different second portion, and a lower inner magnetization pinned layer facing the upper inner magnetization pinned layer with the channel layer interposed therebetween, the upper inner magnetization pinned layer and the lower inner The magnetization direction of the magnetization fixed layer is fixed parallel or antiparallel to each other.

  That is, in the magnetic sensor of the present invention, the two magnetization fixed layers are provided opposite to each other above and below the channel layer. When the magnetization direction of the lower inner magnetization pinned layer and the magnetization direction of the upper inner magnetization pinned layer are pinned so as to be antiparallel to each other, the upper inner magnetization pinned layer passes through the channel layer from the lower inner magnetization pinned layer. To the channel layer from both the lower inner magnetization fixed layer and the upper inner magnetization fixed layer by flowing current to the lower inner magnetization fixed layer from the upper inner magnetization fixed layer through the channel layer. Each spin is magnetically polarized in the direction. On the other hand, when the magnetization direction of the lower inner magnetization fixed layer and the magnetization direction of the upper inner magnetization fixed layer are fixed so as to be parallel to each other, a current flows from the channel layer to the lower inner magnetization fixed layer, and the channel Lower inner magnetization pinned by flowing current from the upper inner magnetization pinned layer to the upper inner magnetization pinned layer or by flowing current from the lower inner magnetization pinned layer to the channel layer and also from the upper inner magnetization pinned layer to the channel layer. Spins magnetically polarized in the same direction are injected from both the layer and the upper inner magnetization fixed layer into the channel layer. As a result, since more spins flow into the channel layer than in the prior art, the potential output in the magnetic sensor can be increased. Here, the direction of magnetization in each of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer can be confirmed based on, for example, the magnetic resistance (AMR, TMR, etc.) indicated by these magnetization fixed layers themselves. In addition, parallel means not only a completely parallel object but also a substantially parallel object and includes an error within 45 degrees with respect to the parallel object.

  In the magnetic sensor of the present invention, the magnetization directions of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer are fixed by at least one of an antiferromagnetic layer, shape anisotropy, and an external magnetic field during film formation. It is preferable. Thereby, it becomes easy to make the magnetization directions of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer difficult to react to the external magnetic field.

  In the magnetic sensor of the present invention, the magnetization directions of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer are fixed by the antiferromagnetic layer, and the antiferromagnetism includes the upper antiferromagnetic layer and the lower antiferromagnetism, The magnetization pinned layer is coupled to the upper outer magnetization pinned layer with the upper magnetic coupling layer interposed therebetween, and the upper antiferromagnetic layer is provided on the upper outer magnetization pinned layer, and the lower inner magnetization pinned layer is provided. Is preferably coupled to the lower outer magnetization fixed layer with the lower magnetic coupling layer interposed therebetween, and the lower antiferromagnetic layer is provided in contact with the lower outer magnetization fixed layer. As a result, the upper outer magnetization pinned layer is in contact with the upper antiferromagnetic layer, so that the magnetization direction of the upper outer magnetization pinned layer is fixed, and the upper inner magnetization pinned layer sandwiches the upper magnetic coupling layer therebetween. By coupling with the upper outer magnetization fixed layer, the magnetization direction of the upper inner magnetization fixed layer can be firmly fixed. On the other hand, the lower outer magnetization pinned layer is in contact with the lower antiferromagnetic layer, so that the magnetization direction of the lower outer magnetization pinned layer is fixed, and the lower inner magnetization pinned layer is sandwiched between the lower magnetic coupling layers. By coupling with the outer magnetization fixed layer, the magnetization direction of the lower inner magnetization fixed layer can be firmly fixed.

  The magnetic sensor of the present invention preferably further includes a barrier layer provided between at least one of the channel layer and the upper inner magnetization fixed layer and between the channel layer and the lower inner magnetization fixed layer. This makes it possible to inject a large amount of spin-polarized electrons from at least one of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer into the channel layer, and to further increase the potential output of the magnetic sensor.

  In the magnetic sensor of the present invention, the channel layer and the magnetization free layer are preferably in direct contact. Thereby, the spin of the channel layer is easily absorbed by the magnetization free layer, and a high output can be obtained.

  The magnetic sensor of the present invention preferably further comprises a permanent magnet for applying a bias magnetic field to the magnetization free layer. Thereby, since the magnetic anisotropy of the magnetization free layer is controlled, the magnetic domain structure of the magnetization free layer is unified and stabilized, and Barkhausen noise caused by the movement of the domain wall can be suppressed.

  In the magnetic sensor of the present invention, the coercivity of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer is preferably larger than the coercivity of the magnetization free layer. Thereby, it is possible to preferably realize the functions as the magnetization fixed layer and the magnetization free layer in the magnetic sensor.

