JP2019004124A - Magnetic element - Google Patents

Abstract

To provide a magnetic element capable of increasing field effect.SOLUTION: A magnetic element includes a first region, a second region having a thickness less than that of a 3 atomic layers, and a third region. The second region is located between the first and third regions. The first region contains at least one selected from a group consisting of Fe, Co and Ni. The second region contains one first atom selected from a group consisting of Co and Ni, and multiple first oxygen atoms. The third region contains a metal atom, and a second oxygen atom. In a first direction from the second region toward the first region, the first atom is between the second oxygen atom and one of the multiple first oxygen atoms. In a second direction crossing the first direction, the first atom is between two of the multiple first oxygen atoms.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a magnetic element.

  2. Description of the Related Art A magnetic element having a magnetic region containing a magnetic metal atom and a nonmagnetic region containing a metal oxide is known. In this magnetic element, information can be stored by changing the magnetization direction of the magnetic region. The magnetization direction of the magnetic region is controlled by applying a voltage to the magnetic element. In this magnetic element, it is desirable that the magnetization direction of the magnetic region can be controlled with a smaller voltage and the electric field effect is large.

Special table 2004-527099 gazette Kohji Nakamura et al. Physical Review B 81, 220409 (R) (2010)

  The problem to be solved by the present invention is to provide a magnetic element capable of increasing the electric field effect.

  The magnetic element according to the embodiment includes a first region, a second region having a thickness of three atomic layers or less, and a third region. The second region is located between the first region and the third region. The first region includes at least one selected from the group consisting of Fe, Co, and Ni. The second region includes one first atom selected from the group consisting of Co and Ni, and a plurality of first oxygen atoms. The third region includes a metal atom and a second oxygen atom. In the first direction from the second region to the first region, the first atom is between the second oxygen atom and one of the plurality of first oxygen atoms. In a second direction intersecting the first direction, the first atom is between two of the plurality of first oxygen atoms.

  According to the embodiment of the present invention, a magnetic element capable of increasing the field effect is provided.

1 is a schematic view illustrating a magnetic element according to a first embodiment. FIG. 6 is a schematic cross-sectional view illustrating another magnetic element according to the first embodiment. It is a schematic diagram showing the structure of the magnetic element used for simulation. FIG. 4A and FIG. 4B are simulation results representing the characteristics of the magnetic element according to the first embodiment. FIG. 5A to FIG. 5C are simulation results representing the characteristics of the magnetic element according to the first embodiment. FIG. 6A to FIG. 6C are simulation results representing the characteristics of the magnetic element according to the first embodiment. It is a schematic diagram which illustrates the magnetic element which concerns on 2nd Embodiment. It is a schematic diagram showing the magnetic element which concerns on the modification of 2nd Embodiment. It is a schematic diagram showing the structure of the magnetic element used for simulation. FIG. 10A to FIG. 10C are simulation results representing the characteristics of the magnetic element according to the second embodiment. Fig.11 (a)-FIG.11 (c) are the simulation results showing the characteristic of the magnetic element which concerns on 2nd Embodiment. It is a schematic diagram which illustrates the magnetic memory device which concerns on 3rd Embodiment. FIG. 13A to FIG. 13C are schematic views illustrating the operation of the magnetic memory device according to the third embodiment. It is a schematic diagram which illustrates another magnetic memory device concerning 4th Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
In the present specification and each drawing, the same elements as those already described are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a schematic view illustrating a magnetic element according to the first embodiment.
As shown in FIG. 1, the magnetic element 100 according to the first embodiment includes a first region 10, a second region 20, and a third region 30. The second region 20 is located between the first region 10 and the third region 30.

  The first region 10 includes a plurality of metal atoms 11. The plurality of metal atoms 11 include at least one selected from the group consisting of Fe, Co, and Ni.

The second region 20 includes a first atom 21 and a plurality of first oxygen atoms 25. The first atom 21 is one selected from the group consisting of Co and Ni.
The third region 30 includes a plurality of metal atoms 31 and a plurality of second oxygen atoms 35.

  The first direction from the second region 20 toward the first region 10 is taken as the z-axis direction. One direction perpendicular to the z-axis direction is taken as the x-axis direction. A direction perpendicular to the z-axis direction and the x-axis direction is taken as a y-axis direction.

  The first atom 21 is located between one of the plurality of second oxygen atoms 35 and one of the plurality of first oxygen atoms 25 in the z-axis direction. The first atom 21 is located between two of the plurality of first oxygen atoms 25 in the x-axis direction.

  In the example illustrated in FIG. 1, the second region 20 includes two atomic layers arranged in the z-axis direction. That is, the thickness of the second region 20 in the z-axis direction is a thickness corresponding to the two atomic layers.

