Spintronic nano-antenna activated by spin injection from a three-dimensional topological insulator

Abstract

Disclosed apparatuses include a spintronic, oscillating injection current activated nano-antenna, include a thin-film topological insulator (3D-TI) body, having a top surface and a bottom surface, a first electrode, disposed on the top surface of the 3D-TI body, and a second electrode, disposed on the top surface of the 3D-TI bode, spaced apart from the first electrode. An array of ferromagnetic nanomagnet is disposed on the top surface of the 3D-TI body, between the first electrode and the second electrode.

Description

BAN-24-076Att’y Docket: 02941784TASpintronic Nano-Antenna Activated by Spin Injection from a Three-Dimensional Topological InsulatorCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of United States Provisional Application 63 / 687,895 filed August 28, 2024, the complete contents of which are incorporated herein by reference.BACKGROUNDTechnical Field

[0002] Embodiments generally relate to subwavelength antennas, and more particularly to extreme subwavelength antennas with high radiation efficiency and steerable anisotropic radiation.

[0003] SUMMARY

[0004] This Summary presents example features and aspects and is not an exclusive or exhaustive description of disclosed subject matter. Whether or not a feature is included in this Summary is not intended as an indication of the feature’s relative importance or benefit.

[0005] One example apparatus. According to various embodiments, can include a spintronic, oscillating injection current activated nano-antenna, comprising a thin-film topological insulator (3D-T1) body, which can have a top surface and a bottom surface, a first electrode, disposed on the top surface of the 3D-TI body, a second electrode, disposed on the top surface of the 3D-TI bode, spaced apart from the first electrode; and a two-dimensional array of ferromagnetic nanomagnets, disposed on the top surface of the 3D-TI body, between the first electrode and the second electrode.

[0006] BRIEF DESCRIPTION OF DRAWINGS

[0007] A further understanding of the nature and advantages of the embodiments may be realized by reference to the following drawings. It will be understood that the drawings show illustrative, not limitative, features and examples. It will also be understood that the drawing graphics are scaled for readability and that graphic representations of functions and features are not necessarily drawn to a scale consistent with their physical implementations. Also, in the drawings, similar components or features may have the same reference label.

[0008] Figure 1 shows a top view of one three-dimensional (3D) topological insulator (TI) spininjection activated spintronic nano-antenna according to various embodiments, showing a top surface of the nano-antenna’s 3D-TI sheet and, disposed on the top surface in accordance with theBAN-24-076Att’y Docket: 02941784TA various embodiments a distribution of ferromagnetic nanomagnets (hereinafter alternatively referenced as “nano FMT distribution”), in combination with a first pair of charge current pads, spaced apart in a first direction, and facing one another from opposite sides of the nano FMT distribution, a second pair of charge current pads, spaced apart in a second direction and facing one another from other opposite sides of the nano FMT distribution.

[0009] Figure 2 shows a cross-cut view, from Figure 1 cross-cut projection plane 2-2, of structural aspects of the Figure 1 example 3D-TI spin-injection activated spintronic nano-antenna according to various embodiments.

[0010] Figure 3 shows an enlarged view of a representative portion of one example two- dimensional (2D) periodic array arrangement for a plurality of nano FMTs disposed on a surface of a 3D-TI body, which can be an example implementation of the nano FMT distribution, e.g., the Figure 1 example and other configurations of 3D-TI spin-injection activated spintronic nanoantenna according to various embodiments.

[0011] Figure 4 shows a scanning electron micrograph of one inventor-made nano FMT array, configured with a 2D periodic array arrangement in general accordance with the Figure 3 example.

[0012] Figure 5 shows a schematic view of one first orientation charge current mode of one 3D- TI spin-injection activated spintronic nano-antenna according to various embodiments.

[0013] Figure 6 shows a 3D model of one extracted 3D structural region of the Figure 4 3D-TI spin-injection activated, extreme sub- wavelength spintronic nano-antenna, annotated with graphic markings representing certain surface spin polarizations and spin injection currents produced by the Figure 5 first orientation charge current and that activate, according to various embodiments, electromagnetic radiation from the nano-antenna’s plurality of nano FMTs.

[0014] Figure 7 shows a schematic view of one first orientation oscillating charge current operating mode of one 3D-TI spin-injection activated spintronic nano-antenna according to some embodiments, annotated with graphics indicating a first orientation oscillating charge current activated magnetic dipole axis.

[0015] Figure 8 shows a schematic view of one second orientation oscillating charge current operating mode of one 3D-TI spin-injection activated FMT array spintronic nano-antenna according to some embodiments, annotated with graphics indicating a second orientation oscillating charge current activated magnetic dipole axis.

[0016] Figure 9 shows a top view of another 3D-TI spin-injection activated spintronic nano- antenna according to various embodiments, which supports another modality of beam steering,BAN-24-076Att’y Docket: 02941784TA comprising activating one fixed electrode and then others sequentially.

[0017] Figure 10 shows a modification of the Figure 9 example.

[0018] Figure 11 shows a measurement set-up that was used by the inventors in conducting certain measurements of certain first orientation charge current activated electromagnetic radiation characteristics, described in more detail in later sections of this disclosure, of an inventor-made real sample of a 3D-TI spin-injection activated, extreme sub-wavelength spintronic nano-antenna according to one or more embodiments and certain measurements of certain first orientation charge current fed electromagnetic radiation characteristics of an inventor-made control sample having certain structural similarities to and certain structural differences from the inventor-made operative sample, as described in more detail in later sections of this disclosure.

