JP6965760B2 - Magnetic wall moving type magnetic recording element - Google Patents

Description

The present invention relates to a magnetic domain wall moving magnetic recording element.

As a next-generation non-volatile memory that replaces flash memory and the like whose miniaturization has reached its limit, attention is focused on resistance-changing magnetic recording devices that store data using resistance-changing elements. Examples of the magnetic recording device include MRAM (Magnetoresistive Random Access Memory), ReRAM (Resistance Random Access Memory), PCRAM (Phase Change Random Access Memory), and the like.

As a method of increasing the density (increasing capacity) of the memory, there is a method of reducing the size of the element itself constituting the memory and a method of increasing the value of the recording bit per element constituting the memory.

Patent Document 1 describes a domain wall moving type magnetic recording element capable of recording multi-valued data by moving the domain wall in the magnetic recording layer. Patent Document 1 describes that the provision of a trap site in the magnetic recording layer stabilizes multi-valued data recording.

Japanese Patent No. 5441005

The magnetic domain wall movable magnetic recording element described in Patent Document 1 is provided with irregularities on the side surface of the magnetic recording layer. The unevenness functions as a trap site for the domain wall and controls the position of the domain wall. However, if the magnetic recording layer is provided with physical irregularities, current concentration may occur in the recesses. Current concentration causes heat generation, destabilizes the operation of the element, and reduces the reliability of data. Further, Patent Document 1 also describes that a trap site is provided on the laminated surface of the ferromagnet in the magnetic recording layer, but it lowers the magnetization stability of the ferromagnet and causes noise.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a domain wall moving type magnetic recording element capable of stably controlling the movement of a domain wall within a predetermined range.

(1) The magnetic wall moving type magnetic recording element according to the first aspect extends in a first direction intersecting the first ferromagnetic layer containing a ferromagnetic material and the stacking direction of the first ferromagnetic layer. A recording unit including a magnetic recording layer including a magnetic wall and a non-magnetic layer sandwiched between the first ferromagnetic layer and the magnetic recording layer, which is opposite to the first ferromagnetic layer of the magnetic recording layer. The magnetic trap layer is located on the side and has a plurality of magnetic trap portions for controlling the movement of the magnetic wall of the magnetic recording layer, and is sandwiched between the magnetic trap layer and the magnetic recording layer. A control unit including a flattening layer for flattening the surface on the magnetic recording layer side of the above.

(2) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the surface of the magnetic trap layer on the magnetic recording layer side may have an uneven shape.

(3) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the magnetic trap layer includes a magnetic trap portion and a non-magnetic trap portion having a weaker force to control the movement of the magnetic wall than the magnetic trap portion. It may be held alternately in the direction.

(4) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the plurality of magnetic trap portions may periodically exist in the first direction.

(5) In the magnetic wall moving type magnetic recording element according to the above aspect, the plurality of magnetic trap units may have a first magnetic trap unit that controls the movement of the magnetic wall more strongly than other magnetic trap units.

(6) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the first magnetic trap portion may be located inside the plan view in the first direction from the first ferromagnetic layer.

(7) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the first magnetic trap portion may be longer in the first direction than the other magnetic trap portions.

(8) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the first magnetic trap portion may be thicker in the stacking direction than the other magnetic trap portions.

(9) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the material constituting the first magnetic trap portion may be different from the material constituting the other magnetic trap portion.

(10) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the magnetic trap layer may have a hard magnetic material, and the hard magnetic material may form a magnetic trap portion.

(11) In the magnetic domain wall moving type magnetic recording element according to the above aspect, the magnetic trap layer may have a soft magnetic material, and the hard magnetic material may form a non-magnetic trap portion.

(12) The magnetic domain wall moving type magnetic recording element according to the above aspect has a plurality of the recording units, and the magnetic trap units of the magnetic trap layers constituting the control unit may traverse the plurality of the magnetic recording layers. ..

(13) The magnetic domain wall moving type magnetic recording element according to the above aspect may include a second ferromagnetic layer that reflects the magnetization state of the magnetic recording layer between the magnetic recording layer and the non-magnetic layer.

According to the magnetic wall moving type magnetic recording element according to the above aspect, the moving range of the magnetic wall can be controlled stably.

