JP2005181071A - Spin wave exciting/detecting device, high-frequency signal processing machine using the same and structure evaluating device of carbon nanotube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spin wave exciting/detecting device for directly exciting/detecting a spin wave having a nano-wavelength using a carbon nano-tube (CNT), a high-frequency signal processing machine using the spin wave exciting/detecting device, and a structure evaluating device which uses the CNT. <P>SOLUTION: The spin wave exciting/detecting device is equipped with the CNT 1, a ferrite 2, a high-frequency current generator or a ratiation electromagnetic field generator and a direct-current magnetic field generator, and constituted so that a high-frequency current 3 flows through the CNT 1, and a direct current magnetic field 5 is applied to the ferrite 2 to excite/detect the spin wave, by the interaction of the current of the CNT 1 with the spin 6 of the ferrite 2. The high-frequency signal processing device and the CNT structure evaluating device, both of which are equipped with this device, are also obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a spin wave excitation / detection device, a high-frequency signal processing device using the device, and a structure evaluation device for a carbon nanotube (hereinafter referred to as CNT).

Conventional devices using spin waves and oscillation devices using CNT include the following.
JP 06-97562 A JP 2001-148596 A JP 2002-182176 A JP-A-06-310976

  In a conventional high-frequency signal processing apparatus using a metal for an excitation / detection electrode, it is difficult to control the size of the nano-size (the limit is about 100 nm). Although there was a signal processing device, spin waves with nano wavelengths could not be directly excited and detected.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a spin wave excitation / detection device for directly exciting / detecting a spin wave having a nano wavelength using CNTs and the spin wave excitation. A high-frequency signal processing device using a detection device and a CNT structure evaluation device are provided.

The spin wave excitation / detection device according to the present invention includes a CNT, a ferrite, and a high frequency current generator or a radiated electromagnetic field generator and a direct current magnetic field generator so that a high frequency current flows through the CNT, A DC magnetic field is applied, and the CNT current interacts with the ferrite spins to excite and detect spin waves.
The high-frequency signal processing device of the present invention includes a device for exciting and detecting the spin wave.
The CNT structure evaluation apparatus of the present invention includes a device for exciting and detecting the spin wave.

Embodiments of the present invention will be described below.
In electronics that utilizes the physical properties of CNTs, changes in physical properties and control of electrical conductivity with respect to the chirality of CNTs, which depend on how the graphene sheet (graphite) is wound, are important issues. The inventors of the present invention have considered the application of CNT to a nanoelectrode structure for spin wave excitation / detection in microwave / millimeter wave devices, and have studied the basic conduction characteristics and interaction with electromagnetic waves.

In the study of nanoelectrodes for spin wave excitation and detection, it is difficult to control the size of conventional metals, and the current limit is 100 nm. On the other hand, CNT is
1. It is promising to control the diameter of the order of nm by self-organization. For example, it has a diameter of 0.783 nm for chirality (10, 0) and 1.357 nm for (10, 10).
2. Ballistic conductivity (long mean free path of about μm) due to adiabatic carrier transport.
These features 1 and 2 are promising for the realization of nanoelectrodes that excite and detect spin waves with a wavelength of nm, and that do not apply thermal fluctuations to the spins. In order to realize nanoelectrodes, the basic conduction characteristics of CNT will be considered from the viewpoint of quantum transport of electron waves, and the following will be described with reference to the drawings.

[CNT band theory]
FIG. 1 is a diagram showing lattice points of a graphene sheet. When the wave function at the lattice point of the graphene sheet of FIG. 1 is approximated by LCAO and the Schrodinger equation is solved, a dispersion relational expression of the graphene sheet is obtained as an eigenvalue equation.
Figure 2 shows the dispersion curve of a graphene sheet in which energy is plotted in contour on the k-space. In FIG. 2, the + branch is shown above and the-branch is shown below. In addition, the Γ point, M point, and K point were overlapped with a hexagonal line. The + branch and the-branch touch each other at the K point, and have a maximum interval at the Γ point. In addition, the energy is constant on the line connecting M point to M point.
Figure 3 shows the first Brillouin zone for CNT with chirality (3, 0). The first Brillouin zone is a line segment that overlaps a (6π / a) × (4π / √3a) rectangle determined by the chiral angle and seven straight lines determined by the boundary conditions in the circumferential direction. Similarly, the first Brillouin zone line can be created for chirality (n, m).

