Magnetic sensor

Abstract

To provide a magnetic sensor that can improve heat resistance and reduce power consumption for magnetization reversal of a ferromagnetic material.SOLUTION: A magnetic sensor according to an embodiment includes a detection layer 901 including YPtBi, a non-magnetic half-Heusler alloy topological semimetal having a Dirac-type surface state and a spin Hall angle greater than 1, and a ferromagnet 902 in contact with the detection layer and having a magnetization oriented in the in-plane direction of a first surface in contact with the detection layer.SELECTED DRAWING: Figure 22

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE The present invention relates to a spin injection source, a magnetic memory, a spin Hall oscillator, a computer, and a magnetic sensor using a topological material. [Background technology]

[0002] Ferromagnetic materials have a magnetoresistance effect, in which the resistance value changes depending on the direction of magnetization. For this reason, ferromagnetic materials are attracting attention for their application to magnetic memories that record information by utilizing the direction of magnetization of ferromagnetic materials. In addition, domain wall-driven magnetic memories that utilize the domain wall motion of ferromagnetic materials are attracting attention as a large-capacity memory application that exceeds NAND flash memory. Furthermore, the magnetization of ferromagnetic materials can precess at frequencies of several GHz or more. For this reason, ferromagnetic materials are expected to be applied to spin Hall oscillators and to computers, including neuromorphic computers, that use spin Hall oscillators.

[0003] One of the fundamental technologies for these devices is the technology to control the magnetization direction of ferromagnetic materials. The mainstream method for controlling magnetization is to use spin current, which is the flow of spin angular momentum of electrons. Methods for generating spin current are broadly divided into two categories.

[0004] The first method is to pass a current through a ferromagnetic material and generate a spin-polarized current by the spin filtering effect of the ferromagnetic material. With this method, the magnetization direction of the ferromagnetic material can be controlled by passing this spin-polarized current through the ferromagnetic material to be controlled. This method is called the spin transfer torque (STT) method. As an application example of the STT method, an example of the cell structure of an STT magnetic memory (STT-MRAM: Magnetoresistive Random Access Memory) is shown in Figure 1. The STT magnetic memory has a structure in which a nonmagnetic insulator functioning as a tunnel barrier layer is provided between a ferromagnetic material (free magnetization layer) having the magnetization to be controlled and a ferromagnetic material (fixed magnetization layer) for generating a spin current. By passing a current perpendicular to the film surface of the ferromagnetic material, a spin current is generated in a direction parallel to the current. In this case, the efficiency of generating the spin current is determined by the spin polarization P of the ferromagnetic material used in the fixed magnetization layer. However, the spin polarization P is generally small, ranging from 0.5 to 0.8, and in principle cannot exceed 1. For this reason, STT magnetic memories require a large current for magnetization control. Magnetization control using a large current has been one of the causes of device degradation. The problem of a large current being required for magnetization control is inherent to the STT method, and is a common problem for all devices that use the STT method.

[0005] To solve this problem, a second method that utilizes the phenomenon of the spin Hall effect (SHE) is attracting attention. SHE is a phenomenon in which a spin current is generated perpendicular to the electric current when electric current is injected into a nonmagnetic material. Heavy metals and topological insulators, which have strong spin-orbit interactions, are known as materials with strong SHE. These materials can be candidates for spin injection source materials. The method that utilizes SHE is called the spin orbit torque (SOT) method. As an application example of the SOT method, an example of the cell structure of an SOT magnetic memory (SOT-MRAM) is shown in Figure 2. In addition to the same layered structure as the STT method, the SOT method has a spin injection source (spin Hall layer) that contacts the magnetization free layer. In the SOT method, the directions of the electric current and the spin current are perpendicular to each other. Therefore, the effective spin current generation efficiency is a function of the spin Hall angle, which represents the strength of the SHE, and the length L of the magnetization free layer. FM and the thickness of the spin Hall layer t SH Compared to L FM / t SH In this way, the SOT method can increase the efficiency of spin current generation not only by the spin Hall material but also by devising the structure. Furthermore, the spin Hall angle and the ratio L FM / t SH Since both can exceed 1, it is easy to reduce the amount of current required for magnetization control.

[0006] From the viewpoint of spin current generation efficiency, it is desirable for the material of the spin Hall layer to have a large spin Hall angle. On the other hand, since the spin Hall layer is in contact with the magnetization free layer, part of the current injected into the spin Hall layer is diverted to the magnetization free layer. Therefore, it is desirable for the spin Hall material to have an electrical conductivity equal to or higher than that of the ferromagnetic material of the magnetization free layer. Due to the magnitude of the magnetoresistance effect, ferromagnetic materials such as CoFe alloys are used for the material of the magnetization free layer, so the spin Hall material is generally 10 5 It is preferable that the electrical conductivity is S / m or higher.

[0007] 10 5Heavy metals such as Pt, Ta, and W have been studied as spin Hall materials with high electrical conductivity exceeding S / m. However, as shown in Non-Patent Documents 1 to 3, the spin Hall angle of heavy metals is small, at the 0.1 level, so the effect of reducing the magnetization control current amount is limited. On the other hand, topological insulators such as Bi2Se3 and Bi2Te3 are known as materials with giant spin Hall angles of 1 or more. The spin Hall angles of these materials are characterized by being caused by strong anti-damping torque resulting from Dirac-type surface states. As shown in Non-Patent Documents 4 to 6, these materials have electrical conductivities of 10 3 ~10 4 However, a spin Hall angle exceeding 1 is promising in terms of the efficiency of generating spin current. 5 A BiSb alloy has been developed, which is a type of topological insulator that can achieve both high electrical conductivity exceeding S / m and a giant spin Hall angle exceeding 1. As shown in Patent Document 1, by using a BiSb alloy as the spin Hall material, it is possible to reduce the amount of magnetization control current by one order of magnitude or more compared to the STT method.

[0008] Topological insulators have a spin Hall angle exceeding 1 due to the Dirac-type surface state. This makes it possible to realize a higher spin current generation efficiency than heavy metals. However, existing topological insulators are mainly composed of group V and group VI elements, and therefore have a low melting point, which makes them incompatible with semiconductor manufacturing processes that involve heating at 400°C or higher. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2019 / 054484 [Non-patent literature]

[0010] [Non-Patent Document 1] Physical Review Letters,(USA),2011,106,036601 [Non-Patent Document 2] Science,(USA),2012,Vol.336,p.555-558 [Non-Patent Document 3] Applied Physics Letters,(USA),2012,101,122404 [Non-Patent Document 4] Nature,(USA),2014,Vol.511,p.449 [Non-Patent Document 5] Nature Materials,(USA),2018,Vol.17,p.800-807 [Non-Patent Document 6] Physical Review Letters,(USA),2019,123,207205 Summary of the Invention [Problem to be solved by the invention]

[0011] In one embodiment of the present invention, there is provided a spin injection source that has high heat resistance exceeding 400° C. and is capable of reducing power consumption, as well as a magnetic memory, a spin Hall oscillator, a computer, and a magnetic sensor that utilize the same. [Means for solving the problem]

