Magnetic element capable of generating magnetic field-free spin-orbit torque and method for manufacturing the same

Abstract

To provide a magnetic element capable of generating a magnetic field-free spin orbit torque by introducing a ferrimagnetic material having a composition corresponding to the range near the magnetization compensation point, thereby improving energy efficiency, and a method for manufacturing the same. [Solution] The structure includes a fixed ferromagnetic layer, a free ferromagnetic layer, and an insulating layer located between the fixed ferromagnetic layer and the free ferromagnetic layer, wherein the free ferromagnetic layer includes an in-plane magnetic anisotropy ferrimagnetic layer, a perpendicular magnetic anisotropy free ferromagnetic layer, and a non-magnetic layer located between the in-plane magnetic anisotropy ferrimagnetic layer and the perpendicular magnetic anisotropy free ferromagnetic layer.

Description

Technical Field

[0001] The present invention relates to a magnetic element capable of generating a magnetic field-free spin-orbit torque and a method for manufacturing the same. More specifically, the present invention relates to a magnetic element capable of generating a magnetic field-free spin-orbit torque with improved energy efficiency by introducing a ferromagnetic material having a composition corresponding to a range near the magnetization compensation point, and a method for manufacturing the same.

Background Art

[0002] A magnetic memory is a memory having a multilayer thin film structure including a magnetic layer, and is a non-volatile memory capable of maintaining information without external power.

[0003] [[ID=|15]] The magnetic memory currently in mass production operates based on spin transfer torque technology. This technology is a technique for injecting a perpendicular current into a magnetic tunnel junction having a ferromagnetic / insulating layer / ferromagnetic structure to cause magnetization reversal. However, it has disadvantages such as a relatively slow operating speed, a high error rate of the element, and poor stability.

[0004] The recently studied spin-orbit torque technology is a switching technology that utilizes the torque generated by a spin current generated by the spin-orbit interaction. The spin-orbit torque technology has advantages such as a fast operating speed, high element stability because a high write current does not flow through the insulating layer, and the ability to reduce the error rate because the read / write currents are different.

[0005] However, an external magnetic field is required for magnetization reversal, and a relatively large switching current is required, and thus there is a need for technological development to overcome this.

[0006] The present invention provides a solution for increasing the switching energy efficiency of a spin-orbit torque magnetic memory by using a meta-magnetic (ferromagnetic) material as a spin current generation material in a spin-orbit torque magnetic memory element capable of switching without an external magnetic field, and utilizing the spin current generated in a ferromagnetic / non-magnetic structure.

Prior Art Documents

[0007] [Patent Document 1] Korean Registered Patent No. 10-1940669 [Overview of the project] [Problems that the invention aims to solve]

[0008] The technical problem that this invention aims to solve is to provide a magnetic element capable of generating a field-free spin orbit torque by introducing a ferrimagnetic material having a composition corresponding to the range near the magnetization compensation point, thereby improving energy efficiency, and a method for manufacturing the same.

[0009] The technical problems that this invention aims to solve are not limited to those mentioned above, and other technical problems not mentioned can be clearly understood by a person with ordinary skill in the art to which this invention pertains from the following description. [Means for solving the problem]

[0010] To achieve the aforementioned technical objectives, one embodiment of the present invention provides a magnetic element capable of generating a magnetic field-free spin-orbit torque.

[0011] The magnetic element capable of generating a magnetic field-free spin orbit torque according to one embodiment of the present invention is, It includes a fixed ferromagnetic layer, a free ferromagnetic layer, and an insulating layer located between the fixed ferromagnetic layer and the free ferromagnetic layer, The free ferromagnetic layer may be a magnetic element capable of generating spin orbit torque without a magnetic field, characterized by a structure that includes an in-plane magnetic anisotropy ferrimagnetic layer, a perpendicular magnetic anisotropy free ferromagnetic layer, and a non-magnetic layer located between the in-plane magnetic anisotropy ferrimagnetic layer and the perpendicular magnetic anisotropy free ferromagnetic layer.

[0012] Furthermore, according to one embodiment of the present invention, the in-plane magnetic anisotropic ferrimagnetic layer has an in-plane magnetic moment (M sA magnetic element capable of zero-field spin-orbit torque may exist, characterized by a value of 500 emu / cc or less.

[0013] Furthermore, according to one embodiment of the present invention, there may be a magnetic element capable of generating zero-field spin-orbit torque, characterized in that the in-plane magnetic anisotropy ferrimagnetic layer has a thickness range of 2 to 20 nm.

[0014] Furthermore, according to one embodiment of the present invention, there may be a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that the material constituting the in-plane magnetic anisotropy ferrimagnetic layer is represented by the following chemical formula 1.

[0015] [Chemical formula 1] Co x Gd y

[0016] In the aforementioned chemical formula 1, x and y represent the composition ratios of Co and Gd, respectively, and the sum of the x and y values ​​is 100.

[0017] Furthermore, according to one embodiment of the present invention, there may be a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that x is a number between 60 and 90.

[0018] Furthermore, according to one embodiment of the present invention, there may be a magnetic element capable of generating zero-magnetic-field spin-orbit torque, characterized in that the non-magnetic layer contains one or more selected from the group consisting of Pt, Ta, W, Ti, and alloys of combinations thereof.