The dispersion curve of CNTs has a cut end of the graphene sheet dispersion curve in Fig. 2 taken along the first Brillouin zone line in Fig. 3 as an actual band representing the dispersion relationship of the electron wave propagating through the CNTs. Also, numerically evaluating the dispersion relations of CNTs using the Muller method, a complex band representing the dispersion curve of the non-propagating wave (evanescent wave) is obtained, and the result is shown in Fig. 4. The dispersion curve in Fig. 4 shows the case where the chirality is (3, 0). There are 2n + 1 i _x in (n, 0) and (n, n), and n pairs are degenerate twice. Yes. On the other hand, when n and m are not equal, the number of dispersion curves varies in a complex manner depending on n and m.

Further, it divided into a case with n, m, and if depending on the i _x having metallic properties no band gap, the semiconductor properties resulting bandgap. Generally, it becomes metallic when nm is a multiple of 3, and it becomes semiconductor when nm is not a multiple of 3. For example, (3, 0) and (6, 0) are metallic, and (4, 0) and (5, 0) are semiconducting. In the case of a semiconductor, the wave number in the band gap became a complex number (A in the figure), the wave number at the band edge became a complex number (same B), and the existence of the complex band was clarified numerically.

[Formulation and numerical calculation results of current flowing through CNT]
Current density, current formulation and numerical calculation results are shown. Here, the Transfer Matrix method (TM method) was used to determine the electron wave propagation in the CNT. As shown in FIG. 5, a voltage V ₀ was applied to both ends of the CNT, and a square potential was assumed in each unit cell. In FIG. 5, CUC is a unit cell of CNT and GUC is a unit cell of graphene sheet, and staircase approximation is performed in which the potential by the applied voltage V ₀ has a constant value U _{J, jp} within each GUC. Black circles in GUC represent carbon atom lattice points.
CNT is composed of L + 2 CUCs (CNT unit cells), and each CUC is composed of n _p pieces of GUC (unit cells of graphene sheet) in the circumferential direction and m _p pieces in the axial direction. A matrix that expresses the relationship between the input and output of the amplitude coefficient of the wave function when the condition (equation 2) in which the adjacent ones in the axial direction are continuous is imposed on the wave function (Equation 1) and the probability density flow of each GUC. (Equation 3) is obtained. The 2 × 2 matrix M in Equation (3) is called a Transfer Matrix.

Probability density flow J _{J, jp, ix, iy} (x, E) is obtained by (Equation 4) as an average value in CUC. The transmission probability is a ratio of the probability density flow at the input output and is expressed by (Equation 5). The current density is expressed by (Equation 6) in terms of transmission probability and Fermi-Dirac distribution function. The total current is obtained by integrating the current density in the circumferential direction.

[Current-voltage characteristics, resistance]
The current-voltage characteristics are as shown in Fig. 6 with chirality (3, 0) and the number L of CNT unit cells as a parameter, and converge to a constant value L → ∞. FIG. 6 is a diagram showing current-voltage characteristics (parameter L). The inset in Fig. 6 is an enlarged view of around 0.01V.
Next, the resistance value is calculated from the slope of the current-voltage characteristics, and L is shown in Fig. 7 along the horizontal axis. FIG. 7 shows the resistance-L characteristics of CNT (3, 0). In the inset, the resistance value and L are not in a proportional relationship and show different characteristics from ohmic resistors. This is because the transmission probability D _{ix, iy} (x, E) in the equation (5) representing the propagation characteristic of the electron wave is not proportional to L- ¹ .

[Current density circumferential distribution]
In designing the nanoelectrode structure for microwave devices, not only the current-voltage characteristics but also the circumferential distribution of the current density of CNTs is important. Figure 8 shows the results of plotting the current density distribution in the circumferential direction at m = 0 and using n as a parameter. This plot is equivalent to using the diameter of a zigzag CNT as a parameter. Analysis shows that n = 3 and 6 are metallic and n = 4 and 5 are semiconducting. Since the current density distribution in the circumferential direction varies with n, it can be seen that the current distribution of CNTs with chirality (n, 0) can be controlled by n.

