JP7055319B2 - Magnetic storage device - Google Patents

Description

Embodiments of the present invention relate to magnetic storage devices .

A magnetic element having a magnetic region containing a magnetic metal atom and a non-magnetic 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.

Japanese Patent Publication No. 2004-527099 Kohji Nakamura et al. Physical Review B 81, 220409 (R) (2010)

An object to be solved by the present invention is to provide a magnetic storage device capable of increasing the electric field effect.

The magnetic storage device according to the embodiment includes a magnetic element and a control unit. The magnetic element includes a first magnetic layer including a first region, an oxide layer containing a second region having a thickness of 3 atomic layers or less, a non-magnetic layer including a third region, and a second magnetic layer. , Have. The control unit is electrically connected to the first magnetic layer and the second magnetic layer, and applies a unipolar voltage to the magnetic element. The oxide layer is provided between the first magnetic layer and the non-magnetic layer so that the second region is located between the first region and the third region. The oxide layer and the non-magnetic layer are provided between the first magnetic layer and the second magnetic layer. The first region comprises at least one selected from the group consisting of Fe, Co, and Ni. The second region contains one first atom selected from the group consisting of Co and Ni, and a plurality of first oxygen atoms. The third region contains 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 the second direction intersecting the first direction, the first atom is between two of the plurality of first oxygen atoms. The control unit controls whether or not information is written to the magnetic element by controlling the magnitude and time of the voltage applied to the magnetic element to control the magnetization direction of the first magnetic layer. As the information, the electric resistance between the first magnetic layer and the second magnetic layer is relatively small, and the electric resistance between the first magnetic layer and the second magnetic layer is relatively small. Either the large state or the large state is used.

According to an embodiment of the present invention, there is provided a magnetic storage device capable of increasing the electric field effect.

It is a schematic diagram which illustrates the magnetic element which concerns on 1st Embodiment. It is a schematic cross-sectional view which illustrates another magnetic element which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of the magnetic element used in the simulation. 4 (a) and 4 (b) are simulation results showing the characteristics of the magnetic element according to the first embodiment. 5 (a) to 5 (c) are simulation results showing the characteristics of the magnetic element according to the first embodiment. 6 (a) to 6 (c) are simulation results showing 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 which shows the magnetic element which concerns on the modification of 2nd Embodiment. It is a schematic diagram which shows the structure of the magnetic element used in the simulation. 10 (a) to 10 (c) are simulation results showing the characteristics of the magnetic element according to the second embodiment. 11 (a) to 11 (c) are simulation results showing the characteristics of the magnetic element according to the second embodiment. It is a schematic diagram which illustrates the magnetic storage device which concerns on 3rd Embodiment. 13 (a) to 13 (c) are schematic views illustrating the operation of the magnetic storage device according to the third embodiment. It is a schematic diagram which illustrates another magnetic storage device which concerns on 4th Embodiment.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings.
It should be noted that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between the parts, and the like are not necessarily the same as the actual ones. Further, even when the same part is represented, the dimensions and ratios may be different from each other depending on the drawing.
Further, in the present specification and each figure, the same elements as those already described are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.

(First Embodiment)
FIG. 1 is a schematic diagram 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 contains a plurality of metal atoms 11. The plurality of metal atoms 11 contains 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 to the first region 10 is defined as the z-axis direction. One direction perpendicular to the z-axis direction is defined as the x-axis direction. The direction perpendicular to the z-axis direction and the x-axis direction is defined as the 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 shown 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 the thickness corresponding to the diatomic layer.

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, for example, Fe, Co, and Ni. As an example, the plurality of metal atoms 11 are Fe. Alternatively, a portion of the plurality of metal atoms 11 is one selected from the group consisting of Fe, Co, and Ni, and another portion 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.

The first atom 21 of the second region 20 is located, for example, in the y-axis direction between two other first oxygen atoms 25. That is, the first atom 21 is located between the oxygen atoms in, for example, the x-axis direction, the y-axis direction, and the z-axis direction. 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. The second atom 22 is located, for example, in the y-axis direction between two other first oxygen atoms 25. 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. The plurality of metal atoms 31 and the plurality of second oxygen atoms 35 are further provided alternately in the y-axis direction, for example. 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 by, for example, 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 contained in the second region 20 are epitaxially arranged with the atoms contained in the third region 30 and the [001] direction of the third region 30 is along the z-axis direction, the [001] direction of the second region 20 is [001]. ] 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 non-magnetic layer 3, a second magnetic layer 4, a first conductive layer 5, and a second conductive layer 6. include.

