Magnetic material structure for realizing paramagnetic and ferromagnetic phase change by utilizing spin-orbit coupling effect

Abstract

The invention relates to a magnetic material structure for realizing paramagnetic and ferromagnetic phase change by utilizing a spin-orbit coupling effect. According to an exemplary embodiment, a magnetic material structure includes: a spin Hall effect layer formed of a non-magnetic metal material having a spin Hall effect; the paramagnetic layer is formed on the spin Hall effect layer; and an antiferromagnetic layer formed on the paramagnetic layer. The magnetic material structure is configured to receive an in-plane current, when the in-plane current flows through the magnetic material structure, the spin Hall effect layer applies a spin orbit torque to the paramagnetic layer, and under the combined action of the spin orbit torque and the interlayer coupling action from the antiferromagnetic layer, the paramagnetic layer exhibits ferromagnetism. The magnetic material structure can broaden the Curie temperature range of the ferromagnetic material, so that the magnetic device can work in a wider temperature range. The invention also provides a magnetic device comprising the magnetic material structure, such as a Hall sensor.

Description

Technical Field

[0001] The present invention generally relates to the field of spin electronics, and more particularly to a magnetic material structure capable of realizing mutual conversion between a paramagnetic phase and a ferromagnetic phase by utilizing a spin-orbit coupling effect, and a magnetic device comprising the magnetic material structure. Background Art

[0002] With the development of science and technology, research in the field of spin electronics has also made great progress in the past decade. For example, the discovery of spin transfer torque (STT) and spin orbit torque (SOT) has made it possible to flip magnetic materials without the need for an Oersted magnetic field, which can greatly increase device integration density and simplify device structure, making it possible to apply structures such as spin valves and magnetic tunnel junctions in the fields of memory, sensors, and logic devices.

[0003] In magnetic device applications, various operations are generally achieved by reversing the magnetization direction of the ferromagnetic material layer, such as data writing, external magnetic field sensing, etc. However, an inherent property of ferromagnetic materials is that when the temperature rises above the Curie temperature, the ferromagnetic properties of the ferromagnetic material will gradually be lost until it completely loses its magnetism, causing the magnetic device to not work properly. Therefore, magnetic devices containing ferromagnetic materials can only work properly at temperatures lower than the Curie temperature. Summary of the invention

[0004] One aspect of the present invention provides a magnetic material structure that can utilize the spin-orbit coupling effect to achieve mutual conversion between a paramagnetic phase and a ferromagnetic phase, thereby widening the operating temperature range of the magnetic device.

[0005] According to an exemplary embodiment, a magnetic material structure may include: a spin Hall effect layer formed of a non-magnetic metal material having a spin Hall effect; a paramagnetic layer formed on the spin Hall effect layer; and an antiferromagnetic layer formed on the paramagnetic layer. The magnetic material structure is configured to receive an in-plane current, and when the in-plane current flows through the magnetic material structure, the spin Hall effect layer applies a spin-orbit torque to the paramagnetic layer, and under the combined effect of the spin-orbit torque and the interlayer coupling effect from the antiferromagnetic layer, the paramagnetic layer exhibits ferromagnetism.

[0006] In an exemplary embodiment, the paramagnetic layer includes a ferromagnetic material that exhibits paramagnetic properties at a temperature higher than its Curie temperature.

[0007] In an exemplary embodiment, the ferromagnetic material includes at least one of FeCrB, FeNiMnCr, 1J30 nickel-iron alloy, CoTiZn ferrite, MnZn ferrite, Ti-doped MnZn ferrite, CoZn ferrite, and Ti-doped CoZn ferrite.

[0008] In an exemplary embodiment, the paramagnetic layer includes a ferromagnetic material, and the ferromagnetic material is formed to have a thin thickness so as to exhibit paramagnetism.

[0009] In an exemplary embodiment, the ferromagnetic material includes at least one of Co, Ni, Fe, or alloys thereof.

[0010] In an exemplary embodiment, the thickness of the ferromagnetic material is less than 3 nm, preferably less than 2 nm.

[0011] In an exemplary embodiment, the antiferromagnetic layer includes at least one of CoO, NiO, IrMn, PtMn, and FeMn.

