Magnetic element and magnetic memory device

Abstract

To realize a magnetic element capable of suppressing deviation of a magnetic structure from a predetermined movement direction.SOLUTION: A magnetic element (1) includes a magnetic member (11), and a first heavy metal member (12) and a second heavy metal member (13) formed on the magnetic member (11), and in the magnetic member (11), a circular magnetic structure can exist across a portion where the first heavy metal member (12) is formed and a portion where the second heavy metal member (13) is formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to magnetic elements and magnetic memory devices in which nanoscale magnetic structures can exist. [Background technology]

[0002] In recent years, magnetic structures called magnetic skyrmions (hereafter referred to as "skyrmions") have been observed in magnetic materials and have attracted attention. Skyrmions are nanoscale circular or elliptical magnetic structures in which the magnetic moments at the center and edges are antiparallel, and the direction of the magnetic moments gradually changes from the center to the edges. Skyrmions can be driven by spin currents derived from electric currents flowing through magnetic materials, and magnetic memory devices using skyrmions as information carriers have been proposed as high-density, low-power magnetic devices (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-082122 [Patent Document 2] Special publication WO2016 / 067744 Summary of the Invention [Problem to be solved by the invention]

[0004] In magnetic devices that use skyrmions, the skyrmions do not travel in a straight line along the direction of the current, but deviate from the direction of the current and disappear, posing a problem due to the skyrmion Hall effect.

[0005] An object of one aspect of the present invention is to provide a magnetic element or the like that can prevent a magnetic structure such as the skyrmion from deviating from a predetermined movement direction. [Means for solving the problem]

[0006] In order to solve the above problems, a magnetic element according to one embodiment of the present invention comprises a magnetic member, and a first heavy metal member and a second heavy metal member formed on the magnetic member, and a circular or elliptical magnetic structure can be present in the magnetic member spanning the portion where the first heavy metal member is formed and the portion where the second heavy metal member is formed.

[0007] In the magnetic member of the magnetic element having the above configuration, the skyrmion number Q of the circular magnetic structure formed across the portion where the first heavy metal member is formed and the portion where the second heavy metal member is formed is a value between ±1 and close to 0. In this case, the influence of the skyrmion Hall effect is reduced. Therefore, the magnetic structure can be prevented from deviating from the direction of the current that moves the magnetic domains.

[0008] In the magnetic element according to this aspect, an interfacial Dzyaloshinskii-Moriya interaction (interfacial DMI) acts on each of the first magnetization near the interface of the magnetic member where it contacts the first heavy metal member and the second magnetization near the interface of the magnetic member where it contacts the second heavy metal member, and the direction in which the first magnetization is tilted due to the interfacial DMI and the direction in which the second magnetization is tilted due to the interfacial DMI may be different from each other.

[0009] In this case, when a simulation was performed on forming the circular magnetic structure in the magnetic member, the skyrmion number Q of the magnetic structure was close to 0. Therefore, the magnetic structure is extremely less affected by the skyrmion Hall effect, and can be prevented from deviating from the direction of the current that moves the magnetic domains.

[0010] In the magnetic element according to this aspect, the first heavy metal member may be provided on a first surface of the magnetic member, and the second heavy metal member may be provided on a second surface of the magnetic member opposite the first surface.

[0011] Furthermore, the first heavy metal component and the second heavy metal component may be made of the same type of heavy metal, in which case the first heavy metal component and the second heavy metal component may be made of the same type of heavy metal.

[0012] When viewed from the direction in which the magnetic member and the first heavy metal member or the second heavy metal member are aligned, one side of the first heavy metal member and one side of the second heavy metal member may be substantially collinear. When viewed from the direction in which the magnetic member and the first heavy metal member or the second heavy metal member are aligned, there may be a portion where the first heavy metal member and the second heavy metal member overlap.

[0013] The magnetic member may be stepped, with the first heavy metal member formed on one step and the second heavy metal member formed on the other step.

[0014] In this case, the magnetic element has a two-layer structure by first forming one stage of the magnetic member and the second heavy metal member, and then forming the first heavy metal member and the other stage of the magnetic member, which makes the magnetic element stable in structure and reduces its height.

[0015] In the magnetic element according to this aspect, the first heavy metal member and the second heavy metal member may be provided on a first surface of the magnetic member. In this case, the magnetic element has a two-layer structure. Therefore, the height of the magnetic element can be reduced.

[0016] Furthermore, the first heavy metal member and the second heavy metal member may be made of different types of heavy metal.

[0017] Furthermore, the sign of the interface DMI of the first heavy metal member with respect to the magnetic member may be different from the sign of the interface DMI of the second heavy metal member with respect to the magnetic member, in which case the direction in which the interface DMI rotates the first magnetization and the direction in which the interface DMI rotates the second magnetization are opposite to each other.

[0018] The first heavy metal member and the second heavy metal member may be adjacent to each other.

[0019] In the magnetic element of this aspect, the magnetic member includes a rectangular main body portion in which the first heavy metal member and the second heavy metal member are formed, and the magnetic member further includes a magnetic protrusion portion protruding from a portion of a side surface of the main body portion, and the first heavy metal member or the second heavy metal member may further include a heavy metal protrusion portion protruding together with the magnetic protrusion portion.

[0020] In this case, skyrmions can be formed in the magnetic protrusion, eliminating the need to perform the operations required for skyrmion formation, such as irradiating laser light and applying a magnetic field, in the main body.

[0021] The magnetic protrusion may have a width that narrows from the main body side toward the outside.

[0022] In this case, the energy of the magnetic protrusion increases from the main body side toward the outside, which allows the skyrmions formed in the magnetic protrusion to move toward the main body without applying any other force.

[0023] Furthermore, when a simulation was performed on the behavior of skyrmions that had moved toward the main body, the skyrmions moved in a direction along the side of the main body even without the current. In this case, since there is no current, the skyrmion Hall effect caused by the current and the movement of the skyrmions does not occur. Therefore, the skyrmions can be prevented from deviating from the direction along the side.

[0024] Furthermore, the magnetic protrusion has a first side and a second side connected to the side of the main body, and if the angle on the magnetic protrusion side formed by the first side of the magnetic protrusion and the side of the main body is a first angle, and the angle on the magnetic protrusion side formed by the second side of the magnetic protrusion and the side of the main body is a second angle, the first angle may be greater than the second angle.

[0025] In this case, the skyrmion formed in the magnetic protruding portion can be smoothly moved to the main body portion.

[0026] A magnetic memory device according to another aspect of the present invention comprises a magnetic element having the above-described configuration, a write device for writing information based on whether or not a magnetic structure is formed in the magnetic member of the magnetic element, and a read device for reading information by detecting whether or not a magnetic structure is present in the magnetic member.