  In the magnetic sensor of the present invention, the magnetization free layer is disposed on the side where the magnetic flux to be detected by the channel layer enters, and the upper inner magnetization fixed layer and the lower inner magnetization fixed layer have the magnetic flux to be detected by the channel layer. It is preferable that it is arrange | positioned on the opposite side to the approaching side. Thus, by setting the magnetization free layer side close to the magnetic recording medium, it is possible to detect the magnetic information of the magnetic recording medium and reproduce the magnetic information.

  In the magnetic sensor of the present invention, the material of the magnetization free 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 selected from the group An alloy containing at least one element and at least one element selected from the group consisting of B, C, and N is preferable. Since these materials are soft magnetic materials, it is possible to suitably realize the function as a magnetization free layer in the magnetic sensor.

  In the magnetic sensor of the present invention, the material of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer is a metal selected from the group consisting of Cr, Mn, Co, Fe and Ni, an alloy containing one or more elements of the group, Alternatively, an alloy containing one or more elements selected from the group and one or more elements selected from the group consisting of B, C, and N is preferable. Since these materials are ferromagnetic materials having a high spin polarizability, the function as a magnetization fixed layer in the magnetic sensor can be suitably realized.

  In the magnetic sensor of the present invention, the material of the channel layer is preferably a material containing one or more elements selected from the group consisting of B, C, Mg, Al, Cu, and Zn. Since these materials have a long spin diffusion length and a relatively small electrical conductivity, it is possible to preferably realize that the channel layer functions as a spin accumulation layer.

  In the magnetic sensor of the present invention, the channel layer is preferably a semiconductor compound containing Si or ZnO. Since these semiconductor compounds have a longer spin diffusion length, it is preferable to make the channel layer function as a spin accumulation layer, and the potential output can be higher than that of the channel layer using the above metal or alloy. It becomes.

  In the magnetic sensor of the present invention, the material of the barrier layer is preferably aluminum oxide, magnesium oxide, or zinc oxide.

  According to the present invention, a magnetic sensor capable of increasing the potential output can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
(First embodiment)

  Hereinafter, a thin film magnetic recording / reproducing head 200A will be described as an example of the magnetic sensor according to the first embodiment.

  FIG. 1 is a partial cross-sectional view showing a thin film magnetic recording / reproducing head 200A. The thin film magnetic recording / reproducing head 200 </ b> A performs magnetic information recording and reading operations at a position where the air bearing surface (air bearing surface) S is disposed opposite to the recording surface 40 a of the magnetic recording medium 40. The magnetic recording medium 40 includes a recording layer 40b having a recording surface 40a and a soft magnetic backing layer 40c laminated on the recording layer 40b, and in the direction indicated by the Y direction in the figure, thin film magnetic recording Progress relative to the reproducing head 200A.

  The thin film magnetic recording / reproducing head 200 </ b> A includes a magnetic sensor 100 </ b> A that reads records from the magnetic recording medium 40 and a magnetic recording unit 100 </ b> B that performs recording on the magnetic recording medium 40. The magnetic sensor 100A and the magnetic recording unit 100B are provided on a substrate SB such as AlTiC or Si, and are covered with a nonmagnetic insulating layer such as alumina.

  As shown in FIG. 1, a magnetic recording unit 100B is provided on the magnetic sensor 100A. In the magnetic recording 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 40b of the magnetic recording medium 40 such as a hard disk. Can be recorded.

  The magnetic sensor 100A includes a channel layer 5 for accumulating electron spins, a magnetization free layer 6 provided on the first portion of the channel layer 5, and a second portion different from the first portion of the channel layer 5. The upper magnetization fixed part 60A provided above and the lower magnetization fixed part 50 opposed to the upper magnetization fixed part 60A with the channel layer 5 interposed therebetween are mainly provided. That is, the magnetic sensor 100A has two parts, an upper magnetization fixed part 60A and a lower magnetization fixed part 50, as parts that function as a magnetization fixed layer.

  A lower barrier layer 13 is provided between the channel layer 5 and the lower magnetization fixed portion 50, and the lower barrier layer 13 extends from the lower magnetization fixed portion 50 side to the magnetization free layer 6 side under the channel layer 5. Is provided. In addition, an upper barrier layer 19 is provided between the channel layer 5 and the magnetization free layer 6 and between the channel layer 5 and the upper magnetization fixed portion 60A. It is provided from the upper magnetization fixed portion 60A side to the magnetization free layer 6 side.

  Furthermore, the magnetic sensor 100A includes a lower first magnetic shield layer 1 and an upper first magnetic shield layer 3 that are opposed to each other with the channel layer 5, the magnetization free layer 6, the lower barrier layer 13, and the upper barrier layer 19 therebetween. A lower second magnetic shield layer 2 and an upper second magnetic shield layer 4 facing each other with the channel layer 5, the lower barrier layer 13, the upper barrier layer 19, the lower magnetization fixed portion 50, and the upper magnetization fixed portion 60A interposed therebetween, A lower insulating layer 7 provided between the lower first magnetic shield layer 1 and the lower barrier layer 13 is provided.