[0012] In an exemplary embodiment, the paramagnetic layer includes a Co layer having a thin thickness so as to exhibit paramagnetism. The antiferromagnetic layer includes CoO or NiO.

[0013] In an exemplary embodiment, the non-magnetic metal material having the spin Hall effect includes a heavy metal material.

[0014] In an exemplary embodiment, the non-magnetic metal material having the spin Hall effect includes at least one of Pt, Pd, Ta, and Ru.

[0015] Another exemplary embodiment of the present invention provides a magnetic device including the above-mentioned magnetic material structure.

[0016] In an exemplary embodiment, the magnetic device may be a Hall sensor.

[0017] The above and other features and advantages of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of a magnetic material structure according to an exemplary embodiment of the present invention.

[0019] Figure 2 yes Figure 1 The relationship curve between the Hall resistance and the external magnetic field of the magnetic material structure shown under different currents.

[0020] Figure 3 yes Figure 1 The relationship curve between Hall resistance and current of the magnetic material structure shown in FIG. 1 under different external magnetic fields. DETAILED DESCRIPTION

[0021] Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the accompanying drawings may not be drawn to scale.

[0022] Figure 1 is a schematic diagram of a magnetic material structure 100 according to an exemplary embodiment of the present invention. Figure 1 As shown, the magnetic material structure 100 may include a spin Hall effect (SHE) layer 112 , a paramagnetic layer 114 , and an antiferromagnetic (AFM) layer 116 sequentially formed on a substrate 110 .

[0023] The substrate 110 may be any suitable substrate, such as an insulating substrate or a semiconductor substrate. Examples of insulating substrates include but are not limited to SiO2 substrates, quartz substrates, glass substrates, sapphire substrates, plastic substrates, etc. Examples of semiconductor substrates include but are not limited to silicon substrates, silicon-on-insulator substrates, silicon carbide substrates, etc.

[0024] The spin Hall effect (SHE) layer 112 may be formed of a non-magnetic metal material having a spin Hall effect, such a material may include a heavy metal material having a strong spin-orbit coupling, thereby exhibiting a spin Hall effect. Examples of such heavy metal materials include, but are not limited to, for example, Pt, Pd, Ta, Ru, etc. When current flows through a heavy metal material, due to spin-orbit coupling, a spin-polarized electron flow will accumulate on the surface of the material, and the spin-polarized electron flow will diffuse to the adjacent magnetic layer, and a spin-orbit torque will be applied to the magnetic moment of the adjacent magnetic layer, thereby affecting the orientation of its magnetic moment. The relevant principles are at least described in the applicant's invention patents 201610064129.8 and 201710093931.4, etc., and will not be repeated here.

[0025] The paramagnetic layer 114 is a layer that exhibits paramagnetic properties, but in the present invention, the paramagnetic layer 114 is formed of a ferromagnetic material. Ferromagnetic materials can exhibit paramagnetism in two cases: the first is that its temperature exceeds the Curie temperature, causing it to lose its ferromagnetic properties and instead exhibit paramagnetism; the second is that its size, such as particle diameter or layer thickness, is very small, so that it exhibits paramagnetism macroscopically. In some exemplary embodiments of the present invention, the paramagnetic layer 114 can be formed of ferromagnetic materials such as FeCrB, FeNiMnCr, 1J30 nickel-iron alloy, CoTiZn ferrite, MnZn ferrite, Ti-doped MnZn ferrite, CoZn ferrite, Ti-doped CoZn ferrite, etc. The Curie temperatures of these ferromagnetic materials cover or are close to the room temperature range, so they can exhibit paramagnetism at appropriate operating temperatures. In other embodiments, the paramagnetic layer 114 may be formed of a ferromagnetic material such as Co, Ni, Fe or an alloy thereof, wherein the alloy may include a doping material such as B, Si, etc., and such a paramagnetic layer 114 has a thin thickness, for example, less than 3 nm, more preferably less than 2 nm, so that even if the paramagnetic layer 114 is formed of these ferromagnetic materials, it exhibits paramagnetism. The specific thickness of such a paramagnetic layer 114 may vary depending on the material from which it is formed, so the present invention does not impose any special limitation on the specific thickness of the paramagnetic layer 114 except that the thickness is small enough to exhibit paramagnetism.