It is sectional drawing which shows typically the magnetic domain wall moving type magnetic recording element which concerns on 1st Embodiment. FIG. 5 is a plan view of the magnetic trap layer of the magnetic domain wall moving magnetic recording element according to the first embodiment from the z direction. It is a figure which looked at the magnetic trap layer of another example of the magnetic domain wall moving type magnetic recording element which concerns on 1st Embodiment in a plan view from the z direction. It is sectional drawing which shows typically another example of the magnetic domain wall moving type magnetic recording element which concerns on 1st Embodiment. It is sectional drawing which shows typically another example of the magnetic domain wall moving type magnetic recording element which concerns on 1st Embodiment. It is sectional drawing of the magnetic domain wall movable type magnetic recording element which concerns on 2nd Embodiment. It is sectional drawing of another example of the magnetic domain wall movable type magnetic recording element which concerns on 2nd Embodiment. It is sectional drawing of another example of the magnetic domain wall movable type magnetic recording element which concerns on 2nd Embodiment. It is sectional drawing of another example of the magnetic domain wall movable type magnetic recording element which concerns on 2nd Embodiment. It is sectional drawing of another example of the magnetic domain wall movable type magnetic recording element which concerns on 2nd Embodiment. It is sectional drawing of the magnetic domain wall movable type magnetic recording element which concerns on 3rd Embodiment. It is a plane schematic diagram of the magnetic domain wall moving type magnetic recording element which concerns on 4th Embodiment. It is a schematic diagram of the magnetic array which concerns on 5th Embodiment.

Hereinafter, the present embodiment will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of the respective components may differ from the actual ones. be. The materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and can be appropriately modified and carried out within the range in which the effects of the present invention are exhibited.

(Magnetic wall moving magnetic recording element)
"First embodiment"
FIG. 1 is a cross-sectional view schematically showing a magnetic domain wall movable magnetic recording element 100 according to the first embodiment. The domain wall moving type magnetic recording element 100 includes a recording unit 60 and a control unit 90. The recording unit 60 includes a first ferromagnetic layer 10, a magnetic recording layer 20, and a non-magnetic layer 30. The magnetic domain wall movable magnetic recording element 100 shown in FIG. 1 includes a first electrode 41 and a second electrode 42 at positions sandwiching the first ferromagnetic layer 10 in a plan view. The control unit 90 includes a magnetic trap layer 70 and a flattening layer 80.

Hereinafter, the first direction in which the magnetic recording layer 20 extends is the x direction, and the second direction orthogonal to the x direction in the plane in which the magnetic recording layer 20 extends is orthogonal to the y direction, the x direction, and the y direction. Let the direction be the z direction. The stacking direction of the domain wall movable magnetic recording element 100 shown in FIG. 1 coincides with the z direction.

"Recording section"
<First ferromagnetic layer>
The first ferromagnetic layer 10 contains a ferromagnet. Examples of the ferromagnetic material constituting the first ferromagnetic layer 10 include a metal selected from the group consisting of Cr, Mn, Co, Fe and Ni, an alloy containing one or more of these metals, and these metals and B. , C, and an alloy containing at least one element of N can be used. Specific examples thereof include Co-Fe, Co-Fe-B, Ni-Fe, CoHo ₂ , and SmFe ₁₂ .

The material constituting the first ferromagnetic layer 10 may be a Whistler alloy. The Whisler alloy is a half metal and has a high spin polarizability. The Heusler alloy is an _{intermetallic compound with a chemical composition of X 2} YZ, where X is a transition metal element or noble metal element of the Co, Fe, Ni or Cu group on the periodic table, and Y is Mn, V, Cr. Alternatively, it is a transition metal of Group Ti or an elemental species of X, and Z is a typical element of Group III to Group V. Examples of the _{Whisler alloy include Co 2} FeSi, Co ₂ FeGe, Co ₂ FeGa, Co ₂ MnSi, Co ₂ Mn _1-a Fe _a Al _b Si _1-b , and Co ₂ FeGe _1-c Ga _c .

The first ferromagnetic layer 10 may be an in-plane magnetization film having an easy magnetization axis in the xy in-plane direction or a perpendicular magnetization film having an easy magnetization axis in the z direction. In FIG. 1, it is assumed that the first ferromagnetic layer 10 is an in-plane magnetizing film.

The film thickness of the first ferromagnetic layer 10 is preferably 2.5 nm or less, preferably 2.0 nm or less, when the easy axis of magnetization of the first ferromagnetic layer 10 is in the z direction (perpendicular magnetization film). Is more preferable. Further, in order to secure a sufficient amount of magnetization, the film thickness of the first ferromagnetic layer 10 is preferably 1.0 nm or more. When the thickness of the first ferromagnetic layer 10 is reduced, the first ferromagnetic layer 10 is perpendicularly magnetic anisotropy (interfacial vertical magnetism) at the interface between the first ferromagnetic layer 10 and another layer (non-magnetic layer 30). Anisotropy) can be added.

<Magnetic recording layer>
The magnetic recording layer 20 extends in the x direction. The magnetic recording layer 20 has a magnetic domain wall 21 inside. The domain wall 21 is a boundary between a first magnetic domain 22 and a second magnetic domain 23 having magnetizations in opposite directions. In the magnetic domain wall moving type magnetic recording element 100 shown in FIG. 1, the first magnetic domain 22 has a magnetization oriented in the + x direction, and the second magnetic domain 23 has a magnetization oriented in the −x direction.