[0019] Furthermore, according to one embodiment of the present invention, there may be a magnetic element capable of zero-field spin-orbit torque, characterized in that the spin current generated in the in-plane magnetic anisotropy ferrimagnetic layer and the non-magnetic layer applies torque to the perpendicular magnetic anisotropy free ferromagnetic layer, thereby switching the magnetization direction of the perpendicular magnetic anisotropy free ferromagnetic layer.

[0020] To achieve the aforementioned technical objectives, another embodiment of the present invention provides a method for manufacturing a magnetic element capable of generating a magnetic field-free spin-orbit torque.

[0021] The magnetic element manufacturing method that enables the aforementioned magnetic field-free spin-orbit torque according to one embodiment of the present invention is: The process includes the steps of forming a fixed ferromagnetic layer, forming an insulating layer on the fixed ferromagnetic layer, and forming a free ferromagnetic layer on the insulating layer, The step of forming the free ferromagnetic layer may be a method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that it includes the steps of forming a perpendicular magnetic anisotropy free ferromagnetic layer, forming a non-magnetic layer on the perpendicular magnetic anisotropy free ferromagnetic layer, and forming an in-plane magnetic anisotropy ferrimagnetic layer on the non-magnetic layer.

[0022] Furthermore, according to one embodiment of the present invention, the step of forming the in-plane magnetic anisotropy ferrimagnetic layer is to determine the in-plane magnetic moment (M) of the in-plane magnetic anisotropy ferrimagnetic layer. s A method for manufacturing magnetic elements that enables zero-field spin-orbit torque may exist, characterized by ensuring that the value is 500 emu / cc or less.

[0023] Furthermore, according to one embodiment of the present invention, the step of forming the in-plane magnetic anisotropy ferrimagnetic layer is characterized in that the in-plane magnetic anisotropy ferrimagnetic layer has a thickness range of 2 to 20 nm, thus providing a method for manufacturing a magnetic element capable of generating a spin orbit torque without a magnetic field.

[0024] Furthermore, according to one embodiment of the present invention, there is a method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that the step of forming the in-plane magnetic anisotropy ferrimagnetic layer is such that the in-plane magnetic anisotropy ferrimagnetic layer is composed of a substance represented by the following chemical formula 1.

[0025] [Chemical formula 1] Co x Gd y

[0026] In the aforementioned chemical formula 1, x and y represent the composition ratios of Co and Gd, respectively, and the sum of the x and y values ​​is 100.

[0027] Furthermore, according to one embodiment of the present invention, there may be a method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that x is a number between 60 and 90.

[0028] Furthermore, according to one embodiment of the present invention, there is a method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that the step of forming a free ferromagnetic layer on the insulating layer is carried out by one or more methods selected from the group consisting of sputtering, molecular beam epitaxy (MBE), atomic layer deposition (ALD), physical vapor deposition (PVD), and chemical vapor deposition (CVD). [Effects of the Invention]

[0029] According to one embodiment of the present invention, a magnetic element capable of generating a magnetic field-free spin orbit torque with improved energy efficiency can be provided by introducing a ferrimagnetic material having a composition corresponding to the range near the magnetization compensation point, and a method for manufacturing the same.

[0030] According to one embodiment of the present invention, the spin-orbit torque magnetic memory energy efficiency can be increased by reducing the magnetic field-free switching current of the spin-orbit torque element.

[0031] According to one embodiment of the present invention, the switching energy efficiency near the magnetization compensation point can be maximized by controlling the composition of the material constituting the ferrimagnetic layer.

[0032] The effects of the present invention are not limited to those described above, but should be understood to include all effects that can be inferred from the detailed description of the present invention or the configuration of the invention as described in the claims. [Brief explanation of the drawing]

[0033] [Figure 1] This is a schematic diagram showing the overall structure of a magnetic element according to one embodiment of the present invention. [Figure 2] This graph shows the magnetic hysteresis curves for different compositions of the in-plane magnetic anisotropy ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention. [Figure 3] This graph shows the in-plane magnetic moment and coercivity of a magnetic element according to one embodiment of the present invention, based on the composition of the in-plane magnetic anisotropy ferrimagnetic layer (CoGd). [Figure 4] This is a schematic diagram illustrating the structure of a magnetic element according to one embodiment of the present invention and the measurement of its spin-orbit torque switching characteristics. [Figure 5] This graph shows the spin-orbit torque switching behavior of a magnetic element (Co100Gd0) according to a comparative example of the present invention. [Figure 6] This graph shows the spin-orbit torque switching behavior of a magnetic element (Co60Gd40) according to one embodiment of the present invention. [Figure 7] This graph shows the switching current density based on the composition of the in-plane magnetic anisotropy ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention. [Figure 8] This graph shows the field-free spin-orbit torque switching behavior of a magnetic element (Co100Gd0) according to a comparative example of the present invention. [Figure 9] This graph shows the field-free spin-orbit torque switching behavior of a magnetic element (Co70Gd30) according to one embodiment of the present invention. [Figure 10] This graph shows the field-free switching current density based on the composition of the in-plane magnetic anisotropy ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention. [Figure 11] This graph shows the anomalous Hall effect movement of a magnetic element (Co70Gd30) according to one embodiment of the present invention when there is an external magnetic field in the in-plane direction. [Figure 12] This graph shows the movement of the anomalous Hall effect in an in-plane direction of a magnetic element (Co70Gd30) according to one embodiment of the present invention when there is no external magnetic field. [Figure 13]This graph shows the spin-orbit torque efficiency of a magnetic element (Co70Gd30) according to one embodiment of the present invention. [Figure 14] This graph shows the y-spin efficiency of the in-plane magnetic anisotropic ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention, depending on the composition. [Figure 15] This graph shows the z-spin efficiency of the in-plane magnetic anisotropic ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention, based on its composition. [Modes for carrying out the invention]

[0034] The present invention will be described below with reference to the accompanying drawings. However, the present invention can be realized in various different forms and is therefore not limited to the embodiments described herein, but includes all modifications, equivalents, or substitutes that fall within the spirit and technical scope of the present invention.