[0027] According to the above configuration, the magnetic structure in the magnetic element can be prevented from deviating from the predetermined movement direction, thereby improving the reliability of the magnetic memory device. Furthermore, when skyrmions are formed in the magnetic protrusion, there is no need to pass a current through the magnetic element to move the skyrmions, thereby reducing the power consumption of the magnetic memory device. [Effects of the Invention]

[0028] According to one aspect of the present invention, it is possible to prevent the magnetic structure from deviating from a predetermined moving direction, and to drive the magnetic structure with low power consumption. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a perspective view showing an overview of a magnetic element according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. 1 is a perspective view showing an overview of a magnetic element as a reference example. [Figure 4] FIG. 4 is a cross-sectional view taken along the line BB in FIG. 3. [Figure 5] FIG. 1 is a plan view showing an outline of a skyrmion formed in a ferromagnetic thin film of the magnetic element of the above-mentioned reference example. [Figure 6] FIG. 10 is a perspective view showing an outline of a magnetic element according to another reference example. [Figure 7] FIG. 7 is a cross-sectional view taken along the line CC in FIG. 6. [Figure 8] FIG. 1 is a plan view showing an outline of a skyrmion formed in a ferromagnetic thin film of the magnetic element of the above-mentioned reference example. [Figure 9] FIG. 2 is a plan view showing a magnetic structure extending over both the first region and the second region in the ferromagnetic thin film in the magnetic element of the embodiment. [Figure 10] FIG. 10 is a plan view showing a magnetic structure stabilized by a ferromagnetic thin film as a result of simulation in a magnetic element that is one example of the above-described embodiment. [Figure 11] 10 is a graph showing the movement of the magnetic structure. [Figure 12] FIG. 10 is a plan view showing a magnetic structure stabilized by a ferromagnetic thin film as a result of simulation in a magnetic element that is another example of the above embodiment. [Figure 13] FIG. 10 is a plan view showing a magnetic structure stabilized by a ferromagnetic thin film as a result of simulation in a magnetic element that is yet another example of the above embodiment. [Figure 14] FIG. 10 is a cross-sectional view showing a modified example of the magnetic element of the embodiment. [Figure 15] FIG. 10 is a cross-sectional view showing another modified example of the magnetic element of the embodiment. [Figure 16] FIG. 10 is a cross-sectional view showing an overview of a magnetic element according to another embodiment of the present invention. [Figure 17] FIG. 10 is a cross-sectional view showing an overview of a magnetic element according to yet another embodiment of the present invention. [Figure 18] FIG. 10 is a perspective view showing an overview of a magnetic element according to yet another embodiment of the present invention. [Figure 19]FIG. 10 is a plan view showing the results of a simulation of the behavior of skyrmions formed in the magnetic element. [Figure 20] FIG. 10 is a plan view showing an overview of a magnetic memory device according to still another embodiment of the present invention. [Figure 21] FIG. 10 is a plan view showing an overview of a magnetic memory device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described in detail. For the sake of convenience, components having the same functions as those shown in each embodiment will be denoted by the same reference numerals, and their description will be omitted as appropriate. Directions will be identified using x, y, and z in the drawings.

[0031] [Embodiment 1] An embodiment of the present invention will be described with reference to FIGS.

[0032] (Magnetic element overview) Fig. 1 is a perspective view showing an overview of the magnetic element according to this embodiment. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. As shown in Figs. 1 and 2, the magnetic element 1 according to this embodiment includes a magnetic member 11, a first heavy metal member 12, and a second heavy metal member 13.

[0033] The magnetic member 11 is a plate-shaped member made of a magnetic material. Here, the magnetic material includes a ferromagnetic material, a ferrimagnetic material, a spherimagnetic material, and the like.

[0034] The magnetic member 11 is a perpendicularly magnetized member having uniaxial anisotropy and an easy axis of magnetization that is substantially perpendicular to the plate surface. The Curie temperature of the magnetic material is preferably higher than the ambient temperature (e.g., room temperature), and more preferably higher than the upper limit of the temperature of the magnetic member 11 that rises due to Joule heat generated when current is applied to the magnetic element 1. The perpendicularly magnetized member can be easily produced by distorting the lattice structure of the magnetic material.

[0035] Examples of the magnetic material include alloys such as TbFeCo (terbium iron cobalt, ferrimagnetic), CoFeB (cobalt iron boron), CoPt (cobalt platinum), CoCrPt (cobalt chromium platinum), CoFeSi (cobalt iron silicon), GeFeCo (germanium iron cobalt, ferrimagnetic), MnSi (silicomanganese), etc. However, the material is not limited to these, and various magnetic materials (ferromagnetic material, ferrimagnetic material, serimagnetic material, etc.) that satisfy the above Curie temperature can be used.

[0036] The magnetic member 11 includes a long plate-shaped first region 21 and a long plate-shaped second region 22 adjacent to each other in the short side direction (y direction). The first heavy metal member 12 is provided on the first region 21, and the second heavy metal member 13 is provided on the second region 22. In this embodiment, the first heavy metal member 12 is provided on a first side (+z direction) (first surface) of the magnetic member 11, while the second heavy metal member 13 is provided on a second side (-z direction) (second surface) opposite to the first side of the magnetic member 11. That is, when viewed from the direction in which the magnetic member 11 and the first heavy metal member 12 or the second heavy metal member 13 are aligned (z direction) (when viewed from above), the side (one side) of the first heavy metal member 12 on the y direction side and the side (one side) of the second heavy metal member 13 on the -y direction side are substantially collinear.

[0037] As a result, the Dzyaloshinsky-Moriya interaction (hereinafter abbreviated as "interface DMI") acts on the magnetization (first magnetization) near the interface of the magnetic member 11 in contact with the first heavy metal member 12. Similarly, the interface DMI also acts on the magnetization (second magnetization) near the interface of the magnetic member 11 in contact with the second heavy metal member 13. The interface DMI acts to tilt the magnetization of the magnetic member 11. The interface DMI between the magnetic member 11 and the first heavy metal member 12 and the interface DMI between the magnetic member 11 and the second heavy metal member 13 tilt the magnetization in different directions.

[0038] For example, if the direction of magnetization tilted by the DMI at the interface between the magnetic member 11 and the first heavy metal member 12 is outward, then the direction of magnetization tilted by the DMI at the interface between the magnetic member 11 and the second heavy metal member 13 is inward. Also, if the direction of magnetization tilted by the DMI at the interface between the magnetic member 11 and the first heavy metal member 12 is clockwise, then the direction of magnetization tilted by the DMI at the interface between the magnetic member 11 and the second heavy metal member 13 is counterclockwise.