  The channel layer 5 is a layer in which spin is accumulated by spin injection, and is provided on a plane formed by the lower barrier layer 13. As the material of the channel layer 5, a non-ferromagnetic conductive material is used, and a material having a long spin diffusion length and a relatively low conductivity is preferably selected. For example, the material of the channel layer 5 includes a material containing one or more elements selected from the group consisting of B, C, Mg, Ag, Al, Cu, and Zn. In particular, Cu and Al are preferable. The channel layer 5 may also be a semiconductor compound such as Si, ZnO, or GaAs. Since these semiconductor compounds have a longer spin diffusion length and relatively low conductivity, the channel layer 5 using these semiconductor compounds is more suitable as a spin accumulation layer, and the channel layer using the metal or alloy described above. It is also possible to make the potential output higher than 5.

  The magnetization free layer 6 is provided on the first portion of the channel layer 5 and is a layer for detecting an external magnetic field to be detected and sensitively detecting a change in the magnetization direction of the magnetic recording medium 40 or the like. The magnetization free layer 6 is disposed on the upper surface of the channel layer 5 on the side where the magnetic flux to be detected by the channel layer 5 enters, that is, on the air bearing surface S side. By placing the magnetization free layer 6 close to the magnetic recording medium 40, magnetic information can be suitably read from the magnetic recording medium 40. A ferromagnetic material, in particular, a soft magnetic material is applied as the magnetization free layer 6, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe and Ni, an alloy containing one or more metals of the group, or Examples thereof include one or more metals selected from the above group and alloys containing at least one of B, C, and N. Specific examples include CoFeB and NiFe.

  Hereinafter, the lower magnetization fixed unit 50 and the upper magnetization fixed unit 60A will be described. The lower magnetization pinned portion 50 includes a lower buffer layer 8, a lower antiferromagnetic layer 9, a lower outer magnetization pinned layer 10, a lower magnetic coupling layer 11, and a lower inner magnetization pinned provided in order from the lower second magnetic shield layer 2 side. It has a layer 12. The upper magnetization fixed portion 60A includes an upper inner magnetization fixed layer 18A, an upper magnetic coupling layer 17, an upper outer magnetization fixed layer 16A, an upper antiferromagnetic layer 15, and an upper buffer layer 14 provided in this order from the channel layer 5 side. .

  The lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A are layers for injecting electrons having a predetermined spin into the channel layer 5, respectively. The lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A are arranged on the opposite side of the channel layer 5 from which the magnetic flux to be detected enters, that is, on the side away from the air bearing surface S. The upper inner magnetization pinned layer 18A is provided on a second portion different from the first portion of the channel layer 5, and the lower inner magnetization pinned layer 12 has the upper inner magnetization pinned with the channel layer 5 interposed therebetween. It is provided facing the layer 18A.

  The coercive force of the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18 </ b> A is larger than the coercivity of the magnetization free layer 6. In the present embodiment, a so-called synthetic pinned structure is employed in order to enhance the magnetization pinning function of the lower inner magnetization pinned layer 12 and the upper inner magnetization pinned layer 18A. That is, the lower magnetization pinned portion 50 is connected to the lower outer magnetization pinned layer 10 and the lower inner magnetization pinned layer 12 coupled via the lower magnetic coupling layer 11, and the lower antimagnetic pinned layer 10 provided below the lower outer magnetization pinned layer 10. And a ferromagnetic layer 9. Similarly, the upper magnetization pinned portion 60A includes the upper inner magnetization pinned layer 18A and the upper outer magnetization pinned layer 16A coupled via the upper magnetic coupling layer 17, and the upper portion provided in contact with the upper outer magnetization pinned layer 16A. And an antiferromagnetic layer 15.

Are fixed mutually different (the anti-parallel) as the magnetization direction S _18A of the magnetization direction S ₁₂ and the upper inner magnetization fixed layer 18A of the lower inner magnetization pinned layer 12. In the present embodiment, as shown in FIG. 1, the magnetization direction S12 of the lower inner magnetization fixed layer ₁₂ is the + X direction, and the magnetization direction S18A of the upper inner magnetization fixed layer _18A is the -X direction.

That is, when the upper outer magnetization fixed layer 16A is in contact with the upper antiferromagnetic layer 15, the magnetization direction of the upper outer magnetization fixed layer 16A is fixed in the + X direction, and the upper inner magnetization fixed layer 18A is further coupled to the upper magnetic coupling. By coupling with the upper outer magnetization fixed layer 16A with the layer 17 interposed therebetween, the magnetization direction of the upper inner magnetization fixed layer 18A is fixed in the −X direction. On the other hand, when the lower outer magnetization pinned layer 10 is in contact with the lower antiferromagnetic layer 9, the magnetization direction of the lower outer magnetization pinned layer 10 is fixed in the −X direction, and the lower inner magnetization pinned layer 12 is further moved to the lower magnetic layer. by bound to the lower outer magnetization fixed layer 10 to sandwich the bonding layer 11 between the magnetization direction of the lower inner magnetization pinned layer 12, in a direction opposite to the magnetization direction S _18A of the upper inner magnetization fixed layer 18A It becomes possible to fix in a certain + X direction.

