JP2020181961A - Magnetoresistance effect element - Google Patents

Abstract

To provide a magnetoresistance effect element in which the ratio of change in magnetic resistance (MR ratio) can be more increased.SOLUTION: The magnetoresistance effect element comprises a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic metal layer located between the first ferromagnetic layer and the second ferromagnetic layer, and at least one of the first ferromagnetic layer and the second ferromagnetic layer includes a first layer including a Heusler alloy, a second layer different from the first layer, and a heavy metal layer including a heavy metal region and located between the first layer and the second layer, the heavy metal region includes a heavy metal element having an atomic number of 39 or more, the heavy metal region is a continuous region having a discontinuity or an opening, and a crystal structure is continuous at the interface between the heavy metal region and the first layer and the second layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a magnetoresistive element.

The magnetoresistive element is an element whose resistance value in the stacking direction changes due to the magnetoresistive effect. The magnetoresistive element includes two ferromagnetic layers and a non-magnetic layer sandwiched between them. Magnetoresistive elements in which a conductor is used for the non-magnetic layer are called giant magnetoresistive (GMR) elements, and magnetoresistive elements in which an insulating layer (tunnel barrier layer, barrier layer) is used for the non-magnetic layer are called giant magnetoresistive (GMR) elements. It is called a tunnel magnetoresistive (TMR) element.

In the magnetoresistive element, the resistance value changes according to the difference in the relative angles of magnetization of the two ferromagnets sandwiching the non-magnetic layer. The resistance value of the magnetoresistive element shows the minimum when the two magnetizations are parallel and the maximum when the two magnetizations are antiparallel. The rate of change of the resistance value of the magnetoresistive element is expressed by the MR ratio. The MR ratio is the ratio obtained by dividing the difference in resistance between the antiparallel state and the parallel state by the resistance value in the parallel state.

Patent Document 1 describes a magnetoresistive element using a Heusler alloy for the magnetic layer. The Heusler alloy has a high spin polarizability, and when the Whistler alloy is used, the MR ratio of the magnetoresistive sensor becomes large.

JP-A-2010-034152

It is said that the Whisler alloy theoretically has a high polarizability and a large MR ratio can be obtained. However, in reality, the crystal structure of the Whistler alloy was disturbed due to atomic diffusion from other layers, and the expected high MR ratio could not be obtained.

In view of such circumstances, it is an object of the present invention to provide a magnetoresistive effect element capable of increasing the rate of change in magnetic resistance (MR ratio).

The present inventors have found that the MR ratio of a magnetoresistive sensor is improved by laminating a ferromagnetic layer on a Whistler alloy and providing a heavy metal layer in which a part is not continuous between them. The present invention provides the following means for solving the above problems.

(1) The magnetic resistance effect element according to the first aspect is non-magnetic located between the first ferromagnetic layer, the second ferromagnetic layer, and the first ferromagnetic layer and the second ferromagnetic layer. A metal layer, and at least one of the first ferromagnetic layer and the second ferromagnetic layer includes a first layer containing a Whistler alloy, a second layer different from the first layer, and the first layer. It has a heavy metal layer located between the layer and the second layer and includes a heavy metal region, the heavy metal region containing a heavy metal element having an atomic number of 39 or more, and the heavy metal region discontinuous or open. It is a continuous region having a continuous crystal structure at the interface between the heavy metal region and the first layer and the second layer.

(2) In the magnetoresistive element according to the above aspect, the thickness of the heavy metal layer may be three times or less the diameter of the heavy metal element.

(3) In the magnetoresistive sensor according to the above aspect, the lattice constant of the heavy metal region and the lattice constants of the first layer and the second layer may be within 5%.

(4) In the magnetoresistive sensor according to the above aspect, the heavy metal element is any one selected from the group consisting of Ag, Gd, Tb, Dy, Ho, Er, Tm, Lu, Pt, Au, Th. It may be the above.

(5) In the magnetoresistive element according to the above aspect, the heavy metal element is represented by the composition formula Pt _α Z _1-α , and Z in the composition formula is a group consisting of Tb, Dy, Ho, Er, Tm, and Lu. It may be any one or more selected from.

(6) In the magnetoresistive element according to the above aspect, α in the composition formula may satisfy 0.6 <α <0.9.

(7) In the magnetoresistive element according to the above aspect, the heavy metal element may be Ag or an alloy containing Ag.

(8) In the magnetoresistive sensor according to the above aspect, the heavy metal element may contain an element constituting the non-magnetic metal layer.

(9) In the magnetoresistive sensor according to the above aspect, the Whistler alloy is represented by the composition formula Co ₂ L _β M _γ , and L in the composition formula is any one selected from the group consisting of Mn, Fe, and Cr. There may be one or more, and M in the composition formula may be any one or more selected from the group consisting of Si, Al, Ga, and Ge.

(10) In the magnetoresistive element according to the above aspect, β and γ in the composition formula may satisfy 2.0 <β + γ <2.6.

(11) In the magnetoresistive element according to the above aspect, the second layer may be an alloy containing Co and Fe.

(12) In the magnetoresistive sensor according to the above aspect, the first layer may be located closer to the non-magnetic metal layer than the second layer.

(13) In the magnetoresistive element according to the above aspect, the film thickness of the first layer is thicker than the spin diffusion length of the first layer, and the film thickness of the second layer is the spin diffusion length of the second layer. It may be thinner.

(14) In the magnetoresistive sensor according to the above aspect, the first ferromagnetic layer and the second ferromagnetic layer include the first layer, the second layer, and a heavy metal layer including the heavy metal region. You may.