[0019] Figure 12 shows a second orientation charge current adaptation of the Figure 11 measurement set-up measurement set-up, and the adaptation was used by the inventors in conducting certain measurements of certain second orientation charge current activated electromagnetic radiation characteristics, also described in more detail in later sections of this disclosure, of the inventor-made real sample of a 3D-TI spin-injection activated, extreme subwavelength spintronic nano-antenna according to one or more embodiments and certain measurements of certain second orientation charge current fed electromagnetic radiation characteristics of the inventor-made control sample, as described in more detail in later sections of this disclosure.

[0020] Figure 13 A shows a measured spectra of the electromagnetic emission, of the inventor- made real sample of a 3D-TI spin-injection activated, extreme sub-wavelength spintronic nanoantenna according to one or more embodiments, and of the inventor-made control sample, each measured using the x-direction arranged hom of the Figure 11 first orientation charge current measurement set-up, positioned in the plane of the nanomagnets. The figure shows the measured spectra for the real sample in blue color and the measured spectra for the control sample in red color.

[0021] Figure 13B shows the measured spectra of the electromagnetic emission, of the same inventor-made real sample of a 3D-TI spin-injection activated, extreme sub-wavelength spintronic nano-antenna according to one or more embodiments, and of the same-made control sample, each measured using the y-direction arranged hom of the Figure 11 first orientation charge current measurement set-up, positioned in the plane of the nanomagnets, with the alternating current source set the same as for the Figure 13A presented measurements.BAN-24-076Att’y Docket: 02941784TA

[0022] Figure 14A shows the spectrum of the S 11 scattering parameters of the real sample and of the control sample, measured by the inventors using the Figure 11 first orientation charge current measurement set-up, positioned in the plane of the nanomagnets, showing measured spectra for the real sample in blue color and the measured spectra for the control sample in red color.

[0023] Figure 14B shows the spectrum of the Sil scattering parameters of the real sample and of the control sample, measured by the inventors using the Figure 12 second orientation charge current measurement set-up, positioned in the plane of the nanomagnets, showing measured spectra for the real sample in blue color and the measured spectra for the control sample in red color.

[0024] Figure 15 shows a mapping onto the plane of the real sample nano FMT array, the X, Y, Z axes of inventor-measured measured radiation patterns shown in Figures 17 A, 17B, 18 A, and 18B.

[0025] Figure 16 shows the spatial relation of the polarization plane of the measured radiation patterns shown in Figures 17A, 17B, 18A, andl8B to the plane of the measured real sample FMT array.

[0026] Figure 17A shows the inventor-measured radiation patterns, in db, for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the inventors’ measurement set-up, for the real sample, while activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0027] Figure 17B shows, in db, the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the control sample, by the above described measurement applying the Figure 11 first orientation current at the same three oscillating current frequencies.

[0028] Figure 18A shows, in db, the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample by the measurement set-up, activated using the Figure 12 second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0029] Figure 18B, shows, in db, the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the control sample, by the measurement set-up, applying the Figure 12 second orientation current at the same three oscillating current frequencies input to the real sample 1102, i.e., 3.4 GHz, 5 GHz, and 10 GHz.

[0030] Figure 19A shows, in db, the measured radiation patterns for the vertical polarization of the electromagnetic wave detected for the real sample by the measurement set-up, activated using the Figure 11 first orientation charge current, applying three different oscillating currentBAN-24-076Att’y Docket: 02941784TA frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0031] Figure 19B shows, in db, measured radiation patterns for the vertical polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement setup. The real sample was activated using the Figure 12 second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0032] Figure 20 shows a mapping onto the plane of the real sample nano FMT array of the X, Y, Z axes of the Figure 22A, 22B, 23A, and 23B measured radiation patterns.

[0033] Figure 21 shows the spatial relation of the polarization plane of the measured radiation patterns shown in Figures 22A, 22B, 23A, and 23B to the plane of the real sample FMT array.

[0034] Figure 22A shows, in db, the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the described measurement setup. The real sample was activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0035] Figure 22B, shows, in db, the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample by the described measurement set-up, activated using the Figure 12, second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0036] Figure 23A shows, in db, the measured radiation patterns for the vertical polarization of the electromagnetic wave detected for the real sample by the described measurement set-up, activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0037] Figure 23B shows, in db, the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample by the described measurement set-up, activated using the Figure 12 second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0038] Figure 24 shows a mapping onto the plane of the real sample nano FMT array of the X, Y, Z axes of the Figure 26 A, 26B, 27 A, and 27B measured radiation patterns.

[0039] Figure 25 shows the spatial relation of the polarization plane of the measured radiation patterns shown in Figures 26A, 26B, 27A, and27B to the plane of the real sample FMT array 1108.

[0040] Figure 26A shows in db the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the described measurement set-up, activated using the Figure 11 first orientation charge current, applying three different oscillatingBAN-24-076Att’y Docket: 02941784TA current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0041] Figure 26B shows in db the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample by the described measurement set-up, activated using the Figure 12, second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz

[0042] Figure 27A shows in db the measured radiation patterns for the vertical polarization of the electromagnetic wave detected for the real sample by the described measurement set-up, activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0043] Figure 27B shows in db the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample by the described measurement set-up, activated using the Figure 12 second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz.