Hereinafter, a specific example of the magnetic element 100 will be described.
The plurality of metal atoms 11 in the first region 10 is one selected from the group consisting of Fe, Co, and Ni, for example. As an example, the plurality of metal atoms 11 is Fe. Alternatively, a part of the plurality of metal atoms 11 is one selected from the group consisting of Fe, Co, and Ni, and another part of the plurality of metal atoms 11 is composed of Fe, Co, and Ni. It may be another one selected from the group. As an example, a part of the plurality of metal atoms 11 is Fe, and another part of the plurality of metal atoms 11 is Co. The first region 10 has, for example, a body-centered cubic structure.

  For example, the first atom 21 of the second region 20 is located between another two of the plurality of first oxygen atoms 25 in the y-axis direction. That is, the first atom 21 is located between oxygen atoms in the x-axis direction, the y-axis direction, and the z-axis direction, for example. The second region 20 has, for example, a NaCl type crystal structure.

  The second region 20 further includes a second atom 22. The second atom 22 is one selected from the group consisting of Fe, Co, and Ni. One of the plurality of first oxygen atoms 25 is located between one of the plurality of metal atoms 31 and the second atom 22 in the z-axis direction. The second atom 22 is located between two of the plurality of first oxygen atoms 25 in the x-axis direction. For example, the second atom 22 is located between the other two of the plurality of first oxygen atoms 25 in the y-axis direction. The position of the first atom 21 in the z-axis direction is different from the position of the second atom 22 in the z-axis direction. The position of the first atom 21 in the x-axis direction is different from the position of the second atom 22 in the x-axis direction.

  Alternatively, the second atom 22 may be one selected from the group consisting of Co and Ni, and the first atom 21 may be one selected from the group consisting of Fe, Co, and Ni.

  The plurality of metal atoms 31 and the plurality of second oxygen atoms 35 in the third region 30 are alternately provided in the x-axis direction and the z-axis direction. For example, the plurality of metal atoms 31 and the plurality of second oxygen atoms 35 are alternately provided in the y-axis direction. The third region 30 has, for example, a NaCl type crystal structure.

  The atomic number of the metal atom 31 in the third region 30 is, for example, smaller than the atomic number of the first atom 21 and smaller than the atomic number of the second atom 22. The metal atom 31 is, for example, Mg.

  The [001] direction of the third region 30 is along the z-axis direction. The [001] direction of the second region 20 is along the z-axis direction. This is based on the fact that the [001] direction of the third region 30 is along the z-axis direction. The [001] direction of the first region 10 is along the z-axis direction. This is based on the fact that the [001] direction of the second region 20 is along the z-axis direction.

  The [100] direction of the third region 30 is along the x-axis direction. The [100] direction of the second region 20 is along the x-axis direction. This is based on the fact that the [100] direction of the third region 30 is along the x-axis direction. The [100] direction of the first region 10 is along the x-axis direction. This is based on the fact that the [100] direction of the second region 20 is along the x-axis direction.

  The crystal orientations of the first region 10, the second region 20, and the third region 30 can be confirmed, for example, with a transmission electron microscope (TEM). When the second region 20 includes one atomic layer or two atomic layers, the crystal orientation of the second region 20 can be defined based on the crystal structure of the third region 30. For example, when the atoms included in the second region 20 are epitaxially arranged with the atoms included in the third region 30 and the [001] direction of the third region 30 is along the z-axis direction, the [001] of the second region 20 is ] Direction can be considered to be along the z-axis direction.

FIG. 2 is a schematic cross-sectional view illustrating another magnetic element according to the first embodiment.
For example, as shown in FIG. 2, the magnetic element 110 includes a first magnetic layer 1, an oxide layer 2, a nonmagnetic layer 3, a second magnetic layer 4, a first conductive layer 5, and a second conductive layer 6. Including.

  The oxide layer 2 is provided between the first magnetic layer 1 and the nonmagnetic layer 3 in the z-axis direction. The first magnetic layer 1 is provided between the oxide layer 2 and the first conductive layer 5 in the z-axis direction. The nonmagnetic layer 3 is provided between the oxide layer 2 and the second magnetic layer 4 in the z-axis direction. The second magnetic layer 4 is provided between the nonmagnetic layer 3 and the second conductive layer 6 in the z-axis direction.

  The first magnetic layer 1 includes a first region 10. The oxide layer 2 includes the second region 20. The nonmagnetic layer 3 includes a third region 30.

  The first magnetic layer 1 and the second magnetic layer 4 have ferromagnetism. The easy axis of magnetization of the first magnetic layer 1 and the easy axis of magnetization of the second magnetic layer 4 are, for example, along the z-axis direction. The easy magnetization axis of the first magnetic layer 1 and the easy magnetization axis of the second magnetic layer 4 may be along the x-axis direction or the y-axis direction. The magnetization direction of the first magnetic layer 1 changes more easily than the magnetization direction of the second magnetic layer 4.

