Terahertz wave emitter and preparation method and regulation and control method thereof

Abstract

The invention discloses a terahertz wave emitter and a preparation method and a regulation and control method thereof, and relates to the technical field of terahertz wave emitters, the terahertz wave emitter comprises a flexible substrate layer, a ferromagnetic metal layer and a heavy metal layer which are stacked, the ferromagnetic metal layer is magnetized in a plane in advance to have magnetism, and when in use, the ferromagnetic metal layer is separated from the heavy metal layer. Incident femtosecond laser pulses penetrate through the flexible substrate layer to irradiate a preset position of the ferromagnetic metal layer to excite the ferromagnetic metal layer to generate ultrafast spin currents, the spin currents are diffused into the heavy metal layer to be converted into transient charge currents, and then terahertz waves are generated, that is, the terahertz waves can be generated under the condition that no external magnetic field exists. The whole laminated layer composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer bends towards one side of the flexible substrate layer or bends towards one side of the heavy metal layer, so that the preset position of the ferromagnetic metal layer is subjected to stress parallel to the magnetic field direction, the magnetic field intensity of the preset position of the ferromagnetic metal layer is changed, the generated terahertz wave intensity is regulated and controlled, the cost is low, and the application range is wide. The practical application is convenient.

Description

Technical Field

[0001] The present application relates to the technical field of terahertz wave transmitters, and in particular to a terahertz wave transmitter and a preparation method and a control method thereof. Background Art

[0002] Terahertz waves are electromagnetic waves with a frequency band of 0.1THz-10THz, which is between infrared and microwaves. They have special electronic energy and therefore have many unique properties. They have important applications in medicine, biology, materials science, security inspection, communications and other fields. With the growing application of terahertz waves, the demand for terahertz sources is increasing. In recent years, terahertz wave transmitters based on spin electronics have emerged. These spin electronic terahertz wave transmitters generate terahertz waves with wide spectrum, flexibility and low cost, and are widely studied and developed by researchers.

[0003] In order to maximize the efficiency of terahertz wave emission, spintronic terahertz wave emitters usually apply an external magnetic field, which is mainly realized by a pair of permanent magnets or electromagnets, which is not conducive to the compactness of the device. The current field-free spintronic terahertz wave emitters are mainly based on the exchange bias between ferromagnetic / antiferromagnetic structures, and their control effect is relatively limited. Summary of the invention

[0004] In order to solve the above technical problems, the embodiments of the present application provide a terahertz wave transmitter and a preparation method and a control method thereof, so as to generate terahertz waves in the absence of an external magnetic field and effectively control the intensity of the terahertz waves.

[0005] To achieve the above objectives, the present application provides the following technical solutions:

[0006] A terahertz wave transmitter, comprising:

[0007] A flexible substrate layer;

[0008] A ferromagnetic metal layer located on one side of the flexible substrate layer, wherein the ferromagnetic metal layer has magnetism;

[0009] a heavy metal layer located on a side of the ferromagnetic metal layer facing away from the flexible substrate layer;

[0010] The stack composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer is bent as a whole toward the flexible substrate layer side or toward the heavy metal layer side, so that a preset position of the ferromagnetic metal layer has tensile stress and compressive stress, the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer is tangent to the surface of the ferromagnetic metal layer, and the preset position is the position where the laser penetrates the flexible substrate layer and irradiates the ferromagnetic metal layer.

[0011] Optionally, the stack consisting of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer is symmetrically bent toward one side of the flexible substrate layer or symmetrically bent toward one side of the heavy metal layer, and the preset position is the middle position of the ferromagnetic metal layer along the bending direction.

[0012] Optionally, the tensile stress direction of the preset position of the ferromagnetic metal layer is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer;

[0013] Alternatively, the compressive stress direction of the preset position of the ferromagnetic metal layer is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer.

[0014] Optionally, the material of the flexible substrate layer includes polydimethylsiloxane or polyimide;

[0015] The thickness of the flexible substrate layer ranges from 10 μm to 10 mm, including end points.

[0016] Optionally, the material of the ferromagnetic metal layer includes Co, Fe, Ni, CoFe or CoFeB;

[0017] The thickness of the ferromagnetic metal layer ranges from 2 nm to 20 nm, including end points.

[0018] Optionally, the material of the heavy metal layer includes Pt, W, Au, Ta, Au or Ir;

[0019] The thickness of the heavy metal layer ranges from 2 nm to 20 nm, including end points.