[0044] DETAILED DESCRIPTION

[0045] Disclosed embodiments provide a novel, high radiation efficiency, 3D-TI body activated nano-antenna that can receive an oscillating feed current, e.g., from a signal source, and can pass the oscillating feed current through a 3D-TI body having, e.g., on a top surface, a distribution of nanomagnets and an arrangement of conductive pads. According to various embodiments the conductive pads may be arranged in pairs, i.e., as groups of two conductive pads that are spaced apart from one another. A results is that connecting the oscillating feed current to the pair produces an alternating polarity charge current flow through the 3D-TI body, in a direction aligned with the direction of the spacing between the pads. In accordance with various embodiments the pairs of conductive pads can be further positioned, in relation to the nanomagnets, such that the charge current flow passes under the distribution of nanomagnets, producing 3D-TI body top surface and bottom surface spin polarizations.

[0046] Also in accordance with various embodiments, the 3D-TI body, the distribution of nanomagnets, and the pairs of conductive pads can be further configured such that the 3D-TI body top surface and bottom surface spin polarizations, which may be oscillating spin polarizations due to the alternating direction of the charge current, can produce spin injection currents in the 3D-T1 body that can couple to the nanomagnets, with sufficiency to produce oscillating magnetic polarizations in the nanomagnets. These oscillating magnetic polarizations in the nanomagnets, in turn, can activate the nanomagnets to radiate electromagnetic waves.BAN-24-076Att’y Docket: 02941784TA

[0047] Further, the radiation efficiency of the nanomagnets, activated by the 3D-TI body in accordance with various embodiments,, can be high. This can include high efficiency extreme subwavelength radiation.

[0048] An additional and significant feature of 3D-TI body activated nano-antennas in accordance with various embodiments is that their activated electromagnetic radiation has an anisotropy and further embodiments and configurations described in more detail later in this disclosure, can incorporate and provide novel, effective utilization and control of this anisotropy. In overview, 3D-TI body activated nano-antennas in accordance with various embodiments can provide, through a particularly controlled anisotropy and high radiation efficiency, a beamsteering, extreme subwavelength point source antenna.

[0049] One example spintronic, oscillating injection current activated nano-antenna according to various embodiments can comprise a topological insulator (3D-TI) body, which can be a thin film a top surface and a bottom surface. The example can include, disposed on the top surface of the 3D-TI body, a first electrode and a second electrode. The first electrode and second electrode may be functionally associated, e.g., for being connected, respectively, to a two-conductor signal output of a signal source. Accordingly, the first electrode and the second electrode may be alternatively referred to as a “pair of electrodes.”

[0050] It will be understood that “electrode,” as used herein, is a function label that, except in instances where otherwise stated, explicitly or clearly by implication, or is not limitative with respect to structure. For example, implementations of the first electrode and the second electrode can include a pair of conductive pads or conductive contacts, disposed on the top surface.

[0051] The example spintronic, oscillating injection current activated nano-antenna according to various embodiments can further include a plurality of separate, meaning a spaced apart distribution of a plurality of ferromagnetic nanomagnets disposed on the top surface, According to some embodiments the distribution of the plurality of ferromagnetic nanomagnets can be configured as a two-dimensional (2D) array of ferromagnetic nanomagnets. According to some embodiments the 2D array of ferromagnetic nano magnets can be arranged as a 2D periodic array. The array, if 2D periodic, may be linearly periodic.

[0052] According to various embodiments the plurality of ferromagnetic nanomagnets may be arranged in an area between the first electrode and the second electrode. Stated differently, according to various embodiments the first electrode and the second electrode may be positioned in an antipodal arrangement in relation to the plurality of ferromagnetic nanomagnets.BAN-24-076Att’y Docket: 02941784TA

[0053] The first electrode and the second electrode can be configured to receive an alternating charge current, which is externally sourced, the alternating charge current having a charge current frequency. The 3D-TI body can be configured to carry, in response, an alternating charge current flow through the 3D-TI body, the alternating charge current flow passing between the first electrode and the second electrode in a direction under the 2D periodic array of ferromagnetic nanomagnets.

[0054] The 3D-TI body can be configured to inject, in response to the alternating charge current flow through the 3D-TI body, alternating spin currents into the ferromagnetic nanomagnets of the 2D periodic array of ferromagnetic nanomagnets. The alternating spin currents can alternate with said charge current frequency and, according to various embodiments, can have magnitudes sufficient to produce oscillations of the ferromagnetic nanomagnets’ respective magnetic polarizations sufficient to produce, from the 2D periodic array of ferromagnetic nanomagnets, an electromagnetic radiation of a frequency equal to said charge current frequency.

[0055] According to various embodiments, ferromagnetic nanomagnets may be spatially arranged as an array, e.g., a row-column array of M rows and N columns, M being an integer greater than one, and N being an integer greater than one. The M rows may extend in a row direction, and the N columns may extend in a column direction.

[0056] In some implementations of spintronic, oscillating injection current activated nanoantenna according to some embodiments, the first electrode and the second electrode may be spatially arranged in an antipodal spatial relation to the 2D periodic array, and the antipodal spatial relation may be configured such that the alternating charge current flow through the 3D-TI body can extend under the 2D periodic array of ferromagnetic nanomagnets in a direction relative to the row direction. In some configurations, the direction relative to the row direction may be perpendicular to the row direction.

[0057] For convenience in describing certain further configurations of oscillating injection current activated nano-antenna according to further embodiments, the above-introduced antipodal spatial relation will be labeled as a first antipodal spatial relation, the direction relative to the row direction as a first direction relative to the row direction, the alternating charge current as an alternating first charge current, the alternating spin currents as alternating first spin currents, and the charge current frequency as a first charge current frequency.