  The nonmagnetic layer 3 is insulative. The nonmagnetic layer 3 functions as a tunnel barrier, for example. The electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 is based on the relative relationship between the magnetization direction of the first magnetic layer 1 and the magnetization direction of the second magnetic layer 4.

  When the magnetization direction of the first magnetic layer 1 and the magnetization direction of the second magnetic layer 4 are the same and the angle between them is relatively small, the electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 Is relatively small. When the magnetization direction of the first magnetic layer 1 and the magnetization direction of the second magnetic layer 4 are opposite to each other and the angle between them is relatively large, the electricity between the first magnetic layer 1 and the second magnetic layer 4 The resistance is relatively large. This is based on the magnetoresistive effect.

  The magnetic element 110 functions as a memory element by associating the state where the electrical resistance is large and the state where the electrical resistance is small with, for example, “0” and “1”. By detecting the electrical resistance of the first magnetic layer 1, the magnetization information stored in the magnetic element 110 can be read. Information can be written in the magnetic element 110 by controlling the magnetization direction of the first magnetic layer 1.

  By applying a voltage between the first magnetic layer 1 and the second magnetic layer 4, the magnetization direction of the first magnetic layer 1 can be controlled. The voltage is applied between the first magnetic layer 1 and the second magnetic layer 4 via the first conductive layer 5 and the second conductive layer 6.

  The change in the magnetization direction of the first magnetic layer 1 is caused by, for example, the crystal magnetic difference in the region including the first magnetic layer 1 and the oxide layer 2 due to an electric field generated between the first magnetic layer 1 and the nonmagnetic layer 3. Based on changes in isotropic energy. In order to reduce power consumption, it is desirable that a larger change in magnetocrystalline anisotropy energy occurs for the same voltage and that the field effect is large.

  The inventor of the present application locates the second region 20 including the first atom 21 and the plurality of first oxygen atoms 25 between the first region 10 and the third region 30, so that the magnetocrystalline magnetic property during voltage application is different. It was discovered that the change in the isotropic energy is large and the field effect can be increased.

FIG. 3 is a schematic diagram showing the structure of the magnetic element used in the simulation.
FIG. 4A, FIG. 4B, FIG. 5A to FIG. 5C, and FIG. 6A to FIG. 6C show the characteristics of the magnetic element according to the first embodiment. It is a simulation result.

  The simulation was performed using the first principle calculation. As shown in FIG. 3, the simulation was performed on a structure including a 3-atomic layer Au, a 3-atomic layer Fe, a 2-atomic layer metal oxide, and a 6-atomic layer MgO. This structure is in a free standing state without a substrate.

  The triatomic layer Au corresponds to, for example, at least a part of the first conductive layer 5 shown in FIG. The triatomic layer of Fe corresponds to the first region 10. The diatomic layer oxide corresponds to the second region 20. The hexaatomic layer of MgO corresponds to the third region 30.

4A and 4B, the horizontal axis represents the oxide included in the second region 20. The vertical axis in FIG. 4A represents the magnetocrystalline anisotropy energy E _MCA (mJ / m ² ). The vertical axis in FIG. 4B represents the change (field effect) ΔE _MCA / ΔE (fJ / Vm) of the magnetocrystalline anisotropy energy with respect to the voltage change. The external electric field is defined by the magnitude of the electric field in the vacuum region separated from the hexaatomic layer of MgO at infinity in the negative z-axis direction. For this reason, the magnitude of the field effect in the MgO layer substantially corresponds to a value obtained by multiplying the value in the graph by the relative dielectric constant (9.8) of MgO.

  In FIG. 4A and FIG. 4B, the solid line represents the result when the second region 20 includes two atomic layers. That is, the solid line represents the result when the second region 20 includes the first atom 21, the second atom 22, and the plurality of first oxygen atoms 25. The broken line represents the result when the second region 20 includes one atomic layer. That is, the broken line represents the result when the second region 20 includes the first atom 21 and some of the plurality of first oxygen atoms 25.

  In the result of FIG. 4A, when the second region 20 includes two atomic layers and the first atom 21 and the second atom 22 are Ni, the magnetocrystalline anisotropy energy has a relatively large positive value. Indicated. That is, it shows a relatively strong magnetocrystalline anisotropy in the direction perpendicular to the plane (z-axis direction). By increasing the magnetocrystalline anisotropy in the perpendicular direction, the magnetization direction of the first region 10 is easily oriented in the perpendicular direction. However, the magnitude of the magnetocrystalline anisotropy energy can be adjusted by changing the atomic species of the Au atomic layer (corresponding to the cap layer). By adjusting the atomic species of the cap layer, even when CoO is inserted, the magnetocrystalline anisotropy energy can be a positive value, that is, the magnetocrystalline anisotropy in the vertical direction (z-axis direction).