(15) In the magnetoresistive sensor according to the above aspect, the area of the heavy metal layer in the first ferromagnetic layer and the area of the heavy metal layer in the second ferromagnetic layer may be different.

The magnetoresistive element according to one aspect of the present invention exhibits a large MR ratio.

It is sectional drawing of the magnetoresistive element which concerns on 1st Embodiment. It is a top view of the heavy metal layer of the magnetoresistive element which concerns on 1st Embodiment. It is a schematic diagram which enlarged the main part of the heavy metal layer which concerns on 1st Embodiment. It is sectional drawing of the magnetoresistive effect concerning the 1st modification. It is sectional drawing of the magnetoresistive effect concerning the 2nd modification. It is sectional drawing of the magnetoresistive effect concerning the 3rd modification. It is a top view of the heavy metal layer of the magnetoresistive element which concerns on the 4th modification. It is sectional drawing of the magnetic recording element which concerns on application example 1. FIG. It is sectional drawing of the magnetic recording element which concerns on application example 2. FIG.

Hereinafter, the present invention will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of the respective components may differ from the actual ones. is there. The materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

"Magnetic resistance effect element"
FIG. 1 is a cross-sectional view of the magnetoresistive element according to the present embodiment. FIG. 1 is a cross-sectional view of the magnetoresistive element 100 cut along the stacking direction of each layer of the magnetoresistive element. The magnetoresistive sensor 100 has a first ferromagnetic layer 10, a second ferromagnetic layer 20, and a non-magnetic metal layer 30. In FIG. 1, the substrate 40, the base layer 50, and the cap layer 60 are shown at the same time.

(1st ferromagnetic layer, 2nd ferromagnetic layer)
The first ferromagnetic layer 10 and the second ferromagnetic layer 20 are magnetic materials. The first ferromagnetic layer 10 and the second ferromagnetic layer 20 are magnetized, respectively. The magnetoresistive sensor 100 outputs a change in the relative angle between the magnetization of the first ferromagnetic layer 10 and the magnetization of the second ferromagnetic layer 20 as a resistance value change.

The magnetization of the second ferromagnetic layer 20 is harder to move than, for example, the magnetization of the first ferromagnetic layer 10. When a predetermined external force is applied, the direction of magnetization of the second ferromagnetic layer 20 does not change (fixed), and the direction of magnetization of the first ferromagnetic layer 10 changes. By changing the direction of magnetization of the first ferromagnetic layer 10 with respect to the direction of magnetization of the second ferromagnetic layer 20, the resistance value of the magnetoresistive sensor 100 changes. In this case, the second ferromagnetic layer 20 is called a magnetization fixed layer, and the first ferromagnetic layer 10 may be called a magnetization free layer. Hereinafter, the case where the first ferromagnetic layer 10 is a magnetized free layer and the second ferromagnetic layer 20 is a magnetized fixed layer will be described as an example.

The difference in the ease of movement between the magnetization of the second ferromagnetic layer 20 and the magnetization of the first ferromagnetic layer 10 when a predetermined external force is applied is maintained between the first ferromagnetic layer 10 and the second ferromagnetic layer 20. It is caused by the difference in magnetic force. For example, when the thickness of the second ferromagnetic layer 20 is made thicker than the thickness of the first ferromagnetic layer 10, the coercive force of the second ferromagnetic layer 20 becomes larger than the coercive force of the first ferromagnetic layer 10. Further, for example, an antiferromagnetic layer is provided on the surface of the second ferromagnetic layer 20 opposite to the non-magnetic metal layer 30 via a spacer layer. The second ferromagnetic layer 20, the spacer layer, and the antiferromagnetic layer have a synthetic antiferromagnetic structure (SAF structure). The synthetic antiferromagnetic structure consists of two magnetic layers sandwiching a non-magnetic layer. Since the second ferromagnetic layer 20 and the antiferromagnetic layer are antiferromagnetic coupled, the coercive force of the second ferromagnetic layer 20 becomes larger than that in the case where the second ferromagnetic layer 20 is not provided. The antiferromagnetic layer is, for example, IrMn, PtMn, or the like. The spacer layer contains, for example, at least one selected from the group consisting of Ru, Ir, Rh. The method of creating a coercive force difference depending on the thickness does not require an additional layer such as an antiferromagnetic layer that can cause parasitic resistance. On the other hand, the method of creating a coercive force difference by the SAF structure can enhance the orientation of the magnetization of the second ferromagnetic layer 20.

The first ferromagnetic layer 10 and the second ferromagnetic layer 20 include first layers 11, 21 and second layers 12, 22 and heavy metal layers 13, 23, respectively.

The first layers 11 and 21 contain a Whistler alloy. The Whisler alloy is a half metal and has a high spin polarizability. The Whisler alloy is an intermetallic compound having a chemical composition of XYZ or X ₂ YZ, where X is a transition metal element or noble metal element of the Co, Fe, Ni, Cu group on the periodic table, and Y is Mn, V, It is a transition metal of Group Cr and Ti or an elemental species of X, and Z is a typical element of Group III to Group V. The first layer 11 and the first layer 21 may have the same composition or different compositions.