[0058] Configuration of oscillating injection current activated nano-antenna according to some further embodiments can further comprise a third electrode and a fourth electrode, which can beBAN-24-076Att’y Docket: 02941784TA disposed on the top surface of the 3D-TI body in what me be a second antipodal spatial relation to the 2D periodic array of ferromagnetic nanomagnets. The third electrode and the fourth electrode can be configured to receive an alternating second charge current, which can be externally sourced. In some practices and some applications, the second alternating charge current may comprise a switching of the above-described alternating first charge current, to the third electrode and the further electrode. In other practices and applications the second alternating charge current may be differently configured and / or differently sourced signal. The alternating second charge current may have, for example, a second charge current frequency.

[0059] According to some embodiments, the 3D-TI body can be further configured to carry, in response to the alternating second charge current, an alternating second charge current flow through the 3D-TI body. The alternating second charge current flow may extend between the third electrode and the fourth electrode, under the 2D periodic array of ferromagnetic nanomagnets. The 3D-TI body may be further configured to inject, in response to the alternating second charge current flow through the 3D-TI body, alternating second spin currents into the ferromagnetic nanomagnets of the 2D periodic array of ferromagnetic nanomagnets / The configuration can be such that the alternating second spin currents alternate with the second charge current frequency and such that the magnitudes are sufficient to produce second oscillations of the ferromagnetic nanomagnets’ respective magnetic polarizations sufficient to produce, from the 2D periodic array of ferromagnetic nanomagnets, a second electromagnetic radiation of a frequency equal to said second charge current frequency

[0060] Example Benefits and Advantages

[0061] Systems and methods according to disclosed embodiments include numerous technical features and advantages, and these can provide a large number of application, performance, and cos advantages. These include, but are not limited to, providing an extreme subwavelength nanoantenna that radiates with an efficiency several orders of magnitude larger than the Harrington limit; providing an extreme subwavelength nano-antenna that does not require any acoustic attenuation. Technical benefits and advantage further include, but are not limited to, providing an extreme subwavelength nano-antenna that can be actuated by alternating current.

[0062] Technical benefits and advantage also include, but are not limited to, providing an extreme subwavelength nano-antenna that provides beam steering from a single antenna element - eliminating as opposed to a phased array

[0063] Illustrative ApplicationsBAN-24-076Att’y Docket: 02941784TA

[0064] Applications for systems and methods according to disclosed embodiments are extensive and span a plurality of technologies. The embodiments provide bcamforming antennas that can have physical dimensions orders of magnitude smaller than the wavelength of the signal, yet can steerably transmit that signal. In other words. This can enable aggressive miniaturization, which has applicability in, for example and without limitation, medical implant antennas , stealth audio, optical, and other and sensor devices, defense, and law-enforcement.

[0065] Systems and methods according to some embodiments can provide, from a single antenna element of physical dimension orders of magnitude smaller than the wavelength of a desired communication signal, a continuously steerable beam transmission of that signal.

[0066] EXAMPLES

[0067] Example 1 - One Example 3D-TI Spin-In jection Activated Spintronic Nano- Antenna

[0068] Figure 1 shows a top view of one 3D-TI spin-injection activated spintronic nano-antenna 100 according to various embodiments, (hereinafter “example 100” and “3D-TI spin-injection activated nano-antenna 100.” Figure 2 shows a cross-cut view, from Figure 1 cross-cut projection plane 2-2, of structural aspects of the Figure 1 example.

[0069] The example 100 can include a 3D-TI body 102, which may be formed as a 3D-TI sheet that can have a top surface 102A and a bottom surface 102B. The 3D-TI body 102 may comprise a material such as, for example, Bi2Se3. Disposed on the top surface 102A, in accordance with various embodiments, is a distribution of ferromagnetic nanomagnets 104 (hereinafter alternatively referenced as, e.g., “nano FMTs 104,” “distribution 104 of nano FMTs”). In accordance with various embodiments, the nano FMTs may be arranged as a 2D array, as described in more detail in subsequent paragraphs of this disclosure. Example 2Also disposed on the top surface 102A, in accordance with various embodiments, may be a plurality of electrode pairs, and each can be implemented as a pair of electrical conductor contact pads, which can be arranged antipodally in spatial relation to the distribution 104 of nano FMTs. The example 100 shown in Figures 1 and 2 implements the plurality of electrode pairs as a first electrode pair, comprising a first contact pad 106 A and a second contact pad 106B, and a second electrode pair, comprising a third contact pad 108A and a fourth contact pad 108B. In the example 1001 the first contact pad 106A and the second contact pad 106B are arranged in a first antipodal relation to the nano FMTs 104, and the third contact pad 108 A and the fourth contact pad 108B are arranged in a second antipodal relation to the nano FMTs 104.

[0070] It will be understood that the Figure 1 and Figure 2 use of two charge current electrodeBAN-24-076Att’y Docket: 02941784TA pairs as the plurality of electrode pairs is an example, not a limitation on the number of charge current electrode pairs according to disclosed embodiments. As one illustration, another example configuration includes a third charge current electrode pair and a fourth charge current electrode pair.

[0071] Example 2 - Spin Coupling from 3D-TI Body to Nano FMT Array

[0072] Figure 5 shows a schematic view of one first orientation charge current mode of one 3D- TI spin-injection activated spintronic nano-antenna according to various embodiments.

[0073] Figure 6 shows a 3D model of one extracted 3D structural region of the Figure 4 3D-TI spin-injection activated, extreme sub-wavelength spintronic nano-antenna, annotated with graphic markings representing certain surface spin polarizations and spin injection currents produced by the Figure 5 first orientation charge current and that activate, according to various embodiments, electromagnetic radiation from the nano-antenna’s plurality of nano FMTs.