[0039] The first heavy metal member 12 and the second heavy metal member 13 are thin films of non-magnetic or paramagnetic heavy metals. Examples of such heavy metals include, but are not limited to, Pt (platinum), Ru (ruthenium), Rh (rhodium), and Ta (tantalum). The magnetic member 11, the first heavy metal member 12, and the second heavy metal member 13 can be formed by sputtering, molecular beam epitaxy, or the like.

[0040] In this embodiment, the first heavy metal member 12 and the second heavy metal member 13 are produced from the same type of heavy metal, which allows the number of types of heavy metals to be reduced to one.

[0041] (Reference example 1) Before describing the magnetic structure formed in the magnetic element 1 having the above configuration, skyrmions that can be formed by stacking ferromagnetic thin films and heavy metal thin films will be described with reference to FIGS. 3 to 8.

[0042] Fig. 3 is a perspective view showing an outline of a magnetic element as a reference example. Fig. 4 is a cross-sectional view taken along line BB in Fig. 3. The magnetic element 100 shown in Figs. 3 and 4 is formed by laminating a plate-shaped heavy metal member 112 on a plate-shaped magnetic member 111. Note that the magnetic member 111 is made of the same material as the magnetic member 11, and therefore its details will be omitted. Furthermore, the heavy metal member 112 is made of the same material as the first heavy metal member 12 and the second heavy metal member 13, and therefore its details will be omitted.

[0043] 3 and 4, the magnetic member 111 is magnetized in a direction substantially perpendicular to the plate surface (±z direction). In this case, interfacial DMI acts at the boundary between the magnetic member 111 and the heavy metal member 112. This allows skyrmions to exist (form) stably in the magnetic member 111.

[0044] Fig. 5 is a plan view showing an overview of a skyrmion formed in the magnetic member 111 of the magnetic element 100 configured as described above. In the example of Fig. 5, the magnetic member 111 is magnetized in the direction opposite to the side on which the heavy metal member 112 is provided (-z direction). Fig. 5 also shows the direction of the magnetic moment in each magnetic domain of the magnetic member 111. The magnetic moment is white in the direction (+z direction and -z direction) approximately perpendicular to the plate surface (xy plane), and becomes darker as the component along the plate surface increases. The same applies to drawings showing magnetic structures such as skyrmions, which will be described later.

[0045] The skyrmion 120 shown in Fig. 5 has a circular shape, and the magnetization (domain wall) of the circumferential portion is Neel type. The magnetic moment of the skyrmion 120 is in the +z direction at the center 120a. As it moves from the center 120a to the edge 120b, the component in the +z direction gradually decreases to zero, while the component in the direction from the edge 120b toward the center 120a (inward) increases. Thereafter, the component in the -z direction of the magnetic moment gradually increases, while the inward component decreases, and it becomes in the -z direction at the edge 120b.

[0046] Generally, the domain wall of the skyrmion 120 is formed as one of an outward Néel type, an inward Néel type, a left-handed (counterclockwise) Bloch type, or a right-handed (clockwise) Bloch type, depending on the strength of the interface DMI and the magnetization direction of the magnetic member 111. The interface DMI between the magnetic member 11 and the first heavy metal member 12 and the interface DMI between the magnetic member 11 and the second heavy metal member 13 have mutually inclined magnetization directions that can be, for example, inward and outward, outward and inward, counterclockwise and clockwise, or clockwise and counterclockwise.

[0047] The method for forming the skyrmion 120 shown in Fig. 5 is as follows. First, a predetermined region of the magnetic member 111 is irradiated with laser light. This increases the temperature of the atomic group in the predetermined region, and the saturation magnetization of the predetermined region decreases. As a result, the magnetic moment of the predetermined region can be controlled with a smaller external magnetic field than in regions other than the predetermined region.

[0048] The irradiation range (or beam diameter) of the laser light corresponds to the size of the skyrmions 120 formed in the magnetic member 111. The irradiation parameters of the laser light (laser light wavelength, irradiation time, etc.) are set so that the atomic group in the predetermined region reaches a target temperature that is slightly higher than the Curie temperature (transition temperature from ferromagnetic to paramagnetic) at most. In the case of TbFeCo, whose Curie temperature is approximately 140°C, the maximum target temperature is set to, for example, 150°C. This allows the magnetization direction only in the predetermined region to be easily changed.

[0049] Next, an external magnetic field is applied in the direction (+Z direction) opposite to the magnetization direction (-Z direction) of the magnetic member 111. The magnitude of the external magnetic field is large enough to reverse the magnetic moment in the predetermined region where the temperature is rising, but small enough not to reverse the magnetic moment in regions other than the predetermined region. As a result, the magnetic moment in the predetermined region reverses to the same direction as the external magnetic field (+Z direction), while the magnetic moment in regions other than the predetermined region maintains the magnetization direction (-Z direction). Furthermore, the magnetic moment in the region outside the predetermined region is tilted to have an in-plane component. As a result, the skyrmion 120 shown in FIG. 5 is formed. The timing to start applying the external magnetic field may be before the timing to start irradiating the laser light. The application time of the external magnetic field is, for example, approximately 10 ns (nanoseconds) or less.

[0050] (Reference example 2) Fig. 6 is a perspective view showing an outline of a magnetic element according to another reference example. Fig. 7 is a cross-sectional view taken along the line CC in Fig. 6. The magnetic element 101 shown in Figs. 6 and 7 is formed by laminating a plate-shaped magnetic member 111 on a plate-shaped heavy metal member 112. That is, the magnetic element 101 shown in Figs. 6 and 7 differs from the magnetic element 100 shown in Figs. 3 and 4 only in the order of lamination.

[0051] 6 and 7, the magnetic member 111 is magnetized in a direction substantially perpendicular to the plate surface (±z direction). In this case, interfacial DMI acts at the boundary between the magnetic member 111 and the heavy metal member 112. This allows skyrmions to exist (form) stably in the magnetic member 111.

[0052] 8 is a plan view showing an outline of skyrmions formed in the magnetic member 111 of the magnetic element 101 having the above configuration. The magnetic member 111 shown in FIG. 8 is magnetized in the same direction (-z direction) as the magnetic member 111 shown in FIG.