The Whisler alloy is preferably one represented by the composition formula Co ₂ L _β M _γ . L in the composition formula is at least one selected from the group consisting of Mn, Fe, and Cr, and M in the composition formula is any one selected from the group consisting of Si, Al, Ga, and Ge. That is all. The Co-based Whistler alloy has a high Curie temperature. The magnetoresistive element using the Co-based Whistler alloy has a large MR ratio even at room temperature. Further, β and γ in the composition formula preferably satisfy 2.0 <β + γ <2.6. When β and γ in the composition formula are in this range, antisites in which Co atoms replace other atomic sites are unlikely to occur, and the characteristics of high spin polarizability of the Whistler alloy can be maintained. The Whisler alloy is, for example, Co ₂ FeSi, Co ₂ FeGe, Co ₂ FeGa, Co ₂ MnSi, Co ₂ Mn _1-a Fe _a Al _b Si _1-b , Co ₂ FeGe _1-c Ga _{c and the} like.

As shown in FIG. 1, the first layers 11 and 21 are located closer to the non-magnetic metal layer 30 than, for example, the second layers 12 and 22. The MR ratio of the magnetoresistive sensor 100 is caused by the difference in the relative angles of magnetization of the two magnetic materials sandwiching the non-magnetic metal layer 30. Therefore, it is the two ferromagnetic layers in contact with the non-magnetic metal layer 30 that have a particularly large effect on the MR ratio of the magnetoresistive element 100. The MR ratio of the magnetoresistive sensor 100 can be further increased by contacting the first layers 11 and 21 having a Whisler alloy and having a high spin polarizability with the non-magnetic metal layer 30.

Further, the thickness of the first layers 11 and 21 in the stacking direction is preferably thicker than the spin diffusion length of the first layers 11 and 21. The spin diffusion length is the distance at which an electron can move while preserving spin information. Further, the thickness of the first layers 11 and 21 is preferably thicker than that of the second layers 12 and 22, for example. By occupying the main part of the first ferromagnetic layer 10 and the second ferromagnetic layer 20, the first layers 11 and 21 enhance the effect of using the Whistler alloy having a high spin polarization rate, and the MR of the magnetoresistive element 100 is enhanced. The ratio can be increased.

The second layers 12 and 22 are magnetic materials different from those of the first layers 11 and 21. The second layer 12 faces the first layer 11. The second layer 22 faces the first layer 21. The second layers 12 and 22 are magnetically coupled to the first layers 11 and 21. When the orientation direction of the magnetization of the first layers 11 and 21 changes, the orientation direction of the magnetization of the second layers 12 and 22 also changes.

The second layers 12 and 22 are, for example, a metal selected from the group consisting of Cr, Mn, Co, Fe and Ni, an alloy containing one or more of these metals, and at least these metals and B, C, and N. Includes alloys containing one or more elements. The second layers 12 and 22 contain, for example, an alloy containing Co and Fe. It has been reported that the Whistler alloys constituting the first layers 11 and 21 have low magnetization stability near the laminated interface. On the other hand, the alloy of Co and Fe has high magnetization stability and high lattice consistency with the Whistler alloy constituting the first layers 11 and 21. The magnetoresistive sensor using an alloy of Co and Fe for the second layers 12 and 22 stabilizes the magnetization of the Whistler alloy constituting the first layers 11 and 21, so that the MR ratio is large even at room temperature. The second layers 12 and 22 are, for example, Co-Fe and Co-Fe-B.

The thickness of the second layers 12 and 22 in the stacking direction is preferably thinner than the spin diffusion length of the second layers 12 and 22. Further, the thickness of the second layers 12 and 22 is preferably thinner than the thickness of the first layers 11 and 21, for example.

The heavy metal layer 13 is located between the first layer 11 and the second layer 12, and the heavy metal layer 23 is located between the first layer 21 and the second layer 22. FIG. 2 is a plan view of the heavy metal layer 13 of the magnetoresistive element 100. The heavy metal layer 13 has a first region 14 and a second region 15.

The first region 14 is a heavy metal region containing a heavy metal element having an atomic number of 39 or more. The second region 15 is a region other than the first region 14. The second region 15 is, for example, a part of the first layer 11 and the second layer 12, and is made of the same material as these. The first region 14 exists discontinuously in the heavy metal layer 13. The first region 14 exists, for example, in an island shape in the heavy metal layer 13. The second region 15 is a continuous region having an opening. The opening of the second region 15 is filled with heavy metals constituting the first region 14. Since the first region 14 does not exist on the entire surface of the heavy metal layer 13, the first layer 11 and the second layer 12 are magnetically coupled.

The thickness of the heavy metal layer 13 is preferably 3 times or less the diameter of the heavy metal element constituting the first region 14, more preferably 2 times or less the diameter of the heavy metal element, and not more than the diameter of the heavy metal element. Is even more preferable. The heavy metal layer 13 is formed by, for example, a sputtering method. When a film thickness of this degree is formed, the film-forming elements do not usually form a uniform layer, but are partially aggregated and scattered. That is, when the thickness of the heavy metal layer 13 is within the above range, the first region 14 is likely to be partially discontinuously formed.

The crystal structure of the first region 14 is continuous with the first layer 11 and the second layer 12. The continuous crystal structure means that the atoms are continuously arranged when the vicinity of the first region 14 is measured with a transmission electron microscope. The continuous arrangement of atoms means that the line connecting the atoms in the film forming direction is not interrupted. When the first region 14 is epitaxially grown with respect to the first layer 11 and the second layer 12, the crystal structure is continuous between the first region 14 and the first layer 11 and the second layer 12.