[0035] Furthermore, in order to clearly illustrate the present invention with drawings, parts unrelated to the description have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0036] In the specification as a whole, when a part is described as being "connected (linked, in contact with, joined)" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other components in between.

[0037] Furthermore, when a part such as a layer, film, region, or plate is said to be "on" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Also, in this specification, when a part such as a layer, film, region, or plate is formed on another part, the direction of formation is not limited to the upward direction, but also includes the case where it is formed on the side or downward. Conversely, when a part such as a layer, film, region, or plate is said to be "below" another part, this includes not only the case where it is "directly below" the other part, but also the case where there is another part in between.

[0038] In this specification, "top surface" and "bottom surface" are used as relative concepts to facilitate understanding of the technical idea of ​​the present invention. Therefore, "top surface" and "bottom surface" do not refer to any particular direction, position, or component, and are interchangeable.

[0039] For example, the "top surface" may be interpreted as the "bottom surface," and the "bottom surface" may be interpreted as the "top surface." Therefore, the "top surface" may be referred to as "first" and the "bottom surface" as "second," or the "bottom surface" may be referred to as "first" and the "top surface" as "second." However, within a single embodiment, "top surface" and "bottom surface" are not used interchangeably.

[0040] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as ideal or overly formal unless expressly defined herein.

[0041] Furthermore, when a part is described as "containing" a certain component, unless otherwise stated, this does not mean that it excludes other components, but rather that it may further comprise other components.

[0042] The terms used herein are used solely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “includes” or “having” are intended to indicate the presence of features, figures, steps, actions, components, parts, or combinations thereof described in the specification, and do not preclude the possibility of the presence or addition of one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0043] The embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0044] Figure 1 is a schematic diagram showing the overall structure of a magnetic element according to one embodiment of the present invention.

[0045] Referring to Figure 1, a magnetic element capable of generating a zero-field spin-orbit torque according to one embodiment of the present invention will be described.

[0046] As an example of the above embodiment, it includes a fixed ferromagnetic layer, a free ferromagnetic layer, and an insulating layer located between the fixed ferromagnetic layer and the free ferromagnetic layer, A magnetic element capable of generating a zero-field spin-orbit torque may exist, characterized in that the free ferromagnetic layer has a structure comprising an in-plane magnetic anisotropy ferrimagnetic layer, a perpendicular magnetic anisotropy free ferromagnetic layer, and a non-magnetic layer located between the in-plane magnetic anisotropy ferrimagnetic layer and the perpendicular magnetic anisotropy free ferromagnetic layer.

[0047] Referring to the schematic diagram in Figure 1, an insulating layer (Tunnel barrier) is located between the fixed ferromagnetic layer and the free ferromagnetic layer. It can be confirmed that the free layer has a structure in which a non-magnetic layer (Ti) is located between an in-plane magnetic anisotropy ferrimagnetic layer (CoGd) and a perpendicular magnetic anisotropy free ferromagnetic layer (Co).

[0048] In this context, in-plane magnetic anisotropy (IMA) refers to the property that the magnetization direction of a magnetic material is aligned in a preferred direction within the plane (i.e., horizontal direction) of the film or thin film.

[0049] The structural properties and crystal structure of the magnetic layer cause the magnetization to prefer a specific direction within the plane, thereby allowing the magnetization to be stably maintained within the plane even in the absence of an external magnetic field.

[0050] The aforementioned perpendicular magnetic anisotropy (PMA) refers to the property that the magnetization direction of a magnetic material is aligned perpendicular to the plane of the film or thin film (i.e., in the vertical direction).

[0051] The aforementioned characteristics are frequently observed in thin magnetic films, and because the magnetization is aligned perpendicular to the plane, high-density magnetic information storage is possible.

[0052] This invention provides a method for improving the switching energy efficiency of a spin-orbit torque magnetic memory element by using a ferrimagnetic material as the spin current generating material and utilizing the spin current generated in a metamagnetic / nonmagnetic structure to construct the free layer of the spin-orbit torque magnetic memory element that can be switched without an external magnetic field.

[0053] In this case, the ferrimagnetic material exhibits magnetism similar to that of a ferromagnetic material, but it is a material in which two or more sub-lattices aligned in opposite directions exist, and the magnitude of magnetization between these sub-lattices differs, resulting in net magnetization.

[0054] The ferrimagnetic material has the property that although the magnetic moments of the lower lattice, which has two different magnetization directions, are aligned in opposite directions, the overall magnetization does not cancel each other out and maintains a certain level of magnetism.

