JPH0127561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic device comprising a single crystal non-magnetic substrate having a surface adapted for depositing layers and supporting a single crystal magnetic layer of hexagonal ferrite material.

Due to its extremely large uniaxial anisotropy and its small linewidth, for example the formula BaO.
Thin ferrite layers in hexagonal single crystals with 6Fe ₂ O ₃ (barium-hexaferrite) can be used as passive microwave components, e.g. as resonant isolation or filters in the centimeter wave range, or in information storage technology, e.g. The magnetic fields of small (sub-micron) cylindrical domains are important as components in magnetic cylindrical domain devices. As is already known, magnetic garnet layers used, for example, in information storage technology
It can no longer be used at frequencies higher than 50 GHz. For example, in order to make a hexagonal single crystal ferrite layer of excellent quality, homogeneity and defect-free crystalline perfection, as is known from components for the same purpose as magnetic garnet layers, it is necessary to requires a single-crystal substrate having a chemical composition equal to that of the layer being grown on the substrate, and having a similar crystal structure and approximately the same lattice constant as the layer deposited on the substrate.

On a hexagonal ferrite substrate with the composition BaFe ₁₂ O ₁₉ by liquid phase epitaxy, e.g.
Attempts have been made to grow hexagonal single crystal ferrite layers with Ba ₂ Zn ₂ Fe ₁₂ O ₂₂ (Mat.
Res. Bull., 10 (1975) p.1255-1258). According to research reports, satisfactory results have not been obtained with these substrates.

Also, by epitaxy the composition ZnGa ₂ O ₄ or
Attempts have been made to grow hexagonal single-crystal ferrite layers of type Ba _0.6 Fe ₂ O ₃ on non-magnetic spinel substrates with Mg(In, Ga) ₂ O ₄ ;
However, this attempt was not successful, as not only could the layer not be grown without defects, but islands formed on the surface of the substrate to be coated (J. Appl. Phys., 49
(1978) No. 3, P. 1578-1580).

It is a requirement that non-magnetic substrates be used in all magnetic applications, since magnetic substrates adversely affect the magnetic properties of the components made with them.

In the past, it has not been possible to produce single crystal hexagonal ferrite layers of good quality, homogeneity and crystalline perfection because suitable substrates were not available for seeding.

The object of the present invention is to provide a magnetic device comprising a magnetic single-crystal hexagonal ferrite layer on a single-crystalline non-magnetic substrate in which the quality of the thin magnetic layer and the crystalline perfection are comparable to the quality of a magnetic garnet layer. The goal is to provide the following.

The magnetic device of the invention has a substrate of the formula: A ²⁺ _1+y Ga _12-2x-y B ²⁺ _x C ⁴⁺ _x O ₁₉ , where A=barium and/or strontium, B=magnesium and/or or manganese and/or zinc and/or iron and/or copper and/or nickel and/or cobalt and/or chromium, C = zirconium and/or hafnium and/or titanium and/or tin, and
0.1≦x≦1.2 and 0≦y≦0.8).

According to a preferred embodiment of the invention, the surface of the substrate on which the layer is deposited exhibits an orientation in the 001 direction and has a deviation in the range of 1 to 2 degrees from the ideal direction of the c-axis.

A qualitatively good layer has a deviation of this magnitude
- It was confirmed that the plant grows from the ideal direction of the axis. c-
At larger deviations (t ~ 10°) from the direction of the axis, a step-like growth of the single crystal layer occurs.
growth occurs on the substrate, whereas island-like growth of the layer occurs in the correct c-axis orientation of the substrate.

In another preferred embodiment of the invention, the thickness of the monocrystalline magnetic layer is in the range 0.5 to 10 μm. It is important that the layer thickness not exceed 10 μm, since flaking of the layer applied to the substrate is observed in thicker layers. This is due to the easy cleavability of the layer material perpendicular to the direction of the c-axis.

The method for manufacturing the magnetic device of the present invention involves first drying and compressing the starting material of a single crystal substrate, then firing the dried and compressed body in an oxygen atmosphere at 1500°C for 12 to 30 hours, and then producing the fired and compressed body. To produce single crystals by the Czyochralski method, the single crystals are melted at ~1600°C in a closed crystal pulling apparatus and the single crystals are extracted from this melt with the help of seed crystals at 5-20 r.p.
This monolayer was pulled at a growth rate of 1-2 mmh ^-1 with a seed crystal rotation speed of m. This can advantageously be achieved by cutting polishing segments from the crystal and epitaxially depositing a single crystal layer of hexagonal hexaferrite material on the surface of at least one substrate layer.