[0012] The magnetic sensor according to the embodiment includes a detection layer including YPtBi, a nonmagnetic half-Heusler alloy topological semimetal having a Dirac-type surface state and a spin Hall angle exceeding 1, and a ferromagnet in contact with the detection layer and having magnetization oriented in the in-plane direction of a first surface in contact with the detection layer. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing an example of a cell structure of an STT type magnetic memory. [Diagram 2] FIG. 1 is a diagram showing an example of a cell structure of a SOT type magnetic memory. [Diagram 3] FIG. 4 is a diagram showing the film formation temperature dependence of the X-ray diffraction spectrum of YPtBi in the first embodiment. [Figure 4] FIG. 4 is a diagram showing the composition ratio analysis results by fluorescent X-ray analysis of YPtBi in the first embodiment. [Diagram 5] FIG. 2 is a diagram showing the structure of Sample 1 used in spin-Hall angle evaluation in the first embodiment. [Figure 6] FIG. 2 is a diagram showing the structure of a sample 2 used in evaluating the spin Hall angle in the first embodiment. [Figure 7] FIG. 2 is a diagram showing an outline of a measurement circuit used for evaluating a spin Hall angle in the first embodiment, and a coordinate system for measurement. [Figure 8] FIG. 11 is a diagram showing the external magnetic field dependence of the second harmonic component of the Hall resistance in Sample 1 in the first embodiment. [Figure 9] FIG. 11 is a diagram showing the relationship between the anti-damping magnetic field and the current density in the YPtBi layer in Sample 1 in the first embodiment. [Figure 10] 1 is a table showing the spin Hall angles measured using CoTb and the spin Hall angles corrected for the spin dissipation effect of CoTb for various spin Hall materials including YPtBi. [Figure 11] FIG. 4 is a diagram showing the relationship between the Hall resistance and the in-plane application angle of the magnetic field in the first embodiment. [Figure 12] 1 is a table showing the absolute value of the spin Hall angle, electrical conductivity, and normalized power consumption of each spin Hall material. [Figure 13] 13 is a table showing the heat resistance, toxicity, SHE, electrical conductivity, and surface roughness of topological insulators and HHA-TSM. [Figure 14] 2 is a diagram showing an example of a cell structure of a three-terminal SOT magnetic memory according to a first example of the first embodiment; FIG. [Figure 15] 13 shows an example of a cell structure of a two-terminal SOT magnetic memory according to a second example of the first embodiment. [Figure 16] 13 is a diagram showing an example of a cell structure of a magnetic memory according to a second embodiment. FIG. [Figure 17] FIG. 13 is a diagram illustrating an example of a three-terminal spin Hall oscillator according to a first example of a third embodiment. [Figure 18] FIG. 13 is a diagram illustrating an example of a two-terminal spin Hall oscillator according to a second example of the third embodiment. [Figure 19] FIG. 13 is a diagram illustrating an example of a two-terminal spin Hall oscillator according to a third example of the third embodiment. [Figure 20] FIG. 13 is a diagram illustrating an example of a two-terminal spin Hall oscillator according to a fourth example of the third embodiment. [Figure 21] FIG. 13 is a diagram showing an example of an artificial neuron using a spin Hall oscillator according to a fourth embodiment. [Figure 22] 13 is a diagram illustrating an example of a magnetic sensor according to a fifth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment will be described with reference to the drawings. In the following description, components having the same functions and configurations are denoted by the same reference numerals.

[0015] 1. First embodiment Hereinafter, as a first embodiment, a spin injection source and a magnetic memory using YPtBi, which is one of half Heusler alloy topological semi-metals (HHA-TSM), as a spin Hall material will be described.

[0016] 1.1 Characteristics of YPtBi First, the characteristics of YPtBi will be described as an example of HHA-TSM. The material of HHA-TSM is not limited to this. For example, it may be one of the alloys having a topological surface state among the ternary alloys having a half-Heusler structure, which are made of two kinds of transition metals or rare earths and one metal belonging to a typical element, or a mixed crystal of these. More specifically, for example, HHA-TSM may be LuPtSb, LuPdBi, LuPtBi, ScPtBi, YAuPb, LaPtBi, CePtBi, ThPtPb, LaAuPb, etc., or a mixed crystal of these.

[0017] 1.1.1 Heat resistance First, the heat resistance of YPtBi will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram showing the film formation temperature dependence of the X-ray diffraction spectrum of YPtBi. Fig. 4 is a diagram showing the composition ratio analysis result of YPtBi by fluorescent X-ray analysis.

[0018] The examples in Figures 3 and 4 show the results of evaluating the crystal structure and composition ratio of YPtBi using samples in which YPtBi was deposited to a thickness of about 50 nm on a substrate while changing the substrate temperature by co-sputtering. The range of change in substrate temperature was 300 to 800°C. c-Sapphire was used as the substrate. In addition, a YPt target and a Bi target were used for the co-sputtering method.

[0019] First, the crystal structure of YPtBi will be described with reference to FIG.

[0020] As shown in FIG. 3, when focusing on the peak of the (111) plane of YPtBi, the peak due to the (111) plane of YPtBi was confirmed in the substrate temperature range of 300 to 600°C.

[0021] Next, the composition ratio of YPtBi will be described with reference to Fig. 4. In Fig. 4, the vertical axis represents the composition ratio of Bi to Y (yttrium), and the horizontal axis represents the substrate temperature during the deposition of YPtBi.

[0022] As shown in Fig. 4, at substrate temperatures below 600°C, the Bi composition ratio is stable at 1, which is the ideal value for the crystal structure of a half-Heusler alloy. This result coincides with the temperature range in which a peak due to the (111) plane of YPtBi was observed in the X-ray diffraction spectrum shown in Fig. 3.

[0023] These results show that YPtBi can maintain the half-Heusler structure even when heated to 400° C. or higher. Therefore, HHA-TSM can have heat resistance of 400° C. or higher. Furthermore, because YPtBi can be deposited over a wide temperature range by sputtering, HHA-TSM can have high compatibility with mass production processes for semiconductor devices.

[0024] 1.1.2 Electrical conductivity Next, the electrical conductivity of YPtBi will be described. The electrical conductivity was measured by a four-terminal method using samples in which YPtBi was formed to a thickness of about 11 nm on a c-sapphire substrate and a SiO2 / Si substrate. The substrate temperature when the YPtBi film was formed by the simultaneous sputtering method was 600°C. As a result of the measurement by the four-terminal method, the electrical conductivity of YPtBi on the c-sapphire substrate was, for example, 1.17×10 5 The electrical conductivity of YPtBi on a SiO2 / Si substrate is, for example, 1.57×10 5 S / m. Therefore, YPtBi is 10 5 It has high electrical conductivity exceeding S / m.

[0025] 1.1.3 Spin Hall angle Next, the spin Hall angle of YPtBi will be described.

[0026] 1.1.3.1 Sample structure and evaluation method The sample structure and measurement circuit for measuring the spin Hall angle will be described with reference to Figs. 5 to 7. In this embodiment, two types of samples were used. Fig. 5 is a cross-sectional view of sample 1. Fig. 6 is a cross-sectional view of sample 2. Fig. 7 is a diagram showing an outline of the measurement circuit and a coordinate system for measurement.

[0027] First, a description will be given of the structures of Sample 1 and Sample 2 used in measuring the spin Hall angle. Sample 1 and Sample 2 each have a heterojunction between YPtBi and a ferromagnetic material.

[0028] As shown in FIG. 5, sample 1 includes a c-sapphire substrate, YPtBi, Pt, Co, and MgAl2O4. For example, YPtBi having a thickness of about 10 nm is formed on the c-sapphire substrate. For example, Pt having a thickness of about 0.5 nm, Co having a thickness of about 0.5 nm, and Pt having a thickness of about 0.5 nm are alternately laminated on the YPtBi. The Pt / Co / Pt laminate functions as a ferromagnetic material CoPt. CoPt has perpendicular magnetic anisotropy. For example, MgAl2O4 having a thickness of about 2 nm is formed on the top Pt layer. MgAl2O4 functions as a cap layer for preventing oxidation.

[0029] As shown in FIG. 6, sample 2 includes a Si substrate, SiO2, YPtBi, CoTb, and MgAl2O4. SiO2 is formed on the Si substrate. The thickness of SiO2 is arbitrary. YPtBi with a thickness of, for example, about 10 nm is formed on SiO2. CoTb with a thickness of, for example, about 3 nm is formed on YPtBi. CoTb has ferromagnetic properties. CoTb has in-plane magnetic anisotropy. MgAl2O4 with a thickness of, for example, about 2 nm is formed on CoTb.

[0030] The applications of Sample 1 and Sample 2 are described below. Generally, a heterojunction between a spin Hall layer and a ferromagnetic material is used for spin Hall angle measurement. At this time, spin dissipation occurs at the interface between the two layers. The magnitude of spin dissipation strongly depends on the type of ferromagnetic material. CoPt used in Sample 1 is a material with relatively small spin dissipation. Therefore, when using Sample 1, it is possible to evaluate the spin Hall angle without correcting for spin dissipation. The structure of Sample 1 has the advantage that the uncertainty factor of spin dissipation correction is small. On the other hand, when comparing the spin Hall angle between multiple spin Hall materials, it is desirable to use the same ferromagnetic material. For this reason, CoTb, which has a relatively large track record of being used to evaluate the spin Hall angle of various spin Hall materials, was used as the ferromagnetic material for Sample 2.