FIG. 3 is an enlarged schematic view of a main part of the heavy metal layer 13 according to the present embodiment. The first layer 11, the second layer 12, and the heavy metal layer 13 are each composed of atoms A. In FIG. 3, the atoms A constituting the first layer 11, the second layer 12, and the heavy metal layer 13 are continuous in the stacking direction. The lattice consistency between the lattice constant L14 of the first region and the lattice constants L11 and L12 of the first layer 11 and the second layer 12 is preferably 5% or less. The lattice consistency is the degree of deviation of the lattice constants L11 and L12 of the first layer 11 or the second layer 12 when the lattice constant L14 of the first region is used as a reference. Although atom A is represented as a representative for convenience of explanation, the atom A differs depending on the atoms constituting the first layer, the second layer, and the heavy metal layer.

In FIGS. 2 and 3, the heavy metal layer 13 is shown as a representative, but the same applies to the heavy metal layer 23.

The heavy metal elements contained in the heavy metal layers 13 and 23 have an atomic number of 39 or more. The heavy metal element preferably contains any one or more selected from the group consisting of Ag, Gd, Tb, Dy, Ho, Er, Tm, Lu, Pt, Au and Th.

The heavy metal elements contained in the heavy metal layers 13 and 23 are represented by, for example, the composition formula Pt _α Z _1-α . Z in the composition formula is any one or more selected from the group consisting of Tb, Dy, Ho, Er, Tm, and Lu. Further, α in the composition formula preferably satisfies 0.6 <α <0.9. When the first region 14 is composed of these materials, the lattice consistency between the first region 14 and the Whistler alloy (first layer 11) and the CoFe alloy (second layer 12) is enhanced. When the lattice consistency is high, the crystal structure is less distorted and the MR ratio of the magnetoresistive element 100 becomes large.

The heavy metal elements contained in the heavy metal layers 13 and 23 are, for example, Ag or an alloy containing Ag. The resistance of Ag or an alloy containing Ag is low, and when these materials are used for the heavy metal layers 13 and 23, the MR ratio of the magnetoresistive element 100 becomes large. Further, the Ag or the alloy containing Ag has high lattice consistency with the Whistler alloy (first layer 11) and the CoFe alloy (second layer 12).

Further, the heavy metal layers 13 and 23 may be made of the same material as the material constituting the non-magnetic metal layer 30 or the base layer 50. That is, the heavy metal layers 13 and 23 may contain materials constituting the non-magnetic metal layer 30 or the base layer 50.

The non-magnetic metal layer 30 is located between the first ferromagnetic layer 10 and the second ferromagnetic layer 20. The non-magnetic metal layer 30 is sandwiched between the first ferromagnetic layer 10 and the second ferromagnetic layer 20.

The non-magnetic metal layer 30 is made of, for example, a non-magnetic metal. The non-magnetic metal layer 30 is, for example, Cu, Au, Ag, Al, Cr or the like. The non-magnetic metal layer 30 preferably contains any one selected from the group consisting of Ag, Cu, Au, Ag, Al, and Cr as a main constituent element. The main constituent element means that the ratio of Cu, Au, Ag, Al, and Cr in the stoichiometric composition formula is 50% or more. The non-magnetic metal layer 30 preferably contains Ag, and preferably contains Ag as a main constituent element.

The non-magnetic metal layer 30 has, for example, a thickness of 1 nm or more and 10 nm or less. The non-magnetic metal layer 30 inhibits the magnetic bond between the first ferromagnetic layer 10 and the second ferromagnetic layer 20.

The substrate 40 is a portion that serves as a base for the magnetoresistive element 100. It is preferable to use a material having excellent flatness for the substrate 40. The substrate 40 includes, for example, a metal oxide single crystal, a silicon single crystal, a silicon single crystal with a thermal oxide film, a sapphire single crystal, ceramic, quartz, and glass. The material contained in the substrate 40 is not particularly limited as long as it has an appropriate mechanical strength and is suitable for heat treatment and microfabrication. Examples of the metal oxide single crystal include an MgO single crystal, and according to a substrate containing the MgO single crystal, for example, an epitaxial growth film is easily formed by using a sputtering method. This epitaxial growth film can exhibit a large magnetoresistive property. The substrate 40 depends on the target product. When the product is MRAM, the substrate 40 is, for example, a Si substrate having a circuit structure. When the product is a magnetic head, the substrate 40 is, for example, an AlTiC substrate that is easy to process.

The base layer 50 is located between the substrate 40 and the magnetoresistive element 100. The base layer 50 may be either a conductive material or an insulating material. When the base layer 50 also serves as an electrode, the base layer 50 contains a conductive material. The base layer 50 is a layer for enhancing the crystallinity of the first ferromagnetic layer 10, the non-magnetic metal layer 30, and the second ferromagnetic layer 20 laminated on the base layer 50.

The base layer 50 has, for example, a (001) oriented NaCl structure. The underlayer 50 having a NaCl structure is, for example, a nitride containing at least one element selected from the group of Ti, Zr, Nb, V, Hf, Ta, Mo, W, B, Al, and Ce, or Mg. , Al, Ce An oxide containing at least one element selected from the group.

As another example, the base layer 50 is, for example, a layer of (002) oriented perovskite-based conductive oxide represented by the composition formula of ABO ₃ . Site A contains at least one element selected from the group Sr, Ce, Dy, La, K, Ca, Na, Pb, Ba, and site B contains Ti, V, Cr, Mn, Fe, Co, Ni, It contains at least one element selected from the group Ga, Nb, Mo, Ru, Ir, Ta, Ce, Pb.

As another example, the base layer 50 has a (001) oriented tetragonal structure or cubic structure, and Al, Cr, Fe, Co, Rh, Pd, Ag, Ir, Pt, Au, Mo, It contains at least one element selected from the group of W and Pt. Further, an alloy of these metal elements and a laminate of materials composed of two or more kinds of these metal elements may be included. Alloys of metal elements include cubic AgZn alloys, AgMg alloys, CoAl alloys, FeAl alloys and NiAl alloys.