[0020] A method for preparing a terahertz wave transmitter, comprising:

[0021] providing a flexible substrate layer;

[0022] forming a ferromagnetic metal layer on one side of the flexible substrate layer;

[0023] forming a heavy metal layer on a side of the ferromagnetic metal layer facing away from the flexible substrate layer;

[0024] Magnetizing the ferromagnetic metal layer in-plane so that the ferromagnetic metal layer has magnetism;

[0025] The stack consisting of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer is bent as a whole toward the flexible substrate layer side or toward the heavy metal layer side, so that a preset position of the ferromagnetic metal layer has tensile stress and compressive stress, the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer is tangent to the surface of the ferromagnetic metal layer, and the preset position is the position where the laser penetrates the flexible substrate layer to irradiate the ferromagnetic metal layer.

[0026] A control method for a terahertz wave transmitter, applied to the terahertz wave transmitter described in any one of the above, the control method for the terahertz wave transmitter comprising:

[0027] The intensity of the terahertz wave emitted by the terahertz wave emitter is regulated by regulating the bending direction and the bending curvature of the stacked layer composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave emitter.

[0028] Optionally, adjusting the bending direction of the stacked body consisting of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave transmitter includes:

[0029] The stack composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave transmitter is regulated to bend as a whole toward the flexible substrate layer or toward the heavy metal layer, so that a preset position of the ferromagnetic metal layer has tensile stress and compressive stress, the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer is tangent to the surface of the ferromagnetic metal layer, and the preset position is the position where the laser penetrates the flexible substrate layer and irradiates the ferromagnetic metal layer;

[0030] Wherein, the tensile stress direction of the preset position of the ferromagnetic metal layer is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer;

[0031] Alternatively, the compressive stress direction of the preset position of the ferromagnetic metal layer is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer.

[0032] Optionally, regulating the bending curvature of the stacked layer consisting of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave transmitter includes:

[0033] The bending curvature of the stack composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave transmitter is regulated so that the stress value along the bending direction of the ferromagnetic metal layer among the tensile stress and compressive stress at a preset position of the ferromagnetic metal layer does not exceed 0.2×d, where d is the thickness of the flexible substrate layer in millimeters.

[0034] Compared with the prior art, the above technical solution has the following advantages:

[0035] The terahertz wave transmitter provided in the embodiment of the present application includes a flexible substrate layer, a ferromagnetic metal layer located on one side of the flexible substrate layer, and a heavy metal layer located on the side of the ferromagnetic metal layer away from the flexible substrate layer, wherein the ferromagnetic metal layer is pre-magnetized in-plane and has magnetism, so that the incident femtosecond laser pulse is irradiated to the preset position of the ferromagnetic metal layer through the flexible substrate layer, and the ferromagnetic metal layer generates an ultrafast spin current under the excitation of the femtosecond laser, and the spin current diffuses into the heavy metal layer, and is converted into a transient charge flow under the action of spin-orbit coupling, thereby generating terahertz waves. It can be seen that the terahertz wave transmitter provided in the embodiment of the present application does not need to apply an external magnetic field device when in use, that is, terahertz waves can be generated without an external magnetic field.

[0036] Furthermore, in the terahertz wave transmitter provided in the embodiment of the present application, the stack composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer is bent as a whole toward the flexible substrate layer side or toward the heavy metal layer side, so that the preset position of the ferromagnetic metal layer has tensile stress and compressive stress, and the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer is tangent to the surface of the ferromagnetic metal layer, and the preset position is the position where the laser irradiates the ferromagnetic metal layer through the flexible substrate layer. In this way, the tensile stress and / or compressive stress of the preset position of the ferromagnetic metal layer will inevitably have a component parallel to the magnetic field direction, so that the preset position of the ferromagnetic metal layer is subjected to stress parallel to the magnetic field direction and generates strain, thereby changing the magnetic field strength of the preset position of the ferromagnetic metal layer.

[0037] If the stress parallel to the direction of the magnetic field on the preset position of the ferromagnetic metal layer is tensile stress, the magnetic field intensity at the preset position of the ferromagnetic metal layer increases, and the terahertz wave intensity generated by the terahertz wave transmitter increases; if the stress parallel to the direction of the magnetic field on the preset position of the ferromagnetic metal layer is compressive stress, the magnetic field intensity at the preset position of the ferromagnetic metal layer decreases, and the terahertz wave intensity generated by the terahertz wave transmitter decreases, thereby regulating the terahertz wave intensity generated by the terahertz wave transmitter, so that the terahertz wave intensity generated by the terahertz wave transmitter in the absence of an external magnetic field can be equivalent to the terahertz wave intensity generated in the presence of an external magnetic field. Therefore, the terahertz wave transmitter can achieve high terahertz wave emission efficiency in the absence of an external magnetic field.