  As the material of the lower inner magnetization fixed layer 12, the upper inner magnetization fixed layer 18A, the lower outer magnetization fixed layer 10, and the upper outer magnetization fixed layer 16A, a ferromagnetic metal material having a large spin polarizability can be used. 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 one or more elements selected from the group and B, C and N An alloy containing one or more elements selected from the group consisting of: Specific examples include CoFe and CoFeB. In addition, examples of the material of the lower magnetic coupling layer 11 and the lower magnetic coupling layer 11 include Ru.

  As described above, when the lower antiferromagnetic layer 9 and the upper antiferromagnetic layer 15 are provided, the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A having a high coercive force in one direction can be obtained. Therefore, the materials used for the lower antiferromagnetic layer 9 and the upper antiferromagnetic layer 15 are selected according to the materials used for the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A. For example, as the lower antiferromagnetic layer 9 and the upper antiferromagnetic layer 15, an alloy exhibiting antiferromagnetism using Mn, specifically, at least one element selected from Mn, Pt, Ir, and Fe An alloy containing Specific examples include IrMn and PtMn.

  The case where the magnetizations of the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A are fixed by the lower antiferromagnetic layer 9 and the upper antiferromagnetic layer 15 has been described above. As another magnetization fixing method, a method of fixing magnetization by the shape anisotropy of the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A, or a film formation of the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A. A method of fixing magnetization by an external magnetic field at the time may be used, and it is preferable that the magnetization is fixed by at least one of these magnetization fixing methods. As a result, the magnetization directions of the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A can be made difficult to react to an external magnetic field.

  When adopting a method of fixing the magnetization by giving shape anisotropy to the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A, the lower antiferromagnetic layer 9 and the upper antiferromagnetic layer 15 are omitted. It is possible. For example, the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A may have a rectangular shape whose major axis is the Z direction when viewed from the Y direction.

  The lower buffer layer 8 is used to electrically connect the lower second magnetic shield layer 2 and the lower antiferromagnetic layer 9 so that a current flows through the lower magnetization fixed portion 50 using the lower second magnetic shield layer 2 as an electrode. The function of functioning as an electrode layer and removing the crystallinity of the underlying film on the lower antiferromagnetic layer 9 is shown. Similarly, the upper buffer layer 14 electrically connects the upper second magnetic shield layer 4 and the upper antiferromagnetic layer 15 so that a current flows through the upper magnetization fixed portion 60A using the upper second magnetic shield layer 4 as an electrode. This function functions as an electrode layer for removing the crystallinity in the upper antiferromagnetic layer 15. For example, a metal material such as Ru or Ta is used as the material of the lower buffer layer 8 and the upper buffer layer 14. When the lower antiferromagnetic layer 9 is not present, the lower buffer layer 8 is in contact with the lower inner magnetization fixed layer 12. When the upper antiferromagnetic layer 15 is not present, the upper buffer layer 14 is present. Is in contact with the upper inner magnetization fixed layer 18A.

  The lower first magnetic shield layer 1 and the lower second magnetic shield layer 2 are for blocking the magnetism that enters the magnetization free layer 6 and the lower magnetization fixed portion 50 from the outside, particularly the lower portion of the magnetic sensor 100A. . As shown in FIG. 1, the lower first magnetic shield layer 1 and the lower second magnetic shield layer 2 are provided separately from each other. As a result, the lower second magnetic shield layer 2 can be used as the other electrode for spin injection into the channel layer 5.

  The upper first magnetic shield layer 3 and the upper second magnetic shield layer 4 are for blocking the magnetism that enters the magnetization free layer 6 and the upper magnetization fixed portion 60A from the outside, particularly the upper portion of the magnetic sensor 100A. . As shown in FIG. 1, the upper first magnetic shield layer 3 and the upper second magnetic shield layer 4 are provided separately from each other. Thus, the upper first magnetic shield layer 3 is used as an electrode for measuring a voltage generated at the interface between the channel layer 5 and the magnetization free layer 6, and the upper second magnetic shield layer 4 is spin-injected into the channel layer 5. Therefore, it can be used as one of the electrodes.

  As materials for the lower first magnetic shield layer 1, the lower second magnetic shield layer 2, the upper first magnetic shield layer 3, and the upper second magnetic shield layer 4, for example, an alloy containing Ni and Fe, Sendust, Fe and Co are used. Examples thereof include soft magnetic materials such as alloys containing Fe, Co, and Ni.