According to another preferred embodiment of the invention, 77.87 g.
SrO, 481.97g Ga ₂ O ₃ , 9.90g MgO and
A mixture of 30.26 g of ZrO ₂ was melted as the starting material for the melt and a single crystal substrate was obtained from this melt.
It can be pulled up by the Czyochralski method according to claim 3 in a CO ₂ atmosphere.

In yet another preferred embodiment of the invention, 19.28
A mixture of g of SrCO ₃ , 112.39 g of Ga ₂ O ₃ , 9.79 g of ZnO and 14.8 g of ZrO ₂ was melted as starting material for the melt and from this melt a single crystal substrate was heated to 1 bar of O ₂ and It can be pulled up by the Czyochralski method according to claim 4 under a pressure of 5 bar N ₂ .

Alternatively, the magnetic layer can be produced on a non-magnetic substrate by liquid phase epitaxy.

The advantages of the present invention are primarily that a defect-free layer of hexagonal hexaferrite of good quality, homogeneity and crystalline perfection, such as barium hexaferrite, can be produced in monocrystalline form on a non-magnetic substrate. It is possible to generate materials. Another advantage of the method of manufacturing magnetic devices of the present invention is that single crystals can be grown to a length to form a sufficient number of substrate slices from one single crystal. Due to the relatively large diameter of the grown substrate single crystals, these substrate slices are large enough for industrial use.

There are many difficulties in growing alkaline earth gallicamate single crystals.

The T-X phase diagrams of BaO/Ba ₂ O ₃ and SrO/Ga ₂ O ₃ systems are known (P. Batey and G. Slogari, "Ann. Chim." 59 (1969), p. 155~ 162;L.
M. Koiba et al. “Russian J. of Inorganic
Chemistry” 20 (1975) 7; VP Kobzareva et al. “Russian J. of Inorganic Chemistry” 21
(1976)6). From this, the compounds BaGa ₁₂ C ₁₉ and SrGa ₁₂ O ₁₉ melt disproportionately. Ga ₂ O ₃ as the first phase crystallizes from the stoichiometric melt. Because of this, it is not possible to grow it from its own melt. Furthermore, according to the phase diagram, the region in which both compounds exist is extremely narrow. For this, strontium gallate, for example, contains approximately 32 mol%
SrO and 68 mol% _{Ga2O3 to} 36 mol% SrO
and crystallizes from the melt in the concentration range of 64 mol% Ga ₂ O ₃ . Crystals contain 14 mol% SrO and 86 mol%
has a molar ratio of Ga ₂ O ₃ of . For this reason,
Similarly, the growth of single crystals along the liquidus from non-stoichiometric melts is excluded. This was confirmed through experiments. In _{the case} of single crystal growth _of alkaline earth gallates, _e.g. It becomes a decisive obstacle in comparison.

Surprisingly, hexagonal alkaline earth gallate phases can be produced from the melt when the gallium ions of hexagonal compounds are partially replaced by other ions, especially divalent and tetravalent ions. I confirmed that. Furthermore, this substitution of gallium ions is important in order to match the lattice constant of the substrate to that of the magnetic layer.

The following four examples demonstrate that excess SrO in the melt can be removed by gallium ion replacement.

The following crystal compositions 1 to 4 are generated from the following melt compositions 1 to 4: Melt composition 1 Sr _2.48 Ga _10.52 O _18.26 2 Sr _1.53 Ga _10.47 Mg _0.5 Zr _0.5 O _18.75 3 Sr _1.085 Ga _9.915 MnZrO _18.96 4 Sr _1.085 Ga _9.915 ZnZrO _18.96 Crystal composition 1 SrGa ₁₂ O ₁₉ 2 Sr _1.03 Ga _10.99 Mg _0.49 Zr _0.49 O _18.99 3 Sr _1.0 Ga _10.6 Mn _0.7 Zr _0.7 O ₁₉ 4 Sr _1.0 Ga _10.38 Z n _0.81 Zr _0.81 O ₁₉ Non-substitution melting 1.48 per formula unit in the field (Example 1)
The excess of SrO can be removed by combined displacement of up to 0.085 gallium ions per formula unit (Example 4). As a result of this, single crystals can be grown from the alkaline earth gallate mixed crystal from the melt.