[0074]

[0075] Example 3 - One 2D Periodic Array Distribution of the Nano FMTs

[0076] Figure 3 shows an enlarged view of a representative portion 300 of one example 2D periodic array arrangement for a plurality of nano FMTs disposed on a surface of a 3D-TI body, which can be an example implementation of the nano FMT distribution, e.g., the Figure 1 example and other configurations of 3D-TI spin-injection activated spintronic nano-antenna according to various embodiments.

[0077] Example 4 - Real Sample Fabrication

[0078] Figure 4 shows a scanning electron micrograph of a region of one inventor-made nano FMT array portion of an inventor-made real sample, configured with a 2D periodic array arrangement in general accordance with the Figure 3 example.

[0079] Fabrication started with a Bi2Se3 film. The Bi2Se3 was first cleaned in acetone and isopropyl alcohol, and Al electrodes implementing the charge current injection electrodes were delineated using optical lithography. After delineation of the electrodes, a substrate was spin-coated, using a spinning rate of 1000 rpm, with a double layer polymethylmethacrylate (PMMA) resist and subsequently baked at 110D for 2 minutes. Next, electron beam lithography was performed using a Raith Voyager Electron Beam Lithography system having accelerating voltage of 50 kV and beam current of 300pA, to open windows for deposition od the nanomagnets. The resists were finally developed in methyl isobutyl ketone and isopropyl alcohol (MIBK-IPA) for 30 seconds, which was followed by a cold isopropyl alcohol (IPA) rinse. A 5 nm thick Ti adhesion layer was deposited onBAN-24-076Att’y Docket: 02941784TA the patterned substrate using electron beam evaporation at a base pressure of 2.3 x 10 -7 Torr, followed by the electron beam deposition of 6nm thick Co. The lift-off was performed using remover PG solution (a proprietary solvent stripper).

[0080] Example 5 - Example Charge Current Orientations

[0081] Figure 7 shows a schematic view of one first orientation oscillating charge current operating mode of one 3D-TI spin-injection activated spintronic nano-antenna according to some embodiments, annotated with graphics indicating a first orientation oscillating charge current activated magnetic dipole axis.

[0082] Figure 8 shows a schematic view of one second orientation oscillating charge current operating mode of one 3D-TI spin-injection activated FMT array spintronic nano-antenna according to some embodiments, annotated with graphics indicating a second orientation oscillating charge current activated magnetic dipole axis.

[0083] Example 6 - Another Example FMT Array and Eharge Electrode Arrangement

[0084] Figure 9 shows an additional embodiment, which includes additional charge current electrode pairs, each capable of passing additionally directed charge currents through the 3D-TI body. Stated different. The additional charge current electrode pairs can provide a further resolution in the direction of the charge current. One example system arrangement can couple to the plurality of charge current electrode pairs a multi-phase clock. These can effect injection between different ones of the pairs of charge current electrodes of respective charge currents, with a sequencing that can provide the equivalent of an active electronically scanned array (AES A) having linear dimension of at least 2 to 3 orders of magnitude smaller that the wavelength of the transmitted signals, e.g., 1 GHz to 10 GHz. These can provide, effectively, an ultraminiaturized beam scanner.

[0085] Figure 10 shows one variation of the Figure 10 example.

[0086] Example 7 - Spectrum Measurement

[0087] Test Set-Up

[0088] The radiation pattern measurements were carried out in an AMS-8100 Anechoic Chamber Antenna Measurement System with a rotating sample holder made of an insulating material while the electromagnetic spectrum measurements were carried out in an AMS-5701 Anechoic Chamber. The measurements were of a real sample made by the inventors according to the Example 4 process described above. Figures 11 and 12 show the real sample 1102 in spatial relation to a horn antenna at an “X” axis measurement position-alignment 1104A, a “Y” axis measurement positionalignment 1104B, and “Z” axis measurement position- alignment 1104C.BAN-24-076Att’y Docket: 02941784TA

[0089] The real sample 1102 comprised a real sample thin-film 3D-TI body 1106 and, disposed on an upper surface of the 3D-TI body, a real sample nano FMT array 1108, a real sample first charge current electrode pair, comprising a real sample first conductor pad 1110A and a real sample second conductor pad 1110B, and a real sample second charge current electrode pair, comprising a real sample third conductor pad 1112A and a real sample fourth conductor pad 1112B.

[0090] In the AMS-8100 Chamber, the real sample 1102 was placed at a distance of 284.5 cm from the measuring horn antenna of cross-section 50 cm x 50 cm, while in the AMS-5701 Chamber, the real sample was placed at a distance of 81 cm from the horn antenna of cross-section 3 cm x 3 cm.

[0091] The measurements included radiation pattern measurements while feeding the real sample different frequencies of a first orientation charge current, and included radiation pattern measurements while feeding the real sample 1102 different frequencies of a second orientation charge current. Figures 11 and 12 show the spatial alignments of the measurement set-up’s horn antenna X axis measurement position-alignment 1104A, Y axis measurement position-alignment 1104B, and Z axis measurement position- alignment 1104C.

[0092] Figure 11 shows the first orientation charge current connection to the real sample 1102 and the direction of the first orientation charge current CT-1 through the real sample 3D-TI body 1106, in relation to the measurement set-up’s horn antenna X axis measurement positionalignment 1104A, Y axis measurement position-alignment 1104B, and Z axis measurement position- alignment 1104C, and in relation to the row-column directions of the real sample’s nano FMT array 1108.