[0038] In summary, the terahertz wave transmitter provided in the embodiment of the present application has low production cost, does not require external magnetic field equipment to be applied when in use, and the intensity of the generated terahertz waves can be flexibly controlled, which is convenient for practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A schematic diagram of the structure of a terahertz wave transmitter provided in an embodiment of the present application;

[0041] Figure 2 A schematic diagram of the structure of a terahertz wave transmitter provided in an embodiment of the present application;

[0042] Figure 3 A schematic diagram of the structure of another terahertz wave transmitter provided in an embodiment of the present application;

[0043] Figure 4 A schematic diagram of the structure of another terahertz wave transmitter provided in an embodiment of the present application;

[0044] Figure 5 A schematic diagram of the structure of another terahertz wave transmitter provided in an embodiment of the present application;

[0045] Figure 6 A schematic flow chart of a method for preparing a terahertz wave transmitter provided in an embodiment of the present application.

[0046] Reference numerals:

[0047] Flexible substrate layer-11; ferromagnetic metal layer 12; heavy metal layer 13. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0050] Secondly, the present application is described in detail with reference to the schematic diagram. When describing the embodiments of the present application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0051] As mentioned in the background technology section, in order to maximize the efficiency of terahertz wave emission, spintronic terahertz wave emitters usually apply an external magnetic field, which is mainly realized by a pair of permanent magnets or electromagnets, which is not conducive to the compactness of the device. The current field-free spintronic terahertz wave emitters are mainly based on the exchange bias between ferromagnetic / antiferromagnetic structures, and their control effect is relatively limited.

[0052] In view of this, an embodiment of the present application provides a terahertz wave transmitter. Figure 1 A schematic diagram of the structure of a terahertz wave transmitter provided in an embodiment of the present application is shown. Figure 1 As shown, the terahertz wave transmitter includes a flexible substrate layer 11, a ferromagnetic metal layer 12 located on one side of the flexible substrate layer 11, and a heavy metal layer 13 located on the side of the ferromagnetic metal layer 12 away from the flexible substrate layer 11, wherein the ferromagnetic metal layer 12 is pre-magnetized in-plane and has magnetism.

[0053] It can be understood that the incident femtosecond laser pulse irradiates the preset position of the ferromagnetic metal layer 12 through the flexible substrate layer 11, the photon energy is absorbed by the ferromagnetic metal layer 12, and the electrons in the ferromagnetic metal layer 12 are excited to a state higher than the Fermi level, forming an unbalanced electron distribution. Due to the difference in physical properties such as density, energy band velocity, lifetime and mobility of spin-up and spin-down electrons, a spin polarization flow along the propagation direction (Z direction) of the laser pulse will be formed in the ferromagnetic metal layer 12. When the spin flow flows into the heavy metal layer 13 (non-ferromagnetic layer), due to the strong spin-orbit coupling effect of the heavy metal layer 13, the spin-up and spin-down electrons will be deflected in opposite directions. This deflection process leads to the generation of lateral in-plane charge flow, namely the anti-spin Hall effect (ISHE). In other words, the ferromagnetic metal layer 12 generates an ultrafast spin flow under the excitation of the femtosecond laser, and the spin flow diffuses into the heavy metal layer 13, and is converted into a transient charge flow under the action of spin-orbit coupling, thereby generating a terahertz wave. It can be seen that the terahertz wave transmitter provided in the embodiment of the present application does not require an external magnetic field device when in use, that is, terahertz waves can be generated without an external magnetic field.

[0054] Furthermore, the flexible substrate layer 11 can be flexibly bent, so that the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 can be bent as a whole, thereby adjusting the magnetism of the ferromagnetic metal layer 12 and adjusting the intensity of the generated terahertz wave.

[0055] Optional, such as Figure 1As shown, the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward one side of the flexible substrate layer 11 as a whole, so that the preset position of the ferromagnetic metal layer 12 can have tensile stress. The preset position of the ferromagnetic metal layer 12 is the position where the laser irradiates the ferromagnetic metal layer 12 through the flexible substrate layer 11. Correspondingly, the preset position of the ferromagnetic metal layer 12 also has compressive stress; it can be understood that the tensile stress direction and the compressive stress direction of the preset position of the ferromagnetic metal layer 12 are tangent to the surface of the ferromagnetic metal layer 12, and the tensile stress direction is perpendicular to the compressive stress direction; it can also be understood that since the ferromagnetic metal layer 12 is pre-magnetized in the plane and has magnetism, the preset position of the ferromagnetic metal layer 12 The direction of the magnetic field is also tangent to the surface of the ferromagnetic metal layer 12; with such an arrangement, the direction of the tensile stress at the preset position of the ferromagnetic metal layer 12 can be along the X direction, and the direction of the compressive stress can be along the Y direction, and the direction of the magnetic field at the preset position of the ferromagnetic metal layer 12 can be any direction within the plane formed by the X direction and the Y direction, or in other words, no matter which direction the magnetic field direction at the preset position of the ferromagnetic metal layer 12 is in the plane formed by the X direction and the Y direction, the tensile stress and / or compressive stress at the preset position of the ferromagnetic metal layer 12 will inevitably have a component parallel to the direction of the magnetic field, so that the preset position of the ferromagnetic metal layer 12 is subjected to stress parallel to the direction of the magnetic field and generates strain, thereby changing the magnetic field strength at the preset position of the ferromagnetic metal layer 12.