[0055] In contrast, ferromagnetic materials such as iron (Fe), cobalt (Co), and nickel (Ni) have the characteristic that their magnetic atoms strongly interact with each other, causing the magnetic moments of the atoms to align in the same direction even in the absence of an external magnetic field, thus differing from the aforementioned ferrimagnetic materials.

[0056] In the above embodiment of the present invention, the in-plane magnetic anisotropy ferrimagnetic layer is made of a material in which the magnetization directions of two lower lattices of different sizes are aligned in antiequilibrium. By adjusting the composition and temperature of the ferrimagnetic material, the coercivity and saturation magnetization value can be adjusted, thereby solving the problems of the prior art described above and maximizing the switching energy efficiency of the spin-orbit torque magnetic memory.

[0057] On the other hand, non-magnetic materials such as copper (Cu), gold (Au), and silver (Ag) are materials in which the magnetic moments of magnetic materials are randomly aligned and are not magnetized by an external magnetic field.

[0058] Such materials have no remanent magnetization when the external magnetic field is removed, and possess very weak or no magnetic properties.

[0059] As described above, the free ferromagnetic layer includes a triple-layer structure of an in-plane magnetic anisotropy ferrimagnetic layer / non-magnetic layer / perpendicular magnetic anisotropy free ferromagnetic layer. In this case, applying a current in the in-plane direction generates a spin current in the in-plane magnetic anisotropy ferrimagnetic / non-magnetic layer structure. This spin current generates a spin torque with an in-plane component and a component perpendicular to the plane, and this spin torque allows the magnetization of the upper perpendicular magnetic anisotropy ferromagnetic layer to be switched without an external magnetic field.

[0060] In the case of the magnetic element according to the above embodiment, the switching efficiency may change depending on the composition of the ferrimagnetic material constituting the ferrimagnetic layer. Basically, the switching efficiency can be improved by ensuring that the ferrimagnetic material has a composition that falls within the range near the magnetization compensation point.

[0061] As mentioned above, ferrimagnetic materials have two or more sub-lattices, each of which has magnetization aligned in opposite directions.

[0062] The magnetization compensation point refers to the point where the magnetization magnitudes of the two sub-lattices are the same and the total magnetization becomes zero.

[0063] Therefore, in the case of a ferromagnetic material with a single magnetization direction where all magnetic atoms in the material attempt to have magnetization in the same direction, there are no two sub-lattices with magnetizations aligned in opposite directions to each other, so the situation where the magnetizations cancel each other out does not occur, and thus the magnetization compensation point does not exist.

[0064] At the magnetization compensation point, it has the smallest saturation magnetization value (M s ) and the largest coercive force (B c ).

[0065] The saturation magnetization value (M s , Saturation Magnetization) means the maximum magnetization value at which the magnetic material can no longer be magnetized.

[0066] That is, it is the magnetization state when an external magnetic field (or current) is applied strongly enough for all magnetic moments in the magnetic material to be aligned in the same direction.

[0067] The coercive force (B c , Coercive Field) means the strength of the external magnetic field required to reverse the magnetization of the magnetic material.

[0068] As an example of the above embodiment, there may be a magnetic element capable of non-magnetic field spin-orbit torque, wherein the in-plane magnetic anisotropy ferrimagnetic layer is characterized in that the value of the in-plane magnetic moment (M s ) is 500 emu / cc or less.

[0069] When the value of the in-plane magnetic moment (M s ) is 50 emu / cc or less, the composition of the ferrimagnetic material corresponds to the range near the magnetization compensation point, Hereinafter, through experimental examples, it can be confirmed that the switching energy efficiency is the highest within the above range.

[0070] More preferably, the in-plane magnetic anisotropy ferrimagnetic layer has an in-plane magnetic moment (M s A magnetic element capable of zero-field spin-orbit torque may exist, characterized by a value of 330 emu / cc or less.

[0071] Most preferably, the in-plane magnetic anisotropy ferrimagnetic layer has an in-plane magnetic moment (M s A magnetic element capable of generating zero-field spin-orbit torque may exist, characterized by a value of 100 emu / cc or less.

[0072] As an example of the above embodiment, there may be a magnetic element capable of generating zero-field spin-orbit torque, characterized in that the in-plane magnetic anisotropy ferrimagnetic layer has a thickness range of 2 to 20 nm.

[0073] When the thickness of the in-plane magnetic anisotropy ferrimagnetic layer is less than 2 nm, there is a problem in that the properties of the ferrimagnetic material are lost or it is difficult to control the desired composition. Conversely, when the thickness of the in-plane magnetic anisotropy ferrimagnetic layer exceeds 20 nm, a high current application is required to obtain the switching current density, which presents a problem in that the effect of increasing switching efficiency is reduced.

[0074] As an example of the above embodiment, there may be a magnetic element capable of generating a zero-field spin-orbit torque, characterized in that the material constituting the in-plane magnetic anisotropy ferrimagnetic layer is represented by the following chemical formula 1.

[0075] [Chemical formula 1] Co x Gd y

[0076] In the aforementioned chemical formula 1, x and y represent the composition ratios of Co and Gd, respectively, and the sum of the x and y values ​​is 100.

[0077] In this case, it is preferable that x in the chemical formula 1 is a number in the range of 60 to 90. More preferably, x may be a number in the range of 60 to 85. Most preferably, x may be a number in the range of 75 to 80.

[0078] The following experimental examples demonstrate the switching and energy efficiency depending on the composition range of Co.