  The lower barrier layer 13 and the upper barrier layer 19 are tunnel insulating layers. As the lower barrier layer 13 and the upper barrier layer 19, an insulator such as aluminum oxide or magnesium oxide, or a semiconductor such as zinc oxide is applied.

The lower insulating layer 7 is provided between the lower barrier layer 13 and the lower first magnetic shield layer 1. The lower insulating layer 7 is for preventing spins of electrons accumulated in the channel layer 5 from flowing out to the lower first magnetic shield layer 1 side. From the viewpoint of efficiently performing spin accumulation, the lower insulating layer 7 is provided on the lower surface of the channel layer 5 from the lower magnetization fixed portion 50 and the upper magnetization fixed portion 60A side to the magnetization free layer 6 side. Examples of the lower insulating layer 7 include SiO ₂ .

  Next, a cross-sectional shape parallel to the Z direction of the magnetic sensor 100A shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a schematic view for explaining a cross-sectional configuration along the line II-II in FIG.

As shown in FIG. 2, the upper insulating layer 20 is provided between the channel layer 5, the magnetization free layer 6, the upper barrier layer 19, and the permanent magnet 21, and the channel layer 5, the magnetization free layer 6, The upper barrier layer 19 and the permanent magnet 21 are insulated from each other. As the upper insulating layer 20, SiO ₂ or the like is used.

  The permanent magnets 21 are disposed on both sides of the magnetization free layer 6 via the upper insulating layer 20. By applying a bias magnetic field to the magnetization free layer 6 using the leakage magnetic flux from the permanent magnet 21, the magnetic domain structure of the magnetization free layer 6 can be stabilized (uniaxial). Thereby, it is possible to suppress Barkhausen noise caused by the movement of the domain wall.

  Below, an example of the manufacturing method of magnetic sensor 100A concerning a 1st embodiment is explained. First, the lower second magnetic shield layer 2, the lower buffer layer 8, the lower antiferromagnetic layer 9, the lower outer magnetization fixed layer 10, the lower magnetic coupling layer 11, and the lower inner magnetization fixed layer 12 are sputtered in this order on the substrate. The film is continuously formed by the method, and a protective film such as Ta is formed on the lower inner magnetization fixed layer 12 by, for example, 5 nm. Thereafter, in order to fix the magnetization direction of the lower outer magnetization fixed layer 10, an external magnetic field is set to, for example, 3000 [Oe], and annealing is performed at a heating temperature of 300 ° C. for 3 hours.

  Next, the excess film is scraped off by photolithography, and the lower magnetization fixed portion 50 is shaped as shown in FIG. Subsequently, the lower first magnetic shield layer 1 and the lower insulating layer 7 are formed in this order. Thereafter, polishing is performed by chemical mechanical polishing (CMP) so that the surfaces of the lower insulating layer 7 and the lower inner magnetization fixed layer 12 become flat surfaces. Thereafter, after the flat surface is plasma-treated in a vacuum chamber, the lower barrier layer 13, the channel layer 5, the upper barrier layer 19, the upper inner magnetization fixed layer 18A, the upper magnetic coupling layer 17, the upper outer magnetization fixed layer 16A, The upper antiferromagnetic layer 15 and the upper buffer layer 14 are successively formed in this order by sputtering. The upper inner magnetization fixed layer 18A is formed in a state where an external magnetic field opposite to the direction in which the external magnetic field is applied during the annealing is applied.

  Then, excess film is removed by photolithography, and the upper magnetization fixed portion 60A is shaped as shown in FIG. Subsequently, as shown in FIG. 2, the upper insulating layer 20 is formed on the scraped portion, and the permanent magnet 21 is formed thereon. Further, as shown in FIG. 1, the film on the magnetization free layer 6 is removed by photolithography, the upper first magnetic shield layer 3 is formed in order, and the upper second magnetic shield layer is formed on the upper magnetization fixed portion 60A. 4 is formed. Thus, the magnetic sensor 100A shown in FIGS. 1 and 2 is completed.

  Hereinafter, operations and effects of the magnetic sensor 100A according to the first embodiment will be described with reference to FIG. As shown in FIG. 1, the lower second magnetic shield layer 2 and the upper second magnetic shield layer 4 are connected to a current source 70 in order to flow a detection current to the lower magnetization fixed portion 50 and the upper magnetization fixed portion 60A. Connect electrically. Further, the upper first magnetic shield layer 3 and the channel layer 5 are electrically connected to the voltage measuring device 80.