[0053] The skyrmion 121 shown in Fig. 8 is circular and Néel type. The magnetic moment of the skyrmion 121 is in the +z direction at the center 121a, and as it moves from the center 121a to the edge 121b, the component in the +z direction gradually decreases to zero, while the component in the direction (outward) from the center 121a to the edge 121b increases. Thereafter, the magnetic moment gradually increases in the -z direction component, while the outward component decreases, until it reaches the -z direction at the edge 121b. The method for forming the skyrmion 121 shown in Fig. 8 is the same as that in Reference Example 1, so its description will be omitted.

[0054] In this way, the magnetization direction of the skyrmions 120 and 121 depends on the arrangement of the heavy metal member 112. Furthermore, when the magnetization direction of the magnetic member 111 is reversed (to the +z direction), the magnetization direction of the skyrmions 120 and 121 also becomes reversed.

[0055] (Current drive of skyrmions) When a current flows from one longitudinal direction to the other (for example, the -x direction) in the magnetic elements 100 and 101 configured as described above, spins flow in the direction of electron flow (opposite to the current), causing a spin transfer torque (STT) to act on the magnetic domains in the magnetic member 111, causing the magnetic domains to move in the direction opposite to the current direction (x direction). This causes the skyrmions 120 and 121 to move in the x direction. Note that whether the magnetic domains move in the same direction as or opposite to the current depends on the spin polarization of the magnetic member 111. When the spin polarization is positive, the skyrmions 120 and 121 move in the opposite direction to the current. When the spin polarization is negative, the skyrmions 120 and 121 move in the same direction as the current.

[0056] At this time, due to the skyrmion Hall effect, a force in the lateral direction (y direction) of the magnetic elements 100 and 101 acts on the skyrmions 120 and 121. Therefore, the skyrmions 120 and 121 moving in the x direction do not move straight along the x direction, but deviate in the y direction. As a result, the skyrmions 120 and 121 may reach the end of the lateral direction (y direction) of the magnetic member 111 and disappear, or may decrease in size and disappear.

[0057] This phenomenon can be explained by the Thiele equation, which describes the current drive of magnetic structures such as skyrmions and bubble domains. The Thiele equation is shown in the following equation (1).

[0058]

number

[0059] Here, G is the magnetic rotation coupling vector, and the vector G = (0, 0, -4πQ), and Q is the skyrmion number, and Q = +1 when the magnetization of the central part 120a is upward (+z direction), and Q = -1 when the magnetization is downward (-z direction).

[0060] The vector u is the spin current velocity vector, and the vector u = (u x,0,0). This has the dimension of velocity and is a quantity proportional to the current flowing through the magnetic member 111. The vector v is the drift velocity vector of the magnetic structure, and the vector v=(v x ,v y , 0). The tensor D is the dissipation force tensor, and the parameters α and β are dimensionless constants that indicate the strength of Gilbert damping and the nonadiabatic effect, respectively. The vector F is the vector of the pinning force resulting from phenomenologically introduced impurities, defects, etc., and the force acting from the edge of the magnetic member 11.

[0061] For the above formula (1), if the vector F=0, the following formula (2) is obtained as an analytical formula for the driving speed (movement speed) of the skyrmion 120.

[0062]

number

[0063] For the above formula (2), D xx =D yy = 1, the following equations (3) and (4) are obtained.

[0064] When Q=±1, v x =(1+αβ)u x / (1+α 2 ), v y =±(α-β)u x / (1+α 2 ) ···(3) If Q=0, v x =βu x / α, v y =0 ···(4).

[0065] With reference to the above formula (3), it can be seen that the skyrmions 120 and 121 with Q = ±1 deviate in the short-side direction (y-direction). With reference to the above formula (4), it can be seen that the magnetic structure with Q = 0 does not deviate in the short-side direction (y-direction) but moves straight in the long-side direction (x-direction). However, with reference to the above formula (2), it can be seen that it is susceptible to relaxation and dissipation.

[0066] (Outline of the magnetic structure) 9 is a plan view showing a magnetic structure extending over both the first region 21 and the second region 22 of the magnetic member 11 in the magnetic element 1 of this embodiment. That is, the magnetic structure 31 is formed across the portion of the magnetic member 11 where the first heavy metal member 12 is formed and the portion where the second heavy metal member 13 is formed. The magnetic structure 31 can be formed by magnetizing the magnetic member 11 in advance in a direction substantially perpendicular to the plate surface (±z direction), and irradiating a laser beam or applying a magnetic field or electric field as described above to a spot region SA1 extending over both the first region 21 and the second region 22 as shown in FIG.

[0067] A first heavy metal member 12 is formed above the first region 21 shown in Figures 1 and 2, as in Figures 3 and 4. Furthermore, a second heavy metal member 13 is formed below the second region 22 shown in Figures 1 and 2, as in Figures 6 and 7. That is, the first heavy metal member 12 is provided on a first surface of the magnetic member 11, and the second heavy metal member 13 is provided on a second surface of the magnetic member 11 opposite the first surface.

[0068] Therefore, in the spot area SA1 of the magnetic member 11, as shown in Fig. 9, a circular magnetic structure 31 can stably exist (can be formed) that includes half of the skyrmion 120 shown in Fig. 5 in the first area 21 and half of the skyrmion 121 shown in Fig. 8 in the second area 22. Such a magnetic structure 31 has a skyrmion number Q of Q = 0, and therefore can be prevented from deviating from the x direction, as shown in the above formula (4).

[0069] Furthermore, from this, it is believed that by making the interface DMI between the magnetic member 11 and the first heavy metal member 12 and the interface DMI between the magnetic member 11 and the second heavy metal member 13 different from each other, the skyrmion number Q of the magnetic structure extending over both the first region 21 and the second region 22 approaches 0 from ±1. As a result, it is believed that deviation from the x direction of the magnetic structure can be reduced.

[0070] Example 1 Regarding the magnetic element 1 shown in FIGS. 1 and 2, the magnetic structure formed in the spot area SA1 shown in FIG. 1 was calculated using micromagnetics simulation, which is often used to simulate the magnetization state of a magnetic material.

[0071] The magnetic member 11 had a length (length in the x direction) of 500 nm, a width (length in the y direction) of 50 nm, and a thickness (length in the z direction) of 7.5 nm. The parameters of TbFeCo were used as the magnetic parameters of the magnetic member 11. The interface DMI between the first heavy metal member 12 and the second heavy metal member 13 and the magnetic member 11 was determined by using the interface DMI parameter between TbFeCo and Pt. The magnetic member 11 was divided into minute cells with a length of 2.5 nm, a width of 2.5 nm, and a thickness of 2.5 nm, and the time change in magnetization of each cell was calculated using the Landau-Lifshitz-Gilbert equation (LLG equation).