[0056] If the stress parallel to the direction of the magnetic field on the preset position of the ferromagnetic metal layer 12 is tensile stress, the magnetic field intensity at the preset position of the ferromagnetic metal layer 12 increases, and the terahertz wave intensity generated by the terahertz wave transmitter increases; if the stress parallel to the direction of the magnetic field on the preset position of the ferromagnetic metal layer 12 is compressive stress, the magnetic field intensity at the preset position of the ferromagnetic metal layer 12 decreases, and the terahertz wave intensity generated by the terahertz wave transmitter decreases, thereby regulating the terahertz wave intensity generated by the terahertz wave transmitter, so that the terahertz wave intensity generated by the terahertz wave transmitter in the absence of an external magnetic field can be equivalent to the terahertz wave intensity generated in the presence of an external magnetic field. Therefore, the terahertz wave transmitter can achieve high terahertz wave emission efficiency in the absence of an external magnetic field.

[0057] Further optional, such as Figure 1As shown, the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is symmetrically bent toward one side of the flexible substrate layer 11 as a whole, and the position where the laser shines through the flexible substrate layer 11 to the ferromagnetic metal layer 12, that is, the preset position, is the middle position of the ferromagnetic metal layer 12 along the bending direction, but the present application is not limited to this. Alternatively, the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 can also be asymmetrically bent toward one side of the flexible substrate layer 11 as a whole, and the position where the laser shines through the flexible substrate layer 11 to the ferromagnetic metal layer 12, that is, the preset position, can also be other positions of the ferromagnetic metal layer 12 along the bending direction except the middle position, depending on the specific circumstances.

[0058] On the basis that the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward one side of the flexible substrate layer 11 as a whole, optionally, as Figure 2 As shown, the tensile stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12. In this way, the stress parallel to the magnetic field direction is tensile stress at the preset position of the ferromagnetic metal layer 12, which increases the magnetic field intensity at the preset position of the ferromagnetic metal layer 12, thereby increasing the terahertz wave intensity generated by the terahertz wave transmitter.

[0059] On the basis that the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward one side of the flexible substrate layer 11 as a whole, another optional method is as follows: Figure 3 As shown, the compressive stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12. In this way, the stress parallel to the magnetic field direction at the preset position of the ferromagnetic metal layer 12 is compressive stress, which reduces the magnetic field intensity at the preset position of the ferromagnetic metal layer 12, thereby reducing the terahertz wave intensity generated by the terahertz wave transmitter.

[0060] Another option, such as Figure 4As shown, the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward the side of the heavy metal layer 13 as a whole, so that the preset position of the ferromagnetic metal layer 12 can have compressive stress. The preset position of the ferromagnetic metal layer 12 is the position where the laser irradiates the ferromagnetic metal layer 12 through the flexible substrate layer 11. Correspondingly, the preset position of the ferromagnetic metal layer 12 also has tensile stress. It can be understood that the compressive stress direction and the tensile stress direction of the preset position of the ferromagnetic metal layer 12 are tangent to the surface of the ferromagnetic metal layer 12, and the compressive stress direction is perpendicular to the tensile stress direction. It can also be understood that since the ferromagnetic metal layer 12 is pre-magnetized in the plane and has magnetism, the preset position of the ferromagnetic metal layer 12 The direction of the magnetic field is also tangential to the surface of the ferromagnetic metal layer 12; with such a configuration, the compressive stress direction of the preset position of the ferromagnetic metal layer 12 can be along the X direction, and the tensile stress direction can be along the Y direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer 12 can be any direction within the plane formed by the X direction and the Y direction, or in other words, no matter which direction the magnetic field direction of the preset position of the ferromagnetic metal layer 12 is within the plane formed by the X direction and the Y direction, the compressive stress and / or tensile stress at the preset position of the ferromagnetic metal layer 12 will inevitably have a component parallel to the magnetic field direction, so that the preset position of the ferromagnetic metal layer 12 is subjected to stress parallel to the magnetic field direction and generates strain, thereby changing the magnetic field strength at the preset position of the ferromagnetic metal layer 12.