First, flow detection current _{I 1} to the both of the lower magnetization fixed portion 50 and the upper magnetization fixed portion 60A of the magnetic sensor 100A. In this embodiment, the magnetization direction S _18A of the magnetization direction S ₁₂ and the upper inner magnetization fixed layer 18A of the lower inner magnetization pinned layer 12 are antiparallel fixed to each other. Therefore, the magnetic sensor 100A according to the present embodiment, by supplying a detection current I ₁ to the upper inner magnetization fixed layer 18A through the channel layer 5 from the lower inner magnetization pinned layer 12, provided above and below the channel layer 5 Spins magnetically polarized in the same direction are respectively injected from the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A thus formed into the channel layer 5. Conversely, the channel layer 5 can also be obtained by flowing a detection current (that is, a current flowing in a direction opposite to the direction of I ₁ ) from the upper inner magnetization fixed layer 18 A through the channel layer 5 to the lower inner magnetization fixed layer 12. Thus, spins magnetically polarized in the same direction are injected from the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A provided above and below the channel layer 5, respectively. As described above, by setting the magnetization direction and the current direction of the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18A to appropriate states, the potential output in the magnetic sensor can be increased.
(Second Embodiment)

  The thin film magnetic recording / reproducing head 200C as an example of the magnetic sensor according to the second embodiment will be described below. FIG. 3 is a partial cross-sectional view showing the thin film magnetic recording / reproducing head 200C.

  The thin film magnetic recording / reproducing head 200C shown in FIG. 3 is different from the thin film magnetic recording / reproducing head 200A according to the first embodiment in that the magnetization direction of the layers constituting the upper magnetization fixing unit 60A in the magnetic sensor 100A is fixed. Only this will be described.

In the present embodiment, as shown in FIG. 3, the magnetization direction S ₁₂ (+ X direction) of the lower inner magnetization fixed layer 12 and the magnetization direction S _18C (+ X direction) of the upper inner magnetization fixed layer 18C are the same. It is fixed so that it becomes parallel. Specifically, by the upper outer magnetization pinned layer 16C is in contact with the upper antiferromagnetic layer 15, the magnetization direction S _16C of the upper outer magnetization pinned layer 16C is fixed to the -X direction and the upper inner magnetization pinned Since the layer 18C is coupled to the upper outer magnetization fixed layer 16C with the upper magnetic coupling layer 17 interposed therebetween, the magnetization direction S _18C of the upper inner magnetization fixed layer 18C is changed to the magnetization direction S of the lower inner magnetization fixed layer 12. ₁₂ can be fixed in the same + X direction.

In the present embodiment, as shown in FIG. 3, the lower second magnetic shield layer 2 and the channel layer 5 are electrically connected to a current source 71 in order to flow the detection current I ₂ to the lower magnetization fixed portion 50. . On the other hand, the upper second magnetic shield layer 4 and the channel layer 5 are electrically connected to the current source 72 in order to flow the detection current I ₃ to the upper magnetization fixed portion 60C. By adopting such a configuration, the magnetic sensor 100C, with from the channel layer 5 can be caused to flow detection current I ₂ to the lower fixed magnetization unit 50, detected from the channel layer 5 to the upper fixed magnetization portion 60C it is possible to flow the use current I _3.

In this embodiment, the magnetization direction S _18C of the magnetization direction S ₁₂ and the upper inner magnetization pinned layer 18C of the lower inner magnetization pinned layer 12 is fixed in parallel to each other. Therefore, the magnetic sensor 100C according to the present embodiment, the flow detection current I ₂ to the lower inner magnetization pinned layer 12 from the channel layer 5, the detection current I ₃ from the channel layer 5 to the upper inner magnetization pinned layer 18C , The spins magnetically polarized in the same direction are injected into the channel layer 5 from both the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18C. On the contrary, the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer can be obtained by flowing current from the lower inner magnetization fixed layer 12 to the channel layer 5 and also flowing current from the upper inner magnetization fixed layer 18C to the channel layer 5. Spins magnetically polarized in the same direction are injected into the channel layer 5 from both of the layers 18C. In this way, by setting the magnetization direction and the current direction of the lower inner magnetization fixed layer 12 and the upper inner magnetization fixed layer 18C to an appropriate state, the potential output in the magnetic sensor is increased as in the first embodiment. It becomes possible to do.

  Hereinafter, modified examples of the present invention will be described with reference to FIGS. FIG. 4 is a partial sectional view showing a thin film magnetic recording / reproducing head 200D. The thin film magnetic recording / reproducing head 200D shown in FIG. 4 differs from the thin film magnetic recording / reproducing head 200A according to the first embodiment in that the magnetization direction of the upper inner magnetization fixed layer 18A in the magnetic sensor 100A is fixed by the shape anisotropy. Therefore, only this will be described. That is, in the magnetic sensor 100D shown in FIG. 4, since the magnetization direction of the upper inner magnetization fixed layer 18D is fixed by shape anisotropy, the upper antiferromagnetic layer 15 and the upper outer magnetization fixed described in the first embodiment. The layer 16A and the upper magnetic coupling layer 17 are not provided. Even when such a configuration is used, the present invention can be implemented.