[0031] Next, we will explain the method for evaluating the spin Hall angle. The second harmonic method was used to evaluate the spin Hall angle. The second harmonic method is a method that uses the second harmonic Hall resistance R generated when an AC current is applied to a sample. H 2ω This is a method to evaluate the spin Hall angle from the external magnetic field dependence of . For example, in the measurement circuit shown in Figure 7, an AC current is applied between terminal -I and terminal +I. Then, H and terminal -V H The second harmonic component of the Hall voltage due to the anomalous Hall effect generated between the external magnetic field H ext is applied parallel to the current.

[0032] The evaluation procedure is as follows: first, to calculate the spin Hall angle, the second harmonic Hall resistance R is calculated by fitting based on Eq. H 2ω From anti-damping-like magnetic field H DL Extract.

[0033]

number

[0034] Here, R AHEis the anomalous Hall resistance, H K eff is the effective perpendicular anisotropic magnetic field, R PHE is the planar Hall resistance, H FL+OF is the sum of the field-like magnetic field and the Oersted magnetic field, C out ONE is the normal Nernst effect caused by the temperature gradient perpendicular to the surface, R out ANE+SSE are the anomalous Nernst effect and spin Seebeck effect caused by the perpendicular temperature gradient. In formula 1, when the material has perpendicular magnetic anisotropy, H K eff >0, H if it has in-plane magnetic anisotropy K eff <0. In addition, in formula 1, H DL , H FL+OF , H K eff , C out ONE , R out ANE+SSE are the fitting parameters.

[0035] Next, the extracted H using Eq. DL is converted to the spin Hall angle.

[0036]

number

[0037] where e is the elementary charge, M S is the saturation magnetization, t FM is the thickness of the ferromagnetic material, h is the Planck constant, J NM is the current density in the YPtBi layer. This gives the spin Hall angle θ SH is calculated.

[0038] 1.1.3.2 Specific examples of measurement results of external magnetic field dependence and spin Hall angle Next, referring to FIG. 8 and FIG. 9, the second harmonic Hall resistance R H 2ω and spin Hall angle θ SHA specific example of the measurement results will be described. FIG. 8 is a diagram showing the external magnetic field dependence of the second harmonic component of the Hall resistance in sample 1. Each plot in FIG. 8 shows the measured value, and the solid line shows the fitting result by Equation 1. The amplitude of the applied AC current is between 1.0 and 3.4 mA. The example in FIG. 8 shows the case where the AC current is changed in increments of 0.4 mA. The frequency of the AC current is 259.68 Hz. FIG. 9 is a diagram showing the relationship between the anti-damping magnetic field and the current density in YPtBi in sample 1.

[0039] As shown in Figure 9, the anti-damping-like magnetic field H DL is the current density J of YPtBi NM It is increasing in proportion to H DL / J NM and the saturation magnetization M obtained, for example, by a superconducting quantum interference device. S =632 emu / cm 3 Substituting into Equation 2, the spin Hall angle θ SH The spin Hall angle θ of YPtBi exceeds 1. SH It has been demonstrated that

[0040] Similarly, the spin Hall angle was measured for sample 2 using CoTb by using the second harmonic method. DL / J NM =5.98 Oe cm 2 / MA, saturation magnetization M S =456 emu / cm 3 The spin Hall angle θ SH In general, the spin Hall angle θ SH When measuring the spin Hall angle θ , the spin dissipation effect of CoTb makes it larger than that measured in other ferromagnetic materials. SH It is known that the ionization rate is underestimated by a factor of 5 to 10. A similar trend was observed for YPtBi.

[0041] 1.1.3.3 Comparison of spin Hall angle with other spin Hall materials Next, referring to FIG. 10, the spin Hall angle θ SH The results of comparing YPtBi with other spin Hall materials are explained below. Figure 10 shows the spin Hall angle (θ SH (CoTb)) and the spin Hall angle corrected for the spin dissipation effect of CoTb (intrinsic θ SH In the example of FIG. 10, the θ SH (CoTb) shows the measurement results for sample 2. Intrinsic θ SH shows the measurement results for sample 1. As spin Hall materials to be compared with YPtBi, the heavy metals Ta and Pt, and the topological insulators Bi2Se3, (Bi,Sb)2Te3, and BiSb are shown.

[0042] As shown in Fig. 10, the spin Hall angle θ SH Focusing on (CoTb), the spin Hall angle θ SH (CoTb) is 0.25. The spin Hall angle θ of YPtBi SH (CoTb) is calculated by the spin Hall angle θ of the heavy metals Ta and Pt. SH The spin Hall angle θ of YPtBi is approximately one order of magnitude larger than that of CoTb. SH Comparing (CoTb) with the topological insulators Bi2Se3, (Bi,Sb)2Te3, and BiSb, it has properties that are approximately one order of magnitude lower than those of BiSb, but equivalent to those of Bi2Se3 and (Bi,Sb)2Te3.

[0043] Next, the spin Hall angle (intrinsic θ SH ), the spin Hall angle of YPtBi (intrinsic θ SH ) is 1.3. Therefore, the spin Hall angle θ SH (CoTb) is the spin Hall angle (intrinsic θ SH ) is about one fifth of the spin Hall angle θ SH(CoTb) is the spin Hall angle (intrinsic θ SH ) Therefore, the measurement results for YPtBi show similar trends to those for other spin Hall materials.

[0044] 1.1.4 Magnetic field dependence of Hall resistance Next, referring to FIG. 11, in order to confirm that YPtBi has a Dirac-type surface state, the Hall resistance R H The results of measuring the magnetic field dependence of the Hall resistance R H and the in-plane application angle of the magnetic field φ H 3 is a graph showing the relationship between the Hall resistance R H The substrate for the measurement sample was c-Sapphire. The substrate temperature during YPtBi film formation was 600°C. The vertical axis of the graph in Figure 11 is the Hall resistance R obtained when an in-plane rotating magnetic field was applied to the sample. H The horizontal axis is the in-plane application angle of the magnetic field φ H Here, the in-plane application angle of the magnetic field φ H The direction was parallel to the applied DC current. The measurement temperature was 4 K, and the magnitude of the magnetic field was 7.6 kOe. The black dots in the graph indicate the measured values, and the solid line indicates the fitting curve.

[0045] As shown in Figure 11, the Hall resistance R H The measured value of cosφ H and sinφ H and sin2φ H The Hall resistance R HThe one-fold symmetric component of originates from the normal Hall effect, which occurs when the angle of the applied magnetic field deviates from the in-plane direction. On the other hand, the two-fold symmetric component is a magnetoresistance effect called the planar Hall effect, which is caused by a Dirac-type topological surface state in the nonmagnetic YPtBi. In other words, the existence of the planar Hall effect indicates that the nonmagnetic YPtBi has a Dirac-type surface state. Therefore, it can be said that the giant spin Hall angle in YPtBi is caused by the strong antidamping torque arising from the Dirac-type surface state.

[0046] 1.1.5 Power consumption when reversing the magnetization of a magnetic material Next, the power consumption when reversing the magnetization of the magnetic material provided on the spin Hall material will be described with reference to Fig. 12. Fig. 12 shows the power consumption when the spin Hall angle θ SH 12 is a table showing the absolute value, electrical conductivity, and normalized power consumption of the spin Hall material. The example of FIG. 12 shows a case where a heavy metal or HHA-TSM is used as the type of spin Hall material. More specifically, the example of FIG. 12 shows a case where Ta, Pt, or W with a thickness of 6 nm is used as the heavy metal, and a case where YPtBi with a thickness of 10 nm is used as the HHA-TSM. The normalized power consumption shows a value obtained by normalizing the power consumption when magnetization is reversed in CoFeB (magnetic material) with a thickness of 1.5 nm, with the power consumption when Ta is used set to 1.