The oxide layer 2 is provided between the first magnetic layer 1 and the non-magnetic 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 non-magnetic 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 non-magnetic 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 non-magnetic layer 3 includes a third region 30.

The first magnetic layer 1 and the second magnetic layer 4 have ferromagnetism. The easy-to-magnetize axis of the first magnetic layer 1 and the easy-to-magnetize axis of the second magnetic layer 4 are, for example, along the z-axis direction. The easy-to-magnetize axis of the first magnetic layer 1 and the easy-to-magnetize 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 non-magnetic layer 3 is insulating. The non-magnetic layer 3 functions as, for example, a tunnel barrier. 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 the two is relatively large, the electricity between the first magnetic layer 1 and the second magnetic layer 4 The resistance is relatively high. This is based on the magnetoresistive effect.

The magnetic element 110 functions as a storage element by associating the state in which the electric resistance is large and the state in which the electric resistance is small correspond to, 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. By controlling the magnetization direction of the first magnetic layer 1, information can be written to the magnetic element 110.

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 due to, for example, the crystal magnetic anisotropy of the region including the first magnetic layer 1 and the oxide layer 2 due to the electric field generated between the first magnetic layer 1 and the non-magnetic layer 3. Based on changes in anisotropic energy. In order to reduce power consumption, it is desirable that a larger change in crystalline magnetic anisotropy energy occurs for the same voltage and the electric field effect is large.

According to the inventor of the present application, the second region 20 including the first atom 21 and the plurality of first oxygen atoms 25 is located between the first region 10 and the third region 30, so that the crystal magnetic anisotropy when a voltage is applied is obtained. It was discovered that the change in directional energy becomes large and the electric field effect can be made large.

FIG. 3 is a schematic diagram showing the structure of the magnetic element used in the simulation.
4 (a), 4 (b), 5 (a) to 5 (c), and 6 (a) to 6 (c) 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 containing Au in the triatomic layer, Fe in the triatomic layer, metal oxide in the 2-atomic layer, and MgO in the 6-atomic layer. This structure is in a self-supporting free standing state without a substrate.

Au of the triatomic layer corresponds to, for example, at least a part of the first conductive layer 5 shown in FIG. Fe in the triatomic layer corresponds to the first region 10. The oxide of the diatomic layer corresponds to the second region 20. The MgO of the 6-atom layer corresponds to the third region 30.

In FIGS. 4 (a) and 4 (b), the horizontal axis represents the oxide contained in the second region 20. The vertical axis of FIG. 4A represents the crystalline magnetic anisotropy energy _EMCA (mJ / m ² ). The vertical axis of FIG. 4B represents the change in crystal magnetic anisotropy energy (field effect) ΔE _MCA / ΔE (fJ / Vm) with respect to the change in voltage. The external electric field is defined by the magnitude of the electric field in the vacuum region separated from MgO of the 6-atom layer at infinity in the negative direction in the z-axis direction. Therefore, the magnitude of the electric field effect in the MgO layer substantially corresponds to the value obtained by multiplying the value in the graph by the relative permittivity (9.8) of MgO.

In FIGS. 4 (a) and 4 (b), 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 dashed line represents the result when the second region 20 contains one atomic layer. That is, the broken line represents the result when the second region 20 includes the first atom 21 and a part of the plurality of first oxygen atoms 25.

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

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

In the result of FIG. 4B, when the second region 20 contains CoO and contains two atomic layers, a larger electric field effect is shown. That is, it is shown that the electric field effect can be further increased by including the first atom 21 and the second atom 22 which are Co in the second region 20. The larger the field effect, the smaller the voltage can be used to change the magnetization direction of the first region 10. As a result, for example, it is possible to reduce the power consumption when storing information in the first region 10.

5 (a) to 5 (c) show the distance between each atom when an external electric field E1 (5 V / nm) is applied to the magnetic element 100, and the external electric field E2 (-5 V / nm) applied to the magnetic element 100. It represents the distance between each atom when applied, and the change in these distances. Here, the result when 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 results when the first atom 21 and the second atom 22 are Ni. FIG. 5C shows the results 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, which are closest to each other in the z-axis direction. The distance d2 is the 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 the interstitial distance between the second atom 22 and the first oxygen atom 25, which are closest to each other in the z-axis direction. The distance d4 is the interstitial distance between the first atom 21 and the second oxygen atom 35, which are closest to each other in the z-axis direction.

The results of FIGS. 5 (a) and 5 (b) show that when the first atom 21 and the second atom 22 are Co or Ni, the distance d4 changes by 0.04 Å due to the switching of 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 0.02 Å due to the switching of the polarity of the external electric field. That is, when the first atom 21 and the second atom 22 were Co or Ni, the change in the distance d4 was doubled as compared with the case where the first atom 21 and the second atom 22 were Fe.