  FIG. 4 shows a mode in which only the upper inner magnetization fixed layer 18A has a magnetization direction fixed by shape anisotropy, but the magnetization direction of the lower inner magnetization fixed layer 12 is further fixed by shape anisotropy. Even if the lower antiferromagnetic layer 9, the lower outer magnetization fixed layer 10, and the lower magnetic coupling layer 11 are not provided, the present invention can be implemented.

  FIG. 5 is a partial sectional view showing the thin film magnetic recording / reproducing head 200E. The thin film magnetic recording / reproducing head 200E shown in FIG. 5 differs from the thin film magnetic recording / reproducing head 200A according to the first embodiment in that the lower insulating layer 7 is not provided and the X of the lower first magnetic shield layer 1 is different. The length of the direction is shorter than the length of the magnetization free layer 6 in the X direction, and the lower first magnetic shield layer 1 is close to the air bearing surface S side (medium side). Even when such a configuration is used, the present invention can be implemented. As shown in FIG. 5, although the lower insulating layer 7 is not provided in the magnetic sensor 100E, the lower barrier layer 13 is located on the lower magnetization fixed portion 50 and the upper magnetization fixed portion 60A side on the lower surface of the channel layer 5. To the magnetization free layer 6 side. For this reason, it is possible to prevent spins of electrons accumulated in the channel layer 5 from flowing out to the lower first magnetic shield layer 1 side, so that there is little possibility of preventing spin accumulation in the channel layer 5.

  FIG. 6 is a partial cross-sectional view showing the thin film magnetic recording / reproducing head 200F. The thin film magnetic recording / reproducing head 200F shown in FIG. 6 is different from the thin film magnetic recording / reproducing head 200A according to the first embodiment in the length and arrangement of the upper barrier layer 19 in the magnetic sensor 100A. In the magnetic sensor 100F shown in FIG. 6, the length of the upper barrier layer 19F is shorter than the length of the upper barrier layer 19 according to the first embodiment, and the upper barrier layer 19F includes the upper magnetization fixed portion 60A, the channel layer 5, and the like. It is provided only between. That is, the channel layer 5 and the magnetization free layer 6 are in direct contact, and the upper barrier layer 19F is fixed between the channel layer 5 and the magnetization free layer 6 and on the channel layer 5 and the upper inner magnetization fixed. It is not provided in the region between the layers 18A. When such a configuration is used, the spin current flowing through the channel layer 5 can be efficiently taken into the magnetization free layer 6 and a high output can be obtained.

  FIG. 7 is a partial cross-sectional view showing a thin film magnetic recording / reproducing head 200G. The thin film magnetic recording / reproducing head 200G shown in FIG. 7 is different from the thin film magnetic recording / reproducing head 200A according to the first embodiment in that the upper barrier layer 19 in the magnetic sensor 100A is not provided. As shown in FIG. 7, in the magnetic sensor 100G, the channel layer 5 and the magnetization free layer 6 are in direct contact. When such a configuration is used, the spin current flowing through the channel layer 5 can be efficiently taken into the magnetization free layer 6 and a high output can be obtained. Although not shown, the lower barrier layer 13 may not be provided in place of the upper barrier layer 19 being provided. That is, a barrier layer may be provided between at least one of the channel layer 5 and the upper inner magnetization fixed layer 18 </ b> A and between the channel layer 5 and the lower inner magnetization fixed layer 12. By adopting such a configuration, it becomes possible to inject a lot of spin-polarized electrons from at least one of the upper inner magnetization fixed layer 18A and the lower inner magnetization fixed layer 12 into the channel layer 5, and the potential output of the magnetic sensor Can be further 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. In the above embodiment, an example in which a synthetic pinned structure is employed when an antiferromagnetic layer is used has been shown, but the lower magnetization pinned portion 50 does not include the lower outer magnetization pinned layer 10 and the lower magnetic coupling layer 11. The lower antiferromagnetic layer 9 and the lower inner magnetization fixed layer 12 may be in contact with each other. Similarly, in the upper magnetization fixed part, the upper antiferromagnetic layer and the upper inner magnetization fixed layer may be in contact with each other without including the upper outer magnetization fixed layer and the upper magnetic coupling layer.

  4 to 7, the configuration corresponding to the first embodiment, that is, the magnetization direction of the upper inner magnetization pinned layer is opposite (antiparallel) to the magnetization direction of the lower inner magnetization pinned layer. Although the case has been described as an example, it is applicable to the configuration corresponding to the second embodiment, that is, the case where the magnetization direction of the upper inner magnetization fixed layer is the same direction (parallel) as the magnetization direction of the lower inner magnetization fixed layer. It is.

  As described above, in each embodiment, the magnetic sensor of the present invention has been described using an example in which the magnetic sensor is applied to a thin-film magnetic recording / reproducing head. The present invention can also be applied to various uses such as a magnetic encoder device, a magnetic field measurement device, and a magnetic detection device used in an ink jet printer.