[0072] FIG. 10 is a plan view showing a magnetic structure stabilized by the magnetic member 11 as a result of the above simulation. The magnetic structure 32 shown in FIG. 10 has an elliptical shape, and has components in diagonal directions (+x direction and -y direction) from the center 32a toward the edge 32b. The skyrmion number of this magnetic structure 32 is Q = -0.017, which is not zero. Note that the above elliptical shape could be made closer to a circular shape by using values ​​such as the dissipation force tensor D. When the above simulation was performed on the magnetic structure 32 shown in FIG. 10, in which a current was passed in the -x direction of the magnetic member 11, the magnetic structure 32 was driven in the x direction and did not deviate from the x direction. That is, v y =0.

[0073] FIG. 11 is a graph showing the movement of the magnetic structure 32 shown in FIG. 10. In FIG. 11, the horizontal axis represents time (unit: ns) and the vertical axis represents distance (unit: nm). The solid line represents the case where α=0.01 and β=0.0, and the dashed line represents the case where α=0.1 and β=0.0. Note that the spin current velocity u x was set to 5.0 m / s.

[0074] Referring to FIG. 11, the magnetic structure 32 shown in solid line is driven at a speed of v x = 4.5 m / s, i.e., v x =0.9u x The magnetic structure 32 shown by the dashed line is driven at a speed of v x = 3.0 m / s, i.e., v x =0.6u x Therefore, it can be understood that the magnetic structure 32 of this example can be driven with low power consumption, similar to the case of skyrmions.

[0075] Here, the driving speed of the magnetic structure 32 is calculated using the above analytical formula. In the above formula (4), when β=0.0, v x = 0. Therefore, it can be seen that the magnetic structure 32 is driven because Q is not zero.

[0076] In addition, in the above formula (2), Q=-0.0167, D xx =0.989, D yy = 2.004, when α = 0.01 and β = 0.0, v x ~0.6u x , v y ≒-0.345u x When α=0.1 and β=0.0, v x =0.013u x , v y ≒-0.082u x That is, the driving speed of the magnetic structure 32 shown in FIG. 11 based on the simulation results was faster than the driving speed based on the analytical formula. This is because the analytical value was v y ≠0, whereas the simulated value is v y =0 (for example, the force vector F from the edge of the magnetic member 11).

[0077] Example 2 1 and 2, the magnetic structure formed in the spot area SA2 on the first region 21 shown in Fig. 1 was investigated using the micromagnetics simulation. Note that the various parameters of the magnetic element 1 are the same as those in Example 1.

[0078] Fig. 12 is a plan view showing a magnetic structure stabilized in the magnetic member 11 as a result of the above simulation. The magnetic structure 33 (skyrmion) shown in Fig. 12 is a Bloch-type skyrmion with a left-handed (counterclockwise) component in the direction along the plate surface (xy plane). This skyrmion 33 continued to move at 20 m / s to the left of the drawing (-x direction) even without passing a current through the magnetic element 1. The reason for this is that the skyrmion 33 was located on the edge side of the magnetic member 11, rather than in the center of the magnetic member 11, and so a force vector F from the edge of the magnetic member 11 acted on the skyrmion 33.

[0079] The reason why the skyrmion 33 is located on the edge side of the magnetic member 11 is as follows: The -y side of the skyrmion 33 has a magnetic structure inclined in the opposite direction to the direction in which the interfacial DMI tilts the magnetization, and is in a high-energy state, whereas the +y side of the skyrmion 33 has a magnetic structure inclined in the same direction as the direction in which the interfacial DMI tilts the magnetization, and is in a low-energy state. For this reason, the position where the center of the skyrmion 33 is closer to the +y side, where the low-energy region is larger, becomes a low-energy stable position.

[0080] Since no current was flowing through the magnetic element 1, the skyrmion Hall effect did not occur, and therefore the skyrmions 33 continued to move without deviating from the longitudinal direction (x direction). Furthermore, the weaker the interfacial DMI at the boundary between the magnetic member 11 and the first heavy metal member 12, the slower the movement speed. This is because the stronger the interfacial DMI, the greater the distance that the skyrmions 33 approach the edge of the magnetic member 11, and the greater the effect of the force vector F from the edge of the magnetic member 11.

[0081] Example 3 1 and 2, the magnetic structure formed in the spot area SA3 on the second region 22 shown in Fig. 1 was investigated using the micromagnetics simulation described above. Note that the various parameters of the magnetic element 1 are the same as those in Example 1.

[0082] FIG. 13 is a plan view showing a magnetic structure stabilized in the magnetic member 11 as a result of the above simulation. The magnetic structure 34 (skyrmion) shown in FIG. 13 is a Bloch-type skyrmion with a rightward (clockwise) component along the plate surface (xy plane). In this example, as in the example shown in FIG. 12, the skyrmion 34 continued to move to the right of the drawing (x direction) at 20 m / s even without current flowing through the magnetic element 1. Furthermore, because no current was flowing through the magnetic element 1, the skyrmion Hall effect did not occur, and therefore the skyrmion 34 continued to move without deviating from the longitudinal direction (x direction). Furthermore, the movement speed was slower as the interfacial DMI at the boundary between the magnetic member 11 and the second heavy metal member 13 was weaker.

[0083] (Variation 1) Fig. 14 is a cross-sectional view showing a modified example of the magnetic element 1 shown in Fig. 1 and Fig. 2. The magnetic element 1a shown in Fig. 14 differs from the magnetic element 1 shown in Fig. 2 in that a first heavy metal member 12 is provided in a part of the first region 21 of the magnetic member 11 and a second heavy metal member 13 is provided in a part of the second region 22 of the magnetic member 11, but the rest of the configuration is similar. As in this modified example, there may be an area in the magnetic member 11 that is free of the first heavy metal member 12 and the second heavy metal member 13.

[0084] Furthermore, in the magnetic member 11, the region where the first heavy metal member 12 is provided and the region where the second heavy metal member 13 is provided may be spaced apart. The maximum width of this space is, for example, about 20 nm, but is thought to be strongly dependent on the magnetic parameters.

[0085] (Variation 2) Fig. 15 is a cross-sectional view showing another modified example of the magnetic element 1 shown in Fig. 1 and Fig. 2. The magnetic element 1b shown in Fig. 15 differs from the magnetic element 1 shown in Fig. 2 in that a first heavy metal member 12 is provided in the first region 21 and a part of the second region 22 of the magnetic member 11, and a second heavy metal member 13 is provided in a part of the second region 22 of the magnetic member 11, but the rest of the configuration is similar. In this case, when viewed from the direction (z direction) in which the magnetic member 11 and the first heavy metal member 12 or the second heavy metal member 13 are aligned (when viewed from above), there are parts where the first heavy metal member 12 and the second heavy metal member 13 overlap.