6 (a) to 6 (c) show the band structure of the d-orbital of the first atom 21 in the structure shown in FIG. In FIGS. 6 (a) to 6 (c), the vertical axis represents energy and the horizontal axis represents a 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.
In FIGS. 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 FIGS. 6 (a) to 6 (c), when the first atom 21 is Co, the localized minority spin d orbital is near the Fermi level as compared with the case where the first atom 21 is Ni or Fe. It can be seen that it is located in.

It is considered that a large field effect was exhibited when the second region 20 contained Co due to the displacement of the atom by the external electric field shown in FIG. 5 and the energy level of the minority spin d-orbital shown in FIG.

As described above, by locating the second region 20 between the first region 10 and the third region 30, at least one of the crystal magnetic anisotropy energy and the electric field effect of the magnetic element 100 is increased. Is possible. However, if the second region 20 is thick, the rate of change (MR ratio) of the tunnel resistance becomes small when the magnetization information stored in the first region 10 is read out. Therefore, it is desirable that the thickness of the second region 20 in the z-axis direction is not more than the thickness corresponding to the three atomic layers. If the thickness of the second region 20 in the z-axis direction is equal to or greater than the thickness corresponding to the 4-atomic layer, the MR ratio may be significantly reduced.

The oxide layer 2 including the second region 20 may include a portion other than the second region 20. For example, the oxide layer 2 may include a region 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 electric 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 the development of an element of 10 × 10 to 100 × 100 nm has been reported.

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

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

In the magnetic element 120, the second region 20 includes, for example, one atomic layer. The second region 20 contains the first atom 21, which 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. The first atom 21 is provided, for example, in the y-axis direction between two other first oxygen atoms 25.

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 displacement of the relative positions of the metal atom and the oxygen atom when an external electric field is applied.

FIG. 8 is a schematic diagram showing a magnetic element according to a modified example of the second embodiment.
As in the magnetic element 121 shown 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, It may be one selected from Os, Ir, and Pt.
stomach.

The thickness of the second region 20 in the z-axis direction may be a thickness corresponding to the triatomic layer. In order to suppress the decrease in the MR ratio, it is desirable that the thickness of the second region 20 in the z-axis direction is not more than the thickness corresponding to the triatomic layer.

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

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

In FIGS. 10 (a) to 10 (c) and FIGS. 11 (a) to 11 (c), the horizontal axis represents the strength of the spin-orbit interaction. In FIGS. 10 (a) to 10 (c), the vertical axis represents the crystal magnetic anisotropy energy. In FIGS. 11 (a) to 11 (c), the vertical axis represents the electric field effect. The external electric field is defined by the magnitude of the electric field in the vacuum region separated from MgO in the 6-atom layer at infinity in the negative direction in the z-axis direction. Therefore, the magnitude of the electric field effect in the MgO layer substantially corresponds to the value obtained by multiplying the value in the graph by the relative permittivity (9.8) of MgO.

10 (a) and 11 (a) show simulation results when the first atom 21 is Fe, Ru, or Os. 10 (b) and 11 (b) show simulation results when the first atom 21 is Co, Rh, or Ir. 10 (c) and 11 (c) show simulation results when the first atom 21 is Ni, Pd, or Pt.

In the results of FIGS. 10 (a) to 10 (c), the crystal magnetic anisotropy energy showed a large positive value when the first atom 21 was Os or Ir. In the results of FIGS. 11 (a) to 11 (c), a large electric field effect was shown when the first atom 21 was Os or Ir. These simulation results show that more desirable properties are obtained when the first atom 21 is Os or Ir.

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

(Third Embodiment)
FIG. 12 is a schematic diagram illustrating the magnetic storage device according to the third embodiment.
As shown 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 70a is electrically connected to the first conductive layer 5. The second wiring 70b 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. As described above, 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 control unit 70 applies a voltage between the first wiring 70a and the second wiring 70b, and by turning on the switch 70s, the voltage is applied to the magnetic element 110. When a voltage is applied to the magnetic element 110, the magnetization direction of the first magnetic layer 1 undergoes an aging motion about the x-axis direction or the y-axis direction, and the z-axis direction components of the magnetization direction are alternately inverted positively and negatively. By appropriately controlling the application time of the voltage to the magnetic element 110, the magnetization direction of the first magnetic layer 1 can be controlled in a desired direction. That is, in the magnetic storage device 210, the magnetization direction of the first magnetic layer 1 can be controlled in a desired direction by applying a unipolar voltage to the magnetic element 110.

