JPS58182302A - Magnetic resonator - Google Patents

Abstract

PURPOSE:To suppress the high-order static magnetic mode generated when a thin film ferrimagnetic substance is used, by providing a magnetic field at a right angle to a base major plane and making the frequency of the static magnetic mode corresponding to each ferrimagnetic thin film. CONSTITUTION:A GGG base 1 is placed on a surface 4a of an alumina base 4 so that circular YIG thin films 2, 3 contact corresponding output and input strip lines 7 and 6. A strip line 8 connecting both thin films 2, 3 is coated so as to cross the strip lines 6, 7 orthogonally and intersects the films 2, 3, and both ends of the strip line 8 are connected to a ground conductor 5. In the band-pass filter 10, the main resonance mode of the two films 2, 3 having slightly different aspect ratio (film thickness/diameter) sigma is overlapped, the other high-order static magnetic modes are cancelled with each other, allowing to obtain the filter characteristics having small spurious response.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic resonance apparatus button using a seven-layer magnetic thin film body.

Yttrium-iron-garnet (commonly known as YIQ) single crystals are already widely used in microwave devices such as fixed-leg and variable filters and variable oscillators by utilizing the phenomenon of ferrimagnetic resonance. 7 Eli When applying the phenomenon of magnetic resonance to a resonant circuit.

YIG single crystal is used as a 0% ferrimagnetic material, which has the characteristics that it can be miniaturized because the resonance frequency does not depend on the size of the sample, and that the resonance frequency can be varied by changing the applied DC magnetic field. When used, it is possible to obtain a resonator with a high unloaded Q value of several thousand in the microwave band because the resonance half width is very narrow.

Incidentally, in YIG microwave devices that have already been put into practical use, it is common to use a YIG single crystal sample processed into a true sphere. The reason for using a true spherical sample is that when the uniformity of the high-frequency magnetic field is good, the magnetostatic mode is less likely to be excited, and there is an advantage that the only resonant mode, which is the uniform precession mode, can be obtained. Bandpass using conventional YIG single crystal
Since the filter's transmission characteristics are not completely uniform in the high-frequency magnetic field, there is a slight spurious mode corresponding to the magnetostatic mode, but the transmission characteristics are almost single-peaked.
sex is obtained. However, when using a spherical ferrimagnetic sample, there are the following drawbacks. In other words, processing a sample into a perfect sphere requires a technically advanced and elaborate process. If the sample surface is not finished without defects using fine abrasive grains, the resonance half-width will not be sufficiently narrow, which will cause the no-load Q value of the resonator to become low.

Therefore, a single microwave device using a single YIG single crystal has problems in terms of mass production and cost.

In view of the above points, the present invention uses a thin film-like ferrimagnetic material and sufficiently suppresses the high-order magnetostatic mode generated at that time,
The present invention provides a magnetic resonance apparatus that solves the above problems.

The magnetic resonance apparatus of the present invention includes a required substrate, ferrimagnetic thin film bodies disposed on the substrate and each having a different aspect ratio, and means for applying a magnetic field perpendicular to the main surface of the substrate, This is characterized in that the frequencies of the corresponding magnetostatic modes of the magnetic thin film are made different.

The present invention will be explained in detail below.

It is possible to fabricate YfG thin films with good crystallinity using liquid phase epitaxial growth of garnet magnetic thin films on gadolinium gallium garnet (commonly known as GGG) substrates, which has become popular in recent years through the experience of magnetic bubble memory devices. . By processing this YIG thin film into a circular or rectangular shape by selective etching and utilizing this ferrimagnetic resonance, a microwave denoisseur can be constructed. In this case, the processability is excellent because ordinary photo-+7 lithography technology can be used, and the mass productivity is excellent because a large number of element forces can be obtained from one GGG substrate. Moreover, since it is a thin film material, it has the advantage that it can be easily integrated into a microwave integrated circuit using four microphones, one knob, a stop line, etc. as a transmission line.

The main drawback of thin film ferrimagnetic samples is that even if the sample is placed in a place with good uniformity of the high-frequency magnetic field, the internal high-frequency magnetic field will not be uniform and many magnetostatic motes will be excited. It is to be done. Figure 1 shows the measurement results of ferrimagnetic resonance of a circular thin film sample measured in a 9 GHz cavity resonator.
A large number of magnetostatic modes (#) are shown being excited. Therefore, if a bandpass filter is constructed using this sample, there will be a large number of spurious modes corresponding to each magnetostatic mode.

On the other hand, perpendicular to the sample surface of the disk-shaped ferrimagnetic sample! Regarding the magnetostatic mode when a current magnetic field is applied, see the literature (
Journal of Applied Physics
m, Vol, 4R.

Julv 1977, pp. 3001-3007), and each mode is expressed as (nlN)m.