The cap layer 60 is located on the opposite side of the magnetoresistive element 100 from the substrate 40. The cap layer 60 is provided to protect the magnetoresistive layer 30. The cap layer 60 suppresses the diffusion of elements from the second ferromagnetic layer 20. The cap layer 60 also contributes to the crystal orientation of each layer of the magnetoresistive element 100. Having the cap layer 60 stabilizes the magnetization of the first ferromagnetic layer 10 and the second ferromagnetic layer 20, and can reduce the resistance of the magnetoresistive sensor 100.

The cap layer 60 contains, for example, a highly conductive material. The cap layer 60 is formed by, for example, one or more metal elements of Ru, Ag, Al, Cu, Au, Cr, Mo, Pt, W, Ta, Pd, and Ir, alloys of these metal elements, or alloys of these metal elements. It may include a laminate of two or more kinds of materials.

Next, a method of manufacturing the magnetoresistive element 100 according to the present embodiment will be described. The magnetoresistive sensor 100 is obtained by laminating a first ferromagnetic layer 10, a non-magnetic metal layer 30, and a second ferromagnetic layer 20 in this order. The film forming method for each layer is, for example, a sputtering method, a thin film deposition method, a laser ablation method, or a molecular beam epitaxy (MBE) method.

Each layer of the first ferromagnetic layer 10 is formed by, for example, a sputtering method. For example, the second layer 12 is first formed. Next, the heavy metal element is sputtered on the surface of the second layer 12. Heavy metal elements are laminated with a thickness of several layers of atoms. The heavy metal element formed by the sputtering method does not become a uniform layer for several atomic layers, and the heavy metal element is unevenly distributed in a part. Further, a part of the heavy metal element is driven into the second layer 12 and invades the second layer 12. As a result, the heavy metal layer 13 having the first region 14 and the second region 15 is formed. Next, by forming the first layer 11, the first ferromagnetic layer 10 is formed. The same applies to the second ferromagnetic layer 20 except that the first layer 21 is formed before the second layer 22.

Further, the magnetoresistive element 100 may be annealed after laminating the magnetoresistive element 100. Annealing enhances the crystallinity of each layer.

The magnetoresistive element 100 according to the first embodiment has heavy metal layers 13 and 23 between the first layers 11 and 21 and the second layers 12 and 22. Since the heavy metal has a large atomic radius and is heavy, it suppresses the diffusion of the elements of the second layers 12 and 22 to the first layers 11 and 21. When the elements of the second layers 12 and 22 diffuse into the first layers 11 and 21, the crystal structure of the Whistler alloy is disturbed and antisite is generated, which contributes to a decrease in the spin polarizability of the Whistler alloy. By preventing the element diffusion between the first layers 11, 21 and the second layers 12, 22 by the heavy metal layers 13 and 23, the high spin polarizability of the Whistler alloy is maintained, and the MR ratio of the magnetoresistive sensor 100 is increased. Can be enhanced.

Tables 1 to 3 are tables for showing an example of the lattice consistency of the magnetoresistive element. Specifically, Table 1 shows examples of materials (1st to 17th examples) and CoFe (18th examples) that can form the heavy metal layers 13 and 23 of the present embodiment, and these materials are cubic crystals. It is a table which shows the literature value of the lattice constant when it has the crystal structure of. Table 2 is a table showing examples of materials (alloys A to H) that can form the first layers 11 and 21 of the present embodiment, and literature values of the lattice constants of those materials.

Table 3 is a table showing the lattice consistency of each of the alloys A to H shown in Table 2 with respect to each of the first to eighteenth examples shown in Table 1. The lattice consistency in Table 3 is expressed as a percentage and is determined by the following formula (1) or formula (2). When the [110] direction of each (001) plane of Examples 1 to 17 and the [100] direction of each (001) plane of alloys A to H are lattice-matched, the equation (1) is used. Lattice consistency is required. In the 18th example, the [100] direction of the (001) plane and the [100] direction of each (001) plane of the alloys A to H are lattice-matched, and the lattice consistency is obtained by the equation (2). Further, in the formula (1) or the formula (2), a represents the lattice constants of Examples 1 to 18 shown in Table 1, and b represents the lattice constants of the alloys A to H shown in Table 2. Also, √2 means the square root of 2.
Lattice consistency (%) = ((a × √2-b) / b) × 100 (%)… (1)
Lattice consistency (%) = ((2ab) / b) x 100 (%) ... (2)

Table 3 also shows the evaluation results of the first to 17th cases. In Table 3, among the first to 17th examples, "especially good" is given for the example showing the lattice consistency smaller than the lattice consistency in the 18th example for three or more of the alloys A to H. It is evaluated as "A" which means. Further, among the 1st to 17th examples, one or more and two or less alloys A to H, which show a lattice consistency smaller than the lattice consistency in the 18th example, means "good". It is evaluated as "B".

As shown in Table 3, in the first to 17th cases, it is evaluated as "A" or "B". When the material of the example of evaluation B is used as the heavy metal layers 13 and 23 of the present embodiment, the lattice matching with the first layers 11 and 21 and the second layers 12 and 22 is also good, so that the first ferromagnetic layer 10 It is considered that the crystallinity of the second ferromagnetic layer 20 is improved and a large magnetoresistive effect is exhibited. When the material of the example of evaluation A is used as the heavy metal layers 13 and 23 of the present embodiment, the lattice matching with the first layers 11 and 21 and the second layers 12 and 22 is also good, so that the first ferromagnetic layer 10 It is considered that the crystallinity of the second ferromagnetic layer 20 is improved and a larger magnetoresistive effect is exhibited.