[Application of CNT to spin wave excitation and detection system]
The influence of current density circumferential distribution on spin wave excitation is shown. FIG. 9 shows an embodiment of a spin wave excitation / detection device using CNTs proposed by the present inventors. In FIG. 9, reference numeral 1 denotes CNT, 2 denotes ferrite, 3 denotes current, 4 magnetic fields, 5 denotes bias magnetic field, 6 denotes spin, and 7 denotes the wavelength of the spin wave.
The spin wave excitation / detection device according to this embodiment includes a CNT1, a ferrite 2 placed under the CNT1, a high-frequency current generator (not shown), and a DC magnetic field generator (not shown).
A high frequency current 3 is applied to the CNT 1, a DC magnetic field 5 is applied to the ferrite 2, and an electric field 4 generated by the current of the CNT 1 interacts with the spin 6 of the ferrite 2 to excite and detect a spin wave. Conventionally, the structure has been used for microwave filters, but the electrodes could not be made on the order of nm.

  Since the current density distribution can be changed by the chirality of CNT, a spin wave having a wavelength of 7 that matches the distribution can be excited and detected. It can be inferred from other examples that the period of the current density distribution and the wavelength of the spin wave have a positive correlation. For example, since (3, 0) has more components with a longer period than (5,0), the spin wave wavelength becomes longer. Therefore, the spin wave wavelength can be controlled by chirality.

  Here, the case of zigzag type was shown as a numerical calculation result, but this analysis method can be applied to any chirality of armchair type and chiral type, so spin wave excitation / detection device in Fig. 9 can be used for spin wave excitation. By appropriately designing the chirality (n, m) of the nanoelectrode, the characteristics of the spin wave excitation / detection device can be controlled.

[Verification of application of spin wave excitation and detection equipment]
Conventionally, among product information wireless tags (RFID), there is a microwave type. This method has a wide communication area, sharp directivity, and high communication speed. However, the problem with this method is that it requires a digital modulation function, so it requires power supply from an internal battery or from the outside and consumes power.
In order to solve the above problems, the present inventors propose a high-frequency signal processing device that uses the characteristics of the above-described spin wave excitation / detection device using CNTs.
We propose here an apparatus that converts the information encoded by a digital modulation microwave filter into a CNT structure and encodes the microwave using the filter. The digital modulation microwave filter has a possibility as a device for dealing with digitization of broadcasting in addition to RFID. In addition, a signal processing device such as a bandpass filter of a predetermined band, for example, a THz band is shown.

Conventionally, as a method for measuring the structure of Carbon Nanotube (CNT), there has been a method for measuring the size of an image using a transmission microscope or the like. This problem is that it takes time to measure each CNT in order to measure chirality from the dimensions of the CNT image.
In order to solve the above problems, the present inventors propose a CNT structure evaluation apparatus that uses the characteristics of the spin wave excitation / detection apparatus using the CNTs described above. In particular, we propose a CNT structure evaluation system that measures multiple bundle CNT chiralities simultaneously.

Specifically, as a spin wave excitation / detection device, the CNT has a self-organized feature with a diameter of about nm, the feature that the spin wave of nm wavelength is easily spatially matched, and the CNT is ballistic. Spin wave excitation / detection that excites and detects spin waves in one type of ferrite YIG (yttrium, iron, garnet) using the feature that it does not give thermal fluctuation to the spin of adjacent YIG because it shows conduction characteristics Use the device.
Below, the application to the spin wave excitation / detection device is verified. CNT will be described as an electrode having a cylindrical cross section.

An embodiment (FIG. 10) _{in which} two CNTs 1 _in and 1 _out , _in which a high-frequency current flows, is placed in parallel on the YIG 2 to which the DC magnetic field H ₀ is applied will be described. FIG. 11 shows a spin wave dispersion curve when the thickness of YIG2 = 100 μm, the saturation magnetization μ ₀ M ₀ = 0.17T, and the applied DC magnetic field μ ₀ H ₀ = 0.1T. The wavelength λ is about 2.5 nm, the frequency is 5 THz, and the frequency of the wave that can propagate is about three orders of magnitude higher than that of the conventional magnetostatic wave device. The higher frequency is Weiss molecular field H _e is to work as enhance H _0. In the dispersion curve when the solid line assumed in same 46T and internal magnetic field of mu ₀ H _e in FIG. 11, a dashed line, one-dot chain line is obtained when the increased or decreased by 10% respectively H _e. On the other hand, compared to metal electrodes that have a problem in processing accuracy when exciting and detecting this spin wave, the CNT can be made shorter than the wavelength of the spin wave by self-organization, for example, 1.357 nm with chirality (10,10). Wide band operation can be expected.