[0047] As shown in FIG. 12, YPtBi in HHA-TSM has a larger spin Hall angle θ than the heavy metals Ta, Pt, and W. SH The absolute value of Ta, Pt, W, and YPtBi is 1.0×10 5 The normalized power consumption of Pt and W relative to Ta is 3.6×10 -1 and 1.6×10 -1 In contrast, the normalized power consumption of YPtBi relative to Ta is 3.3×10 -2In other words, when YPtBi is used as the spin Hall material, the power consumption is 3.3% of that when Ta is used. Furthermore, the power consumption when YPtBi is used is about one-fifth of that when W is used, which has the lowest power consumption among heavy metals.

[0048] In this way, the inventors of the present application found that HHA-TSM containing YPtBi can reverse the magnetization of a magnetic material with lower power consumption than heavy metals.

[0049] 1.1.6 Comparison with topological insulators Next, the results of comparing the topological insulator and HHA-TSM will be described with reference to Fig. 13. Fig. 13 is a table showing the heat resistance, toxic substances, SHE, electrical conductivity, and surface roughness of the topological insulator and HHA-TSM. Here, the toxic substances indicate whether or not a toxic material is included as a component of the material.

[0050] As shown in Fig. 13, the heat resistance of topological insulators is approximately 300°C or less, whereas that of HHA-TSM is approximately 600°C. Since the back-end process of semiconductor manufacturing requires materials to have a heat resistance of 400°C or more, HHA-TSM has a higher affinity with the semiconductor manufacturing process than topological insulators.

[0051] For example, materials such as Sb, Se, or Te that can be included in topological insulators are toxic, whereas HHA-TSM can be composed of non-toxic materials such as YPtBi.

[0052] The SHE of topological insulators and HHA-TSM is stronger than that of heavy metals, i.e., the spin Hall angle is larger. Furthermore, the electrical conductivity of topological insulators tends to be relatively low, except for BiSb. In contrast, the electrical conductivity of HHA-TSM is relatively high.

[0053] The HHA-TSM has a smaller surface roughness than a topological insulator, which reduces the surface roughness of the interface of the magnetic material in contact with the HHA-TSM, improving the perpendicular magnetic anisotropy of the magnetic material.

[0054] Thus, the inventors found that HHA-TSM containing YPtBi has high heat resistance of over 400°C, is a material that does not contain toxic substances, and has a relatively small surface roughness. In other words, the inventors found that as a spin Hall material, HHA-TSM has a higher affinity for the manufacturing process of semiconductor devices than topological insulators.

[0055] 1.2 Magnetic memory configuration Next, two examples of magnetic memory configurations using the HHA-TSM as a spin injection source are described. In the following description, one of the source and drain of a transistor is referred to as "one end of the transistor," and the other of the source and drain of the transistor is referred to as "the other end of the transistor."

[0056] 1.2.1 First Example First, a first example will be described. In the first example, an example of a cell structure of a three-terminal SOT magnetic memory will be described with reference to Fig. 14. Fig. 14 is a diagram showing an example of a cell structure of a three-terminal SOT magnetic memory.

[0057] 14, the SOT magnetic memory 100 includes a magnetic memory element 101, a spin injection source 102, a write transistor 103, and a read transistor 104. The magnetic memory element 101 is a memory element having a magnetoresistive effect due to a magnetic tunnel junction (MTJ) (hereinafter, also referred to as an "MTJ element").

[0058] The MTJ element 101 includes a ferromagnetic body 111, an insulator 112, and a ferromagnetic body 113. For example, on the spin injection source 102, the ferromagnetic body 113, the insulator 112, and the ferromagnetic body 111 are stacked in this order.

[0059] The ferromagnetic body 111 has ferromagnetism and has an easy axis of magnetization perpendicular to the film surface. The magnetization direction of the ferromagnetic body 111 is fixed. That is, the ferromagnetic body 111 functions as a magnetization fixed layer. The magnetization direction of the ferromagnetic body 111 does not change due to the spin current injected from the spin injection source 102.

[0060] The insulator 112 is in contact with the ferromagnetic materials 111 and 113 and is provided between the ferromagnetic materials 111 and 113. The insulator 112 is a non-magnetic insulator. The insulator 112 functions as a tunnel barrier layer. MgO is preferably used for the insulator 112. Note that another material such as AlO may be used for the insulator 112. Furthermore, a metal oxide containing at least one of Ga, Al, Mg, Hf, and Zr may be used for the insulator 112.

[0061] The ferromagnetic body 113 has ferromagnetism and has an easy axis of magnetization perpendicular to the film surface. The magnetization direction of the ferromagnetic body 113 is controlled by a spin current injected from the spin injection source 102. That is, the ferromagnetic body 113 functions as a magnetization free layer.

[0062] When the magnetization directions of the ferromagnetic bodies 111 and 113 are parallel, the MTJ element 101 is in a low resistance state. On the other hand, when the magnetization directions of the ferromagnetic bodies 111 and 113 are antiparallel, the MTJ element 101 is in a high / low resistance state. Data is assigned according to the resistance state of the MTJ element 101.

[0063] The ferromagnetic body 111 and the ferromagnetic body 113 each contain at least one of Co, Fe, Ni, Mn, B, Si, Zr, Nb, Ta, Ru, Ir, Pt, Ga, Al, Pd, Tb, and Gd. The ferromagnetic body 111 and the ferromagnetic body 113 may each be a laminated body made up of a plurality of layers. The ferromagnetic body 111 and the ferromagnetic body 113 may have the same configuration or different configurations.

[0064] The spin injection source 102 includes an HHA-TSM. For example, YPtBi is used for the HHA-TSM. A write transistor 103 is connected to one end of the HHA-TSM in a direction parallel to the film surface of the HHA-TSM. The other end of the HHA-TSM facing the one end of the HHA-TSM is grounded (connected to a ground voltage wiring).

[0065] A control signal is input to the gate of the write transistor 103. The write transistor 103 has one end connected to the spin injection source 102 (HHA-TSM) and the other end connected to, for example, a power supply (not shown).

[0066] One end of the read transistor 104 is connected to the ferromagnetic material 111 of the MTJ element 101, and the other end is connected to, for example, a read circuit (not shown).

[0067] For example, in the memory 100, when data is written to the MTJ element 101, the write transistor 103 is turned on and the read transistor 104 is turned off. Then, a current flows from the power supply to the ground through the write transistor 103 in the on state and the spin injection source 102. At this time, a pulsed current (hereinafter, referred to as an "in-plane current") flows in a direction parallel to the surface of the HHA-TSM (spin injection source 102) that contacts the ferromagnetic material 113. When the pulsed in-plane current flows in the HHA-TSM, a spin current is generated in a direction perpendicular to the surface. Then, the spin current is injected from the HHA-TSM to the ferromagnetic material 113 (magnetic free layer). The magnetization reversal of the ferromagnetic material 113 occurs due to the resultant force of the anti-damping torque generated by the spin current and the torque generated by an external magnetic field (in-plane bias magnetic field) applied parallel to the in-plane current, that is, the magnetization direction is controlled, and data is written to the MTJ element 101.

[0068] For example, when reading data from the MTJ element 101, the write transistor 103 is turned off and the read transistor 104 is turned on. A read current flows from a power source to the MTJ element 101 through the on-state read transistor 104. At this time, the data of the MTJ element 101 is read based on the resistance value of the MTJ element 101.

[0069] 1.2.2 Second Example Next, a second example will be described. In the second example, an example of a cell structure of a two-terminal SOT magnetic memory will be described with reference to Fig. 15. Fig. 15 is a diagram showing an example of a cell structure of a two-terminal SOT magnetic memory.

[0070] 15, the SOT magnetic memory 200 includes an MTJ element 201, a spin injection source 202, and a write / read transistor 203. The difference from the first example is that the transistor connected to the MTJ element 201 is eliminated, and the ferromagnetic material 211 is grounded.

[0071] The configuration of the MTJ element 201 is similar to that of the MTJ element 101 of the first example. More specifically, the MTJ element 201 includes a ferromagnetic body 211, an insulator 212, and a ferromagnetic body 213. The ferromagnetic body 211 functions as a magnetization fixed layer, similar to the ferromagnetic body 111. The insulator 212 functions as a tunnel barrier layer, similar to the insulator 112. The ferromagnetic body 213 functions as a magnetization free layer, similar to the ferromagnetic body 113.