The domain wall moving type magnetic recording element 100 records data at multiple values depending on the position of the domain wall 21 of the magnetic domain wall 20. The data recorded on the magnetic recording layer 20 is read out as a change in the resistance value in the stacking direction of the first ferromagnetic layer 10 and the magnetic recording layer 20. When the domain wall 21 moves, the ratio of the first magnetic domain 22 and the second magnetic domain 23 in the magnetic recording layer 20 changes. The magnetization of the first ferromagnetic layer 10 is in the same direction (parallel) as the magnetization of the first magnetic domain 22, and is in the opposite direction (antiparallel) to the magnetization of the second magnetic domain 23. When the domain wall 21 moves in the x direction and the area of the first magnetic domain 22 in the portion overlapping with the first ferromagnetic layer 10 when viewed from the z direction becomes large, the resistance value of the domain wall moving type magnetic recording element 100 becomes low. On the contrary, when the domain wall 21 moves in the −x direction and the area of the second magnetic domain 23 in the portion overlapping with the first ferromagnetic layer 10 when viewed from the z direction becomes large, the resistance value of the domain wall moving magnetic recording element 100 becomes large. Will be higher. The resistance value of the domain wall moving type magnetoresistive sensor 100 is measured between the upper electrode electrically connected to the first ferromagnetic layer 10 and the first electrode 41 or the second electrode 42.

The domain wall 21 moves by passing a current in the extending direction of the magnetic recording layer 20 or applying an external magnetic field. For example, when a current pulse is applied from the first electrode 41 to the second electrode 42, the first magnetic domain 22 expands in the direction of the second magnetic domain 23, and the domain wall 21 moves in the direction of the second magnetic domain 23. That is, the position of the domain wall 21 is controlled by setting the direction and intensity of the current flowing through the first electrode 41 and the second electrode 42, and data is written to the domain wall moving type magnetic recording element 100.

The magnetic recording layer 20 is made of a magnetic material. As the magnetic material constituting the magnetic recording layer 20, the same magnetic material as that of the first ferromagnetic layer 10 can be used. Further, the magnetic recording layer 20 preferably has at least one element selected from the group consisting of Co, Ni, Pt, Pd, Gd, Tb, Mn, Ge and Ga. For example, a laminated film of Co and Ni, a laminated film of Co and Pt, a laminated film of Co and Pd, an MnGa-based material, a GdCo-based material, and a TbCo-based material can be mentioned. Ferrimagnetic materials such as MnGa-based materials, GdCo-based materials, and TbCo-based materials have a small saturation magnetization, and can reduce the threshold current required for moving the domain wall. Further, the laminated film of Co and Ni, the laminated film of Co and Pt, and the laminated film of Co and Pd have a large coercive force, and the moving speed of the domain wall can be suppressed.

<Non-magnetic layer>
A known material can be used for the non-magnetic layer 30.
For example, when the non-magnetic layer 30 is made of an insulator (when it is a tunnel barrier layer), Al ₂ O ₃ , SiO ₂ , Mg O _{, Mg Al 2 O 4, and the} like can be used as the material thereof. In addition to these, a material in which a part of Al, Si, and Mg is replaced with Zn, Be, and the like can also be used. Among these, MgO and MgAl ₂ O ₄ are materials that can realize a coherent tunnel, so that spin can be efficiently injected. When the non-magnetic layer 30 is made of metal, Cu, Au, Ag or the like can be used as the material. Further, when the non-magnetic layer 30 is made of a semiconductor, Si, Ge, CuInSe ₂ , CuGaSe ₂ , Cu (In, Ga) Se _{2 and the} like can be used as the material.

<1st electrode, 2nd electrode>
The first electrode 41 and the second electrode 42 are arranged at positions sandwiching the first ferromagnetic layer 10 in the x direction when viewed from the z direction. In FIG. 1, the first electrode 41 is a ferromagnet whose magnetization is oriented in the x direction, and the second electrode 42 is a ferromagnet whose magnetization is oriented in the −x direction. When passing through the first electrode 41 or the second electrode 42, the current is spin-polarized. By injecting a spin-polarized current into the magnetic recording layer 20, the ratio of the first magnetic domain 22 and the second magnetic domain 23 of the magnetic recording layer 20 changes.