[0061] If the stress parallel to the direction of the magnetic field at the preset position of the ferromagnetic metal layer 12 is compressive stress, the magnetic field intensity at the preset position of the ferromagnetic metal layer 12 is reduced, and the terahertz wave intensity generated by the terahertz wave transmitter is reduced; if the stress parallel to the direction of the magnetic field at the preset position of the ferromagnetic metal layer 12 is tensile stress, the magnetic field intensity at the preset position of the ferromagnetic metal layer 12 is increased, and the terahertz wave intensity generated by the terahertz wave transmitter is increased, thereby regulating the terahertz wave intensity generated by the terahertz wave transmitter, so that the terahertz wave intensity generated by the terahertz wave transmitter in the absence of an external magnetic field can be equivalent to the terahertz wave intensity generated in the presence of an external magnetic field. Therefore, the terahertz wave transmitter can achieve high terahertz wave transmission efficiency in the absence of an external magnetic field.

[0062] Further optional, such as Figure 4As shown, the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is symmetrically bent toward the side of the heavy metal layer 13 as a whole, and the position where the laser shines through the flexible substrate layer 11 to the ferromagnetic metal layer 12, that is, the preset position, is the middle position of the ferromagnetic metal layer 12 along the bending direction, but the present application is not limited to this. Alternatively, the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 can also be asymmetrically bent toward the side of the heavy metal layer 13 as a whole, and the position where the laser shines through the flexible substrate layer 11 to the ferromagnetic metal layer 12, that is, the preset position, can also be other positions of the ferromagnetic metal layer 12 along the bending direction except the middle position, depending on the specific circumstances.

[0063] On the basis that the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward the heavy metal layer 13, optionally, Figure 4 As shown, the compressive stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12. In this way, the stress parallel to the magnetic field direction at the preset position of the ferromagnetic metal layer 12 is compressive stress, which reduces the magnetic field intensity at the preset position of the ferromagnetic metal layer 12, thereby reducing the terahertz wave intensity generated by the terahertz wave transmitter.

[0064] On the basis that the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward the heavy metal layer 13, another optional method is as follows: Figure 5 As shown, the tensile stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12. In this way, the stress parallel to the magnetic field direction is tensile stress at the preset position of the ferromagnetic metal layer 12, which increases the magnetic field intensity at the preset position of the ferromagnetic metal layer 12, thereby increasing the terahertz wave intensity generated by the terahertz wave transmitter.

[0065] It can be understood that no matter whether the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward the side of the flexible substrate layer 11 or toward the side of the heavy metal layer 13, when the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent symmetrically as a whole, when the laser is irradiated through the flexible substrate layer 11 to the position of the ferromagnetic metal layer 12, that is, the preset position is the middle position of the ferromagnetic metal layer 12 along the bending direction, the tensile stress and compressive stress of the ferromagnetic metal layer 12 in the middle position along the bending direction are relatively large, which is also convenient for regulating the relationship between the tensile stress direction and the compressive stress direction of the ferromagnetic metal layer 12 in the middle position along the bending direction and the magnetic field direction, and then it is convenient to regulate the intensity of the generated terahertz wave.

[0066] It can also be understood that no matter whether the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward the flexible substrate layer 11 or the heavy metal layer 13, when the tensile stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12, the magnetic field strength of the preset position of the ferromagnetic metal layer 12 is increased, thereby increasing the intensity of the terahertz wave generated by the terahertz wave transmitter; when the compressive stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12, the magnetic field strength of the preset position of the ferromagnetic metal layer 12 is reduced, thereby reducing the intensity of the terahertz wave generated by the terahertz wave transmitter; in this way, it is convenient to regulate the relationship between the tensile stress direction and the compressive stress direction and the magnetic field direction of the preset position of the ferromagnetic metal layer 12, thereby facilitating the regulation of the intensity of the generated terahertz wave.

[0067] Optionally, the flexible substrate layer 11 needs to be able to transmit 800 nm laser light, so that the 800 nm laser light can be transmitted through the flexible substrate layer 11 to irradiate the ferromagnetic metal layer 12 and excite the ferromagnetic metal layer 12 to generate a spin current.

[0068] Optionally, the material of the flexible substrate layer 11 includes but is not limited to flexible materials such as polydimethylsiloxane (PDMS) or polyimide (PI).

[0069] Optionally, the thickness of the flexible substrate layer 11 may range from 10 μm to 10 mm, including end values. For example, the thickness of the flexible substrate layer 11 may be 100 μm, or 500 μm, or 1 mm.

[0070] Optionally, the material of the ferromagnetic metal layer 12 includes but is not limited to magnetic materials such as Co, Fe, Ni, CoFe or CoFeB.

[0071] Optionally, the thickness of the ferromagnetic metal layer 12 may range from 2 nm to 20 nm, including end values. For example, the thickness of the ferromagnetic metal layer 12 may be 2 nm, or 4 nm, or 10 nm.