[0072] The spin injection source 202 includes an HHA-TSM. The HHA-TSM may be made of, for example, YPtBi.

[0073] A control signal is input to the gate of the write / read transistor 203. The write / read transistor 203 has one end connected to one end of the HHA-TSM (spin injection source 202) and the other end connected to, for example, a power supply (not shown).

[0074] For example, when writing data to the MTJ element 201, the write / read transistor 203 is turned on. Then, a current flows from the power supply to the ground via the write / read transistor 203, the spin injection source 202, the ferromagnetic material 213, the insulator 212, and the ferromagnetic material 211. At this time, a pulsed in-plane current flows through the HHA-TSM (spin injection source 202), so that a spin current is injected from the spin injection source 202 to the ferromagnetic material 213 (magnetic free layer). The magnetization reversal of the ferromagnetic material 213 occurs due to an anti-damping torque generated by the spin current, and data is written. At this time, the spin-polarized current generated from the ferromagnetic material 211 can also assist the magnetization reversal of the ferromagnetic material 213. By assisted magnetization reversal by the spin-polarized current generated from the ferromagnet 211, magnetization reversal can be performed without an external magnetic field (in-plane bias magnetic field) regardless of the orientation relationship between the magnetization easy axis of the ferromagnet 213 and the spin quantization axis of the spin current generated from the spin injection source 202.

[0075] 1.3 Effects of this embodiment The inventors of the present application have demonstrated that the HHA-TSM exhibits a giant spin Hall angle of over 1 due to the Dirac-type surface state and a spin-Hall angle of over 10 5 The inventors have found that HHA-TSM has a high electrical conductivity exceeding 1000 S / m and consumes less power when reversing the magnetization of a magnetic material than heavy metals. The inventors have also found that HHA-TSM has high heat resistance exceeding 400°C. That is, the inventors have found that HHA-TSM has excellent properties as a spin Hall material and has good affinity with semiconductor manufacturing processes. By using HHA-TSM as a spin injection source, the power consumption for reversing the magnetization of a ferromagnetic material can be reduced. Furthermore, by applying HHA-TSM to the spin injection source of an SOT magnetic memory, the write current and write power of the SOT magnetic memory can be reduced.

[0076] 2. Second embodiment Next, a second embodiment will be described. In the second embodiment, a domain wall driving type magnetic memory different from the first embodiment will be described. The following mainly describes the points different from the first embodiment.

[0077] 2.1 Magnetic memory configuration The configuration of the magnetic memory will be described with reference to Fig. 16. Fig. 16 is a diagram showing an example of a cell structure of the magnetic memory.

[0078] 16, the magnetic memory 300 includes a ferromagnetic material 301, a spin injection source 302, a readout unit 303, conductors 304 to 306, a ferromagnetic material 307, and terminals T1 to T4. In the following description, a direction parallel to the film surface of the ferromagnetic material 301 and extending from the conductor 304 to the conductor 306 is referred to as an X-direction. A direction parallel to the film surface of the ferromagnetic material 301 and intersecting with the X-direction is referred to as a Y-direction. A direction perpendicular to the film surface of the ferromagnetic material 301 is referred to as a Z-direction.

[0079] The ferromagnetic body 301 is provided on the spin injection source 302. The ferromagnetic body 301 has ferromagnetism and has an easy axis of magnetization in the Z direction perpendicular to the film surface. The ferromagnetic body 301 functions as a magnetization free layer. The ferromagnetic body 301 includes a plurality of magnetic domains MD separated by a domain wall DW. Each magnetic domain MD functions as a memory element. In the example of FIG. 16, the ferromagnetic body 301 includes four magnetic domains MD1 to MD4. The magnetic domains MD1 to MD4 are arranged in a line in the X direction. The ferromagnetic body 301 includes at least one of Co, Fe, Ni, Mn, B, Si, Zr, Nb, Ta, Ru, Ir, Pt, Ga, Al, Pd, Tb, and Gd. The ferromagnetic body 301 may be a laminated body consisting of a plurality of layers.

[0080] The spin injection source 302 includes an HHA-TSM. The HHA-TSM may be made of, for example, YPtBi.

[0081] The reading unit 303 reads out the magnetization direction of the magnetic domain MD (magnetic domain MD1 in the example of FIG. 16). The reading unit 303 includes a ferromagnetic material 311 and an insulator 312.

[0082] The ferromagnetic body 311 has ferromagnetism and has an easy axis of magnetization oriented in the Z direction perpendicular to the film surface. The magnetization direction of the ferromagnetic body 311 is fixed. That is, the ferromagnetic body 311 functions as a magnetization fixed layer. The magnetization direction of the ferromagnetic body 311 does not change due to the spin current injected from the spin injection source 302. The ferromagnetic body 311 includes at least one of Co, Fe, Ni, Mn, B, Si, Zr, Nb, Ta, Ru, Ir, Pt, Ga, Al, Pd, Tb, and Gd. The ferromagnetic body 311 may be a laminate consisting of multiple layers.

[0083] The insulator 312 contacts one magnetic domain (magnetic domain MD1 in the example of FIG. 16) of the ferromagnetic body 301 and the ferromagnetic body 311, and is provided between the ferromagnetic body 301 and the ferromagnetic body 311. The insulator 312 is a non-magnetic insulator. The insulator 312 functions as a tunnel barrier layer. MgO is preferably used for the insulator 112. Note that another material such as AlO may be used for the insulator 312. Furthermore, the insulator 312 may be a metal oxide containing at least one of Ga, Al, Mg, Hf, and Zr.

[0084] The MTJ element is composed of the ferromagnetic body 311, the insulator 312, and one magnetic domain MD of the ferromagnetic body 301 that is in contact with the insulator 312. That is, the reading section 303 includes the MTJ element.

[0085] The conductors 304 to 306 are provided on the ferromagnetic material 301 along the X direction. The conductors 304 to 306 may be provided on the spin injection source 302, or may be in contact with both the ferromagnetic material 301 and the spin injection source 302. The conductor 304 is provided on the vicinity of an end of the ferromagnetic material 301 in the X direction. The conductor 305 is disposed at a position separated from the conductor 304 in the X direction, with the readout unit 303 in between. In the ferromagnetic material 301, one magnetic domain MD is formed in a region including the ground plane between the conductors 304 and 305. The conductor 306 is provided on the vicinity of an end of the ferromagnetic material 301 opposite to the vicinity of the end of the ferromagnetic material 301 to which the conductor 304 is in contact in the X direction. The conductors 304 to 306 include a conductive material. The conductor 305 may be discarded.

[0086] The ferromagnetic material 307 is disposed in the Z direction, separated from the spin injection source 302 via an insulator (not shown). The conductor 304 and the conductor 305 are disposed above the ferromagnetic material 307 in the Z direction, via the spin injection source 302 and the ferromagnetic material 301. The ferromagnetic material 307 has ferromagnetism and has an easy axis of magnetization in the X direction parallel to the film surface. The magnetization direction of the ferromagnetic material 307 is fixed. The ferromagnetic material 307 applies a bias magnetic field to the ferromagnetic material 301 and the spin injection source 302. The bias magnetic field is used to reverse the magnetization direction of the ferromagnetic material 301 in a write operation. The ferromagnetic material 307 includes at least one of Co, Fe, Ni, Mn, B, Si, Zr, Nb, Ta, Ru, Ir, Pt, Ga, Al, Pd, Tb, and Gd. The ferromagnetic material 307 may be a laminated body consisting of multiple layers.

[0087] The terminal T1 is connected to the conductor 304. The terminal T2 is connected to the conductor 305. The terminal T3 is connected to the readout unit 303 (the ferromagnetic material 311). The terminal T4 is connected to the conductor 306.

[0088] For example, when writing data to magnetic domain MD1, a write current flows between terminals T1 and T2. The write current flows through ferromagnetic material 301 (free magnetization layer) and HHA-TSM (spin injection source 302). A pulsed in-plane current flows through the HHA-TSM, and a spin current is injected into ferromagnetic material 301. An anti-damping torque generated by the spin current causes magnetization reversal of magnetic domain MD1 of ferromagnetic material 301, and data is written.