[0086] As in this modification, there may be an area in which both the first heavy metal member 12 and the second heavy metal member 13 are provided in the magnetic member 11. The maximum width of the area in which the first heavy metal member 12, the magnetic member 11, and the second heavy metal member 13 overlap is, for example, about 20 nm, but is thought to be strongly dependent on the magnetic parameters.

[0087] (Additional notes) 1 and 2, a non-magnetic and electrically insulating thin film may be provided on the side of the first region 21 opposite to the side where the first heavy metal member 12 is provided, and on the side of the second region 22 opposite to the side where the second heavy metal member 13 is provided. In this case, the magnetic element 1 has a three-layer rectangular parallelepiped shape, which stabilizes the structure.

[0088] Furthermore, the magnetic member 11 may be entirely or partially constituted by the first region 21 and the second region 22. The first region 21 and the second region 22 may be approximately the same in size. When forming the skyrmions 33 and 34 shown in FIG. 12, the first region 21 may be larger in size than the second region 22. Similarly, when forming the skyrmion 34 shown in FIG. 13, the second region 22 may be larger in size than the first region 21.

[0089] [Embodiment 2] Another embodiment of the present invention will now be described with reference to FIG.

[0090] FIG. 16 is a cross-sectional view showing an outline of the magnetic element of this embodiment. The magnetic element 2 shown in FIG. 16 differs from the magnetic element 1 shown in FIGS. 1 and 2 in that the magnetic member 11 is stepped, with the lower step being a first region 21 and the upper step being a second region 22, but the rest of the configuration is similar. That is, in this embodiment, a first heavy metal member 12 is formed in the lower step (one step) of the magnetic member 11, and a second heavy metal member 13 is formed in the upper step (the other step). The magnetic element 2 shown can be realized by first forming the lower step of the magnetic member 11 and the second heavy metal member 13, and then forming the first heavy metal member 12 and the upper step of the magnetic member 11.

[0091] The magnetic element 2 of this embodiment has a two-layer rectangular parallelepiped shape as shown in Fig. 16, and therefore has a more stable structure than the magnetic element 1 shown in Fig. 1 and Fig. 2. Furthermore, the magnetic element 2 of this embodiment can be made thinner than the above-mentioned three-layer rectangular parallelepiped shape.

[0092] [Embodiment 3] Yet another embodiment of the present invention will now be described with reference to FIG.

[0093] Fig. 17 is a cross-sectional view showing an outline of the magnetic element of this embodiment. The magnetic element 3 shown in Fig. 17 differs from the magnetic element 1 shown in Fig. 1 and Fig. 2 in that a first heavy metal member 14 is provided instead of the first heavy metal member 12, but the rest of the configuration is the same.

[0094] 17, the first heavy metal member 14 is provided on the magnetic member 11 on the side opposite (-z direction) to the side on which the first heavy metal member 12 shown in FIGS. 1 and 2 is provided. That is, the first heavy metal member 14 and the second heavy metal member 13 are provided on the lower surface (first surface) of the magnetic member 11. The first heavy metal member 14 is provided on the magnetic member 11 adjacent to the second heavy metal member 13. The region where the first heavy metal member 14 is provided and the region where the second heavy metal member 13 is provided may be spaced apart (for example, by about 20 nm).

[0095] The first heavy metal member 14 and the second heavy metal member 13 are made of different types of heavy metal. Specifically, the first heavy metal member 14 is made of a heavy metal such that the sign of the interface DMI between the magnetic member 11 and the first heavy metal member 14 is opposite to the sign of the interface DMI between the magnetic member 11 and the second heavy metal member 13 (first heavy metal member 12).

[0096] As a result, the magnetic element 3 of this embodiment can form a magnetic structure as shown in Figures 9, 10, 12, and 13. Furthermore, the magnetic element 3 of this embodiment has a two-layer rectangular parallelepiped shape as shown in Figure 17, and therefore can have a more stable structure than the magnetic element 1 shown in Figures 1 and 2. Furthermore, the magnetic element 2 of this embodiment can be made thinner than the above-mentioned three-layer rectangular parallelepiped shape.

[0097] [Embodiment 4] Yet another embodiment of the present invention will now be described with reference to FIGS.

[0098] 18 is a perspective view showing an outline of the magnetic element according to this embodiment. The magnetic element 4 according to this embodiment differs from the magnetic element 1 shown in FIGS. 1 and 2 in that a second heavy metal member 13 is provided in the first region 21, a first heavy metal member 12 is provided in the second region 22, and a supply portion 41 (protrusion) is newly provided, but the rest of the configuration is the same.

[0099] Hereinafter, the portion of the magnetic member 11 that includes the first region 21 and the second region 22 will be referred to as the main body 23. That is, the main body 23 is a plate-shaped portion (rectangular parallelepiped) on which the first heavy metal member 12 and the second heavy metal member 13 are formed. The main body 23 also has a side surface 23a that is positioned in the direction in which the first heavy metal member 12 and the second heavy metal member 13 are aligned (y direction).

[0100] Since the second heavy metal member 13 is provided in the first region 21, skyrmions 34 shown in Fig. 13 can exist in the first region 21. Furthermore, since the first heavy metal member 12 is provided in the second region 22, skyrmions 33 shown in Fig. 12 can exist in the second region 22.

[0101] 18, the supply unit 41 is provided with a magnetic protruding portion 42 protruding laterally (in the -y direction) from a part of the side surface 23a of the first region 21 of the magnetic member 11, and a second heavy metal protruding portion 43 protruding together with the magnetic protruding portion 42.

[0102] 13 can be formed in the magnetic protrusion 42 by magnetizing the magnetic member 11 and the magnetic protrusion 42 in the −z direction in advance and then irradiating the magnetic member 11 with laser light, applying a magnetic field or electric field, or injecting spins using the supply unit 41. This eliminates the need to perform the operations required for forming the skyrmion 34, such as irradiating the laser light or applying a magnetic field, in the main body 23 including the first region 21 and the second region 22.

[0103] The supply unit 41 has a wide base end 41a and a narrow tip end 41b. That is, the magnetic protrusion 42 narrows in width from the main body 23 side toward the outside (in the -y direction). In this case, the energy of a magnetic structure such as a skyrmion is lower when it is located at the base end 41a rather than at the tip end 41b. As a result, the skyrmion 34 formed at the magnetic protrusion 42 can move toward the base end 41a and then to the main body 23 without passing a current through the supply unit 41.