[0072] Optionally, the material of the heavy metal layer 13 includes but is not limited to Pt, W, Au, Ta, Au or Ir.

[0073] Optionally, the thickness of the heavy metal layer 13 may range from 2 nm to 20 nm, including end points. For example, the thickness of the heavy metal layer 13 may be 2 nm, or 4 nm, or 10 nm.

[0074] In summary, the terahertz wave transmitter provided in the embodiment of the present application has low production cost, does not require external magnetic field equipment to be applied when in use, and the intensity of the generated terahertz waves can be flexibly controlled, which is convenient for practical application.

[0075] Accordingly, the present application also provides a method for preparing a terahertz wave transmitter. Figure 6 A schematic diagram of a process for preparing a terahertz wave transmitter provided in an embodiment of the present application is shown, Figure 6 As shown, combined with Figure 1-Figure 5 As shown, the preparation method of the terahertz wave transmitter includes:

[0076] S10: providing a flexible substrate layer 11.

[0077] S20 : ​​forming a ferromagnetic metal layer 12 on one side of the flexible substrate layer 11 .

[0078] Optionally, the ferromagnetic metal layer 12 may be grown by using a thin film preparation method such as magnetron sputtering technology, molecular beam epitaxial growth technology, pulsed laser deposition technology, etc.

[0079] S30 : forming a heavy metal layer 13 on the side of the ferromagnetic metal layer 12 facing away from the flexible substrate layer 11 .

[0080] Optionally, the heavy metal layer 13 may be grown by using a thin film preparation method such as magnetron sputtering technology, molecular beam epitaxial growth technology, pulsed laser deposition technology, etc.

[0081] S40: performing in-plane magnetization on the ferromagnetic metal layer 12 so that the ferromagnetic metal layer 12 has magnetism.

[0082] S50: bend the stack consisting of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 as a whole toward the flexible substrate layer 11 or toward the heavy metal layer 13, so that the preset position of the ferromagnetic metal layer 12 has tensile stress and compressive stress, the directions of the tensile stress and the compressive stress are both tangent to the surface of the ferromagnetic metal layer 12, the direction of the tensile stress is perpendicular to the direction of the compressive stress, and the direction of the magnetic field at the preset position of the ferromagnetic metal layer 12 is tangent to the surface of the ferromagnetic metal layer 12, and the preset position is the position where the laser penetrates the flexible substrate layer 11 and irradiates the ferromagnetic metal layer 12.

[0083] It should be noted that the present application does not limit the order of performing in-plane magnetization on the ferromagnetic metal layer 12 in step S40 and bending the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 as a whole toward the flexible substrate layer 11 side or toward the heavy metal layer 13 side in step S50, that is, step S40 can be performed first to perform in-plane magnetization on the ferromagnetic metal layer 12 so that the ferromagnetic metal layer 12 has magnetism, and then step S50 can be performed to bend the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 as a whole toward the flexible substrate layer 11 side or toward the heavy metal layer 13 side. Bending; step S50 may also be performed first to bend the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 toward the flexible substrate layer 11 or toward the heavy metal layer 13, and then step S40 may be performed to magnetize the ferromagnetic metal layer 12 in a plane so that the ferromagnetic metal layer 12 has magnetism; finally, the preset position of the ferromagnetic metal layer 12 has tensile stress and compressive stress, the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer 12, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer 12 is tangent to the surface of the ferromagnetic metal layer 12.

[0084] It should also be noted that since the ferromagnetic metal layer 12 is a thin film, after the ferromagnetic metal layer 12 is magnetized in-plane, the direction of the magnetic field at each location of the ferromagnetic metal layer 12 is parallel to the surface of the ferromagnetic metal layer 12, and then, the stack consisting of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent as a whole toward the flexible substrate layer 11 or toward the heavy metal layer 13, and the direction of the magnetic field at a preset position of the ferromagnetic metal layer 12 is tangent to the surface of the ferromagnetic metal layer 12, and the direction of the magnetic field at the preset position of the ferromagnetic metal layer 12 can be controlled when the ferromagnetic metal layer 12 is magnetized in-plane, and after the in-plane magnetization of the ferromagnetic metal layer 12 is completed, the direction of the magnetic field at the preset position of the ferromagnetic metal layer 12 can be fixed.

[0085] The embodiment of the present application further provides a control method for a terahertz wave transmitter, which is applied to the terahertz wave transmitter provided in any of the above embodiments. The control method for the terahertz wave transmitter includes:

[0086] S100: regulating the bending direction and curvature of the stacked body consisting of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter to regulate the intensity of the terahertz wave emitted by the terahertz wave transmitter.