[0079] In the above embodiment, Figure 1 and others disclose Ti as the non-magnetic layer, but the invention is not limited to this, and there may be magnetic elements capable of generating zero-field spin orbit torque, characterized in that the non-magnetic layer includes one or more selected from the group consisting of Pt, Ta, W, Ti, and alloys of combinations thereof.

[0080] As an example of the above embodiment, there may be a magnetic element capable of zero-field spin-orbit torque, characterized in that the interfacial spin current between the in-plane magnetic anisotropy ferrimagnetic layer and the non-magnetic layer applies torque to the perpendicular magnetic anisotropy free ferromagnetic layer, thereby switching the magnetization direction of the perpendicular magnetic anisotropy free ferromagnetic layer.

[0081] The following describes a method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque according to the present invention and other embodiments.

[0082] The aforementioned method for manufacturing a magnetic element capable of generating zero-magnetic-field spin-orbit torque belongs to a different category of inventions that share the same technical concept as the magnetic element capable of generating zero-magnetic-field spin-orbit torque described earlier. It is hereby stated that the above-mentioned content can be directly applied to the magnetic element capable of generating zero-magnetic-field spin-orbit torque.

[0083] As an example of the above embodiment, the step includes forming a fixed ferromagnetic layer, forming an insulating layer on the fixed ferromagnetic layer, and forming a free ferromagnetic layer on the insulating layer, The step of forming the free ferromagnetic layer is, A method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque may exist, characterized by comprising the steps of: forming a perpendicular magnetic anisotropy free ferromagnetic layer; forming a non-magnetic layer on the perpendicular magnetic anisotropy free ferromagnetic layer; and forming an in-plane magnetic anisotropy ferrimagnetic layer on the non-magnetic layer.

[0084] As an example of the above embodiment, the step of forming the in-plane magnetic anisotropy ferrimagnetic layer is to determine the in-plane magnetic moment (M) of the in-plane magnetic anisotropy ferrimagnetic layer. s A method for manufacturing magnetic elements that enables zero-field spin-orbit torque may exist, characterized by ensuring that the value is 500 emu / cc or less.

[0085] The in-plane magnetic moment (M s If the value is 50 emu / cc or less, the composition of the ferrimagnetic material falls within the range near the magnetization compensation point. The following experimental examples confirm that the switching energy efficiency is highest within the aforementioned range.

[0086] More preferably, the step of forming the in-plane magnetic anisotropy ferrimagnetic layer is to determine the in-plane magnetic moment (M) of the in-plane magnetic anisotropy ferrimagnetic layer. s A method for manufacturing magnetic elements that enables zero-field spin-orbit torque may exist, characterized by ensuring that the value is 330 emu / cc or less.

[0087] Most preferably, the step of forming the in-plane magnetic anisotropy ferrimagnetic layer is to determine the in-plane magnetic moment (M) of the in-plane magnetic anisotropy ferrimagnetic layer. s A method for manufacturing magnetic elements that enables zero-field spin-orbit torque may exist, characterized by ensuring that the value is 100 emu / cc or less.

[0088] As an example of the above embodiment, there is a method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that the step of forming the in-plane magnetic anisotropy ferrimagnetic layer is such that the in-plane magnetic anisotropy ferrimagnetic layer has a thickness range of 2 to 20 nm.

[0089] When the thickness of the in-plane magnetic anisotropy ferrimagnetic layer is less than 2 nm, there is a problem in that the ferrimagnetic properties are lost or it is difficult to control the desired composition. Conversely, when the thickness of the in-plane magnetic anisotropy ferrimagnetic layer exceeds 20 nm, a high current application is required to obtain the switching current density, which presents a problem as it reduces the effect of increasing switching efficiency.

[0090] As an example of the above embodiment, there is a method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that the step of forming the in-plane magnetic anisotropy ferrimagnetic layer is such that the in-plane magnetic anisotropy ferrimagnetic layer is composed of a substance represented by the following chemical formula 1.

[0091] [Chemical formula 1] Co x Gd y

[0092] In the aforementioned chemical formula 1, x and y represent the composition ratios of Co and Gd, respectively, and the sum of the x and y values ​​is 100.

[0093] In this case, it is preferable that x in the chemical formula 1 is a number in the range of 60 to 90. More preferably, x may be a number in the range of 60 to 85. Most preferably, x may be a number in the range of 75 to 80.

[0094] The following experimental examples demonstrate the switching and energy efficiency depending on the composition range of Co.

[0095] As an example of the above embodiment, there is a method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque, characterized in that the step of forming a free ferromagnetic layer on the insulating layer is carried out by one or more methods selected from the group consisting of sputtering, molecular beam epitaxy (MBE), atomic layer deposition (ALD), physical vapor deposition (PVD), and chemical vapor deposition (CVD).

[0096] Comparative manufacturing example 1. Formation of a free ferromagnetic layer using a ferromagnetic layer (Co 100 ) Ta(2nm) / Pt(2nm) / Co(1.2nm) / Ti(2nm) / Co 100 A ferrimagnetic substrate ferromagnetic electrode multilayer film composed of (10nm) / Ta(3nm) is sequentially deposited using a sputtering method.

[0097] Manufacturing Example 1. Free ferromagnetic layer (Co) of a ferrimagnetic substrate according to one embodiment of the present invention 90 Gd 10 ) The free ferromagnetic layer of the magnetic element having the structure shown in Figure 1 is fabricated through the following process.