One structure of the magnetic device of the invention is described with reference to the accompanying drawings: A 10 μm thick hexagonal single crystal magnetic hexaferrite layer 2 is formed on a non-magnetic hexagonal substrate (0.5 mm thick) 1.
grown by epitaxy from alkaline earth gallate crystals on top, in this case two cylindrical magnetic domains 3
is formed by applying a magnetic field of approximately 20 KOe perpendicular to the layer. The magnetization of the layer is indicated by arrow 4.

Example 1 As an example of making a non-magnetic hexagonal single crystal substrate suitable for isolating a single crystal hexagonal hexaferrite layer for the production of the magnetic device shown in the accompanying drawings, a composition Sr _1.03 Ga _{10.99 is} used. The growth of strontium gallate single crystals with Mg _0.49 Zr _0.49 O _18.99 is described. As a starting material for the melt
77.87g SrO, 481.97g Ga ₂ O ₃ , 9.90g MgO
and 30.26 g of ZrO ₂ were mixed, pressed into a cylindrical shape, and fired at a temperature of 1500° C. in an oxygen atmosphere. The calcined compacts were then melted in a carbon dioxide atmosphere (flow rate: 500/h) at a temperature of 1600° C. in an induction heating crucible made of iridium in a closed crystal pulling apparatus known from the Czyochralski method. A cylindrical single crystal rod having the same chemical composition as the produced single crystal was used as a seed crystal. The lifting method was carried out by a known method based on the Czyochralski method. The growth rate was 1 nmh ^-1 and the seed crystals were rotated at a speed of 8 r.pm. After this process, Sr _1.03 Ga _10.99 with length 65mm and diameter 30mm
A Mg _0.49 Zr _0.49 O _18.99 single crystal was obtained. The lattice constants were 0.582 nm at a ₀ and 2.307 nm at c ₀ (a and c are the crystal directions in the hexagonal lattice). For comparison, the lattice constants of BaFe ₁₂ O ₁₉ are 0.589 nm at a ₀ and 2.320 nm at c ₀
It was hot.

Example This example describes the growth of a Sr _1.0 Ga _10.38 Zn _0.81 Zr _0.81 O ₁₉ single crystal.

The following starting materials were mixed, compressed into a cylindrical shape, and fired at 1500°C in an oxygen atmosphere: SrCo ₃ 19.28g Ga ₂ O ₃ 112.39g ZnO 9.79g ZrO ₂ 14.84g The fired compact was then It was melted at a temperature of 1600 °C in an induction-heated crucible made of platinum or iridium in a closed crystal pulling apparatus known in the art. The apparatus contained oxygen at a pressure of 1 bar and nitrogen at a pressure of 5 bar.
A cylindrical single crystal rod with the same chemical composition as the single crystal to be grown was used as a seed crystal. The pulling method is a well-known method based on the Czyochralski method. The growth rate is 2 nmh ^-1 , and the rotation speed of the seed crystal is
At 20 rpm, crystals with a length of 23.5 mm and a diameter of 10 mm were grown. The lattice constants were 0.583 nm at a ₀ and 2.324 nm at c ₀ .

All crystals grown in the above examples and above were colorless and optically clear. Crystal integrity was determined by the Schlieren method using a polarized microscope. Displacement and occlusion were made to be <1.10 ² /cm ² .

These examples describe growing strontium gallate single crystals by replacing a portion of the gallium ions with magnesium and zirconium ions, or with zinc and zirconium ions, but due to the extremely small ionic radius. Manganese or iron or copper or nickel or cobalt or chlorine can be used instead of magnesium or zinc, and hafnium or titanium or tin can be used instead of zirconium.

To construct a magnetic device for use as a microwave component in a magnetic cylindrical domain device or as a magnetic cylindrical domain device, the crystals grown as described above are cut and oriented substantially in the 001 direction; A substrate slice having a thickness of 0.5 to 1 mm was formed (deviation from the [001] orientation should be about 1 to 2 degrees). The substrate slices were then polished.
A magnetic hexagonal single crystal hexaferrite layer, preferably a barium hexaferrite layer, with a thickness of up to 10 μm was deposited on these substrate slices, preferably by liquid phase epitaxy (LPE).
However, separation from the gas phase (CVD) can also be used to deposit the layer.