It is a schematic diagram for explaining the thin film magnetic recording / reproducing head 200A including the magnetic sensor 100A and its operation. It is the schematic for demonstrating the cross-sectional structure along the II-II line | wire of FIG. It is a schematic diagram for explaining the thin film magnetic recording / reproducing head 200C including the magnetic sensor 100C and the operation. It is a schematic diagram for demonstrating thin film magnetic recording / reproducing head 200D provided with magnetic sensor 100D, and operation | movement. It is the schematic diagram for demonstrating the thin film magnetic recording / reproducing head 200E provided with the magnetic sensor 100E, and operation | movement. It is the schematic diagram for demonstrating thin film magnetic recording / reproducing head 200F provided with the magnetic sensor 100F, and operation | movement. It is a schematic diagram for explaining the thin film magnetic recording / reproducing head 200G including the magnetic sensor 100G and the operation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 5 ... Channel layer, 6 ... Magnetization free layer, 12 ... Lower inner magnetization fixed layer, 18A ... Upper inner magnetization fixed layer, 50 ... Lower magnetization fixed part, 60A ... Upper magnetization fixed part, 100A ... Magnetic sensor, 100B ... Magnetic recording Part, 200A: Thin-film magnetic recording / reproducing head.

Claims (12)

The channel layer,
A magnetization free layer provided on a first portion of the channel layer and detecting an external magnetic field;
An upper inner magnetization pinned layer provided on a second portion different from the first portion of the channel layer;
A lower inner magnetization pinned layer facing the upper inner magnetization pinned layer with the channel layer interposed therebetween,
The magnetization directions of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer are fixed parallel or antiparallel to each other,
A magnetic sensor further comprising a permanent magnet for applying a bias magnetic field to the magnetization free layer. 2. The magnetic sensor according to claim 1 , further comprising a barrier layer provided between at least one of the channel layer and the upper inner magnetization fixed layer and between the channel layer and the lower inner magnetization fixed layer. The channel layer,
A magnetization free layer provided on a first portion of the channel layer and detecting an external magnetic field;
An upper inner magnetization pinned layer provided on a second portion different from the first portion of the channel layer;
A lower inner magnetization pinned layer facing the upper inner magnetization pinned layer with the channel layer interposed therebetween,
A barrier layer provided between at least one of the channel layer and the upper inner magnetization fixed layer and between the channel layer and the lower inner magnetization fixed layer, and
The magnetization directions of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer are fixed parallel or antiparallel to each other,
A magnetic sensor in which the channel layer and the magnetization free layer are in direct contact. The magnetization direction of the upper inner magnetization pinned layer and the lower inner magnetization fixed layer, an antiferromagnetic layer, the shape anisotropy, and the claims 1-3, which is fixed by at least one of an external magnetic field during deposition The magnetic sensor according to any one of the above. The magnetization directions of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer are fixed by the antiferromagnetic layer,
The antiferromagnet includes an upper antiferromagnetic layer and a lower antiferromagnet,
The upper inner magnetization fixed layer is
It is coupled with the upper outer magnetization pinned layer with the upper magnetic coupling layer in between,
An upper antiferromagnetic layer is provided in contact with the upper outer magnetization fixed layer,
The lower inner magnetization fixed layer is coupled to the lower outer magnetization fixed layer with the lower magnetic coupling layer interposed therebetween,
The magnetic sensor according to claim 4 , wherein a lower antiferromagnetic layer is provided in contact with the lower outer magnetization fixed layer. The upper coercive force of the inner magnetization pinned layer and the lower inner magnetization fixed layer, a magnetic sensor according to any one of the magnetization free layer claim 1 greater than the coercive force of 5. The magnetization free layer is disposed on a side where a magnetic flux to be detected by the channel layer enters, and the magnetic flux to be detected by the channel layer enters the upper inner magnetization fixed layer and the lower inner magnetization fixed layer. magnetic sensor according to any one of claims 1 to 6 arranged on the opposite side of the side. The material of the magnetization free layer is 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 one or more elements selected from the group and B , C, and magnetic sensor according to any one of claims 1 to 7, which is an alloy containing one or more elements selected from the group consisting of N. The material of the upper inner magnetization fixed layer and the lower inner magnetization fixed layer is a metal selected from the group consisting of Cr, Mn, Co, Fe and Ni, an alloy including one or more elements of the group, or from the group one or more elements and B, C, and magnetic sensor according to any one of claims 1-8 is an alloy containing one or more elements selected from the group consisting of N is selected. The magnetic material according to any one of claims 1 to 9 , wherein the material of the channel layer is a material including one or more elements selected from the group consisting of B, C, Mg, Al, Cu, and Zn. sensor. Material of the channel layer, a magnetic sensor according to any one of claims 1 to 10 which is a semiconductor compound containing Si or ZnO. The magnetic sensor according to claim 2 or 3 , wherein the material of the barrier layer is aluminum oxide, magnesium oxide, or zinc oxide.

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