[0098] Ta(2nm) / Pt(2nm) / Co(1.2nm) / Ti(2nm) / Co 90 Gd 10 A ferrimagnetic substrate ferromagnetic electrode multilayer film composed of (10nm) / Ta(3nm) is sequentially deposited using a sputtering method.

[0099] In the aforementioned free ferromagnetic layer, Co can be utilized as a free magnetic layer in the magnetic tunnel junction, and the magnetization direction of Co can be switched by the spin-orbit torque generated in Ti / CoGd.

[0100] Manufacturing Example 2. Free ferromagnetic layer (Co) of a ferrimagnetic substrate according to one embodiment of the present invention 85 Gd 15 ) The free ferromagnetic layer of the magnetic element having the structure shown in Figure 1 is fabricated through the following process.

[0101] Ta(2nm) / Pt(2nm) / Co(1.2nm) / Ti(2nm) / Co 85 Gd 15 A ferrimagnetic substrate ferromagnetic electrode multilayer film composed of (10nm) / Ta(3nm) is sequentially deposited using a sputtering method.

[0102] Manufacturing Example 3. Free ferromagnetic layer (Co) of a ferrimagnetic substrate according to one embodiment of the present invention 80 Gd 20 ) The free ferromagnetic layer of the magnetic element having the structure shown in Figure 1 is fabricated through the following process.

[0103] Ta(2nm) / Pt(2nm) / Co(1.2nm) / Ti(2nm) / Co 80 Gd 20 A ferrimagnetic substrate ferromagnetic electrode multilayer film composed of (10nm) / Ta(3nm) is sequentially deposited using a sputtering method.

[0104] Manufacturing Example 4. Free ferromagnetic layer (Co) of a ferrimagnetic substrate according to one embodiment of the present invention 75 Gd 25 ) The free ferromagnetic layer of the magnetic element having the structure shown in Figure 1 is fabricated through the following process.

[0105] Ta(2nm) / Pt(2nm) / Co(1.2nm) / Ti(2nm) / Co 75 Gd 25 A ferrimagnetic substrate ferromagnetic electrode multilayer film composed of (10nm) / Ta(3nm) is sequentially deposited using a sputtering method.

[0106] Manufacturing Example 5. Free ferromagnetic layer (Co) of a ferrimagnetic substrate according to one embodiment of the present invention 70 Gd 30 ) The free ferromagnetic layer of the magnetic element having the structure shown in Figure 1 is fabricated through the following process.

[0107] Ta(2nm) / Pt(2nm) / Co(1.2nm) / Ti(2nm) / Co70 Gd 30 A ferrimagnetic substrate ferromagnetic electrode multilayer film composed of (10nm) / Ta(3nm) is sequentially deposited using a sputtering method.

[0108] Manufacturing Example 6. Free ferromagnetic layer (Co) of a ferrimagnetic substrate according to one embodiment of the present invention 60 Gd 40 ) The free ferromagnetic layer of the magnetic element having the structure shown in Figure 1 is fabricated through the following process.

[0109] Ta(2nm) / Pt(2nm) / Co(1.2nm) / Ti(2nm) / Co 60 Gd 40 A ferrimagnetic substrate ferromagnetic electrode multilayer film composed of (10nm) / Ta(3nm) is sequentially deposited using a sputtering method.

[0110] Experimental Example 1. Confirmation of magnetization compensation point of ferromagnetic electrode on ferrimagnetic substrate. Experimental Example 1 will be explained with reference to Figures 2 and 3.

[0111] Figure 2 is a graph showing the magnetic hysteresis curves of the in-plane magnetic anisotropic ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention, depending on the composition.

[0112] Referring to Figure 2, the in-plane magnetic history curve of the deposited thin film was measured to determine the saturation magnetization value (M) of the CoGd thin film depending on the Co composition. s ) and coercivity value (B c ) can be confirmed.

[0113] Figure 3 is a graph showing the in-plane magnetic moment and coercivity of the in-plane magnetic anisotropic ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention, depending on the composition.

[0114] As mentioned above, ferrimagnetic materials are materials in which the magnetization directions of two lower lattices of different sizes are aligned in antiequilibrium. Therefore, they have the smallest saturation magnetization value and the largest coercivity at the magnetization compensation point. Referring to Figure 3, this means that the magnetization compensation point of the CoGd thin film is Co 75 Gd 15 and Co 85 Gd 15 It can be confirmed that it is located between the compositions.

[0115] Table 1 below summarizes the values ​​in Figure 3.

[0116] [Table 1]

[0117] Experimental Example 2. Measurement of Switching and Energy Efficiency of Magnetic Elements The experimental example 2 will be explained with reference to Figures 4 to 10.

[0118] Figure 4 is a schematic diagram illustrating the structure of a magnetic element according to one embodiment of the present invention and the measurement of its spin-orbit torque switching characteristics.

[0119] To evaluate the spin-orbit torque switching characteristics of a magnetic element according to one embodiment of the present invention, a Holbar element with a current line of 5 μm and a voltage line of 3 μm was manufactured as shown in Figure 4.

[0120] Figure 5 shows a magnetic element (Co) according to a comparative example of the present invention. 100 This graph shows the spin-orbit torque switching behavior of Gd0).