  In the result of FIG. 4B, when the second region 20 contains CoO, a larger electric field effect is shown than when the second region 20 contains Fe or Ni. That is, it is shown that the field effect can be increased by including the first atom 21 or the second atom 22 that is Co in the second region 20.

  In the result of FIG. 4B, when the second region 20 includes CoO and includes two atomic layers, a larger electric field effect is shown. That is, it is shown that the field effect can be further increased by including the first atom 21 and the second atom 22 that are Co in the second region 20. As the field effect is larger, the magnetization direction of the first region 10 can be changed with a smaller voltage. As a result, for example, power consumption when information is stored in the first region 10 can be reduced.

5A to 5C show the distance between atoms when the external electric field E1 (5 V / nm) is applied to the magnetic element 100, and the external electric field E2 (−5 V / nm) on the magnetic element 100. FIG. It represents the distance between each atom when applied, and the change in these distances. Here, the result in the case where the second region 20 includes two atomic layers is shown. The unit of each distance is Å (× 10 ⁻¹ nm).

  FIG. 5A shows the result when the first atom 21 and the second atom 22 are Co. FIG. 5B shows the result when the first atom 21 and the second atom 22 are Ni. FIG. 5C shows the result when the first atom 21 and the second atom 22 are Fe.

  In the tables of FIGS. 5A to 5C, the distances d1 to d4 between the atoms correspond to the distances d1 to d4 shown in FIG. The distance d1 is the interstitial distance between the metal atom 11 and the first oxygen atom 25 that are closest to each other in the z-axis direction. The distance d2 is an interstitial distance between the first atom 21 and the first oxygen atom 25 that are closest to each other in the z-axis direction. The distance d3 is an interstitial distance between the second atom 22 and the first oxygen atom 25 that are closest to each other in the z-axis direction. The distance d4 is an interstitial distance between the first atom 21 and the second oxygen atom 35 that are closest to each other in the z-axis direction.

  The results of FIGS. 5A and 5B show that when the first atom 21 and the second atom 22 are Co or Ni, the distance d4 changes by 0.04Å by switching the polarity of the external electric field. Represents. The result of FIG. 5C shows that when the first atom 21 and the second atom 22 are Fe, the distance d4 changes by 0.02Å by switching the polarity of the external electric field. That is, when the first atom 21 and the second atom 22 are Co or Ni, the change of the distance d4 is twice as compared with the case where the first atom 21 and the second atom 22 are Fe.

6A to 6C show the band structure of the d orbital of the first atom 21 in the structure shown in FIG. 6A to 6C, the vertical axis represents energy, and the horizontal axis represents the wave vector. FIG. 6A shows the result when the first atom 21 is Co. FIG. 6B shows the result when the first atom 21 is Ni. FIG. 6C shows the result when the first atom 21 is Fe.
6A to 6C, the solid line represents the band structure at the magnetic quantum number m = ± 1, and the broken line represents the band structure at the magnetic quantum number m = ± 2.

  From FIG. 6A to FIG. 6C, when the first atom 21 is Co, the localized minority spin d orbital is near the Fermi level compared to the case where the first atom 21 is Ni or Fe. It can be seen that

  It is considered that a large electric field effect appears when the second region 20 contains Co due to the atomic displacement due to the external electric field shown in FIG. 5 and the energy level of the minority spin d orbit shown in FIG.

  As described above, the second region 20 is positioned between the first region 10 and the third region 30 to increase at least one of the magnetocrystalline anisotropy energy and the field effect of the magnetic element 100. Is possible. However, if the second region 20 is thick, the rate of change (MR ratio) of the tunnel resistance decreases when the magnetization information stored in the first region 10 is read. Therefore, it is desirable that the thickness of the second region 20 in the z-axis direction is equal to or less than the thickness corresponding to the three atomic layers. If the thickness of the second region 20 in the z-axis direction is greater than or equal to the thickness corresponding to the four atomic layers, the MR ratio may be greatly reduced.

  A portion other than the second region 20 may be included in the oxide layer 2 including the second region 20. For example, the oxide layer 2 may include a region that is thicker than the second region 20. If the area along the xy plane of the second region 20 is 10% or more with respect to the area along the xy plane of the oxide layer 2, the field effect can be further increased. The cross-sectional area (effective element area) of the element is not limited, but it is in the direction of miniaturization in order to increase the recording density, and a development report of an element of 10 × 10 to 100 × 100 nm has been made.

  The above is a model for simulation, and the number of atomic layers included in each of Au, Fe, and MgO is not limited to the above. Each of Au, Fe, and MgO may include more atomic layers. Further, instead of Au, another non-magnetic conductive metal may be used.