However, the (n, N)m mode has Kn nodes in the circumferential direction, KN nodes in the diametrical direction, and K(m-1) in the thickness direction.
It is a mode with nodes. When compared with FIG. 1, it can be seen that the (1,N)m series is the main magnetostatic mode. The (1.1) 1 mode, which is most strongly excited, is similar to the uniform precession mode. By the way, the analysis results in the above literature show that all magnetic fields are saturated magnetized 4πM8
It can be seen that if the frequency is normalized by ω,=r4KMS, it can be classified very uniformly. However, γ is the gyromagnetic ratio. Figure 2 shows the resonance frequencies of the (1,N)1 mode for two types of disk-shaped ferrimagnetic samples with relatively similar aspect ratios C (i.e. C; thickness t/diameter d). This is the result. The vertical axis shows the N value, and the horizontal axis shows the resonance frequency. However, when the DC applied magnetic field is Ho. −Ho/4πM,=1. In the same figure, the * mark indicates the case when Da=0.030, and the O mark indicates the case when 1=Q, l) 31. As can be seen from this result, the main resonance mode is N
Regarding -IK, the resonant frequencies are close to each other, but as the NtQ value increases, the difference in the resonant frequencies becomes larger and larger.

Therefore, for example, a circular YI with a slightly different aspect ratio σ
If a pantone filter is constructed using G thin films in multiple stages, the main resonant modes will almost overlap (・, and other higher-order magnetostatic modes will effectively cancel each other out, making it possible to create a filter with small spurious response. You can make it.

Figures 3 to 5 show an embodiment of the present invention, in which a circular YIG thin film of 200 mm is used. (Two circular YIG thin films (21 and (3) facing each other are formed by liquid phase epitaxial growth on the top of the film. In this case,
Both YIQ thin films (21 and (3) have their thin thicknesses t1 and tz
are aligned with each other by liquid phase epitaxial growth, K (immediately?) tl = tz), and the diameters of the circles d1 and d
! The aspect ratios σ are made different by slightly changing the respective values. On the other hand, a board (4) for mounting is provided, and the nose surface (4b) of this board is
A ground conductor (5) is formed on the substrate surface (4).
A) is coated with a manual stripline (6) and an output stripline (7), and both striplines (
Connect the respective ends of 6) and (7) to the ground conductor (5) button. The surface (4a) of this Arunna substrate (4) K, the above G
GG substrate +11 and its husband kll) circular YIG thin film (21
and (3) are arranged so as to face the corresponding output stripline (7) and input stripline (6). , and a strip line (8) connecting both thin films (2) and (3) on the other surface (1b) of the GGG substrate (1).
The input/output strip line f6) is formed so as to be perpendicular to 71 and across both thin II!
Connect to. A DC magnetic field is applied in a direction perpendicular to the surface (1b) of the substrate (1). Note that (9) indicates a high-frequency magnetic field. According to the bandpass filter αeK with such a configuration, two circular YIG thin films 12) and (3) with slightly different aspect ratios (thickness/diameter) σ are used. According to
As described above, the main resonance modes in each of the thin films (2) and (31) almost overlap, and other higher-order magnetostatic modes cancel each other out, resulting in filter characteristics with small spurious response.

In addition, on the upper side, the diameters d1 and dz of the circular YIQ thin lines 12) and (3) are the same (dl-dz) K and the film thickness t
Even if 1 and t2 are changed (t1, tg), the aspect ratio can be changed, so the same effect can be obtained in this case as well.

Further, the shape of the thin films (2) and (3) is not limited to a circle, but may be a square or a rectangle. In this case, the aspect ratio - is the ratio of the film thickness t to the side length (t/Q), so by changing the ratio of the film thickness t to the side length t, the spurious response can also be reduced. Small filter characteristics can be obtained. The ferrimagnetic sample to be fired is not limited to V-sniff, but may also be a disk processed from a bulk material, and the material is not limited to YIG single crystal, but any ferrimagnetic material with a narrow resonance half-width can be used. .

WIKThe present invention is not limited to bandpass filters, but also applies to 153
A ferrimagnetic resonance apparatus 1lIK such as YIG Town Variable Oscillator S which applies the principle of 411 can also be applied.

As mentioned above, the present invention uses a plurality of thin film-like ferrimagnetic materials, and in this case, the aspect ratio of each ferrimagnetic material is set to be slightly [f
Since high-order magnetostatic modes can be suppressed by increasing the magnetic field, it becomes possible to provide microwave devices using ferrimagnetic materials at low cost and in mass production.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the state of magnetostatic mode generation in a circular ferrimagnetic thin film used to explain the present invention. Figure 2 is a characteristic diagram of the resonance frequency of the (1,N)t mode for two types of circular ferrimagnetic thin films with different aspect ratios, and Figure 3 is a diagram of a bandpass filter showing an embodiment of the present invention. A perspective view, FIG. 4 is a sectional view taken along line AA, and FIG. 5 is a sectional view taken along line BB@. (11 is GGG substrate, +21 (31 is ferrimagnetic thin film, (6) is input strip line, (7) is output strip line.

Claims (1)

[Claims] A plurality of ferrimagnetic thin film bodies each having a shape having a different aspect ratio are disposed on a substrate and a core substrate, and a means for applying a magnetic field perpendicularly to the main surface of the substrate is provided, and a static magnetic field corresponding to each of the ferrimagnetic thin film bodies is provided. Magnetic resonance device with different magnetic mode frequencies =