[0104] Furthermore, the supply unit 41 is inclined in the direction (x direction) in which the skyrmions 34 move from the tip end 41b toward the base end 41a. Specifically, the magnetic protrusion 42 has a first side surface 42a and a second side surface 42b connected to the side surface 23a of the main body 23 (see FIG. 18). The first side surface 42a is positioned in the opposite direction (-x direction) to the movement direction of the skyrmions 34 compared to the second side surface 42b. The angle formed by the first side surface 42a of the magnetic protrusion 42 and the side surface 23a of the main body 23 on the magnetic protrusion 42 side is defined as a first angle θ1. The angle formed by the second side surface 42b of the magnetic protrusion 42 and the side surface 23a of the main body 23 on the magnetic protrusion 42 side is defined as a second angle θ2 (see FIG. 19). In this case, in this embodiment, the first angle θ1 is greater than the second angle θ2.

[0105] This allows the skyrmions 34 formed in the magnetic protruding portion 42 to move smoothly to the first region 21 (main body portion 23). Then, the skyrmions 34 that have moved to the first region 21 move in the x direction without causing a current to flow through the magnetic element 4.

[0106] Example 4 For the magnetic element 4 shown in FIG. 18 , the behavior of the skyrmions 34 formed in the supply unit 41 was calculated using the micromagnetics simulation described above. The magnetic member 11 had a length (length in the x direction) of 500 nm, a width (length in the y direction) of 60 nm, and a thickness (length in the z direction) of 6.0 nm. The first heavy metal member 12 and the second heavy metal member 13 had a length of 500 nm and a width of 30 nm. The length of the supply unit 41 was 86 nm, the length of its tip end was 60 nm, and the length in the y direction from the tip end to its base end was 60 nm. The parameters of the TbFeCo / Pt multilayer film were used as the magnetic parameters and interface DMI value of the magnetic member 11 and the supply unit 41. The magnetic member 11 and the supply unit 41 were divided into minute cells with a length of 2.0 nm, a width of 2.0 nm, and a thickness of 2.0 nm, and the behavior of the skyrmions 34 formed in the supply unit 41 was calculated.

[0107] Fig. 19 is a plan view showing the behavior of the skyrmion 34 calculated by the above simulation. As shown by reference numeral 1001 in Fig. 19, when the skyrmion 34 is formed in the magnetic protrusion 42 of the supply unit 41, the skyrmion 34 moves in a direction having an x ​​component and a y component while increasing in size, as shown by reference numeral 1002 in Fig. 19. When the skyrmion 34 moves to the magnetic member 11, the skyrmion 34 moves in the x direction while decreasing in size. Then, as shown by reference numeral 1003 in Fig. 19, the skymion 34 moves in the x direction to a position closer to the first region 21 from the center while maintaining an appropriate size.

[0108] [Embodiment 5] Yet another embodiment of the present invention will now be described with reference to FIG.

[0109] Fig. 20 is a plan view showing an outline of a magnetic memory device according to this embodiment. As shown in Fig. 20, a magnetic memory device 50 according to this embodiment includes the magnetic element 1 shown in Figs. 1 and 2, a power supply 51, a write device 52, and a read device 53. The magnetic element 1 is divided into a plurality of magnetic domains.

[0110] The power supply 51 is connected to both longitudinal ends of the magnetic element 1, and a predetermined current flows from one end to the other or vice versa, thereby moving the magnetic domain of the magnetic element 1 in the direction opposite to the direction of the current.

[0111] The writing device 52 is configured to form, for example, the magnetic structure 31 shown in Fig. 9 at a predetermined writing position in the magnetic element 1. The writing device 52 includes, but is not limited to, a device that irradiates the spot area SA1 shown in Fig. 1 with laser light and a device that applies an external magnetic field, and any device that can form the magnetic structure 31 can be used.

[0112] The read device 53 is configured to detect the presence or absence of the magnetic structure 31 at a predetermined read position in the magnetic element 1. Specifically, the read device 53 detects the magnetic moment of a predetermined region in the magnetic member 11 of the magnetic element 1 and converts it into an electric signal. The read device 53 may be, for example, a magnetic sensor that utilizes GMR (giant magnetoresistance), TMR (tunnel magnetoresistance), Hall effect, or the like.

[0113] In the magnetic memory device 50 configured as described above, when writing one bit of data "1" to a certain address, the power supply 51 applies a current so that the magnetic domain corresponding to the address moves to the write position. Next, the write device 52 forms a magnetic structure 31 at the write position. The magnetic structure 31 is formed in the magnetic domain corresponding to the address. Note that when writing one bit of data "0" to a certain address, nothing special is done.

[0114] Furthermore, when reading one bit of data at a certain address, the power supply 51 applies a current so that the magnetic domain corresponding to the address moves to the read position. Next, the read device 53 detects the magnetic moment at the read position. If the read device 53 detects the magnetic moment of the magnetic structure 31, it outputs an electrical signal indicating one bit of data "1" to the outside. On the other hand, if the read device 53 does not detect the magnetic moment of the magnetic structure 31, it outputs an electrical signal indicating one bit of data "0" to the outside.

[0115] When erasing information stored in the magnetic memory device 50, the power supply 51 applies a current so that all magnetic domains move to one of the ends of the magnetic element 1. As a result, the magnetic structure 31 comes into contact with one of the ends of the magnetic element 1 and disappears.

[0116] Therefore, in the magnetic memory device 50 of this embodiment, the magnetic structure 31 can be prevented from moving in the direction opposite to the direction of current flow and deviating from that direction, thereby improving the reliability of the magnetic memory device 50.

[0117] (Additional notes) 18 may be added to the magnetic element 1 of the magnetic memory device 50 shown in Fig. 20. In this case, the work required to form the skyrmions 34 does not need to be performed in the main body 23 where the skyrmions 34 move based on the current.

[0118] [Embodiment 6] Another embodiment of the present invention will be described with reference to FIG.

[0119] 21 is a plan view showing an outline of a magnetic memory device according to this embodiment. As shown in Fig. 21, a magnetic memory device 60 according to this embodiment includes the magnetic element 4 shown in Fig. 18, a write device 61, a read device 62, and an erase device 63.

[0120] In this embodiment, the main body of the magnetic element 4 has a closed path shape. The writing device 61 is configured to form skyrmions 34 shown in FIG. 13 at a predetermined writing position in the supply unit 41 of the magnetic element 4. Therefore, the skyrmions 34 formed in the supply unit 41 move to the closed path and circulate leftward (counterclockwise). The writing device 61 is similar to the writing device 52 shown in FIG. 20, so a detailed description thereof will be omitted.