The first electrode 41 and the second electrode 42 may be replaced with spin-orbit torque wiring. For example, spin-orbit torque wiring extending in the y direction is arranged at the positions of the first electrode 41 and the second electrode 42. When a current is passed through the spin-orbit torque wiring, a spin Hall effect occurs in the spin-orbit torque wiring. The spin polarized by the spin Hall effect flows into the magnetic recording layer 20, so that the ratio of the first magnetic domain 22 and the second magnetic domain 23 of the magnetic recording layer 20 changes. Both the first electrode 41 and the second electrode 42 may be replaced with spin-orbit torque wiring, or only one of them may be replaced. When both are replaced with spin-orbit torque wiring of the same material, the direction of the current flowing through each is opposite. The spin orbit torque wiring is composed of any of metals, alloys, intermetal compounds, metal borides, metal carbides, metal silices, and metal phosphors having the function of generating a spin flow by the spin Hall effect when an electric current flows. Will be done.

Further, it is not necessary to install the first electrode 41 and the second electrode 42. In this case, the magnetic domain wall of the magnetic recording layer 20 is moved by an external magnetic field.

"Control unit"
<Magnetic trap layer>
The magnetic trap layer 70 is located on the opposite side of the magnetic recording layer 20 from the first ferromagnetic layer 10. The magnetic trap layer 70 has a plurality of magnetic trap portions that control the movement of the magnetic wall.

The magnetic trap layer 70 contains a magnetic material. The magnetic trap layer 70 is not particularly limited as long as it can generate a magnetic potential distribution in the x direction of the magnetic recording layer 20. The distribution of the magnetic potential changes the ease of movement of the domain wall 21 and controls the range of movement of the domain wall 21. Hereinafter, a specific example of the magnetic trap layer 70 will be described as an example.

FIG. 2 is a plan view of the magnetic trap layer of the magnetic domain wall movable magnetic recording element according to the first embodiment in the z direction. The magnetic trap layer 70A shown in FIG. 2 has a convex portion 71 and a concave portion 72 in the y direction. The portion provided with the convex portion 71 in the x direction has a larger volume than the portion serving as the concave portion 72, and the generated magnetic field strength is larger. That is, the convex portion 71 functions as a magnetic trap portion, and the concave portion 72 functions as a non-magnetic trap portion. The non-magnetic trap portion means a portion having a weaker force to control the movement of the domain wall than the magnetic trap portion.

FIG. 3 is a plan view of the magnetic trap layer of another example of the magnetic domain wall movable magnetic recording element according to the first embodiment in the z direction. The magnetic trap layer 70A shown in FIG. 3 includes a first region 73 and a second region 74. The first region 73 and the second region 74 are made of different materials. When the magnetic field strength generated by the first region 73 is larger than the magnetic field strength generated by the second region 74, the first region 73 functions as a magnetic trap portion and the second region 74 functions as a non-magnetic trap portion.

For example, the first region 73 is a hard magnetic material, and the second region 74 is a non-magnetic material. The magnetic domain wall 21 is trapped by the magnetic coupling between the hard magnetic material forming the first region 73 and the magnetization of the magnetic recording layer 20. That is, in this case, the hard magnetic material forming the first region 73 functions as a magnetic trap portion, and the non-magnetic material forming the second region 74 functions as a non-magnetic trap portion.

Further, for example, the first region 73 is a soft magnetic material, and the second region 74 is a non-magnetic material. The soft magnetic material absorbs the magnetization of the magnetic recording layer 20, and the domain wall 21 easily moves in the vicinity of the first region 73. That is, in this case, the soft magnetic material forming the first region 73 functions as a non-magnetic trap portion, and the non-magnetic material forming the second region 74 functions as a magnetic trap portion.

FIG. 4 is a cross-sectional view schematically showing another example of the domain wall movable magnetic recording element according to the first embodiment. The magnetic domain wall movable magnetic recording element 101 shown in FIG. 4 is different from the domain wall movable magnetic recording element 100 shown in FIG. 1 in that the surface of the magnetic trap layer 70C on the magnetic recording layer 20 side has an uneven shape. The magnetic trap layer 70C shown in FIG. 4 has a convex portion 75 and a concave portion 76 in the z direction. The portion provided with the convex portion 75 in the x direction has a larger volume than the portion serving as the concave portion 76, and produces a larger magnetic field strength. That is, the convex portion 75 functions as a magnetic trap portion, and the concave portion 76 functions as a non-magnetic trap portion.

FIG. 5 is a cross-sectional view schematically showing another example of the domain wall movable magnetic recording element according to the first embodiment. In the magnetic domain wall moving magnetic recording element 102 shown in FIG. 5, the point that the first region 77 made of a predetermined material is scattered in the second region 74 in the magnetic trap layer 70D is the domain wall moving magnetic recording element shown in FIG. It is different from the recording element 100. For example, when the first region 77 is a ferromagnetic material and the second region 78 is a non-magnetic material, the second region does not generate a magnetic field, and the first region 77 generates a stronger magnetic field strength. That is, the first region 77 functions as a magnetic trap unit, and the second region 78 functions as a non-magnetic trap unit. When the first region 77 is a soft magnetic material, the first region 77 functions as a non-magnetic trap portion.