The growth method is "Cryst.Growth" 17 (1972) by SL Blank and JW Nielsen, P.302
311, but in the present invention the concentration of ferrite material to be crystallized is significantly higher.

The melt in which the ferrite layer is grown has the following composition (expressed in % by weight): PbO 76.99 B ₂ O ₃ 1.91 BaO 2.71 Fe ₂ O ₃ 16.90 Ga ₂ O ₃ 0.99 Al ₂ O ₃ 0.50 100.00 The starting material is platinum. It was melted in a crucible at 1100°C and stirred for several hours with a platinum stirrer to homogenize the melt. The saturation temperature for a given composition is approximately
It was 905℃. The melt was cooled to 975°C and the temperature was maintained constant. This method is called the isothermal growth method. The substrate, supported in a platinum holder in a vertical or horizontal position, depending on the growth conditions, with or without rotational movement, was immersed in the melt by known means. A ~4 μm thick layer was crystallized by immersing the substrate in the melt composition for 90 seconds in a vertical position without rotation. Chemical analysis of the layer by microprobe, determined by melt composition and growth parameters, showed a lead content of ~6% PbO by weight. Chemical analysis, lattice parameter analysis and measurement of the anisotropic magnetic field of the layer at 60-90 GHz were carried out on barium hexaferrite with magnetoplumbite structure.
It was shown that Ba(Pb)Fe ₁₂ O ₁₉ . The saturation magnetization (4πMS) of the layer material was measured at 4000 Gauss. The difference in lattice constant between layer and substrate, ie lattice mismatch, was determined by X-ray measurements in reflection. In the art, the lattice constant of the layer can be matched to the lattice constant of the substrate by using weighed adducts of gallium or aluminum. barium hexaferrite layer
In the case of Ba(Pb)Fe ₁₂ O ₁₉ , the lattice mismatch is around −0.013 nm and is reduced to −0.007 nm by incorporation of gallium or aluminum ions.

The magnetic domain structure (see attached drawing) can be observed in the layer formed by the method described above, but it should be noted that: The polarization effect is annihilated by birefringence, i.e.
Weiss magnetic domains that can be observed based on Faraday rotation are not observed. However, although the magnetic domains can be easily recognized in the deposited layer, the birefringence of the substrate cannot eliminate Faraday rotation and polarization effects. By applying a magnetic field of about 20 KOe orthogonally to the layer, cylindrical domains were generated from the strip domains present in this layer. This size, that is, the diameter of the cylindrical magnetic domain, is influenced by the thickness of the magnetic layer, and when the thickness is reduced to 1 μm or less, the diameter of the cylindrical magnetic domain becomes less than 1 μm, but the wavelength of light Due to certain limitations, cylindrical magnetic domains can no longer be observed with a light microscope. This phenomenon is described in "Berichte der Deutschen
54 (1977), No.
11, pp. 373-378, in the paper by F. Habeley, G. Oelschleger, and K. Sahal.

Components for applying a cylindrical magnetic domain made as described above using a substrate provided with a single-crystal barium hexaferrite layer are, for example, "Proc.IEEE".
63 (1975), No. 8, P. 1176-1195, by the well-known technique described by AH Bovecz, PI Bonyhard, and JE Sewczyk.

[Brief explanation of drawings]

The accompanying drawings are diagrams illustrating the magnetic device of the invention in the form of a cylindrical domain device. DESCRIPTION OF SYMBOLS 1...Nonmagnetic hexagonal substrate, 2...Hexagonal single crystal magnetic hexaferrite layer, 3...Cylindrical magnetic domain, 4...Arrow.