[0121] The readout device 62 is configured to detect the presence or absence of the skyrmion 34 at a predetermined readout position in the closed path. Note that the readout device 62 is similar to the readout device 53 shown in Fig. 20, and therefore a detailed description thereof will be omitted.

[0122] The erasing device 63 is configured to erase the skyrmions 34 at a predetermined erasing position in the closed path. Specifically, the erasing device 63 applies a magnetic field at the erasing position in the magnetization direction (-z direction) of the magnetic member 11 in the magnetic element 4. The erasing device 63 may be configured to irradiate the erasing position with laser light so that the temperature at the erasing position becomes higher than the Curie temperature.

[0123] In the magnetic memory device 60 configured as above, when writing one bit of data "1" to a certain address, the writing device 61 is operated so that when the magnetic domain corresponding to the address reaches the junction between the supply unit 41 and the closed path, the skyrmion 34 moves from the supply unit 41 to the junction.

[0124] On the other hand, when writing 1-bit data "0" to a certain address or erasing 1-bit data from a certain address, the erasing device 63 can be operated when the magnetic domain corresponding to the address reaches the erasing position.

[0125] Therefore, the magnetic memory device 60 of this embodiment does not require a power source for moving magnetic domains, and therefore power consumption can be further reduced.

[0126] (Additional notes) 21 may be replaced with the magnetic element 1 shown in FIGS. 1 and 2, and the main body of the magnetic element 1 may have a closed path shape. In this case, it is necessary to pass a current through the magnetic element 1 to move the magnetic structure 31, but the magnetic structure 31 can be moved along the direction of the current.

[0127] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0128] 1, 1a, 1b, 2, 3, 4 Magnetic elements 11 Magnetic components 12, 14 First heavy metal component 13 Second heavy metal component 21 First area 22 Second area 23 Main body 23a side 31, 32 Magnetic Structure 33 Skyrmion (magnetic structure) 34 Skyrmion (magnetic structure) 32a center 32b Edge 41 Supply section 41a Proximal end 41b Tip 42 Magnetic protrusion 42a 1st side 42b Second side 43 Second heavy metal protrusion 50, 60 Magnetic memory device 51 Power supply 52, 61 Write device 53, 62 Readout device 63 Erasing Device

Claims

1. A magnetic member, a first heavy metal member and a second heavy metal member formed on the magnetic member, In the magnetic member, a circular or elliptical magnetic structure can be present across a portion where the first heavy metal member is formed and a portion where the second heavy metal member is formed, an interfacial Dzyaloshinsky-Moriya interaction (interfacial DMI) acts on each of a first magnetization in the magnetic member near the interface where the magnetic member contacts the first heavy metal member and a second magnetization in the magnetic member near the interface where the magnetic member contacts the second heavy metal member; a direction in which the first magnetization is tilted due to the interface DMI and a direction in which the second magnetization is tilted due to the interface DMI are different from each other; Magnetic element.

2. A magnetic member, a first heavy metal member and a second heavy metal member formed on the magnetic member, In the magnetic member, a circular or elliptical magnetic structure can be present across a portion where the first heavy metal member is formed and a portion where the second heavy metal member is formed, the first heavy metal member is provided on a first surface of the magnetic member, and the second heavy metal member is provided on a second surface of the magnetic member opposite to the first surface; Magnetic element.

3. The first heavy metal member and the second heavy metal member are made of the same heavy metal. The magnetic element according to claim 2 .

4. The magnetic element according to claim 2 or 3, wherein when viewed from the direction in which the magnetic member and the first heavy metal member or the second heavy metal member are aligned, one side of the first heavy metal member and one side of the second heavy metal member are approximately in the same straight line.

5. When viewed from a direction in which the magnetic member and the first heavy metal member or the second heavy metal member are aligned, there is a portion where the first heavy metal member and the second heavy metal member overlap. The magnetic element according to claim 2 or 3.

6. The magnetic member is stepped, with the first heavy metal member formed on one step and the second heavy metal member formed on the other step. The magnetic element according to claim 2 or 3.

7. the first heavy metal member and the second heavy metal member are provided on a first surface of the magnetic member; The magnetic element according to claim 1 .

8. A magnetic member; a first heavy metal member and a second heavy metal member formed on the magnetic member, In the magnetic member, a circular or elliptical magnetic structure can be present across a portion where the first heavy metal member is formed and a portion where the second heavy metal member is formed, the first heavy metal member and the second heavy metal member are provided on a first surface of the magnetic member, a sign of an interface DMI between the first heavy metal member and the magnetic member and a sign of an interface DMI between the second heavy metal member and the magnetic member are different from each other; Magnetic element.

9. The first heavy metal member and the second heavy metal member are different in type of heavy metal. The magnetic element according to claim 7 or 8.

10. The first heavy metal member and the second heavy metal member are adjacent to each other. The magnetic element according to claim 7 or 8.

11. the magnetic member includes a rectangular parallelepiped main body in which the first heavy metal member and the second heavy metal member are formed, the magnetic member further includes a magnetic protrusion protruding from a portion of a side surface of the main body, The first heavy metal member or the second heavy metal member further includes a heavy metal protrusion that protrudes together with the magnetic protrusion. The magnetic element according to claim 1 .

12. A magnetic member; a first heavy metal member and a second heavy metal member formed on the magnetic member, In the magnetic member, a circular or elliptical magnetic structure can be present across a portion where the first heavy metal member is formed and a portion where the second heavy metal member is formed, the magnetic member includes a rectangular parallelepiped main body in which the first heavy metal member and the second heavy metal member are formed, the magnetic member further includes a magnetic protrusion protruding from a portion of a side surface of the main body, The first heavy metal member or the second heavy metal member further includes a heavy metal protrusion that protrudes together with the magnetic protrusion. Magnetic element.

13. The magnetic protrusion has a width that narrows from the main body side toward the outside. The magnetic element according to claim 11 or 12.

14. the magnetic protrusion has a first side surface and a second side surface connected to the side surface of the main body portion; When an angle formed on the magnetic protrusion side by the first side surface of the magnetic protrusion and the side surface of the main body is defined as a first angle, and an angle formed on the magnetic protrusion side by the second side surface of the magnetic protrusion and the side surface of the main body is defined as a second angle, the first angle is larger than the second angle. The magnetic element according to claim 13 .

15. A magnetic element according to any one of claims 1 to 14; a writing device for writing information by forming or not forming a magnetic structure on the magnetic member of the magnetic element; a reading device for reading information by detecting the presence or absence of magnetic structures on the magnetic member; A magnetic memory device comprising:

Images