  In order to evaluate the broadband operation, a test for detecting the insertion loss IL of the high-frequency signal processing apparatus was performed. IL is basically defined by the ratio of output power to input power to the high-frequency signal processing device.

FIG. 12 shows an analysis model of the high-frequency signal processing device used for detecting the insertion loss IL. The operation will be described with reference to the analysis model of FIG. A DC magnetic field 5 is applied to the YIG 2, the input side CNT 1 _in generates a high frequency magnetic field 4 by a high frequency current 3 supplied from a high frequency power supply 8, and the magnetic field 4 couples with a spin 6 to cause a spin wave 9 into the YIG 2. The excited and propagated spin wave 9 creates a high frequency magnetic field, and the output side CNT1 _out detects the magnetic field to cause a high frequency current to flow, and the load resistor consumes the current as output power. In this electromagnetic field analysis, CNT1 _{in and} CNT1 _out are treated as electrodes having a cylindrical cross section, and boundary conditions including the CNT electrode and YIG2 are applied. Determine the radiation resistance R _w of the spin-wave excitation than the electromagnetic field. In addition, IL is obtained from the resistance of the CNT itself and the power supply resistance or matching load resistance R _G obtained by the quantum transport analysis of the CNT.

Next, the results of numerical evaluation of this IL will be shown. IL depends on the diameter of the CNT via the wavelength of the spin wave. Therefore, when the IL-frequency characteristic is evaluated using the diameter as a parameter, FIG. 13 is obtained. The horizontal axis represents frequency and the vertical axis represents IL. The thickness of _{YIG2 10nm, CNT1 in, 1 CNT1} in the length of the _out as 1 [mu] m, 1 _out assumes a zigzag, and the chirality and (n, 0). In order to achieve metallic chirality, n was changed to 3, 30, 45, 60, 90 and multiples of 3. Here, it was assumed that the distribution of excited electron waves was uniform in the circumferential direction. From FIG. 13, a bandpass characteristic whose frequency is variable by n except n = 3 was obtained. This indicates the possibility of a signal processing device such as a bandpass filter in the THz band. As n increases, the diameter increases, so the wavelength of the spin wave that is detected by excitation becomes longer, and the center frequency of the bandpass characteristic becomes lower.

[High-frequency signal processor]
From the above, it can be seen that the above-described spin wave excitation / detection device can be applied to a high-frequency signal processing device such as a BPF filter. In other words, it can be seen that CNT can be applied to a nanoelectrode for spin wave excitation of a high-frequency signal processing device. As a main configuration of the high-frequency signal processing device, a configuration similar to that shown in FIGS. 9, 10, and 12 can be used.
When the above-described spin wave excitation / detection device is applied to a BPF filter which is one of high frequency signal processing devices, the center frequency f ₀ and the 3 dB bandwidth BW and BW / B of the BPF filter obtained from the IL-frequency characteristics of FIG. FIG. 14 shows the characteristics of f ₀ and n.
The characteristics began to appear at n = 24, the center frequency at this time became the highest passing center frequency of 5.2 THz, and the maximum bandwidth at n = 45. From this, f ₀ and BW may be controlled by chirality.

[CNT structure evaluation equipment]
In the verification of the application of the spin wave excitation / detection device described above, the case of chirality (n, 0) has been shown. However, since the same analysis can be performed for the case of arbitrary chirality (n, m), any It is thought that the chirality discrimination of CNTs in the CNT can be realized.

  Controlling the method of exciting the current in the CNT can change the current density distribution in the circumferential direction, and it is thought that this control can read information on the CNT chirality in more detail. As a result, CNT can be discriminated and a CNT structure evaluation apparatus can be obtained.