(Operation example)
An operation example of the magnetic storage device according to the third embodiment will be described.
13 (a) to 13 (c) are schematic views illustrating the operation of the magnetic storage device according to the third embodiment.
The horizontal axis of these figures represents time ti. The vertical axis of 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 shown in FIG. 13A, the control unit 70 carries out the first operation OP1 in which the first pulse P1 (for example, a rewrite pulse) is applied between the first wiring 70a and the second wiring 70b. .. 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. As a result, 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 same as that of the first magnetic layer 1 and the second magnetic layer 4 before the first operation OP1. It is different from the first electrical resistance 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). The relative relationship in the magnetization direction between the first magnetic layer 1 and the second magnetic layer 4 is changed by the first pulse P1 (rewrite pulse). Multiple states with different electrical resistances correspond to the stored information.

As shown in FIG. 13A, the control unit 70 may further perform the second operation OP2. In the second operation OP2, the control unit 70 performs a 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. Pulse P2 (reading pulse) is applied. The third electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 obtained by the readout pulse is the second between the first magnetic layer 1 and the second magnetic layer 4 after the first operation. It is different from electrical resistance. The third electric resistance is the electric resistance before rewriting. The second electric resistance is the electric resistance after rewriting. The third electric resistance is, for example, the same as the first electric 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). It may be smaller, the same, or larger than the absolute value of. When the crystal magnetic anisotropy of the magnetic layer is controlled by a voltage, it is possible to suppress the change in the magnetization direction of the magnetic layer at the time of reading by using a read pulse of opposite polarity.

When the magnetic storage device 210 has the above characteristics, it is as follows.
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 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. It is 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, the following Become.
The third electrical 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, the information is rewritten by applying the first pulse P1, and the 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 70a electrically connected to the first magnetic layer 1 and to the second magnetic layer 4. Corresponds to the electrical resistance between the second wire 70b and the second wire.

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

Information can be rewritten when an 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 reach the desired low resistance state. If an improper pulse is applied, the low resistance state will not be the desired high resistance state.

The pulse width of the inappropriate 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 a change in resistance is low.

For example, the control unit 70 applies the above-mentioned 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 same as that of the first magnetic layer 1 and the second magnetic layer 4 before the first operation OP1. It is different from the first electrical resistance between. At this time, when another pulse P1x as shown in FIG. 13C is applied, the change in electrical resistance does not substantially occur. Another pulse P1x has a pulse width that is twice the first pulse width T1 and a first pulse height H1.

Another is the third electrical resistance between the first magnetic layer 1 and the second magnetic layer 4 after applying such another pulse P1x between the first magnetic layer 1 and the second magnetic layer 4. 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 change substantially. 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 above changes in electrical resistance can be compared more reliably. For example, the process of applying the above-mentioned first pulse P1 and detecting the change in electrical resistance before and after the first pulse P1 is performed a plurality of times. Obtain the average value of the absolute values of the changes in electrical resistance at this time. On the other hand, the process of applying the above-mentioned other pulse P1x and detecting the change in electrical resistance before and after the pulse P1x is performed a plurality of times. Obtain the average value of the absolute values of the changes in electrical resistance at this time. By comparing the above two average values, it can be seen more reliably 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 storage device 210 according to the third embodiment, for example, the change in electrical resistance when the above-mentioned other pulse P1x is applied is smaller than the change in the electrical resistance when the above-mentioned first pulse P1 is applied. ..

(Fourth Embodiment)
FIG. 14 is a schematic diagram illustrating another magnetic storage device according to the fourth embodiment.
As shown in FIG. 14, the magnetic storage device 220 according to the present embodiment has 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 wires 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 a switch 70s included in one of a plurality of storage units ME is electrically connected to one of a plurality of word line WLs. The third terminal of the switch 70s is electrically connected.

The plurality of first bit wires BL1 and the plurality of second bit wires BL2 are electrically connected to at least one of the first circuit 71 and the second circuit 72. The plurality of word line WLs are electrically connected to the third circuit 73. These circuits include a selection switch (eg, a selection transistor, etc.). These circuits select a plurality of wires and apply a predetermined voltage. By these circuits and the switch 70s, a predetermined voltage pulse is applied to one of the plurality of magnetic elements 110. As a result, the resistance of 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, for example, a value (voltage, current, resistance, etc.) corresponding to the resistance state of the magnetic element 110. As a result, the stored information is read out. These circuits are included in the control unit 70.