[0093] Figure 12 shows the second orientation charge current connection to the real sample 1102 and the direction of the second orientation charge current CT-2 through the real sample 3D-TI body 1106, in relation to the measurement set-up’s horn antenna X axis measurement positionalignment 1104A, Y axis measurement position-alignment 1104B, and Z axis measurement position- alignment 1104C, and in relation to the row-column directions of the real sample’s nano FMT array 1108.

[0094] Control Sample

[0095] The inventors made control sample, having radiative structures with radiating characteristics having similarity to the radiative characteristics of the real sample.

[0096] TestsBAN-24-076Att’y Docket: 02941784TA

[0097] Using the Figure 11 the first orientation alternating current source arrangement, the inventors connected the alternating current source to input to the 1102 sample’s first electrode pair first conductor pad 1110A and second conductor pad 1110B a current frequency of 3.4 GHz and the input power of 31 mW (15 dbm), which produced in the real sample 1102 what the inventors concluded to be a flow according to Figure 11 flow CT-1. The inventors The figure shows the measured spectra for the real sample in blue color and the measured spectra for the control sample in red color.

[0098] Measured X-Axis and Y-Axis Radiation Spectra

[0099] Figure 13A shows the measured radiation spectra of the electromagnetic emission of real sample 1102 and of the inventor-made control sample, and the measurements used the horn antenna X axis measurement position-alignment 1104A. Figure 13A shows the measured spectra for the real sample 1102 in blue color and the measured spectra for the control sample in red.

[0100] Figure 13B shows the measured radiation spectra, using the horn antenna Y axis measurement position-alignment 1104B, of the electromagnetic emission of real sample 1102 and of the inventor-made control sample. Figure 13B shows the measured spectra for the real sample 1102 in blue color and the measured spectra for the control sample in red.

[0101] Scattering Parameters Si l

[0102] The inventors measured the scattering parameters S 11 of the real sample 1102 and of the control sample using the Figure 11 first orientation charge current set-up and the Figure 12 second orientation charge current set-up, respectively.

[0103] Figure 14A shows, in blue, the Sil scattering parameters S 11 of the real sample 1102 activated by the first orientation charge current, and shows in red the SI 1 scattering parameters Si l of the control sample fed by the first orientation charge current.

[0104] Figure 14B shows, in blue, the Sil scattering parameters Si l of the real sample 1102 activated by the second orientation charge current, and shows in red the SI 1 scattering parameters SI 1 of the control sample fed by the second orientation charge current.

[0105] Radiation Patterns

[0106] Horizontal Polarization - Plane of Nano FMT Array

[0107] Radiation pattern measurements were taken by the inventors on the above-described measurements set-up, using the feed arrangement shown in Figures 11 and 12. Measured radiation patterns are shown in Figures 17A, 17B, 18A, and 18B. Figure 15 shows a mapping onto the plane of the real sample nano FMT array 1108, of the X, Y, Z axes of the Figure 17A, 17B, 18A, andBAN-24-076Att’y Docket: 02941784TA18B measured radiation patterns. Figure 16 shows the spatial relation of the polarization plane of the measured radiation patterns shown in Figures 17A, 17B, 18A, andl8B to the plane of the real sample 1102 FMT array 1108.

[0108] Horizontal Polarization - Plane of Nano FMT Array - First Orientation

[0109] Figure 17A, real sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0110] Figure 17B, control sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the control sample, by the above described measurement set-up, applying the Figure 11 first orientation current at the same three oscillating current frequencies input to the real sample 1102, i.e., 3.4 GHz, 5 GHz, and 10 GHz.

[0111] Horizontal Polarization - Plane of Nano FMT Array - Second Orientation

[0112] Figure 18A, real sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 12 second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0113] Figure 18B, control sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the control sample, by the above described measurement set-up, applying the Figure 12 second orientation current at the same three oscillating current frequencies input to the real sample 1102, i.e., 3.4 GHz, 5 GHz, and 10 GHz.

[0114] Plane of Nano FMT Array - Vertical Polarization - First Orientation

[0115] These measurement plots are relative to the Figure 15 and 16 plane and axis relations.

[0116] Figure 19A, real sample measurements, shows the measured radiation patterns for the vertical polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0117] Plane of Nano FMT Array - Vertical Orientation - Second Orientation

[0118] Figure 19B, real sample measurements, shows the measured radiation patterns for theBAN-24-076Att’y Docket: 02941784TA vertical polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 12 second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0119] First Plane Traverse to the FMT Array Plane

[0120] The measured radiation patterns are shown in Figures 22A, 22B, 23A, and 23B. Figure 20 shows a mapping onto the plane of the real sample nano FMT array 1108, of the X, Y, Z axes of the Figure 22A, 22B, 23A, and 23B measured radiation patterns. Figure 21 shows the spatial relation of the polarization plane of the measured radiation patterns shown in Figures 22A, 22B, 23 A, and23B to the plane of the real sample 1102 FMT array 1108.

[0121] Plane Traverse to the FMT Array Plane, Horizontal Polarization, First Orientation

[0122] Figure 22A, real sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0123] First Plane Traverse to the FMT Array Plane, Horizontal Polarization, Second Orientation

[0124] Figure 22B, real sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 12, second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0125] First Plane Traverse to the FMT Array Plane, Vertical Polarization, First Orientation

[0126] Figure 23A, real sample measurements, shows the measured radiation patterns for the vertical polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0127] First Plane Traverse to the FMT Array Plane, Horizontal Polarization, Second Orientation

[0128] Figure 23B, real sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 12 second orientationBAN-24-076Att’y Docket: 02941784TA charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns arc plotted in db.