[0089] For example, when reading data of the magnetic domain MD1, a read current flows between the terminal T3 and the terminal T1 or the terminal T2. Based on the resistance value of the MTJ element of the reading section 303, the magnetization direction (data) of the magnetic domain MD1 is read.

[0090] For example, when moving the magnetic domain MD, a current for driving the magnetic domain wall flows between terminals T1 and T4. When a current flows through the HHA-TSM and the ferromagnetic body 301, the magnetic domain wall DW of the ferromagnetic body 301, i.e., the magnetic domain MD, moves. This magnetic domain wall movement makes it possible to control the magnetization direction of each magnetic domain MD in the ferromagnetic body 301. Using a similar principle, the magnetization direction of each magnetic domain MD in the ferromagnetic body 301 can be read by the readout unit 303.

[0091] 2.2 Effects of this embodiment With the configuration according to this embodiment, the HHA-TSM can be applied to a domain wall driven magnetic memory.

[0092] 3. Third embodiment Next, a third embodiment will be described. In the third embodiment, four examples will be described in which the HHA-TSM is applied to a spin injection source of a spin Hall oscillator. The following will focus on the differences from the first and second embodiments.

[0093] 3.1 First Example First, a first example will be described. In the first example, a three-terminal spin Hall oscillator will be described with reference to Fig. 17. Fig. 17 is a diagram showing an example of a three-terminal spin Hall oscillator.

[0094] As shown in FIG. 17, a three-terminal spin Hall oscillator 400 includes an MTJ element 401, a spin injection source 402, a magnetization driving transistor 403, and a power supply terminal 404 for the MTJ.

[0095] The MTJ element 401 includes a ferromagnetic material 411, an insulator 412, and a ferromagnetic material 413. For example, on the spin injection source 402, the ferromagnetic material 413, the insulator 412, and the ferromagnetic material 411 are stacked in this order.

[0096] The ferromagnetic body 411 has ferromagnetism and has a magnetization hard axis similar to that of the ferromagnetic body 413. The magnetization direction of the ferromagnetic body 411 is fixed. That is, the ferromagnetic body 411 functions as a magnetization fixed layer. The magnetization direction of the ferromagnetic body 411 is not changed by the spin current injected from the spin injection source 402.

[0097] The insulator 412 is in contact with the ferromagnetic materials 411 and 413 and is provided between the ferromagnetic material 411 and the ferromagnetic material 413. The insulator 412 is a non-magnetic insulator. The insulator 412 functions as a tunnel barrier layer. MgO is preferably used for the insulator 412. Note that another material such as AlO may be used for the insulator 412. Furthermore, a metal oxide containing at least one of Ga, Al, Mg, Hf, and Zr may be used for the insulator 412.

[0098] The ferromagnetic material 413 has ferromagnetism and has a hard magnetization axis or an easy magnetization axis parallel to the spin quantization axis of the spin current injected from the spin injection source 402 into the ferromagnetic material 413. The ferromagnetic material 413 functions as a magnetization free layer. The magnetization of the ferromagnetic material 413 may undergo precession due to the spin current injected from the spin injection source 402. In addition, the frequency and amplitude of the precession may be modulated by applying an external magnetic field (in-plane bias magnetic field) parallel to the hard magnetization axis or the easy magnetization axis of the ferromagnetic material 413.

[0099] The ferromagnetic body 411 and the ferromagnetic body 413 each contain at least one of Co, Fe, Ni, Mn, B, Si, Zr, Nb, Ta, Ru, Ir, Pt, Ga, Al, Pd, Tb, and Gd. The ferromagnetic body 411 and the ferromagnetic body 413 may be a laminated body made up of a plurality of layers. The ferromagnetic body 411 and the ferromagnetic body 413 may have the same configuration or different configurations.

[0100] The spin injection source 402 includes an HHA-TSM. The HHA-TSM may be made of, for example, YPtBi.

[0101] One end of the magnetization driving transistor 403 is connected to one end of the HHA-TSM (spin injection source 402), and the other end is connected to, for example, a power supply (not shown). A control signal is input to the gate of the magnetization driving transistor 403. The other end of the HHA-TSM, which faces the one end of the HHA-TSM (spin injection source 402) to which the magnetization driving transistor 403 is connected, is grounded.

[0102] The MTJ power supply terminal 404 is connected to the ferromagnetic material 411 of the MTJ element 401. The magnetization direction of the ferromagnetic material 413 can be electrically detected by a current supplied from the MTJ power supply terminal 404 due to a tunneling magnetoresistive (TMR) effect generated in the MTJ element 401.

[0103] When the spin Hall oscillator 400 is operated as an oscillator, the magnetization driving transistor 403 is turned on. An in-plane current flows from one end of the spin injection source 402 to the other end via the magnetization driving transistor 403 in the on-state. When an in-plane current flows through the HHA-TSM (spin injection source 402), a spin current is injected into the ferromagnetic material 413. This causes the magnetization of the ferromagnetic material 413 to precess. The precession of the magnetization of the ferromagnetic material 413 is converted into an electric signal by the TMR effect of the MTJ element 401. Then, the signal is output as an AC voltage from a voltage output terminal (not shown) connected to the ferromagnetic material 411.

[0104] 3.2 Second Example Next, a second example will be described. In the second example, a two-terminal spin Hall oscillator will be described with reference to Fig. 18. Fig. 18 is a diagram showing an example of a two-terminal spin Hall oscillator.

[0105] As shown in FIG. 18, a two-terminal spin Hall oscillator 500 includes a ferromagnet 501, a spin injection source 502, and a magnetization driving transistor 503.

[0106] The ferromagnetic body 501 is provided on the spin injection source 502. The ferromagnetic body 501 has ferromagnetism and has a hard magnetization axis parallel to the spin quantization axis of the spin current injected from the spin injection source 502 into the ferromagnetic body 501. The ferromagnetic body 501 functions as a magnetization free layer. The magnetization of the ferromagnetic body 501 may undergo precession due to the spin current injected from the spin injection source 502. In addition, the frequency and amplitude of the precession may be modulated by applying an external magnetic field (in-plane bias magnetic field) parallel to the hard magnetization axis of the ferromagnetic body 501.

[0107] The ferromagnetic material 501 includes at least one of Co, Fe, Ni, Mn, B, Si, Zr, Nb, Ta, Ru, Ir, Pt, Ga, Al, Pd, Tb, and Gd. The ferromagnetic material 501 may be a laminate made up of multiple layers.

[0108] The spin injection source 502 includes an HHA-TSM. For the HHA-TSM, for example, YPtBi is used.

[0109] One end of the magnetization driving transistor 503 is connected to one end of the HHA-TSM (spin injection source 502), and the other end is connected to, for example, a power supply (not shown). A control signal is input to the gate of the magnetization driving transistor 503. The other end of the HHA-TSM, which faces the one end of the HHA-TSM (spin injection source 502) to which the magnetization driving transistor 503 is connected, is grounded.

[0110] When the spin Hall oscillator 500 is operated as an oscillator, the magnetization driving transistor 503 is turned on. An in-plane current is supplied from one end of the spin injection source 502 to the other end via the magnetization driving transistor 503 in the on-state. When an in-plane current flows through the HHA-TSM (spin injection source 502), a spin current is injected into the ferromagnetic material 501. This causes the magnetization of the ferromagnetic material 501 to precess. The precession of the magnetization of the ferromagnetic material 501 is output to the outside as a leakage magnetic field generated from the magnetization.

[0111] 3.3 Third Example Next, a third example will be described. In the third example, a two-terminal spin Hall oscillator different from the second example will be described with reference to Fig. 19. Fig. 19 is a diagram showing an example of a two-terminal spin Hall oscillator.

[0112] As shown in FIG. 19, a two-terminal spin Hall oscillator 600 includes an MTJ element 601 , a spin injection source 602 , and a magnetization driving transistor 603 .