[0087] Specifically, regulating the bending direction of the stacked layer consisting of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter includes:

[0088] S110: regulating the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter to bend as a whole toward the flexible substrate layer 11 side or toward the heavy metal layer 13 side, so that a preset position of the ferromagnetic metal layer 12 has tensile stress and compressive stress, the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer 12, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer 12 is tangent to the surface of the ferromagnetic metal layer 12, and the preset position is the position where the laser penetrates the flexible substrate layer 11 and irradiates the ferromagnetic metal layer 12;

[0089] Wherein, the tensile stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12;

[0090] Alternatively, the compressive stress direction at the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction at the preset position of the ferromagnetic metal layer 12 .

[0091] As is known from the foregoing, no matter the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 is bent toward the flexible substrate layer 11 or the heavy metal layer 13, when the tensile stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12, the magnetic field intensity of the preset position of the ferromagnetic metal layer 12 is increased, thereby increasing the intensity of the terahertz wave generated by the terahertz wave transmitter; when the compressive stress direction of the preset position of the ferromagnetic metal layer 12 is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer 12, the magnetic field intensity of the preset position of the ferromagnetic metal layer 12 is reduced, thereby decreasing the intensity of the terahertz wave generated by the terahertz wave transmitter; in this way, it is convenient to regulate the relationship between the tensile stress direction and the compressive stress direction and the magnetic field direction of the preset position of the ferromagnetic metal layer 12, thereby facilitating the regulation of the intensity of the generated terahertz wave.

[0092] Further, regulating the bending curvature of the stacked layer consisting of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter includes:

[0093] S120: regulating the bending curvature of the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter, so that the stress value along the bending direction of the ferromagnetic metal layer 12 among the tensile stress and compressive stress at a preset position of the ferromagnetic metal layer 12 does not exceed 0.2×d, where d is the thickness of the flexible substrate layer 11 in millimeters.

[0094] It can be understood that, within a certain degree, the greater the bending degree of the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter, that is, the greater the bending curvature and the smaller the curvature radius, the greater the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12, and the easier it is to control the intensity of the generated terahertz wave. However, when the bending curvature of the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter is large to a certain degree, that is, the curvature radius is small to a certain degree, the ability of the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12 to control the intensity of the generated terahertz wave will tend to saturation.

[0095] It can also be understood that when the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter is bent toward the flexible substrate layer 11, as shown in FIG. Figure 2 and Figure 3 As shown, among the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12, the tensile stress is the stress along the bending direction of the ferromagnetic metal layer 12. At this time, if the tensile stress is parallel to the direction of the magnetic field, the intensity of the generated terahertz wave can be increased; if the tensile stress is perpendicular to the direction of the magnetic field, the intensity of the generated terahertz wave can be reduced.

[0096] Similarly, when the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter is bent toward the heavy metal layer 13, Figure 4 and Figure 5 As shown, among the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12, the compressive stress is the stress along the bending direction of the ferromagnetic metal layer 12. At this time, if the compressive stress is parallel to the direction of the magnetic field, the intensity of the generated terahertz wave can be reduced; if the compressive stress is perpendicular to the direction of the magnetic field, the intensity of the generated terahertz wave can be increased.

[0097] Moreover, the stress along the bending direction of the ferromagnetic metal layer 12 among the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12 can be expressed as ε = T / 2R, wherein T is the total thickness of the laminate composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13, and R is the bending radius of the laminate composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13. The thickness of the flexible substrate layer 11 is d in millimeters.

[0098] The inventors have found through experimental research that after the bending curvature of the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter is regulated so that the value of the stress ε along the bending direction of the ferromagnetic metal layer 12 in the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12 exceeds 0.2×d, the ability of the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12 in the tensile stress and compressive stress along the bending direction of the ferromagnetic metal layer 12 to regulate the intensity of the generated terahertz wave tends to be saturated. Therefore, the bending curvature of the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter is regulated so that the value of the stress ε along the bending direction of the ferromagnetic metal layer 12 in the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12 does not exceed 0.2×d, so as to better regulate the intensity of the generated terahertz wave.

[0099] For example, the thickness of the flexible substrate layer 11 is 25 μm, and the value d of the thickness of the flexible substrate layer 11 in millimeters is 0.025. The bending curvature of the stack composed of the flexible substrate layer 11, the ferromagnetic metal layer 12 and the heavy metal layer 13 in the terahertz wave transmitter is regulated so that the stress value along the bending direction of the ferromagnetic metal layer 12 in the tensile stress and compressive stress at the preset position of the ferromagnetic metal layer 12 does not exceed 0.2×d=0.005, so as to better regulate the intensity of the generated terahertz wave. It can be understood that the greater the thickness of the flexible substrate layer 11, the greater the stress value corresponding to 0.2×d.

[0100] The various parts in this manual are described in a combination of parallel and progressive ways. Each part focuses on the differences from other parts, and the same or similar parts between the various parts can be referenced to each other.