[0026] The antiferromagnetic layer 116 is formed of an antiferromagnetic material, examples of which include but are not limited to CoO, NiO, IrMn, PtMn, FeMn, etc. The material of the antiferromagnetic layer 116 can be selected so that its lattice matches that of the adjacent paramagnetic layer 114, thereby enabling better growth quality. It should be understood that the various layers can be formed in the same manner as Figure 1 The reverse order is formed on the substrate 110 .

[0027] Although Figure 1 Although not shown, a protective layer such as SiO 2 layer.

[0028] In a preferred embodiment of the present invention, the magnetic material structure 100 may be formed to have the following structure: Si substrate / Pt (3 nm) / Co (0.5-1.2 nm) / CoO (0.1-1.5 nm) / SiO 2 (5nm), wherein the CoO antiferromagnetic layer can be formed by oxidizing the Co layer, thereby simplifying the manufacturing process and achieving good lattice matching. In another embodiment, the CoO layer can also be replaced by a 1-3nm thick NiO layer, in which case a special step is required to deposit the NiO layer. There is also good lattice matching between the NiO layer and the Co layer, thereby ensuring good interlayer coupling between the antiferromagnetic layer and the paramagnetic layer.

[0029] The principle of the magnetic material structure 100 is described below. The magnetic material structure 100 is configured to receive an in-plane current. When no current is applied to the magnetic material structure 100, the paramagnetic layer 114 exhibits paramagnetic properties because the ambient temperature is higher than the Curie temperature of the ferromagnetic material forming the paramagnetic layer 114, or because the thickness of the ferromagnetic material is small. When the in-plane current flows through the magnetic material structure 100, on the one hand, the spin Hall effect layer 112 will apply a spin-orbit torque to the paramagnetic layer 114; on the other hand, the antiferromagnetic layer 116 will also affect the magnetic moment of the paramagnetic layer 114 through the interlayer coupling effect. Under the combined effect of the spin-orbit torque from the spin Hall effect layer 112 and the interlayer coupling effect from the antiferromagnetic layer 116, the magnetic moment at the interface between the paramagnetic layer 114 and the antiferromagnetic layer 116 will present a zigzag arrangement, that is, it will show the consistency of the magnetic moment orientation within a certain range, and this consistency will increase with the external magnetic field, so the paramagnetic layer 114 can be ferromagnetic as a whole. In other words, the paramagnetic layer 114 realizes a phase transition from a paramagnetic phase to a ferromagnetic phase. This phase transition can broaden the Curie temperature range of the ferromagnetic material forming the paramagnetic layer 114, that is, it can enable the ferromagnetic material to maintain ferromagnetic properties at a higher temperature, thereby expanding its operating temperature range.

[0030] Figure 2 yes Figure 1 The relationship curve between the Hall resistance R and the external magnetic field H of the magnetic material structure 100 shown in FIG. 1 under different currents, wherein the magnetic material structure 100 includes a structure Pt (3nm) / Co (1.0nm) / CoO (1.2nm) formed on a Si substrate, Figure 2 The sign of the current indicates its direction. Figure 2 It can be seen that as the current increases, the ferromagnetic property of the Co layer (ie, the paramagnetic layer 114 ) is significantly enhanced, and exhibits chiral characteristics with the current direction. Figure 2 The RH relationship curve shown has a clear hysteresis loop shape at high current, indicating that the paramagnetic layer 114 exhibits ferromagnetic characteristics.

[0031] Figure 3 yes Figure 2 The relationship curve between the Hall resistance and the current of the measured magnetic material structure 100 under different external magnetic fields. Figure 3 As shown, as the external magnetic field increases, the magnetism of the Co layer (ie, the paramagnetic layer 114) increases, and exhibits chiral characteristics with the magnetic field. Figure 3 The resistance-current relationship curve has an obvious hysteresis loop shape, indicating that the paramagnetic layer 114 exhibits ferromagnetic properties.