The possibility of applying the above-described spin wave excitation / detection device to the CNT structure evaluation device is verified.
The structural parameters of the various CNTs shown in FIG. 15 were changed as follows by the same method as described above with reference to FIGS.
In FIG.
(1) is a case where the diameter of the CNT is changed by a single layer. The diameter was changed within the following ranges and conditions.
Diameter change: n = 150-240, mx = 1, my = 1, L = 1, N = 500 × 150 / n
(2) is a case where the number of CNTs is varied and the number of layers is changed. The number of layers was changed within the following ranges and conditions.
Layer number change: L = 1 ~ 4, n = 150,120,90,60 = n _min , mx = my = 1, N = 500 × 150 / n _min
(3) shows a case where the number of CNTs in the horizontal direction is changed. The change in the number in the horizontal direction was performed within the following ranges and conditions.
Change in number of horizontal direction: my = 1 ~ 250, mx = 1, L = 4, n = 150,120,90,60 = n _min , N = 500 × 150 / n _min
(4) shows a case where the number of CNTs in the vertical direction is changed. The change in the number in the vertical direction was performed within the following ranges and conditions.
Change in number of vertical direction: mx = 1 ~ 250, my = 1, L = 4, n = 150,120,90,60 = n _min , N = 500 × 150 / n _min
(5) is a case where the number of CNTs is changed in the vertical and horizontal directions. Changes in the numbers in the vertical and horizontal directions were made in the following ranges and conditions.
Change in number of vertical and horizontal directions: mx, my = 1 to 250, L = 4, n = 150,120,90,60 = n _min , N = 500 × 150 / n _min
Where (n, 0) is chirality, L is the number of CNT layers, mx and my are the number of CNTs in the vertical and horizontal directions, and N is the number of analysis divisions in the vertical direction of CNTs.

In order to measure the CNT chirality, the frequency characteristics of IL were measured. FIG. 16 shows the IL frequency characteristics for the parameter change (1). As a result, in the case of one CNT, when n increases, the center frequency f ₀ of the IL frequency characteristics decreases.
Regarding the parameter change (2), the frequency characteristics of IL are as shown in FIG. 17, and in the case of multiple layers, the n dependence of f ₀ is smaller for the inner CNT diameter than for the outermost CNT diameter.
Regarding the parameter change (3), the frequency characteristics of IL are shown in FIG. 18. When CNTs are arranged in the horizontal direction, the number of four-layered CNTs (n = 150, 120, 90, 60) is 250 As the value increases, a certain IL-frequency characteristic is obtained.
For the parameter change (4), the frequency characteristics of IL are shown in FIG. 19, and when CNTs are arranged in the vertical direction, f ₀ decreases as the number of arranged CNTs increases.
The frequency characteristics of IL with respect to the parameter change (5) are shown in FIG. 20. When CNTs are arranged in the vertical and horizontal directions (bundle CNT), f ₀ decreases as the number of arranged CNTs increases, and 1 × 1 Compared to the THz band with ~ 3x3, it fell to the microwave band with 100x100.

From the above, the following effects can be given as specific effects produced by the present invention.
1. Chirality can be measured from the correlation between n and f ₀ .
2. When CNTs are arranged in the horizontal direction, the chirality of bundle CNTs can be measured as an average value from the shape of IL frequency characteristics.
3. In the case of bundled CNTs, if the number is increased to some extent, chirality can be measured from the THz band, where the measurement technology is still developing, using the measurement technology of the GHz band, where the measurement technology has advanced to some extent.
4). Since there is a limit to the allowable current amount per CNT, increasing the number allows increasing the allowable current and generating a large amount of generated magnetic field, allowing for the propagation loss of spin waves from the input CNT to the output CNT. It is possible to excite a high-frequency magnetic field of a certain size.

  From the above, it can be seen that chirality can be measured, and the above-described spin wave excitation / detection device can be applied to a CNT structure evaluation device. In particular, according to this apparatus, the number of CNTs is not limited to one single layer, and a plurality of bundle CNT chiralities can be measured simultaneously. If the chirality is known, it is possible to discriminate and evaluate the characteristics and structure of the CNT, such as whether the measured CNT is a metal, a semiconductor, or whether the characteristics of a metal and a semiconductor are mixed.

As a specific main structure of the CNT structure evaluation apparatus, the same structure as that shown in FIGS. 9, 10, and 12 can be used.
Further, in the cases shown in FIGS. 9, 10, and 12, the propagation loss of the spin wave is not considered in the analysis, but in order to actually propagate the spin wave from the input side CNT to the output side CNT, It is necessary to excite a high-frequency magnetic field that is large enough to allow for the propagation loss of spin waves.
As shown in the analysis model of FIG. 12, the structure is not limited to a structure in which a metal and CNT are brought into contact with each other and a conduction current is allowed to flow. Similarly, a structure in which a THz-band radiated electromagnetic field is applied to the CNT to generate a current in the CNT is also conceivable.