[0101] With respect to the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other, so that professionals in the field can implement or use the present application. Various modifications to these embodiments will be apparent to professionals in the field, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A terahertz wave transmitter, characterized in that: include: A flexible substrate layer; A ferromagnetic metal layer located on one side of the flexible substrate layer, wherein the ferromagnetic metal layer has magnetism; a heavy metal layer located on a side of the ferromagnetic metal layer facing away from the flexible substrate layer; The stack composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer is bent as a whole toward the flexible substrate layer side or toward the heavy metal layer side, so that a preset position of the ferromagnetic metal layer has tensile stress and compressive stress, the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer is tangent to the surface of the ferromagnetic metal layer, and the preset position is the position where the laser penetrates the flexible substrate layer and irradiates the ferromagnetic metal layer.

2. The terahertz wave transmitter according to claim 1, characterized in that: The stack composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer is symmetrically bent toward one side of the flexible substrate layer or symmetrically bent toward one side of the heavy metal layer, and the preset position is the middle position of the ferromagnetic metal layer along the bending direction.

3. The terahertz wave transmitter according to claim 1, characterized in that: The tensile stress direction of the preset position of the ferromagnetic metal layer is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer; Alternatively, the compressive stress direction of the preset position of the ferromagnetic metal layer is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer.

4. The terahertz wave transmitter according to any one of claims 1 to 3, characterized in that: The material of the flexible substrate layer includes polydimethylsiloxane or polyimide; The thickness of the flexible substrate layer ranges from 10 μm to 10 mm, including end points.

5. The terahertz wave transmitter according to any one of claims 1 to 3, characterized in that: The material of the ferromagnetic metal layer includes Co, Fe, Ni, CoFe or CoFeB; The thickness of the ferromagnetic metal layer ranges from 2 nm to 20 nm, including end points.

6. The terahertz wave transmitter according to any one of claims 1 to 3, characterized in that: The material of the heavy metal layer includes Pt, W, Au, Ta, Au or Ir; The thickness of the heavy metal layer ranges from 2 nm to 20 nm, including end points.

7. A method for preparing a terahertz wave transmitter, characterized in that: include: providing a flexible substrate layer; forming a ferromagnetic metal layer on one side of the flexible substrate layer; forming a heavy metal layer on a side of the ferromagnetic metal layer facing away from the flexible substrate layer; Magnetizing the ferromagnetic metal layer in-plane so that the ferromagnetic metal layer has magnetism; The stack consisting of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer is bent as a whole toward the flexible substrate layer side or toward the heavy metal layer side, so that a preset position of the ferromagnetic metal layer has tensile stress and compressive stress, the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer is tangent to the surface of the ferromagnetic metal layer, and the preset position is the position where the laser penetrates the flexible substrate layer to irradiate the ferromagnetic metal layer.

8. A method for controlling a terahertz wave transmitter, characterized in that: Applicable to the terahertz wave transmitter according to any one of claims 1 to 6, the control method of the terahertz wave transmitter comprises: The intensity of the terahertz wave emitted by the terahertz wave emitter is regulated by regulating the bending direction and the bending curvature of the stacked layer composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave emitter.

9. The control method of the terahertz wave transmitter according to claim 8, characterized in that: Adjusting the bending direction of the stacked layer consisting of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave transmitter includes: The stack composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave transmitter is regulated to bend as a whole toward the flexible substrate layer or toward the heavy metal layer, so that a preset position of the ferromagnetic metal layer has tensile stress and compressive stress, the tensile stress direction and the compressive stress direction are both tangent to the surface of the ferromagnetic metal layer, the tensile stress direction is perpendicular to the compressive stress direction, and the magnetic field direction of the preset position of the ferromagnetic metal layer is tangent to the surface of the ferromagnetic metal layer, and the preset position is the position where the laser penetrates the flexible substrate layer and irradiates the ferromagnetic metal layer; Wherein, the tensile stress direction of the preset position of the ferromagnetic metal layer is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer; Alternatively, the compressive stress direction of the preset position of the ferromagnetic metal layer is parallel to the magnetic field direction of the preset position of the ferromagnetic metal layer.

10. The control method of the terahertz wave transmitter according to claim 9, characterized in that: Regulating the bending curvature of the stacked layer consisting of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave transmitter includes: The bending curvature of the stack composed of the flexible substrate layer, the ferromagnetic metal layer and the heavy metal layer in the terahertz wave transmitter is regulated so that the stress value along the bending direction of the ferromagnetic metal layer among the tensile stress and compressive stress at a preset position of the ferromagnetic metal layer does not exceed 0.2×d, where d is the thickness of the flexible substrate layer in millimeters.

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