[0129] Second Plane Traverse to the FMT Array Plane

[0130] The measured radiation patterns are shown in Figures 26A, 26B, 27A, and 27B. Figure 24 shows a mapping onto the plane of the real sample nano FMT array 1108, of the X, Y, Z axes of the Figure 26A, 26B, 27A, and 27B measured radiation patterns. Figure 25 shows the spatial relation of the polarization plane of the measured radiation patterns shown in Figures 26 A, 26B, 27 A, and27B to the plane of the real sample 1102 FMT array 1108.

[0131] Second Plane Traverse to the FMT Array Plane, Horizontal Polarization, First Orientation

[0132] Figure 26A, real sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0133] Second Plane Traverse to FMT Array Plane, Horizontal Polarization. Second Orientation

[0134] Figure 26B, real sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 12, second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0135] Second Plane Traverse to the FMT Array Plane, Vertical Polarization, First Orientation

[0136] Figure 27A, real sample measurements, shows the measured radiation patterns for the vertical polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 11 first orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns are plotted in db.

[0137] Second Plane Traverse to FMT Array Plane, Horizontal Polarization, Second Orientation

[0138] Figure 27B, real sample measurements, shows the measured radiation patterns for the horizontal polarization of the electromagnetic wave detected for the real sample 1102 by the above described measurement set-up. The real sample was activated using the Figure 12 second orientation charge current, applying three different oscillating current frequencies, which were 3.4 GHz, 5 GHz, and 10 GHz. The patterns arc plotted in db.BAN-24-076Att’y Docket: 02941784TA

[0139] Conclusion

[0140] The testing demonstrated a novel spintronic nano-antenna activated by spin injection, with alternating spin polarization from a three-dimensional topological insulator, with an array of nonmagnets deposited on a surface of the topological insulator. Antenna according to disclosed embodiments can be order s of magnitude smaller than the radiated electromagnetic wavelength, yet emits efficiently.

[0141] It is to be understood that practices that are within the scope of the appended claims are not limited to particular' embodiments described, as embodiments described herein are susceptible to various modifications and alternative forms. Embodiments are disclosed by way of example in the drawings and are described in detail herein. The example embodiments described, though, are not limited to the particular explicit implementations, configurations, arrangements, and forms disclosed. Rather, the instant disclosure supports all modifications, equivalents, and alternatives that fall within the scope of the appended claims.

[0142] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, as the scope of exclusivity will be limited only by the appended claims.

[0143] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly indicates or dictates otherwise, between the upper limit and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the range. The upper and lower limits of these smaller ranges may independently be included in and encompassed in the smaller ranges, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0144] Ordinal terms such as “first,” “second,” “third,” etc., as used in this specification and the appended claims to modify, e.g., step(s), functional block(s), signal(s), instruction(s), element(s) are to be understood as a labelling to individually reference separate step(s), functional block(s), signal(s), instruction(s), and / or element(s), and are not to be understood, except where expressly stated or clearly indicated as otherwise, to be any indication of any ordering of the step(s), functional block(s), signal(s), instruction(s), and / or element(s), in terms of time, spatial arrangement, priority, or to be any indication of the presence or inclusion of any of ordinal term referenced step(s), functional block(s), signal(s), instruction(s), and / or element(s) being conditional on the presence or inclusion of any different ordinal term referenced stcp(s), functional block(s),BAN-24-076Att’y Docket: 02941784TA signal(s), instruction(s), and / or element(s) indication of relative priority.

[0145] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art(s) to which this disclosure relates.

[0146] Representative and illustrative methods and materials are described herein. Methods and materials similar or equivalent to those described herein can also be used in practices according to disclosed embodiments.

[0147] It is to be understood that, as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as support for the recitation in the claims of such exclusive terminology as "solely," "only" and the like in connection with the recitation of claim elements, or use of a "negative" limitations, such as "wherein [a particular feature or element] is absent", or "except for [a particular feature or element]", or "wherein [a particular feature or element] is not present (included, etc.)...".

[0148] As will be apparent to those of skill in the art upon reading this disclosure in its entirety, each of the individual embodiments described and illustrated herein has discrete components and features that may be readily separated from the embodiment or combined with features of any of the other several embodiments without departing from the scope or spirit of the present invention.

[0149] It is to be understood that various methods and operations are described as a plurality of separate actions, steps, or operations but it will also be understood that such description can be for further assisting the reader in gaining an understanding of, for example, concepts and / or logic relationships and should not be understood as limiting the order in which the actions, steps, or operations can be performed and that these can be carried out in the temporal order or spatial arrangement recited or in any other order or arrangement that is logically possible.

[0150] While the disclosure describes features and aspects in terms of its several exemplary embodiments, those skilled in the ait will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims. Accordingly, the appended claims are not limited to the embodiments as described above, but should further include all modifications and equivalents thereof within the spirit and scope of the description provided herein.

Claims

BAN-24-076Att’y Docket: 02941784TACLAIMSWc claim:

1. A spintronic, oscillating injection current activated nano-antenna, comprising: a thin-film topological insulator (3D-TI) body, having a top surface and a bottom surface; a first electrode, disposed on the top surface of the 3D-TI body; a second electrode, disposed on the top surface of the 3D-TI bode, spaced apart from the first electrode; and a two-dimensional (2D) periodic array of ferromagnetic nanomagnets, disposed on the top surface of the 3D-TI body, between the first electrode and the second electrode.