[0032] An exemplary embodiment of the present invention further provides a magnetic device including the magnetic material structure 100, which may be, for example, a Hall sensor. As described above, compared with conventional Hall sensors, the Hall sensor of the present invention can operate normally in a wider temperature range (e.g., at a higher temperature, such as a temperature higher than the Curie temperature).

[0033] Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprise", "comprising", "including", "comprising", etc. should be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense. That is, the meaning is "including but not limited to". The word "connected" as generally used herein refers to two or more elements that can be directly connected or connected through one or more intermediate elements. As generally used herein, the word "connected" refers to two or more elements that can be directly connected or connected through one or more intermediate elements. In addition, when used in this application, the words "herein", "above", "below" and words of similar meanings should refer to the entirety of this application rather than to any particular part of this application. Where the context permits, the word "or" refers to a list of two or more items, which covers all of the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list.

[0034] Furthermore, unless otherwise specifically stated or understood in the context of use, conditional language used herein, such as "can," "may," "might," "could," "for example," "for example," "such as," and the like, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and / or states. Thus, such conditional language is generally not intended to imply that one or more embodiments require features, elements, and / or states in any way, or that one or more embodiments must include logic for making decisions, with or without author input or prompting, that such features, elements, and / or states are included or will be performed in any particular embodiment.

[0035] Although certain embodiments have been described, these embodiments are presented only by way of example and are not intended to limit the scope of the present disclosure. In fact, the novel facilities, methods, and systems described herein may be embodied in various other forms; in addition, various omissions, substitutions, and changes may be made to the forms of the methods and systems described herein without departing from the spirit of the present disclosure. For example, although blocks are presented in a given arrangement, alternative embodiments may perform functions similar to different components and / or circuit topologies, and may delete, move, add, subdivide, combine, and / or modify some blocks. Each of these blocks may be implemented in a variety of different ways. Any suitable combination of the elements and actions of the various embodiments described above may be combined to provide further embodiments. The attached claims and their equivalents are intended to cover these forms or modifications that fall within the scope and spirit of the present disclosure.

[0036] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A magnetic material structure, comprising: A spin Hall effect layer, formed of a non-magnetic metal material having a spin Hall effect; a paramagnetic layer formed on the spin Hall effect layer; as well as an antiferromagnetic layer formed on the paramagnetic layer, Wherein, the magnetic material structure is configured to receive in-plane current. When the in-plane current flows through the magnetic material structure, the spin Hall effect layer applies a spin-orbit torque to the paramagnetic layer. Under the combined action of the spin-orbit torque and the interlayer coupling from the antiferromagnetic layer, the paramagnetic layer exhibits ferromagnetism.

2. The magnetic material structure according to claim 1, wherein: The paramagnetic layer includes a ferromagnetic material that exhibits paramagnetic properties when exposed to a temperature higher than its Curie temperature.

3. The magnetic material structure according to claim 2, wherein: The ferromagnetic material includes at least one of FeCrB, FeNiMnCr, 1J30 nickel-iron alloy, CoTiZn ferrite, MnZn ferrite, Ti-doped MnZn ferrite, CoZn ferrite, and Ti-doped CoZn ferrite.

4. The magnetic material structure according to claim 1, wherein: The paramagnetic layer includes a ferromagnetic material formed to have a thin thickness so as to exhibit paramagnetism.

5. The magnetic material structure according to claim 4, wherein: The ferromagnetic material includes at least one of Co, Ni, Fe, or alloys thereof.

6. The magnetic material structure according to claim 4, wherein: The thickness of the ferromagnetic material is less than 3 nm, preferably less than 2 nm.

7. The magnetic material structure according to claim 1, wherein: The antiferromagnetic layer includes at least one of CoO, NiO, IrMn, PtMn, and FeMn.

8. The magnetic material structure according to claim 1, wherein: The non-magnetic metal material having the spin Hall effect includes at least one of Pt, Pd, Ta and Ru.

9. A magnetic device, comprising the magnetic material structure according to any one of claims 1 to 8.

10. The magnetic device according to claim 9, wherein: The magnetic device is a Hall sensor.

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