[0113] The configuration of the MTJ element 601 is the same as that of the MTJ element 401 of the first example. More specifically, the MTJ element 601 includes a ferromagnetic body 611, an insulator 612, and a ferromagnetic body 613. For example, the ferromagnetic body 613, the insulator 612, and the ferromagnetic body 611 are stacked in this order on the spin injection source 602. The ferromagnetic body 611 functions as a magnetization fixed layer, similar to the ferromagnetic body 411. Unlike the first example, the ferromagnetic body 611 is grounded. The insulator 612 functions as a tunnel barrier layer, similar to the insulator 412. The ferromagnetic body 613 functions as a magnetization free layer, similar to the ferromagnetic body 413.

[0114] The spin injection source 602 includes an HHA-TSM. For the HHA-TSM, for example, YPtBi is used.

[0115] One end of the magnetization driving transistor 603 is connected to one end of the HHA-TSM (spin injection source 602), and the other end is connected to, for example, a power supply (not shown). A control signal is input to the gate of the magnetization driving transistor 603.

[0116] When the spin Hall oscillator 600 is operated as an oscillator, the magnetization driving transistor 603 is turned on. A current flows from the spin injection source 602 to the ferromagnetic material 611 through the magnetization driving transistor 603 in the on state. At this time, when an in-plane current flows through the HHA-TSM (spin injection source 602), a spin current is injected into the ferromagnetic material 613. As a result, the magnetization of the ferromagnetic material 613 precesses. Since the current input through the magnetization driving transistor 603 flows through the MTJ element 601, the magnetization direction of the ferromagnetic material 613 can be electrically detected by the TMR effect generated in the MTJ element 601. As a result, the precession of the magnetization of the ferromagnetic material 613 is converted into an electric signal by the TMR effect of the MTJ element 101, and is output as an AC voltage from a voltage output terminal (not shown) connected to the spin injection source 602.

[0117] 3.4 Fourth Example Next, a fourth example will be described. In the fourth example, a two-terminal spin Hall oscillator having an MTJ element and a parallel resistor will be described with reference to Fig. 20. Fig. 20 is a diagram showing an example of a two-terminal spin Hall oscillator.

[0118] As shown in FIG. 20, a two-terminal spin Hall oscillator 700 includes an MTJ element 701, a spin injection source 702, a resistive element 703, a conductor 704, and a magnetization driving transistor 705.

[0119] The configuration of the MTJ element 701 is the same as that of the MTJ element 401 of the first example. More specifically, the MTJ element 701 includes a ferromagnetic material 711, an insulator 712, and a ferromagnetic material 713. For example, the ferromagnetic material 713, the insulator 712, and the ferromagnetic material 711 are stacked in this order on the spin injection source 702. The ferromagnetic material 711 functions as a magnetization fixed layer, similar to the ferromagnetic material 411. The insulator 712 functions as a tunnel barrier layer, similar to the insulator 412. The ferromagnetic material 713 functions as a magnetization free layer, similar to the ferromagnetic material 413.

[0120] The spin injection source 702 includes an HHA-TSM. For the HHA-TSM, for example, YPtBi is used.

[0121] The resistive element 703 is disposed in parallel with the MTJ element 701. One end of the resistive element 703 is in contact with the spin injection source 702. For example, the resistance value of the resistive element 703 is lower than the resistance value of the MTJ element 701.

[0122] The conductor 704 contacts the other end of the ferromagnetic material 711 and the resistive element 703 of the MTJ element 701. The conductor 704 is grounded. That is, the other ends of the ferromagnetic material 711 and the resistive element 703 are grounded. The conductor 704 includes a conductive material.

[0123] One end of the magnetization driving transistor 705 is connected to one end of the HHA-TSM (spin injection source 702), and the other end is connected to, for example, a power supply (not shown). A control signal is input to the gate of the magnetization driving transistor 705.

[0124] When the spin Hall oscillator 700 is operated as an oscillator, the magnetization driving transistor 705 is turned on. A current flows from the spin injection source 702 to the conductor 704 through the magnetization driving transistor 705 in the on state. At this time, when an in-plane current flows through the HHA-TSM (spin injection source 702), a spin current is injected into the ferromagnetic material 713. As a result, the magnetization of the ferromagnetic material 713 precesses. The current input through the magnetization driving transistor 705 flows from the MTJ element 701 and the resistance element 703 to the conductor 704. Since the resistance value of the resistance element 703 is lower than the resistance value of the MTJ element 701, the in-plane current of the HHA-TSM mainly flows to the conductor 704 through the resistance element 703. Therefore, the magnitude of the in-plane current can be controlled by the magnitude of the resistance value of the resistance element 703. Also, a part of the current injected through the magnetization driving transistor 705 flows through the MTJ element 701. Therefore, the magnetization direction of the ferromagnetic material 713 can be electrically detected by the TMR effect of the MTJ element 701. As a result, the precession of the magnetization of the ferromagnetic material 713 is converted into an electric signal by the TMR effect of the MTJ element 701 and is output as an AC voltage from a voltage output terminal (not shown) connected to the spin injection source 702.

[0125] 3.5 Effects of this embodiment With the configuration according to this embodiment, the HHA-TSM can be applied to a spin Hall oscillator.

[0126] 4. Fourth embodiment Next, a fourth embodiment will be described. In the fourth embodiment, a case where a spin Hall oscillator including a spin injection source including HHA-TSM is used for an artificial neuron of an artificial neuron computer will be described. Below, the differences from the first to third embodiments will be mainly described.

[0127] 4.1 Construction of artificial neurons An example of the configuration of an artificial neuron will be described with reference to Fig. 21. Fig. 21 is a diagram showing an example of an artificial neuron using a spin Hall oscillator.

[0128] As shown in FIG. 21, an artificial neuron 800 includes a spin Hall oscillator 801, a DC power supply 802, an input capacitor 803, an AC power supply 804, a diode 805, an output capacitor 806, and an output terminal 807.

[0129] The spin Hall oscillator 801 includes an MTJ element 811 , a spin injection source 812 , and a resistor element 813 .

[0130] The configuration of the MTJ element 811 is the same as that of the MTJ element 401 of the first example of the third embodiment. More specifically, the MTJ element 811 includes a ferromagnetic body 821, an insulator 822, and a ferromagnetic body 823. For example, the ferromagnetic body 823, the insulator 822, and the ferromagnetic body 821 are stacked in this order on the spin injection source 812. The ferromagnetic body 821 functions as a magnetization fixed layer, similar to the ferromagnetic body 411. The ferromagnetic body 821 is grounded. The insulator 822 functions as a tunnel barrier layer, similar to the insulator 412. The ferromagnetic body 823 functions as a magnetization free layer, similar to the ferromagnetic body 413. The ferromagnetic body 821 may function as a magnetization free layer, and the ferromagnetic body 823 may function as a magnetization fixed layer.

[0131] The spin injection source 812 includes an HHA-TSM. For example, YPtBi is used for the HHA-TSM. One end of the HHA-TSM is connected to a node ND1, and the other end is connected to a node ND2.

[0132] The resistive element 813 is arranged in parallel with the MTJ element 811. One end of the resistive element 813 is connected to the node ND2. That is, one end of the resistive element 813 is connected to the spin injection source 812 via the node ND2. The other end of the resistive element 813 is grounded. For example, the resistance value of the resistive element 813 is lower than the resistance value of the MTJ element 811. Note that the resistive element 813 may be omitted.

[0133] The DC power supply 802 is connected to one end of the HHA-TSM (spin injection source 812) via a node ND1. The DC power supply 802 supplies a bias DC voltage V DC is applied.

[0134] One electrode of the input capacitor 803 is connected to the node ND 1 , and the other electrode is connected to an AC power supply 804 .

[0135] The AC power supply 804 supplies an input signal V in Apply the bias DC voltage V DC and the input signal V in The combined voltage of the input signal V in is a voltage signal obtained by sampling a time-axis input signal from audio or a sensor and multiplying it by a random matrix (mask data).

[0136] One end of the diode 805 is connected to the node ND2, and the other end is connected to the node ND3. The diode 805 is disposed so as to be forward biased from the node ND2 to the node ND3.

[0137] One electrode of the output capacitor 806 is connected to the node ND3, and the other electrode is grounded.