(Second Embodiment)
FIG. 7 is a schematic view illustrating a magnetic element according to the second embodiment.
The magnetic element 120 according to the second embodiment differs from the magnetic element 100 according to the first embodiment, for example, in the structure of the second region 20.

  In the magnetic element 120, the second region 20 includes, for example, one atomic layer. The second region 20 includes a first atom 21 that is one selected from Ru, Rh, Pd, Os, Ir, and Pt. The first atom 21 is provided between two of the plurality of first oxygen atoms 25 in the x-axis direction. For example, the first atom 21 is provided between the other two of the plurality of first oxygen atoms 25 in the y-axis direction.

  The first atom 21 is located between the second oxygen atom 35 and the metal atom 11 in the z-axis direction. The distance in the z-axis direction between the first atom 21 and the metal atom 11 is longer than, for example, the distance in the z-axis direction between the first oxygen atom 25 and the metal atom 11.

  The spin orbit interaction force of Ru, Rh, Pd, Os, Ir, and Pt is larger than the spin orbit interaction force of Fe, Co, and Ni. Further, since the second region 20 contains these oxides, a larger electric field effect can be expected due to the relative displacement of the metal atom and the oxygen atom when an external electric field is applied.

FIG. 8 is a schematic diagram illustrating a magnetic element according to a modification of the second embodiment.
Like the magnetic element 121 illustrated in FIG. 8, the second region 20 may include two atomic layers. That is, the second region 20 includes the first atom 21 and the second atom 22. The first atom 21 is one selected from Ru, Rh, Pd, Os, Ir, and Pt. The second atom 22 is one selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt.

Alternatively, the first atom 21 is one selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt, and the second atom 22 is Ru, Rh, Pd, One selected from Os, Ir, and Pt may be used.
Yes.

  The thickness of the second region 20 in the z-axis direction may be a thickness corresponding to a triatomic layer. In order to suppress a decrease in the MR ratio, it is desirable that the thickness of the second region 20 in the z-axis direction is equal to or less than the thickness corresponding to the three atomic layers.

FIG. 9 is a schematic diagram showing the structure of the magnetic element used in the simulation.
10 and 11 are simulation results representing the characteristics of the magnetic element according to the second embodiment.

  As shown in FIG. 9, the simulation was performed on a structure including Au of 3 atomic layers, Fe of 3 atomic layers, metal oxide MO of 1 atomic layer, and MgO of 6 atomic layers. These atomic layers are self-supporting and free-standing without a substrate. The diatomic layer oxide corresponds to the second region 20 shown in FIG.

  10 (a) to 10 (c) and FIGS. 11 (a) to 11 (c), the horizontal axis represents the strength of the spin-orbit interaction. 10A to 10C, the vertical axis represents the magnetocrystalline anisotropy energy. 11A to 11C, the vertical axis represents the field effect. The external electric field is defined by the magnitude of the electric field in the vacuum region separated from the hexaatomic layer of MgO at infinity in the negative z-axis direction. For this reason, the magnitude of the field effect in the MgO layer substantially corresponds to a value obtained by multiplying the value in the graph by the relative dielectric constant (9.8) of MgO.

  FIG. 10A and FIG. 11A show simulation results when the first atom 21 is Fe, Ru, or Os. FIG. 10B and FIG. 11B show simulation results when the first atom 21 is Co, Rh, or Ir. FIG.10 (c) and FIG.11 (c) represent the simulation result in case the 1st atom 21 is Ni, Pd, or Pt.

  In the results of FIGS. 10A to 10C, when the first atom 21 is Os or Ir, the magnetocrystalline anisotropy energy has a large positive value. In the results of FIG. 11A to FIG. 11C, a large electric field effect was shown when the first atom 21 was Os or Ir. These simulation results indicate that more desirable characteristics can be obtained when the first atom 21 is Os or Ir.

  The above is a model for simulation, and the number of atomic layers included in each of Au, Fe, and MgO is not limited to the above. Each of Au, Fe, and MgO may include more atomic layers. Further, instead of Au, another non-magnetic conductive metal may be used.

(Third embodiment)
FIG. 12 is a schematic view illustrating a magnetic memory device according to the third embodiment.
As illustrated in FIG. 12, the magnetic storage device 210 includes a magnetic element 110, a control unit 70, a first wiring 70a, and a second wiring 70b.

  The first wiring 70 a is electrically connected to the first conductive layer 5. The second wiring 70 b is electrically connected to the second conductive layer 6. The second wiring 70b includes, for example, a switch 70s. The switch 70s is, for example, a selection transistor. Thus, the state in which a switch or the like is provided on the current path is also included in the state of being electrically connected.