Although an example of the first embodiment has been described in detail above, the present invention is not limited to this example, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. is there.

For example, instead of the non-magnetic metal layer 30, a non-magnetic layer made of an insulator or a semiconductor may be used. The non-magnetic insulator is, for example, Al ₂ O ₃ , SiO ₂ , MgO, MgAl ₂ O ₄ , and a material in which some of these Al, Si, and Mg are replaced with Zn, Be, and the like. Non-magnetic semiconductors are, for example, Si, Ge, CuInSe ₂ , CuGaSe ₂ , Cu (In, Ga) Se _{2, and the} like.

Further, FIG. 4 is a cross-sectional view of the magnetoresistive element 101 according to the first modification. The magnetoresistive element 101 is different from the magnetoresistive element 100 shown in FIG. 1 in that the positional relationships between the first layers 11 and 21 and the second layers 12 and 22 are opposite. The same components as those in FIG. 1 are designated by the same reference numerals.

The second ferromagnetic layer 20A has a second layer 22, a heavy metal layer 23, and a first layer 21 in this order from the side closer to the non-magnetic metal layer 30. The first ferromagnetic layer 10A has a second layer 12, a heavy metal layer 13, and a first layer 11 in this order from the side closer to the non-magnetic metal layer 30.

Since the magnetoresistive element 101 according to the first modification also has the heavy metal layers 13 and 23 between the first layers 11 and 21 and the second layers 12 and 22, the first layers 11 and 21 and the second layer 12 , 22 and the element diffusion between them is suppressed. Therefore, the magnetoresistive element 101 exhibits a large MR ratio.

Further, FIG. 5 is a cross-sectional view of the magnetoresistive element 102 according to the second modification. The magnetoresistive sensor 102 differs from the magnetoresistive element 100 shown in FIG. 1 in that the second ferromagnetic layer 20B is composed of the first layer 21 and the second layer 22, and does not have the heavy metal layer 23. The same components as those in FIG. 1 are designated by the same reference numerals.

Since the magnetoresistive element 102 according to the second modification also has the heavy metal layer 13 between the first layer 11 and the second layer 12, element diffusion between the first layer 11 and the second layer 12 is suppressed. Has been done. Therefore, the magnetoresistive element 102 exhibits a large MR ratio. Further, although the configuration in which the second ferromagnetic layer 20B does not have the heavy metal layer 23 is illustrated here, the configuration in which the first ferromagnetic layer 10 does not have the heavy metal layer 13 may be used. The magnetoresistive element may include at least one of the first ferromagnetic layer 10 and the second ferromagnetic layer 20 as a first layer, a second layer, and a heavy metal layer.

Further, FIG. 6 is a cross-sectional view of the magnetoresistive element 103 according to the third modification. The magnetoresistive element 103 differs from the magnetoresistive element 100 shown in FIG. 1 in that the side surface of the magnetoresistive element 103 is inclined with respect to the laminated surface. The same components as those in FIG. 1 are designated by the same reference numerals.

The magnetoresistive sensor 103 has a first ferromagnetic layer 10C, a second ferromagnetic layer 20C, a non-magnetic metal layer 30C, a substrate 40, a base layer 50C, and a cap layer 60C. The side surfaces of the first ferromagnetic layer 10C, the second ferromagnetic layer 20C, the non-magnetic metal layer 30C, the base layer 50C, and the cap layer 60C are inclined with respect to the laminated surface. The outer diameter or outer diameter of the magnetoresistive element 103 increases as it approaches the substrate 40. In the cross-sectional view, the width of the magnetoresistive element 103 increases as it approaches the substrate 40.

The first ferromagnetic layer 10C has a first layer 11C, a second layer 12C, and a heavy metal layer 13C. The second ferromagnetic layer 20C has a first layer 21C, a second layer 22C, and a heavy metal layer 23C. The area of the heavy metal layer 13C in the first ferromagnetic layer 10C and the area of the heavy metal layer 23C in the second ferromagnetic layer 20C are different. For example, the area of the heavy metal layer 13C is larger than the area of the heavy metal layer 23C. In the magnetoresistive element 103, the influence from the base layer 50C is larger than the influence from the cap layer 60C. Since the area of the heavy metal layer 13C on the side closer to the base layer 50C is large, the influence from the base layer 50C can be further suppressed.

Since the magnetoresistive element 103 according to the third modification also has heavy metal layers 13C and 23C between the first layers 11C and 21C and the second layers 12C and 22C, the first layers 11C and 21C and the second layer 12C , Element diffusion between 22C is suppressed. Therefore, the magnetoresistive element 103 exhibits a large MR ratio.

Further, FIG. 7 is a plan view of the heavy metal layer 13A of the magnetoresistive element according to the fourth modification. The heavy metal layer 13A has a first region 14A and a second region 15A. The relationship between the first region 14A and the second region 15A is different from that of the heavy metal layer 13 shown in FIG.

The first region 14A is a heavy metal region containing a heavy metal element having an atomic number of 39 or more. The second region 15A is a region other than the first region 14A. The first region 14A is a continuous region having an opening. The opening of the first region 14A is filled with the material constituting the first layer or the second layer. The second region 15A exists discontinuously in the heavy metal layer 13A. The second region 15A exists, for example, in an island shape in the heavy metal layer 13A.