[0121] Figure 6 shows a magnetic element (Co) according to one embodiment of the present invention. 60 Gd 40 This graph shows the spin-orbit torque switching behavior of ).

[0122] Figure 7 is a graph showing the switching current density based on the composition of the in-plane magnetic anisotropy ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention.

[0123] In Figures 5 to 7, first, an in-plane current is applied while an external magnetic field is applied to determine the Hall resistance (R) due to the spin-orbit torque. H We measured the changes and confirmed spin-orbit torque switching.

[0124] In Figures 5 and 6, the switching behavior was measured by applying an in-plane external magnetic field (+30mT) to each element composition and changing the magnitude of the current from (+) to (-) and from (-) to (+). At this time, the switching current is R H This represents the current at which the value equals 0. The switching critical current density is calculated by dividing the switching critical current into 5 μm (current line width) × 20 nm (total element thickness).

[0125] Figures 5 and 6 above show the results for samples with 100% and 60% Co, respectively. Figure 7 shows the in-plane external magnetic field B depending on the Co composition. x This figure illustrates the switching critical current density when +30mT is applied. By referring to this, it can be confirmed that the switching critical current density decreases as the Co composition decreases.

[0126] Furthermore, by applying an in-plane current in a magnetic-free state (without applying an external magnetic field) and measuring the change in Hall resistance due to spin-orbit torque, we demonstrate that magnetic-free switching is possible.

[0127] Figure 8 shows a magnetic element (Co) according to a comparative example of the present invention. 100 This graph shows the magnetic field-free spin-orbit torque switching behavior of Gd0).

[0128] Figure 9 shows a magnetic element (Co) according to one embodiment of the present invention. 70 Gd 30 This graph shows the magnetic field-free spin-orbit torque switching behavior of ).

[0129] Figure 10 is a graph showing the zero-field switching current density based on the composition of the in-plane magnetic anisotropy ferrimagnetic layer (CoGd) of a magnetic element according to one embodiment of the present invention.

[0130] In Figures 8 and 9, the magnetization direction is the +z (-z) direction (R H With the parameters initialized to (=1, -1), the critical current is increased in increments of 0.5mA to the Hall resistance (R H The switch is completed when the value reaches the -z (+z) state.

[0131] At this time, the switching critical current is R H This represents the current at which the value equals 0. The switching critical current density is calculated by dividing the switching critical current into 5 μm (current line width) × 20 nm (total element thickness).

[0132] Figure 10 illustrates the switching critical current density for zero-magnetic-field switching with respect to Co composition. Referring to this, it can be confirmed that the switching critical current density is smallest near the magnetization compensation point, and that the switching critical current density increases as the Co composition increases or decreases (moving away from the magnetization compensation point).

[0133] At this time, the current density required for magnetization reversal of the magnetic element according to the embodiment of the present invention is 6.5 × 10 6 A / cm 2 That is the case.

[0134] The aforementioned value is 2.0 × 10⁻¹⁰, which is the zero-magnetic-field spin-orbit torque switching current density in a ferromagnetic (Co100%) / non-magnetic structure. 7 A / cm 2 This is an effect that is reduced by more than 300%, This technology can be applied to spin-orbit torque magnetic memory, thereby increasing the energy efficiency of the spin-orbit torque magnetic memory.

[0135] From the above results, it can be confirmed that in samples containing CoGd with a composition corresponding to the range near the magnetization compensation point, the magnitude of the spin current and spin orbit torque increases, and as a result, the switching efficiency increases.

[0136] Experimental Example 3. Quantitative Measurement of Spin Current Based on the Composition of Ferrimagnetic Materials To quantitatively analyze the spin current generated in metamagnets, an in-plane magnetic field (B) is used. x The abnormal Hall effect of the element was measured by applying ( ).

[0137] The above experimental example 3 will be explained with reference to Figures 11 to 15.

[0138] Figure 11 shows a magnetic element (Co) according to one embodiment of the present invention. 70 Gd 30 This graph shows the anomalous Hall effect movement when there is an external magnetic field in the in-plane direction.

[0139] Figure 12 shows a magnetic element (Co) according to one embodiment of the present invention. 70 Gd 30 This graph shows the anomalous Hall effect movement when there is no external magnetic field in the in-plane direction.

[0140] Figures 11 and 12 above show a metamagnetic material (Co 70 Gd 30 With a sample having ), the measurement current is ±5mA and B x The measurements were taken under the conditions that the currents were 200mT and 0mT, and the measurement curves for the anomalous Hall effect measured at +5mA and the anomalous Hall effect measured at -5mA are shifted in opposite directions. The degree of translation described above is ΔB eff From this, the in-plane spin current (y-spin) and the spin current perpendicular to the plane (z-spin) can be extracted and quantified.

[0141] Figure 13 shows a magnetic element (Co) according to one embodiment of the present invention. 70 Gd 30 This is a graph showing the spin-orbit torque efficiency of ).

[0142] More specifically, FIG. 13 shows the measured ΔB eff as a function of Bx, where when B x = 0, the spin - orbit torque due to z - spin is the main cause, and the magnitude of z - spin can be obtained from ΔB eff .

[0143] Also, as B x increases, ΔB eff gradually increases and saturates when B x = 300 mT or more. The spin - orbit torque generated by y - spin can be quantified from the saturated ΔB eff .