  The controller 70 applies a voltage to the magnetic element 110 by applying a voltage between the first wiring 70a and the second wiring 70b and turning on the switch 70s. When a voltage is applied to the magnetic element 110, the magnetization direction of the first magnetic layer 1 precesses about the x-axis direction or the y-axis direction, and the z-axis direction component of the magnetization direction is alternately reversed between positive and negative. By appropriately controlling the voltage application time to the magnetic element 110, the magnetization direction of the first magnetic layer 1 can be controlled to a desired direction. That is, in the magnetic memory device 210, the magnetization direction of the first magnetic layer 1 can be controlled to a desired direction by applying a unipolar voltage to the magnetic element 110.

(Operation example)
An operation example of the magnetic memory device according to the third embodiment will be described.
FIG. 13A to FIG. 13C are schematic views illustrating the operation of the magnetic memory device according to the third embodiment.
The horizontal axis of these figures represents time ti. The vertical axis in these figures represents the potential of the signal S1 applied between the first wiring 70a and the second wiring 70b. The signal S1 substantially corresponds to a signal applied between the first magnetic layer 1 and the second magnetic layer 4.

  As illustrated in FIG. 13A, the control unit 70 performs a first operation OP <b> 1 that applies a first pulse P <b> 1 (for example, a rewrite pulse) between the first wiring 70 a and the second wiring 70 b. . In the first operation OP1, the first pulse P1 is supplied between the first magnetic layer 1 and the second magnetic layer 4. For example, the stored information is rewritten by the first pulse P1. Thereby, the electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 changes.

  For example, the second electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 after the first operation OP1 is the difference between the first magnetic layer 1 and the second magnetic layer 4 before the first operation OP1. It is different from the first electrical resistance in between.

  This change in electrical resistance is based on, for example, a change in the magnetization direction of the first magnetic layer 1 due to the first pulse P1 (rewrite pulse). Between the first magnetic layer 1 and the second magnetic layer 4, the relative relationship of the magnetization direction is changed by the first pulse P1 (rewrite pulse). Each of the plurality of states having different electrical resistances corresponds to stored information.

  As illustrated in FIG. 13A, the control unit 70 may further perform the second operation OP2. In the second operation OP2, the control unit 70 performs the second operation between the first magnetic layer 1 and the second magnetic layer 4 (between the first wiring 70a and the second wiring 70b) before the first operation OP1. A pulse P2 (readout pulse) is applied. The third electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 obtained by the read pulse is the second electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 after the first operation. It is different from electrical resistance. The third electrical resistance is an electrical resistance before rewriting. The second electric resistance is an electric resistance after rewriting. The third electrical resistance is, for example, the same as the first electrical resistance.

  For example, the polarity of the second pulse P2 (read pulse) is opposite to the polarity of the first pulse P1 (rewrite pulse). When the second pulse P2 (reading pulse) having such a reverse polarity is used, the absolute value of the second pulse height H2 of the second pulse P2 is the first pulse height H1 of the first pulse P1 (rewriting pulse). The absolute value may be smaller, the same or larger. When the magnetocrystalline anisotropy of the magnetic layer is controlled by a voltage, it is possible to suppress a change in the magnetization direction of the magnetic layer at the time of reading by using a reading pulse having a reverse polarity.

When the magnetic storage device 210 has the above characteristics, the following occurs.
The controller 70 applies the first pulse P1 between the first magnetic layer 1 and the second magnetic layer 4 in the first operation OP1. The second electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 after the first operation OP1 is between the first magnetic layer 1 and the second magnetic layer 4 before the first operation OP1. Different from the first electrical resistance. The first pulse P1 has a first polarity, a first pulse width T1, and a first pulse height H1.

At this time, when another pulse having a second polarity opposite to the first polarity, a first pulse width T1, and a pulse height having the same absolute value as the first pulse height H1, is applied as follows: Become.
The third electric resistance between the first magnetic layer 1 and the second magnetic layer 4 after applying this other pulse between the first magnetic layer 1 and the second magnetic layer 4, and this other pulse The absolute value of the difference between the fourth electric resistance before being applied between the first magnetic layer 1 and the second magnetic layer 4 is smaller than the absolute value of the difference between the second electric resistance and the first electric resistance. . That is, information is rewritten by applying the first pulse P1, and information is not rewritten by applying another pulse.

  The electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 is electrically connected to the first wiring 70 a electrically connected to the first magnetic layer 1 and the second magnetic layer 4. This corresponds to the electrical resistance between the second wiring 70b.

  When the stored information is not rewritten, as shown in FIG. 13B, the control unit 70 performs the third operation OP3 after the second operation OP2. In the third operation OP3, the first pulse P1 is not applied. At this time, rewriting does not occur.