Since the magnetoresistive element according to the fourth modification also has the heavy metal layer 13A between the first layer and the second layer, the element diffusion between the first layer and the second layer is suppressed. Therefore, the magnetoresistive element according to the fourth modification shows a large MR ratio.

Next, an application example of the magnetoresistive element 100 according to the present embodiment will be described. The magnetoresistive element 100 can be used, for example, as a memory such as a magnetic sensor or an MRAM.

FIG. 8 is a cross-sectional view of the magnetic recording element 200 according to Application Example 1. FIG. 8 is a cross-sectional view of the magnetoresistive element 100 cut along the stacking direction of each layer of the magnetoresistive element. The magnetic recording element 200 shown in FIG. 8 is an example of an application example of the magnetoresistive element 100.

The magnetic recording element 200 includes a magnetoresistive element 100, a first electrode 51, a second electrode 61, a power supply 70, and a measuring unit 80. The first electrode 51 may also serve as the base layer 50 of the magnetoresistive element 100. The second electrode 61 may also serve as the cap layer 60 of the magnetoresistive element 100. The power supply 70 and the measuring unit 80 are connected to the first electrode 51 and the second electrode 61, respectively. The power supply 70 gives a potential difference in the stacking direction of the magnetoresistive element 100. The measuring unit 80 measures the resistance value of the magnetoresistive element 100 in the stacking direction.

When a potential difference is created between the first electrode 51 and the second electrode 61 by the power supply 70, a current flows in the stacking direction of the magnetoresistive element 100. When the current passes through the second ferromagnetic layer 20, it spin-polarizes and becomes a spin-polarized current. The spin polarization current reaches the first ferromagnetic layer 10 via the non-magnetic metal layer 30. The magnetization of the first ferromagnetic layer 10 is reversed by receiving a spin transfer torque (STT) due to a spin polarization current. By changing the direction of magnetization of the first ferromagnetic layer 10 and the direction of magnetization of the second ferromagnetic layer 20, the resistance value in the stacking direction of the magnetoresistive sensor 100 changes. The resistance value in the stacking direction of the magnetoresistive element 100 is read out by the measuring unit 80. That is, the magnetic recording element 200 shown in FIG. 8 is a spin transfer torque (STT) type magnetic recording element.

FIG. 9 is a cross-sectional view of the magnetic recording element 201 according to Application Example 2. FIG. 9 is a cross-sectional view of the magnetoresistive element 100 cut along the stacking direction of each layer of the magnetoresistive element. The magnetic recording element 201 shown in FIG. 9 is an example of an application example of the magnetoresistive element 100.

The magnetic recording element 201 includes a magnetoresistive element 100, a first wiring 52, a second electrode 62, a power supply 71, and a measuring unit 81. The second electrode 62 is connected to the first surface of the magnetoresistive element 100 in the stacking direction. The first wiring 52 is connected to the second surface of the magnetoresistive element 100 in the stacking direction. The second electrode 62 is a conductor, for example, Cu. The first wiring 52 includes any one of a metal, an alloy, an intermetal compound, a metal boride, a metal carbide, a metal siliceate, and a metal phosphate having a function of generating a spin current by the spin Hall effect when a current flows. .. The first wiring 52 is, for example, a non-magnetic metal having an atomic number of 39 or more having d electrons or f electrons in the outermost shell. The power supply 71 is connected to the first end and the second end of the first wiring 52. The measuring unit 81 is connected to the second electrode 62 and the first wiring 52, and measures the resistance value of the magnetoresistive element 100 in the stacking direction.

When the power supply 71 creates a potential difference between the first end and the second end of the first wiring 52, a current flows along the first wiring 52. When a current flows along the first wiring 52, a spin Hall effect is generated by spin-orbit interaction. The spin Hall effect is a phenomenon in which a moving spin is bent in a direction orthogonal to the current flow direction. The spin Hall effect creates an uneven distribution of spins in the first wiring 52 and induces a spin current in the thickness direction of the first wiring 52. The spin is injected from the first wiring 52 into the first ferromagnetic layer 10 by the spin current.

The spin injected into the first ferromagnetic layer 10 gives spin-orbit torque (SOT) to the magnetization of the first ferromagnetic layer 10. The first ferromagnetic layer 10 receives spin-orbit torque (SOT) and reverses its magnetization. By changing the direction of magnetization of the first ferromagnetic layer 10 and the direction of magnetization of the second ferromagnetic layer 20, the resistance value in the stacking direction of the magnetoresistive sensor 100 changes. The resistance value in the stacking direction of the magnetoresistive element 100 is read out by the measuring unit 81. That is, the magnetic recording element 201 shown in FIG. 9 is a spin-orbit torque (SOT) type magnetic recording element.

(Example 1)
The magnetoresistive element 100 shown in FIG. 1 was manufactured. The structure of each layer is as follows.
Base layer 50: Ag, thickness 70 nm
First ferromagnetic layer 10
First layer 11: Co ₂ Mn _β Si _γ (β = 0.95, γ = 0.95), thickness 10 nm
Second layer 12: CoFe alloy, thickness 2 nm
Heavy metals constituting the heavy metal layer 13: Ag, thickness 0.41 nm
Non-magnetic metal layer 30: Ag, thickness 5 nm
Second ferromagnetic layer 20
First layer 21: Co ₂ Mn _β Si _γ (β = 0.95, γ = 0.95), thickness 8 nm
Second layer 22: CoFe alloy, thickness 2 nm
Heavy metals constituting the heavy metal layer 23: Ag, thickness 0.41 nm
Cap layer 60: Ru, thickness 5 nm

(Examples 2 to 5)
Examples 2 to 5 are different from Example 1 in that the heavy metals constituting the heavy metal layer 13 are changed. Other conditions were the same as in Example 1.