[0144] FIG. 14 is a graph showing the y - spin efficiency according to the composition of the in - plane magnetic anisotropy ferrimagnetic layer (CoGd) of a magnetic element according to an embodiment of the present invention.

[0145] More specifically, FIG. 14 shows the spin - orbit torque efficiency (χ = ΔB eff - B x relationship) generated by y - spin by repeating the above experiment according to the CoGd composition. It can be confirmed that the spin - orbit torque efficiency increases as the Co composition decreases, which is consistent with the switching current density tendency examined in Experimental Example 2. eff / J (measured current density).

[0146] FIG. 15 is a graph showing the z - spin efficiency according to the composition of the in - plane magnetic anisotropy ferrimagnetic layer (CoGd) of a magnetic element according to an embodiment of the present invention.

[0147] More specifically, FIG. 15 shows the z - spin efficiency according to the CoGd composition, and it can be confirmed that χ is maximized when the Co composition is close to 80%.

[0148] This means that the zero-magnetic-field condition examined in Experimental Example 2 is consistent with the spin-orbit torque switching current density trend, and that the switching energy efficiency is particularly excellent at the CoGd magnetization compensation point.

[0149] The foregoing description of the present invention is illustrative, and a person with ordinary skill in the art to which the invention pertains will understand that the invention can be easily modified into other specific forms without altering the technical idea or essential features. Therefore, the embodiments described above should be understood to be illustrative and not limiting in all respects. For example, each component described as a single type can be implemented in a distributed manner, and similarly, components described as distributed can be implemented in a combined manner.

[0150] The scope of the present invention is defined by the claims described below, and all modifications or alterations derived from the meaning and scope of the claims and the concept of equivalents thereof are included within the scope of the present invention.

Claims

1. It includes a fixed ferromagnetic layer, a free ferromagnetic layer, and an insulating layer located between the fixed ferromagnetic layer and the free ferromagnetic layer, The aforementioned free ferromagnetic layer is The structure includes an in-plane magnetic anisotropy ferrimagnetic layer, a perpendicular magnetic anisotropy free ferromagnetic layer, and a non-magnetic layer located between the in-plane magnetic anisotropy ferrimagnetic layer and the perpendicular magnetic anisotropy free ferromagnetic layer. A magnetic element capable of generating spin-orbit torque without a magnetic field, characterized by the following features.

2. The in-plane magnetic anisotropy ferrimagnetic layer has an in-plane magnetic moment (M ｓ The value is 500 emu / cc or less. A magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 1.

3. The in-plane magnetic anisotropy ferrimagnetic layer has a thickness range of 2 to 20 nm. A magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 1.

4. The material constituting the in-plane magnetic anisotropy ferrimagnetic layer is given by the following chemical formula 1: [Chemical formula 1] Co ｘ Gd ｙ (In the above chemical formula 1, x and y represent the composition ratios of Co and Gd, respectively, and the sum of the x and y values ​​is 100.) It is represented A magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 1.

5. The aforementioned x is a number between 60 and 90. A magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 4.

6. The non-magnetic layer includes one or more selected from the group consisting of Pt, Ta, W, Ti, and alloys of these materials. A magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 1.

7. The interfacial spin current between the in-plane magnetic anisotropy ferrimagnetic layer and the non-magnetic layer applies torque to the perpendicular magnetic anisotropy free ferromagnetic layer, thereby switching the magnetization direction of the perpendicular magnetic anisotropy free ferromagnetic layer. A magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 1.

8. The steps include forming a fixed ferromagnetic layer, The steps include forming an insulating layer on the fixed ferromagnetic layer, The step includes forming a free ferromagnetic layer on the insulating layer, The step of forming the free ferromagnetic layer is, The steps include forming a perpendicular magnetic anisotropy free ferromagnetic layer, The steps include forming a non-magnetic layer on the perpendicular magnetic anisotropy free ferromagnetic layer, The step includes forming an in-plane magnetic anisotropy ferrimagnetic layer on the non-magnetic layer. A method for manufacturing a magnetic element that enables magnetic field-free spin-orbit torque, characterized by the following features.

9. The step of forming the in-plane magnetic anisotropy ferrimagnetic layer is, The in-plane magnetic moment (M) of the in-plane magnetic anisotropy ferrimagnetic layer ｓ ) Ensure the value is 500 emu / cc or less. A method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 8.

10. The step of forming the in-plane magnetic anisotropy ferrimagnetic layer is, The in-plane magnetic anisotropy ferrimagnetic layer is made to have a thickness range of 2 to 20 nm. A method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 8.

11. The step of forming the in-plane magnetic anisotropy ferrimagnetic layer is, The in-plane magnetic anisotropy ferrimagnetic layer is given by the following chemical formula 1: [Chemical formula 1] Co ｘ Gd ｙ (In the above chemical formula 1, x and y represent the composition ratios of Co and Gd, respectively, and the sum of the x and y values ​​is 100.) It is made to consist of the substance represented by A method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 8.

12. The aforementioned x is a number between 60 and 90. A method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 11.

13. The step of forming a free ferromagnetic layer on the insulating layer is, The process is carried out by one or more methods selected from the group consisting of sputtering, molecular beam epitaxy (MBE), atomic layer deposition (ALD), physical vapor deposition (PVD), and chemical vapor deposition (CVD). A method for manufacturing a magnetic element capable of generating a magnetic field-free spin orbit torque as described in claim 8.

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