Claims (1)

Claims: 1. In a magnetic device having a single crystal non-magnetic substrate with a surface adapted to deposit a layer and to support a single crystal magnetic layer of hexagonal ferrite material, the substrate has the formula: A ²⁺ _1+y Ga _12-2x-y B ²⁺ _x C ⁴⁺ _x O ₁₉ (wherein: A=barium and/or strontium B=magnesium and/or manganese and/or zinc and/or iron and/or copper and/or nickel and/or cobalt and/or chromium C=zirconium and/or hafnium and/or titanium and/or tin and alkaline earth gallium represented by 0.1≦x≦1.2 and 0≦y≦0.8) A magnetic device characterized by being composed of an acid salt mixed crystal. 2. The magnetic device according to claim 1, which satisfies the requirement of 0.4≦x≦0.8. 3. A magnetic device according to claim 1 or 2, wherein the substrate has a composition according to the formula Sr _1.03 Ga _10.99 Mg _0.49 Zr _0.49 O _18.99 . 4. The magnetic device according to claim 1 or 2, wherein the substrate has a composition of Sr _1.0 Ga _10.38 Zn _0.81 Zr _0.81 O ₁₉ . 5. Magnetic device according to any one of claims 1 to 4, wherein the surface of the substrate for depositing the layer has an orientation in the 001 direction and a deviation in the range from 1 to 2 degrees from the c-axis direction. . 6. The magnetic device according to claim 1, wherein the material of the magnetic layer is alkaline earth hexaferrite. 7 The material of the magnetic layer is barium hexaferrite.
The magnetic device according to claim 6, wherein Ba(Pb)Fe ₁₂ O ₁₉ is used. 8. A magnetic device according to any one of claims 1 to 7, wherein the thickness of the magnetic layer is in the range of 0.5 to 10 μm. 9 Formula: A ²⁺ _1+y Ga _12-2x-y B ²⁺ _x C ⁴⁺ _x O ₁₉ (wherein: A=barium and/or strontium B=magnesium and/or manganese and/or zinc and/or iron and/or copper and/or nickel and/or cobalt and/or chromium C=zirconium and/or hafnium and/or titanium and/or tin and 0.1≦x≦1.2 and 0≦y≦0.8) Hexagonal mixed crystal. 10. The hexagonal mixed crystal according to claim 9, which satisfies the requirement of 0.4≦x≦0.8. 11. A hexagonal mixed crystal according to claim 9, the composition of which is of the formula: Sr _1.03 Ga _10.99 Mg _0.49 O _18.99 . 12. A hexagonal mixed crystal according to claim 9, the composition of which is of the formula: Sr _1.0 Ga _10.28 Zn _0.81 Zr _0.81 O ₁₉ . 13 The starting material for the single crystal substrate is dried, compressed, and fired in an oxygen atmosphere, and the fired compact for producing a single crystal is melted in a closed crystal pulling apparatus using the Czyochralski method, and the single crystal is extracted from this melt. With the help of a seed crystal, a slice is cut and polished from this single crystal with an orientation deviating from 1 to 2 degrees from the direction of the c-axis to obtain the formula: A ²⁺ _1+y Ga _12-2x-y B ²⁺ _x C ⁴⁺ _x O ₁₉ where: A=barium and/or strontium B=magnesium and/or manganese and/or zinc and/or iron and/or copper and/or nickel and/or cobalt and/or chromium C = zirconium and/or hafnium and/or titanium and/or tin and 0.1≦x≦1.2 and 0≦y≦0.8). manufacturing method. 14 Pulling the crystal from the melt, at least 1
Hexagonal mixture according to claim 13, in which other oxides of divalent elements and at least one tetravalent element are added to the starting materials of alkaline earth oxides and gallium oxide Ga ₂ O ₃ . Crystal manufacturing method. 15. The method for producing a hexagonal mixed crystal according to claim 14, wherein at least one oxide of barium or strontium is added as an alkaline earth oxide. 16 Magnesium, manganese, zinc, iron, copper,
At least one of nickel, cobalt or chlorine
15. The method for producing a hexagonal mixed crystal according to claim 14, wherein the seed oxide is added as an oxide of a divalent element. 17. The method for producing a hexagonal mixed crystal according to claim 14, wherein at least one oxide of zirconium, hafnium, titanium, or tin is added as an oxide of a tetravalent element. 18 Starting materials SrO, Ga ₂ O ₃ , MgO and ZrO ₂
15. The method for producing a hexagonal mixed crystal according to claim 14, wherein the hexagonal mixed crystal is melted in a closed crystal pulling apparatus in a CO ₂ atmosphere. 19 Starting materials SrCO ₃ , Ga ₂ O ₃ , ZnO and ZrO ₂
15. A process for producing a hexagonal mixed crystal according to claim 14, wherein the hexagonal mixed crystal is melted in a closed crystal pulling apparatus under a pressure of 1 bar _O2 and 5 bar _N2 .