  Information can be rewritten when the appropriate first pulse P1 is applied. When an appropriate first pulse P1 is applied, the electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 changes from a high resistance state to a low resistance state, or from a low resistance state to a high resistance state. ,Change. On the other hand, when an inappropriate pulse is applied, the high resistance state does not become the desired low resistance state. If an inappropriate pulse is applied, the low resistance state will not be the desired high resistance state.

  The pulse width of the unsuitable pulse is, for example, about twice the appropriate first pulse width T1. When an inappropriate pulse is applied between the first magnetic layer 1 and the second magnetic layer 4, the probability of resistance change is low.

  For example, the control unit 70 applies the first pulse P1 between the first magnetic layer 1 and the second magnetic layer 4 in the first operation OP1. The first pulse P1 has a first pulse width T1 and a first pulse height H1. Rewriting is appropriately performed by the first pulse P1. That is, the second electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 after the first operation OP1 is the difference between the first magnetic layer 1 and the second magnetic layer 4 before the first operation OP1. It is different from the first electrical resistance in between. At this time, when another pulse P1x as shown in FIG. 13C is applied, the electric resistance does not change substantially. Another pulse P1x has a pulse width twice the first pulse width T1 and a first pulse height H1.

  The third electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 after the application of such another pulse P1x between the first magnetic layer 1 and the second magnetic layer 4, and another The absolute value of the difference between the fourth electric resistance before applying the pulse P1x between the first magnetic layer 1 and the second magnetic layer 4 is the absolute value of the difference between the second electric resistance and the first electric resistance. Smaller than. That is, when another pulse P1x is applied, the electrical resistance does not substantially change. Alternatively, the change in electrical resistance when another pulse P1x is applied is smaller than the change in electrical resistance when the first pulse P1 is applied.

  By using the average value in a plurality of operations, the change in the electrical resistance can be more reliably compared. For example, the process of applying the first pulse P1 and detecting the change in electrical resistance before and after the first pulse P1 is performed a plurality of times. The average value of the absolute value of the change in electrical resistance at this time is obtained. On the other hand, the process of applying the other pulse P1x and detecting the change in electric resistance before and after the pulse P1x is performed a plurality of times. The average value of the absolute value of the change in electrical resistance at this time is obtained. By comparing the above two average values, it can be more reliably understood that the change in electrical resistance when another pulse P1x is applied is smaller than the change in electrical resistance when the first pulse P1 is applied.

  In the magnetic memory device 210 according to the third embodiment, for example, the change in electrical resistance when the other pulse P1x is applied is smaller than the change in electrical resistance when the first pulse P1 is applied. .

(Fourth embodiment)
FIG. 14 is a schematic view illustrating another magnetic memory device according to the fourth embodiment.
As shown in FIG. 14, the magnetic storage device 220 according to the present embodiment includes a plurality of storage units ME, a plurality of wirings (a plurality of first bit lines BL1, a plurality of second bit lines BL2, and a plurality of word lines). WL) and the control unit 70.

  In this example, the plurality of bit lines BL1 and BL2 extend in the y-axis direction. The plurality of bit lines BL1 and BL2 are arranged in the x-axis direction. The plurality of word lines WL extend in the x-axis direction. The plurality of word lines WL are arranged in the y-axis direction.

  One of the plurality of storage units ME includes a magnetic element 110 and a switch 70s (for example, a transistor). The switch 70s is connected in series with the magnetic element 110. One end of the magnetic element 110 is connected to one end of the switch 70s. The magnetic element 110 corresponds to one memory cell MC.

  The other end of the magnetic element 110 included in one of the plurality of storage units ME is electrically connected to one of the plurality of first bit lines BL1. The other end of the switch 70s included in one of the plurality of storage units ME is electrically connected to one of the plurality of second bit lines BL2.

  A control terminal (for example, a gate) of the switch 70s included in one of the plurality of storage units ME is electrically connected to one of the plurality of word lines WL. A third terminal of the switch 70s is electrically connected.

  The plurality of first bit lines BL1 and the plurality of second bit lines BL2 are electrically connected to at least one of the first circuit 71 and the second circuit 72. The plurality of word lines WL are electrically connected to the third circuit 73. These circuits include a selection switch (for example, a selection transistor). These circuits select a plurality of wirings and apply a predetermined voltage. A predetermined voltage pulse is applied to one of the plurality of magnetic elements 110 by these circuits and the switch 70s. Thereby, the resistance in the magnetic element 110 changes. The high resistance state or the low resistance state corresponds to “0” or “1” of the stored information. These circuits include, for example, a detection circuit (such as a sense amplifier). The detection circuit detects values (voltage, current, resistance, etc.) corresponding to the resistance state of the magnetic element 110, for example. Thereby, the stored information is read out. These circuits are included in the control unit 70.