2. The spintronic, oscillating injection current activated nano-antenna of claim 1, wherein the first electrode and the second electrode are configured to receive an alternating charge current, which is externally sourced, the alternating charge current having a charge current frequency, and the 3D-TI body is configured to carry, in response, an alternating charge current flow through the 3D-TI body, the alternating charge current flow extending between the first electrode and the second electrode and under the 2D periodic array of ferromagnetic nanomagnets, and the 3D-TI body is configured to inject, in response to the alternating charge current flow through the 3D-TI body, alternating spin currents into the ferromagnetic nanomagnets of the 2D periodic array of ferromagnetic nanomagnets, the alternating spin currents alternating with said charge current frequency and having magnitudes sufficient to produce oscillations of the ferromagnetic nanomagnets’ respective magnetic polarizations sufficient to produce, from the 2D periodic array of ferromagnetic nanomagnets, an electromagnetic radiation of a frequency equal to said charge current frequency.

3. The spintronic, oscillating injection current activated nano-antenna of claim 2, wherein the 2D periodic array of ferromagnetic nanomagnets is spatially arranged as a row-column array that includes M rows and N columns, M being an integer greater than one, and N being an integer greater than one, wherein the M rows extend in a row direction, and the N columns extend in a column direction.BAN-24-076Att’y Docket: 02941784TA4. The spintronic, oscillating injection current activated nano-antenna of claim 3, wherein the first electrode and the second electrode arc spatially arranged in an antipodal spatial relation to the 2D periodic array, wherein the antipodal spatial relation is configured such that the alternating charge current flow through the 3D-TI body extends under the 2D periodic array of ferromagnetic nanomagnets in a direction relative to the row direction.

5. The spintronic, oscillating injection current activated nano-antenna of claim 4, wherein the direction relative to the row direction is perpendicular to the row direction.

6. The spintronic, oscillating injection current activated nano-antenna of claim 4, wherein the antipodal spatial relation is a first antipodal spatial relation, the direction relative to the row direction is a first direction relative to the row direction, the alternating charge current is an alternating first charge current, the alternating spin currents are alternating first spin currents, the charge current frequency is a first charge current frequency, and wherein the spintronic, the electromagnetic radiation is a first electromagnetic radiation, and the oscillating injection current activated nano-antenna further comprises: a third electrode and a fourth electrode, disposed on the top surface of the 3D-T1 body in a second antipodal spatial relation to the 2D periodic array of ferromagnetic nanomagnets, the third electrode and the fourth electrode are configured to receive an alternating second charge current, which is externally sourced, the alternating second charge current having a second charge current frequency, and the 3D-TI body is further configured to carry, in response to the alternating second charge current, an alternating second charge current flow through the 3D-TI body, the alternating second charge current flow extending between the third electrode and the fourth electrode and under the 2D periodic array of ferromagnetic nanomagnets, and the 3D-TI body is configured to inject, in response to the alternating second charge current flow through the 3D-TI body, alternating second spin currents into the ferromagnetic nanomagnets of the 2D periodic array of ferromagnetic nanomagnets, the alternating second spin currents alternating with said second charge current frequency and having magnitudes sufficient to produce second oscillations of the ferromagnetic nanomagnets’ respective magnetic polarizations sufficient to produce, from the 2D periodic array of ferromagnetic nanomagnets, a second electromagnetic radiation of a frequency equal to said second charge current frequency.BAN-24-076Att’y Docket: 02941784TA5. The spintronic, oscillating injection current activated nano-antenna of claim 4, wherein the second antipodal spatial relation to the 2D periodic array is configured such that the alternating second charge current flow through the 3D-TI body extends under the 2D periodic array of ferromagnetic nanomagnets in a second direction relative to the row direction, which is different from the first direction relative to the row direction.

6. The spintronic, oscillating injection current activated nano-antenna of claim 4, wherein the ferromagnetic nanomagnets in the 2D periodic array are configured such that the first electromagnetic radiation has a first anisotropy and the second electromagnetic radiation has a second anisotropy, the first electrode and the second electrode are arranged as a first electrode pair and the third electrode and the fourth electrode are arranged as a second electrode pair, and the spintronic, oscillating injection current activated nano-antenna further comprises: a beam adjusting charge current feed circuit, configured to receive an externally supplied oscillating signal and coupled to the electrode pair and to the second electrode pair, and configured to cause the ferromagnetic nanomagnets of the 2D periodic array of ferromagnetic nanomagnets to radiate an electromagnetic signal corresponding to the externally supplied oscillating signal in a selectable beam direction, by steps comprising , allocating the externally supplied oscillating signal, in an allocation process that is based at least in part on a desired beam direction, the first anisotropy, and the second anisotropy, between being the alternating first charge current flow through the 3D-TI body and being the alternating second charge current flow through the 3D-TI.

7. (The spintronic, oscillating injection current activated nano-antenna of claim 3, wherein: i) the M rows are spaced apart, in the column direction, with a linear periodicity, or ii) the N columns are spaced apart, in the row direction, with a linear periodicity, or iii) both (i) and (ii).

8. The spintronic, oscillating injection current activated nano-antenna of claim 7, wherein i) the rows are spaced apart, in the column direction, and / or the columns are spaced apart, in the row direction, by a column spacing, andBAN-24-076Att’y Docket: 02941784TA ii) the row spacing is at least an order of magnitude smaller than a free-space wavelength of said charge current frequency.

9. The spintronic, oscillating injection current activated nano-antenna of claim 2, wherein at least some of the ferromagnetic nanomagnets in the 2D periodic array of ferromagnetic nanomagnets are elliptical, with a major axis and a minor axis, the major axis extends in the column direction and the minor axis extends in the row direction.

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