The magnetic trap portion and the non-magnetic trap portion preferably exist alternately in the x direction. By alternately providing the magnetic trap portion and the non-magnetic trap portion in the x direction, the magnetic wall 21 is likely to be stopped stepwise, and the magnetic wall moving type magnetic recording element is easy to record data at multiple values. Further, the magnetic trap portion preferably exists periodically in the x direction. Since the portion of the magnetic recording layer 20 where the domain wall 21 tends to stop becomes periodic, the amount of resistance change when recording data at multiple values can be made constant, and data can be stably recorded at multiple values.

The closer the magnetic trap layer 70 and the magnetic recording layer 20 are, the more preferable. The distance between the magnetic trap layer 70 and the magnetic recording layer 20 means the maximum distance between the magnetic trap layer 70 and the magnetic recording layer 20, and as shown in FIG. 4, when the magnetic trap layer 70C has irregularities, a convex portion is provided. It means the distance between the top surface of 75 and the magnetic recording layer 20. The distance between the magnetic trap layer 70 and the magnetic recording layer 20 is preferably 20 nm or less, more preferably 10 nm or less, and further preferably 5 nm or less. The distance between the magnetic trap layer 70 and the magnetic recording layer 20 can be easily controlled by the thickness of the flattening layer 80 described later.

<Flat layer>
The flattening layer 80 is arranged between the magnetic recording layer 20 and the magnetic trap layer 70. The flattening layer 80 flattens the surface of the magnetic trap layer 70 on the magnetic recording layer 20 side and the surface of the magnetic recording layer 20 on the magnetic trap layer 70 side.

The flattening layer 80 can suppress the shape change of the magnetic recording layer 20. When the shape of the magnetic recording layer 20 becomes constant, the current density of the current flowing in the magnetic recording layer 20 becomes constant in the x direction. It is possible to prevent the magnetic domain wall 21 from moving quickly locally in the magnetic recording layer 20 and to prevent the magnetic recording layer 20 from generating heat due to current concentration and reducing the reliability of data. That is, the noise of the domain wall moving type magnetic recording element is reduced, and it becomes easy to stably record data with multiple values.

The flattening layer 80 is preferably made of an insulating material. This is to prevent the current flowing between the first electrode 41 and the second electrode 42 from flowing through a portion other than the magnetic recording layer 20. When the resistance of the flattening layer 80 is sufficiently larger than the resistance of the magnetic recording layer 20, a conductor, a semiconductor, or the like may be used for the flattening layer 80.

The thickness of the flattening layer 80 is preferably 20 nm or less, more preferably 10 nm or less, and even more preferably 5 nm or less. The thickness of the flattening layer 80 is preferably 2 nm or more. When the thickness of the flattening layer 80 is within the above range, the surface of the magnetic trap layer 70 on the magnetic recording layer 20 side and the surface of the magnetic recording layer 20 on the magnetic trap layer 70 side can be sufficiently flattened, and the magnetic trap layer can be sufficiently flattened. The distance between the 70 and the magnetic recording layer 20 can be made sufficiently close.

As described above, the domain wall moving type magnetic recording elements 100, 101, and 102 according to the first embodiment can control the movement of the domain wall 21 of the magnetic domain wall 20 by the magnetic trap layer 70. Further, by providing the flattening layer 80, the shape of the recording layer 60 can be made constant, and noise can be reduced from being generated in the magnetic domain wall moving type magnetic recording elements 100, 101, and 102. Further, by providing the magnetic trap layer 70 in the stacking direction via the flattening layer 80, the magnetic trap layer 70 and the magnetic recording layer 20 can be easily brought close to each other.

"Second embodiment"
FIG. 6 is a schematic cross-sectional view of the domain wall movable magnetic recording element according to the second embodiment. The domain wall moving type magnetic recording element 103 shown in FIG. 6 is different from the domain wall moving type magnetic recording element 101 shown in FIG. 4 in that the magnetic trap layer has a first magnetic trap portion. The same components as those of the domain wall movable magnetic recording element according to the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The first magnetic trap portion is a portion that controls the movement of the magnetic wall 21 of the magnetic recording layer 20 more strongly than the other magnetic trap portions. Although the condition is not particularly limited as long as the conditions are satisfied, a specific example of the magnetic trap layer will be described as an example.

The magnetic trap layer 70E shown in FIG. 6 has a convex portion 75 and a concave portion 76. Among the convex portions 75, there is a first convex portion 75a whose width in the x direction is wider than that of the other convex portions 75. The first convex portion 75a has a larger volume than the other convex portions 75, produces a larger magnetic field strength, and controls the movement of the domain wall 21 more strongly than the other convex portions 75. Therefore, the first convex portion 75a becomes the first magnetic trap portion, and the convex portion 75 becomes another magnetic trap portion.