According to each embodiment described above, the oxide layer 2 having a thickness of 1 to 3 atoms with a specific atom is provided between the first magnetic layer 1 and the non-magnetic layer 3, whereby the crystal magnetism is formed. At least one of the anisotropic energy and the electric 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, the 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 appropriately changed. Even if a person skilled in the art appropriately modifies a magnetic element or a magnetic storage device according to an embodiment, the above-mentioned features are included in the scope of the present invention. In addition, the elements included in the above-described embodiments can be appropriately combined as technically possible.

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

Claims (10)

A magnetic element having a first magnetic layer including a first region, an oxide layer containing a second region having a thickness of 3 atomic layers or less, a non-magnetic layer including a third region, and a second magnetic layer. When,
A control unit that is electrically connected to the first magnetic layer and the second magnetic layer and applies a unipolar voltage to the magnetic element .
Equipped with
The oxide layer is provided between the first magnetic layer and the non-magnetic layer so that the second region is located between the first region and the third region.
The oxide layer and the non-magnetic layer are provided between the first magnetic layer and the second magnetic layer.
The first region comprises at least one selected from the group consisting of Fe, Co, and Ni.
The second region contains one first atom selected from the group consisting of Co and Ni, and a plurality of first oxygen atoms.
The third region contains 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 the second direction intersecting the first direction, the first atom is between two of the plurality of first oxygen atoms.
The control unit controls whether or not information is written to the magnetic element by controlling the magnitude and time of the voltage applied to the magnetic element to control the magnetization direction of the first magnetic layer.
As the information, the electric resistance between the first magnetic layer and the second magnetic layer is relatively small, and the electric resistance between the first magnetic layer and the second magnetic layer is relatively small. A magnetic storage device in which either the large state or is used . The second region further comprises one second atom selected from the group consisting of Fe, Co, and Ni.
The second atom is located between the two of the plurality of first oxygen atoms in the second direction.
The magnetic storage device according to claim 1, wherein another one of the plurality of first oxygen atoms is located between the second atom and the metal atom in the first direction. The magnetic storage device according to claim 2, wherein the first atom is located between another two of the plurality of first oxygen atoms in the second direction. A magnetic element having a first magnetic layer including a first region, an oxide layer containing a second region having a thickness of 3 atomic layers or less, a non-magnetic layer including a third region, and a second magnetic layer. When,
A control unit that is electrically connected to the first magnetic layer and the second magnetic layer and applies a unipolar voltage to the magnetic element .
Equipped with
The oxide layer is provided between the first magnetic layer and the non-magnetic layer so that the second region is located between the first region and the third region.
The oxide layer and the non-magnetic layer are provided between the first magnetic layer and the second magnetic layer.
The first region comprises at least one selected from the group consisting of Fe, Co, and Ni.
The second region comprises 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 contains 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.
The position of the first atom in the second direction intersecting the first direction is different from the position of the second atom in the second direction.
The control unit controls whether or not information is written to the magnetic element by controlling the magnitude and time of the voltage applied to the magnetic element to control the magnetization direction of the first magnetic layer.
As the information, the electric resistance between the first magnetic layer and the second magnetic layer is relatively small, and the electric resistance between the first magnetic layer and the second magnetic layer is relatively small. A magnetic storage device in which either the large state or is used . The magnetic storage device according to claim 4, wherein the first atom is located between two of the plurality of first oxygen atoms in the second direction. A magnetic element having a first magnetic layer including a first region, an oxide layer containing a second region having a thickness of 3 atomic layers or less, a non-magnetic layer including a third region, and a second magnetic layer. When,
A control unit electrically connected to the first magnetic layer and the second magnetic layer,
Equipped with
The oxide layer is provided between the first magnetic layer and the non-magnetic layer so that the second region is located between the first region and the third region.
The oxide layer and the non-magnetic layer are provided between the first magnetic layer and the second magnetic layer.
The first region comprises at least one selected from the group consisting of Fe, Co, and Ni.
The second region comprises one first atom selected from Ru, Rh, Pd, Os, Ir and Pt and a plurality of first oxygen atoms.
In the second direction intersecting the first direction from the second region to the first region, the first atom is located between two of the plurality of first oxygen atoms.
The control unit is a magnetic storage device that controls the magnetization direction of the first magnetic layer by applying a unipolar voltage to the magnetic element. The third region contains a metal atom and a second oxygen atom.
The sixth aspect of the invention, wherein in the first direction, the first atom is between the metal atom and at least one selected from the group consisting of Fe, Co, and Ni in the first region. Magnetic storage device. The magnetic storage device according to any one of claims 1 to 7, wherein the first direction is along the [001] direction. The magnetic storage device according to any one of claims 1 to 8, wherein the second direction is along the [100] direction. The magnetic storage device according to any one of claims 1 to 9, wherein the second region is 10% or more of the effective element area.

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