  FIG. 21 shows a type that absorbs a THz spin wave, for example, a THz electromagnetic wave radiated from a THz radiation source hits the CNT 1, and only a frequency component resonating with the propagating spin wave 9 is absorbed by the ferrite 2. Other than that, it is transparent. Such band elimination characteristics can be obtained by measuring the output spectrum. With such a measurement system, the connection between the CNT1 and the external circuit can be omitted, so that the measurement can be speeded up.

In the CNT structure evaluation apparatus having the above-described spin wave excitation / detection apparatus as a main configuration, it is possible to specify the chirality from the wavelength of the spin wave and evaluate the physical properties of the CNT. Specifically, when a high frequency current is input to the CNT, a spin wave is excited and detected via the CNT, and the output is measured, a high frequency spectrum is observed. From this spectrum, the chirality that is the structural parameter of the CNT can be measured, for example, by the following procedure. According to this measurement method and apparatus, the number of CNTs is not limited to one single layer, and a plurality of bundle CNTs can be measured simultaneously.
1. A standard dispersion curve regarding the wavelength of the spin wave propagating through the ferrite is prepared in advance by experiments.
The wavelength of the spin wave is obtained from the measured high frequency spectrum of CNT and the dispersion curve relating to the wavelength of the spin wave propagating through the ferrite.
2. The CNT current density circumferential distribution period is obtained from the wavelength of the spin wave propagating through the ferrite. This can be determined because a positive correlation is expected from the wave nature of other devices.
3. The chirality is identified from the current density circumferential distribution period of the CNT.

  In addition, although this invention is described in said preferable embodiment example, this invention is not restrict | limited only to it. It will be understood that various other exemplary embodiments may be made without departing from the spirit and scope of the invention.

It is optimal as a power source for high-frequency signal processing equipment such as microwave / millimeter-wave devices that already have many applications in the industry.
In addition, CNT is currently mass-produced in the industry, and is optimal as a discriminator for the CNT structure.

Diagram showing lattice points of graphene sheet Diagram showing graphene sheet dispersion curve Figure showing the first Brillouin zone Diagram showing dispersion curve of CNT Diagram showing analysis model of TM method Diagram showing current-voltage characteristics (parameter L) Diagram showing resistance-L characteristics of CNT (3, 0) Diagram showing current density circumferential distribution The figure which shows one Embodiment of a spin wave excitation and a detection apparatus The figure which shows one Embodiment of a high frequency signal processing apparatus Diagram showing dispersion curve of spin wave The figure which shows the analysis model of the high frequency signal processor Diagram to evaluate IL-frequency characteristics Diagram showing characteristics of center frequency f ₀ and 3 dB bandwidth BW and BW / f ₀ and n Diagram showing examples of changing the structural parameters of various CNTs Diagram showing frequency characteristics of IL when the diameter is changed Diagram showing frequency characteristics of IL when the number of layers is changed Diagram showing frequency characteristics of IL when the number in the horizontal direction is changed Diagram showing frequency characteristics of IL when the number in the vertical direction is changed Diagram showing frequency characteristics of IL when the number in the vertical and horizontal directions is changed The figure which shows other one Embodiment of a spin wave excitation and a detection apparatus

Explanation of symbols

1 CNT,
2 Ferrite,
3 current,
4 magnetic field,
5 Bias magnetic field 6 Spin,
7 Wavelength 8 Power supply 9 Spin wave

Claims (3)

A carbon nanotube, a ferrite, a high-frequency current generator or a radiated electromagnetic field generator, and a DC magnetic field generator;
A spin wave excitation / detection device configured to cause a high-frequency current to flow through the carbon nanotube, apply a DC magnetic field to the ferrite, and the current of the carbon nanotube interacts with the spin of the ferrite to excite and detect a spin wave.   A high frequency signal processing device comprising the spin wave excitation / detection device according to claim 1. A carbon nanotube structure evaluation apparatus comprising the spin wave excitation / detection apparatus according to claim 1.

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