FIG. 7 is a schematic cross-sectional view of another example of the domain wall movable magnetic recording element according to the second embodiment. The magnetic trap layer 70F shown in FIG. 7 has a convex portion 75 and a concave portion 76. Among the convex portions 75, there is a second convex portion 75b whose thickness in the z direction is thicker than that of the other convex portions 75. Like the first convex portion 75a, the second convex portion 75b also has a larger volume than the other convex portion 75 and controls the movement of the domain wall 21 more strongly than the other convex portion 75. Therefore, the second convex portion 75b becomes the first magnetic trap portion, and the convex portion 75 becomes another magnetic trap portion.

The case where the magnetic trap layers 70E and 70F have irregularities has been described so far, but the same applies to the case where the magnetic trap layer is composed of the first region 77 and the second region 78 made of different materials, as shown in FIG.

FIG. 8 is a schematic cross-sectional view of another example of the domain wall movable magnetic recording element according to the second embodiment. The magnetic trap layer 70G shown in FIG. 8 has a first region 77 and a second region 78. In the first region 77, there is a specific region 77a whose width in the x direction is wider than that of the other first region 77. The specific region 77a has a larger volume than the other first region 77, produces a larger magnetic field strength, and controls the movement of the domain wall 21 more strongly than the other first region 77. Therefore, the specific region 77a becomes the first magnetic trap portion, and the other first region 77 becomes another magnetic trap portion.

FIG. 9 is a schematic cross-sectional view of another example of the domain wall movable magnetic recording element according to the second embodiment. The magnetic trap layer 70H shown in FIG. 9 has a first region 77 and a second region 78. In the first region 77, there is a second specific region 77b whose thickness in the z direction is wider than that of the other first region 77. The second specific region 77b has a larger volume than the other first region 77, produces a larger magnetic field strength, and controls the movement of the domain wall 21 more strongly than the other first region 77. Therefore, the second specific region 77b becomes the first magnetic trap portion, and the other first region 77 becomes another magnetic trap portion.

Although the first magnetic trap portion that can be confirmed in the cross-sectional shape of the domain wall moving type magnetic recording element has been described so far, for example, the shape of the convex portion 71 may be changed in the plan view shape shown in FIG. Further, the first magnetic trap portion may be provided by a method other than the shape.

FIG. 10 is a schematic cross-sectional view of another example of the domain wall movable magnetic recording element according to the second embodiment. The magnetic trap layer 70I shown in FIG. 10 has a first region 77 and a second region 78. In the first region 77, there is another material region 77c having a different constituent material. When the material constituting the separate material region 77c has a stronger magnetization strength than the material constituting the other first region 77, the domain wall 21 is strongly trapped in the vicinity of the separate material region 77c. That is, the separate material region 77c becomes the first magnetic trap portion, and the other first region 77 becomes the other magnetic trap portion.

When the magnetic trap layer has a first magnetic trap portion that controls the movement of the magnetic wall more strongly than other magnetic trap portions, the moving speed of the magnetic wall 21 changes significantly in the vicinity thereof. Therefore, it can be used as a change point of data of the domain wall moving type magnetic recording element. Further, the first magnetic trap portion is preferably located inside the first ferromagnetic layer 10 in the x direction in a plan view, and is arranged at a position overlapping both ends of the first ferromagnetic layer 10 in the x direction. Is more preferable. The change in the resistance value of the domain wall moving type magnetic recording element occurs when the domain wall 21 exists at a position where it overlaps with the first ferromagnetic layer 10 in a plan view. By providing the first magnetic trap portion at a position overlapping both ends of the first ferromagnetic layer 10 in the x direction, it becomes easy to determine the maximum value and the minimum value of the resistance value change. That is, the start point and the end point of the multi-valued recording can be clarified, and the reliability of the data of the domain wall moving type magnetic recording element can be improved.

"Third embodiment"
FIG. 11 is a schematic cross-sectional view of the domain wall movable magnetic recording element according to the third embodiment. FIG. 1 shows that the domain wall movable magnetic recording element 108 shown in FIG. 11 is provided with a second ferromagnetic layer 50 that reflects the magnetization state of the magnetic recording layer 20 between the magnetic recording layer 20 and the non-magnetic layer 30. It is different from the magnetic domain wall moving type magnetic recording element 100 shown in 1. The same components as those of the domain wall movable magnetic recording element according to the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The domain wall movable magnetic recording element according to the third embodiment can be applied to any of the elements of the first embodiment and the second embodiment.

The second ferromagnetic layer 50 contains a magnetic material. As the magnetic material constituting the second ferromagnetic layer 50, the same magnetic material as that of the first ferromagnetic layer 10 can be used.