[0138] The output terminal 807 is connected to the node ND3. The output voltage V out will be output.

[0139] For example, in the artificial neuron 800, the HHA-TSM is connected to a bias DC voltage V DC and the input signal v in When a combined voltage of the two is applied, an in-plane current flows in the HHA-TSM. This in-plane current injects a spin current from the HHA-TSM into the ferromagnet 823, causing the magnetization of the ferromagnet 823 to precess. This precession is output as an AC voltage via the MTJ element 811. Furthermore, the AC voltage of the MTJ element 811 is smoothed by the diode 805 and the output capacitor 806, and is output as the output voltage V out The output of the spin Hall oscillator 801 is the input signal V in Since the output voltage V of the artificial neuron 800 changes nonlinearly with out The input signal V in Therefore, the output voltage V of the artificial neuron 800 out It can be used as an artificial neuron computer by using it as a new input signal for other artificial neurons or for itself.

[0140] 4.2 Effects of this embodiment With the configuration according to this embodiment, the HHA-TSM can be applied to the artificial neurons of an artificial neuron computer.

[0141] It should be noted that any of the spin Hall oscillators according to the first to fourth examples of the third embodiment can be applied to the spin Hall oscillator 801 used in the artificial neuron.

[0142] 5. Fifth embodiment Next, a fifth embodiment will be described. In the fifth embodiment, a case where HHA-TSM is used for the detection layer of the magnetic sensor will be described. The following mainly describes the differences from the first to fourth embodiments.

[0143] 5.1 Magnetic sensor configuration An example of the configuration of the magnetic sensor will be described with reference to Fig. 22. Fig. 22 is a diagram showing an example of the magnetic sensor.

[0144] 22, the magnetic sensor 900 includes a detection layer 901, a ferromagnetic material 902, a conductor 903, current terminals 904 and 905, and voltage terminals 906 and 907. In the following description, the direction parallel to the film surface of the detection layer 901 and in which a current flows through the current terminals 904 and 905 is defined as the X direction. The direction parallel to the film surface of the detection layer 901 and intersecting with the X direction is defined as the Y direction. The direction perpendicular to the film surface of the detection layer 901 is defined as the Z direction.

[0145] The detection layer 901 includes HHA-TSM. For example, YPtBi is used for the HHA-TSM.

[0146] The ferromagnetic material 902 is provided on the detection layer 901 in the Z direction. The ferromagnetic material 902 has ferromagnetism and has an easy axis direction of magnetization parallel to the film surface in contact with the detection layer 901 (in-plane direction). The ferromagnetic material 902 includes at least one of Co, Fe, Ni, Mn, B, Si, Zr, Nb, Ta, Ru, Ir, Pt, Ga, Al, Pd, Tb, and Gd. The ferromagnetic material 902 may be a laminate consisting of multiple layers.

[0147] An intermediate layer may be inserted between the detection layer 901 and the ferromagnetic material 902, the intermediate layer being in contact with the detection layer 901 and the ferromagnetic material 902. The intermediate layer may be made of a non-magnetic metal or a metal oxide containing at least one of Ga, Al, Mg, Hf, and Zr.

[0148] The conductor 903 is provided on the ferromagnetic body 902 in the Z direction. The conductor 903 includes a conductive material.

[0149] A current terminal 904 is connected to the end of the detection layer 901 facing the X direction.

[0150] The current terminal 905 is connected to an end of the conductor 903 facing the X direction. For example, a current supplied to the current terminal 904 flows to the current terminal 905 via the conductor 903, the ferromagnetic material 902, and the detection layer 901.

[0151] A voltage terminal 906 is connected to one end of the detection layer 901 facing the Y direction.

[0152] A voltage terminal 907 is connected to the other end of the detection layer 901 facing the Y direction.

[0153] A direct current is applied between a current terminal 904 and a current terminal 905 of the magnetic sensor 900. When this direct current penetrates (passes) the ferromagnetic material 902 in a direction perpendicular to the film surface (Z direction), it is converted into a spin-polarized current having a spin quantization axis parallel to the magnetization direction of the ferromagnetic material 902 by the spin filtering effect of the ferromagnetic material 902. As a result, a spin-polarized current is injected from the ferromagnetic material 902 to the HHA-TSM (detection layer 901) in the Z direction perpendicular to the film surface. In the HHA-TSM, the spin-polarized current is converted into a current by the inverse spin Hall effect of the HHA-TSM. A part of the converted current generates an electromotive force between the voltage terminal 906 and the voltage terminal 907. The magnitude of the electromotive force generated between the voltage terminal 906 and the voltage terminal 907 is proportional to the component of the magnetization of the ferromagnetic material 902 in the X direction. Therefore, when an external magnetic field changes the X-direction component of the magnetization of the ferromagnetic material 902, in the HHA-TSM, the electromotive force generated between the voltage terminals 906 and 907 changes due to the inverse spin Hall effect. Therefore, the external magnetic field can be estimated from the amount of change.

[0154] 5.2 Effects of this embodiment With the configuration according to this embodiment, the HHA-TSM can be applied to a magnetic sensor.

[0155] 6.Other In the above embodiments, the spin injection source, magnetic memory, spin Hall oscillator, artificial neuron computer, and magnetic sensor using the HHA-TSM have been described, but are not limited thereto. The HHA-TSM can also be applied to other products using spin Hall materials. For example, in a magnetic recording device, the microwave generated by the spin Hall oscillator described in the third embodiment may be used to assist recording.

[0156] The above embodiments can be combined as much as possible.

[0157] For example, the spin Hall oscillator may be configured by having the same structure as any one of the spin Hall oscillators described in the first to fourth examples of the third embodiment, or a plurality of the spin Hall oscillator structures of a plurality of examples, and synchronizing them by electrically or magnetically coupling them.

[0158] In the above embodiment, "connected" also includes a state in which something else, such as a transistor or a resistor, is interposed between them and indirectly connected.

[0159] The embodiments are illustrative and the scope of the invention is not limited thereto. [Explanation of symbols]

[0160] 100, 200...SOT magnetic memory 101, 201, 401, 601, 701, 811...MTJ elements 102, 202, 302, 402, 502, 602, 702, 812...Spin injection source 103...Write transistor 104...Readout transistor 111, 113, 211, 213, 301, 307, 311, 411, 413, 501, 611,613, 711, 713, 821, 823, 902...Ferromagnetic material 112, 212, 312, 412, 612, 712, 822...Insulator 203...Write / read transistor 300…Magnetic memory 303...Readout section 304~306, 704, 903...Conductors 400, 500, 600, 700, 801...Spin Hall Oscillators 403, 503, 603, 705...Magnetization driving transistor 404…MTJ power supply terminal 703, 813...Resistance element 800…Artificial neurons 802…DC power supply 803…Input capacitor 804…AC power supply 805...Diode 806…Output capacitor 807…Output terminal 900...Magnetic sensor 901…Detection layer 904, 905...Current terminal 906, 907...Voltage terminals MD1~MD4…magnetic domain ND1~ND3...nodes T1~T4…Terminals

Claims

1. a detection layer including YPtBi, a non-magnetic half-Heusler alloy topological semimetal having a Dirac-type surface state and a spin Hall angle greater than 1; a ferromagnetic body in contact with the detection layer and having a magnetization oriented in an in-plane direction of a first surface in contact with the detection layer; Equipped with Magnetic sensor.

2. a current is passed through the ferromagnetic material in a direction perpendicular to the first surface, and a spin-polarized current is injected into the YPtBi, thereby generating a voltage that depends on the magnetization direction of the ferromagnetic material due to the inverse spin Hall effect of the YPtBi. The magnetic sensor according to claim 1 .

3. The ferromagnetic material includes at least one of Co, Fe, Ni, Mn, B, Si, Zr, Nb, Ta, Ru, Ir, Pt, Ga, Al, Pd, Tb, and Gd; 3. The magnetic sensor according to claim 1 or 2.

4. The YPtBi has a (111) crystal face. The magnetic sensor according to claim 1 .

5. The YPtBi has a heat resistance of 300° C. or more and 600° C. or less. The magnetic sensor according to claim 1 .

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