  According to each embodiment described above, by providing the oxide layer 2 having a specific atom thickness of 1 to 3 atoms between the first magnetic layer 1 and the nonmagnetic layer 3, the crystalline magnetic At least one of anisotropic energy and field effect can be increased. Therefore, for example, the rewriting current can be suppressed, and the current required for magnetization reversal can be reduced to 1/10 or less as compared with a device using a conventional magnetoresistance.

  The embodiments of the present invention have been described above with reference to specific examples. However, embodiments of the present invention are not limited to these specific examples. The specific configuration of each element included in the magnetic element and the magnetic storage device according to the embodiment can be changed as appropriate. Even if a person skilled in the art appropriately changes the design of the magnetic element and the magnetic storage device according to the embodiment, the case where the above-described features are included is included in the scope of the present invention. Further, the elements included in the above-described embodiments can be appropriately combined as long as technically possible.

  DESCRIPTION OF SYMBOLS 1 1st magnetic layer, 2 Oxide layer, 3 Nonmagnetic layer, 4 2nd magnetic layer, 5 1st conductive layer, 6 2nd conductive layer, 10 1st area | region, 11 Metal atom, 20 2nd area | region, 21 1st 1 atom, 22 2nd atom, 25 1st oxygen atom, 30 3rd region, 31 metal atom, 35 2nd oxygen atom, 70 control part, 70a 1st wiring, 70b 2nd wiring, 70s switch, 71 1st circuit 72 second circuit, 73 third circuit, 100-121 magnetic element, 210, 220 magnetic storage device, BL1 first bit line, BL2 second bit line, H1 first pulse height, H2 second pulse height, MC memory cell, ME storage unit, MO metal oxide, OP1 first operation, OP2 second operation, OP3 third operation, P1 first pulse, P1x pulse, P2 second pulse, S1 signal , T1 pulse width, WL word line, d1-d4 distance

Claims (10)

A first region;
A second region having a thickness of 3 atomic layers or less;
A third region;
With
The second region is located between the first region and the third region;
The first region includes at least one selected from the group consisting of Fe, Co, and Ni;
The second region includes one first atom selected from the group consisting of Co and Ni, and a plurality of first oxygen atoms,
The third region includes a metal atom and a second oxygen atom,
In the first direction from the second region to the first region, the first atom is between the second oxygen atom and one of the plurality of first oxygen atoms;
The magnetic element in which the first atom is between two of the plurality of first oxygen atoms in a second direction intersecting the first direction. The second region further includes one second atom selected from the group consisting of Fe, Co, and Ni,
The second atom is located between two of the plurality of first oxygen atoms in a second direction intersecting the first direction;
2. The magnetic element according to claim 1, wherein another one of the plurality of first oxygen atoms is between the second atom and the metal atom in the first direction.   The magnetic element according to claim 2, wherein the first atom is located between the other two of the plurality of first oxygen atoms in the second direction. A first region;
A second region having a thickness of 3 atomic layers or less;
A third region;
With
The second region is located between the first region and the third region;
The first region includes at least one selected from the group consisting of Fe, Co, and Ni;
The second region includes one first atom selected from the group consisting of Fe, Co, and Ni, one second atom selected from the group consisting of Co and Ni, and a plurality of first oxygen atoms. Including,
The third region includes a metal atom and a second oxygen atom,
In the first direction from the second region to the first region, the first atom is between the second oxygen atom and one of the plurality of first oxygen atoms;
Another one of the plurality of first oxygen atoms is between the second atom and the metal atom in the first direction;
A magnetic element in which a position of the first atom in a second direction intersecting the first direction is different from a position of the second atom in the second direction.   The magnetic element according to claim 4, wherein the first atom is positioned between two of the plurality of first oxygen atoms in the second direction. A first region;
A second region having a thickness of 3 atomic layers or less;
A third region;
With
The second region is located between the first region and the third region;
The first region includes at least one selected from the group consisting of Fe, Co, and Ni;
The second region includes one first atom selected from Ru, Rh, Pd, Os, Ir, and Pt, and a plurality of first oxygen atoms,
In the second direction intersecting with the first direction from the second region toward the first region, the first atom is located between two of the plurality of first oxygen atoms. A third region including a metal atom and a second oxygen atom;
The second region is located between the first region and the third region;
7. The first direction according to claim 6, wherein the first atom is between the metal atom and the at least one selected from the group consisting of Fe, Co, and Ni in the first region. Magnetic element.   The magnetic element according to claim 1, wherein the first direction is along a [001] direction.   The magnetic element according to claim 1, wherein the second direction is along the [100] direction.   The magnetic element according to claim 1, wherein the second region is 10% or more of an effective element area.

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