The second ferromagnetic layer 50 is adjacent to the magnetic recording layer 20. The magnetization of the second ferromagnetic layer 50 is magnetically coupled with the magnetization of the magnetic recording layer 20. Therefore, the second ferromagnetic layer 50 reflects the magnetic state of the magnetic recording layer 20. When the second ferromagnetic layer 50 and the magnetic recording layer 20 are ferromagnetically coupled, the magnetic state of the second ferromagnetic layer 50 becomes the same as the magnetic state of the magnetic recording layer 20, and the second ferromagnetic layer 50 and the magnetism When the recording layer 20 is anti-conductive coupled, the magnetic state of the second ferromagnetic layer 50 is opposite to the magnetic state of the magnetic recording layer 20.

When the second ferromagnetic layer 50 is inserted between the magnetic recording layer 20 and the non-magnetic layer 30, the functions of the second ferromagnetic layer 50 and the magnetic recording layer 20 in the domain wall moving magnetic recording element 108 can be separated. can. The MR ratio of the domain wall moving magnetic recording element 108 is caused by a change in the magnetization state of two magnetic materials (first ferromagnetic layer 10 and second ferromagnetic layer 50) sandwiching the non-magnetic layer 30. Therefore, the second ferromagnetic layer 50 can mainly have a function of improving the MR ratio, and the magnetic recording layer 20 can mainly have a function of moving the domain wall 21.

When the functions of the second ferromagnetic layer 50 and the magnetic recording layer 20 are separated, the degree of freedom of the magnetic material constituting each of them is increased. A material that can obtain a coherent tunneling effect with the first ferromagnetic layer 10 can be selected for the second ferromagnetic layer 50, and a material that slows down the moving speed of the domain wall can be selected for the magnetic recording layer 20.

As described above, the same effect as that of the first embodiment and the second embodiment can be obtained in the magnetic domain wall moving type magnetic recording element 108 according to the third embodiment. Further, by inserting the second ferromagnetic layer 50, the degree of freedom in selecting the material used for these layers can be increased. Further, by increasing the degree of freedom in material selection, the MR ratio of the domain wall movable magnetic recording element 108 can be further increased.

"Fourth embodiment"
FIG. 12 is a schematic plan view of the domain wall movable magnetic recording element 109 according to the fourth embodiment. The domain wall movable magnetic recording element 109 shown in FIG. 12 is different from the domain wall movable magnetic recording element 102 shown in FIG. 5 in that a plurality of recording units 60 are provided. The same components as those of the domain wall movable magnetic recording element according to the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The domain wall movable magnetic recording element according to the fourth embodiment can be applied to any of the elements of the first embodiment, the second embodiment, and the third embodiment.

The domain wall movable magnetic recording element 109 shown in FIG. 12 has a plurality of recording units 60. The plurality of recording units 60 are respectively arranged in the control unit 90 extending in the xy plane. The magnetic trap unit of the magnetic trap layer constituting the control unit 90 crosses a plurality of magnetic recording layers 20. In FIG. 12, a first region 77 that functions as a magnetic trap unit crosses a plurality of recording units 60 extending in the y direction. The positional relationship between the magnetic trap unit and the recording unit 60 is not limited to orthogonal to the plan view, and may intersect.

Since the magnetic trap unit exists over the plurality of recording units 60, the respective recording units 60 can perform multi-value recording in the same manner. That is, the multi-valued signal can be changed evenly. Since the threshold value for recording data in each recording unit 60 becomes constant, the difference between the respective recording units 60 becomes small. As a result, the noise of the domain wall moving type magnetic recording element 109 as a whole is reduced, and data can be stably recorded in multiple values.

The magnetic domain wall movable magnetic recording element according to the present embodiment has been described in detail with reference to the drawings. However, each configuration and a combination thereof in each embodiment are examples, and are within a range that does not deviate from the gist of the present invention. , Configuration can be added, omitted, replaced, and other changes are possible.

"Fifth embodiment"
FIG. 13 is a plan view of the magnetic recording array 200 according to the fifth embodiment. In the magnetic recording array 200 shown in FIG. 13, the recording unit 60 of the magnetic domain wall moving magnetic recording element has a 3 × 3 matrix arrangement. FIG. 13 is an example of a magnetic recording array, and the type, number, and arrangement of the recording units 60 are arbitrary. Further, the control unit may exist over all the recording units 60, or may be provided for each recording unit 60.

One word line WL1 to 3, one bit line BL1 to 3, and one lead line RL1 to 3, respectively, are connected to each of the domain wall moving type magnetic recording elements 100.