(Examples 6 to 26)
Examples 6 to 26 are different from Example 1 in that the composition of the Whistler alloy constituting the first layers 11 and 21 is changed. Other conditions were the same as in Example 1. In Examples 6 to 16, γ is fixed at 0.95 and β is changed between 0.4 and 1.7. In Examples 17 to 26, β is fixed at 1.3 and β is changed between 0.55 and 1.45.

(Comparative Example 1)
Comparative Example 1 is different from Example 1 in that the first ferromagnetic layer 10 and the second ferromagnetic layer 20 do not have the heavy metal layers 13 and 23. Other conditions were the same as in Example 1.

The results of Examples 1 to 26 and Comparative Example 1 are summarized in Table 4. As shown in Table 4, the MR ratios of Examples 1 to 26 are higher than those of Comparative Example 1. Further, as shown in Table 4, when 2 <β + γ <2.6, the magnetoresistive element according to the embodiment can have an MR ratio of more than 10. This large MR ratio is a result that the Whistler alloy tends to have a half-metal property when 2 <β + γ <2.6, and the Whistler alloy having this half-metal property shows a large magnetoresistive effect. ..

Although the present invention has been described above with reference to the embodiments and examples, the present invention is not limited to these embodiments and examples, and various modifications are possible. For example, the magnetoresistive sensor 100 of the above embodiment may have a CIP (Curent In Plane) structure in which a detection current is passed along the stacking surface direction, instead of a CPP (Currant Perpendicular to Plane) structure.

According to the magnetoresistive element satisfying the present embodiment, a high MR ratio can be obtained, and the magnetic head, the sensor, the high frequency filter or the oscillating element provided with the above-mentioned magnetoresistive element has a large magnetoresistive effect. Due to this, excellent characteristics can be exhibited.

10, 10A, 10C First ferromagnetic layers 11, 11C, 21, 21C First layers 12, 12C, 22, 22C Second layers 13, 13A, 13C, 23, 23C Heavy metal layers 14, 14A First regions 15, 15A 2nd region 20, 20A, 20B, 20C 2nd ferromagnetic layer 30, 30C Non-magnetic metal layer 40 Substrate 50, 50C Underlayer 51 1st electrode 52 1st wiring 60, 60C Cap layer 61, 62 2nd electrode 70, 71 Power supply 80, 81 Measuring unit 100, 101, 102, 103 Magnetic resistance effect element 200, 201 Magnetic recording element

Claims (15)

A first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic metal layer located between the first ferromagnetic layer and the second ferromagnetic layer are provided.
At least one of the first ferromagnetic layer and the second ferromagnetic layer includes a first layer containing a Whistler alloy, a second layer different from the first layer, and the first layer and the second layer. With a heavy metal layer, which is located between and contains a heavy metal region,
The heavy metal region contains a heavy metal element having an atomic number of 39 or more.
The heavy metal region is a continuous region having a discontinuity or an opening.
A magnetoresistive element having a continuous crystal structure at the interface between the heavy metal region and the first layer and the second layer. The magnetoresistive element according to claim 1, wherein the thickness of the heavy metal layer is three times or less the diameter of the heavy metal element. The magnetoresistive sensor according to claim 1 or 2, wherein the lattice constant of the heavy metal region and the lattice constants of the first layer and the second layer are within 5%. The heavy metal element is any one or more selected from the group consisting of Ag, Gd, Tb, Dy, Ho, Er, Tm, Lu, Pt, Au, and Th, any one of claims 1 to 3. The magnetoresistive element according to the section. The heavy metal element is represented by the composition formula Pt _α Z _1-α .
The magnetoresistive element according to claim 4, wherein Z in the composition formula is at least one selected from the group consisting of Tb, Dy, Ho, Er, Tm, and Lu. The magnetoresistive element according to claim 5, wherein α in the composition formula satisfies 0.6 <α <0.9. The magnetoresistive element according to claim 4, wherein the heavy metal element is Ag or an alloy containing Ag. The magnetoresistive sensor according to any one of claims 1 to 7, wherein the heavy metal element contains an element constituting the non-magnetic metal layer. The Whistler alloy is represented by the composition formula Co ₂ L _β M _γ .
L in the composition formula is any one or more selected from the group consisting of Mn, Fe, and Cr.
The magnetoresistive element according to any one of claims 1 to 8, wherein M in the composition formula is any one or more selected from the group consisting of Si, Al, Ga, and Ge. The magnetoresistive element according to claim 9, wherein β and γ in the composition formula satisfy 2.0 <β + γ <2.6. The magnetoresistive element according to any one of claims 1 to 10, wherein the second layer is an alloy containing Co and Fe. The magnetoresistive element according to any one of claims 1 to 11, wherein the first layer is located closer to the non-magnetic metal layer than the second layer. The film thickness of the first layer is thicker than the spin diffusion length of the first layer.
The magnetoresistive element according to any one of claims 1 to 12, wherein the film thickness of the second layer is thinner than the spin diffusion length of the second layer. The invention according to any one of claims 1 to 13, wherein the first ferromagnetic layer and the second ferromagnetic layer have the first layer, the second layer, and a heavy metal layer containing the heavy metal region. Magnetic resistance effect element. The magnetoresistive sensor according to claim 14, wherein the area of the heavy metal layer in the first ferromagnetic layer is different from the area of the heavy metal layer in the second ferromagnetic layer.

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