By selecting the word lines WL1 to 3 and the bit lines BL1 to 3 to which the current is applied, a pulse current is passed through the magnetic recording layer 20 of the arbitrary recording unit 60 to perform a writing operation. Further, by selecting the lead lines RL1 to 3 and the bit lines BL1 to 3 to which the current is applied, the current is passed in the stacking direction of the arbitrary recording unit 60 to perform the reading operation. The word lines WL1 to 3, the bit lines BL1 to 3 and the lead lines RL1 to 3 to which the current is applied can be selected by a transistor or the like. Since each recording unit 60 records information at multiple values, it is possible to increase the capacity of the magnetic recording array.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and varies within the scope of the gist of the present invention described in the claims. Can be transformed / changed.

10 First ferromagnetic layer 20 Magnetic recording layer 21 Domain wall 22 First magnetic domain 23 Second magnetic domain 30 Non-magnetic layer 41 First electrode 42 Second electrode 50 Second ferromagnetic layer 60 Recording units 70, 70A, 70B, 70C , 70D, 70E, 70F, 70G, 70H, 70I Magnetic trap layers 71, 75 Convex 72, 76 Concave 73, 77 First region 74, 78 Second region 75a First convex 75b Second convex 77a Specific region 77b 2nd specific area 77c Separate material area 80 Flattening layer 90 Control unit 100 Magnetic wall moving type magnetic recording element 200 Magnetic recording array

Claims (15)

The first ferromagnet containing a ferromagnet and
A magnetic recording layer extending in the first direction intersecting the stacking direction of the first ferromagnetic layer and including a domain wall,
A recording unit including a non-magnetic layer sandwiched between the first ferromagnetic layer and the magnetic recording layer.
A magnetic trap layer located on the opposite side of the magnetic recording layer to the first ferromagnetic layer and having a plurality of magnetic trap portions for controlling the movement of the domain wall of the magnetic recording layer.
A control unit including a flattening layer sandwiched between the magnetic trap layer and the magnetic recording layer and flattening a surface of the magnetic trap layer on the magnetic recording layer side.
Equipped with a,
The first ferromagnetic layer is a magnetic domain wall moving magnetic recording element located at a position overlapping the plurality of magnetic trap portions when viewed from the stacking direction. The magnetic domain wall movable magnetic recording element according to claim 1, wherein the surface of the magnetic trap layer on the magnetic recording layer side has an uneven shape. The magnetic wall according to claim 1 or 2, wherein the magnetic trap layer alternately has a magnetic trap portion and a non-magnetic trap portion having a weaker force for controlling the movement of the magnetic wall than the magnetic trap portion in the first direction. Mobile magnetic recording element. The magnetic domain wall movable magnetic recording element according to any one of claims 1 to 3, wherein the plurality of magnetic trap portions are periodically present in the first direction. The magnetic wall moving type magnetic recording element according to any one of claims 1 to 4, wherein the plurality of magnetic trap units have a first magnetic trap unit that controls the movement of the magnetic wall more strongly than other magnetic trap units. The magnetic wall moving type magnetic recording element according to claim 5, wherein the first magnetic trap portion is located inside the first ferromagnetic layer in a plan view. The magnetic domain wall movable magnetic recording element according to claim 5 or 6, wherein the first magnetic trap unit is longer than the other magnetic trap unit in the first direction. The magnetic domain wall movable magnetic recording element according to any one of claims 5 to 7, wherein the first magnetic trap portion is thicker in the stacking direction than the other magnetic trap portions. The magnetic domain wall movable magnetic recording element according to any one of claims 5 to 8, wherein the material constituting the first magnetic trap portion is different from the material constituting the other magnetic trap portion. The magnetic domain wall movable magnetic recording element according to any one of claims 1 to 9, wherein the magnetic trap layer has a hard magnetic material, and the hard magnetic material forms a magnetic trap portion. The magnetic domain wall movable magnetic recording element according to any one of claims 1 to 9, wherein the magnetic trap layer has a soft magnetic material, and the soft magnetic material forms a non-magnetic trap portion. There are multiple recording units
The magnetic domain wall movable magnetic recording element according to any one of claims 1 to 11, wherein the magnetic trap unit of the magnetic trap layer constituting the control unit crosses the plurality of the magnetic recording layers. A first electrode and a second electrode connected to the magnetic recording layer are further provided.
The magnetic domain wall moving type according to any one of claims 1 to 12, wherein the first electrode and the second electrode sandwich the first ferromagnetic layer in the first direction when viewed from the stacking direction. Magnetic recording element. The magnetic trap layer has an uneven shape in which convex portions and concave portions are alternately arranged in the first direction.
The magnetic domain wall movable magnetic recording element according to any one of claims 1 to 13, wherein the thickness of the convex portion in the stacking direction is thicker than the thickness of the concave portion in the stacking direction. The magnetic domain wall moving magnetic recording according to any one of claims 1 to 14 , further comprising a second ferromagnetic layer reflecting the magnetization state of the magnetic recording layer between the magnetic recording layer and the non-magnetic layer. element.
array.

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