JPH039079B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic garnet liquid phase epitaxial film grown on a non-magnetic (110) gallium garnet substrate and having orthorombic anisotropy in which the axis of easy magnetization is perpendicular to the film surface. Bell System Technical Journal
System Technical Journal) Volume 58 No. 6 No. 2
The bubble magnetic domain element using a dual conductor pattern (dual conductor pattern) announced by Bobetsk et al. on page 1453 (1979) is different from the conventional bubble magnetic domain element. It has the following characteristics: () high frequency drive of the bubble magnetic domain is possible; () the diameter of the bubble magnetic domain can be miniaturized, so the storage density of the device can be improved. In order to realize this element, it has been proposed to use a material having orthorombic anisotropy, which has an axis of easy magnetization perpendicular to the film surface and also has magnetic anisotropy within the film surface. In a material with orthorombic anisotropy, if the in-plane anisotropic magnetic field is large enough, this in-plane anisotropic magnetic field acts on the domain wall, and the saturation value of the domain wall movement speed is compared to that in a normal material. Can be made significantly larger. Also,
Orthorombic materials do not produce hard bubbles and are characterized by the fact that the S state of the domain wall can be maintained at a low level. Therefore, even in an element using a normal permalloy pattern instead of a conductor pattern, the hard bubble suppression process can be omitted.
(2) It has advantages such as the possibility of high-frequency driving of bubbles. In addition, when using a magnetic garnet film as an element for reproducing information from a magnetic recording medium by magnetic transfer and optical readout, the Institute of Electronics and Communication Engineers Technical Research Report
As stated on page 15 of MR80-6 (1980), as long as conventional materials are used, there is a limit to the domain wall motion speed of the garnet, which causes the domain wall motion speed of garnet to follow the motion speed of the magnetic recording medium. Can not. If an orthorombic anisotropic material is used in such an element, the maximum movement speed of the domain wall will be much higher than the 25 to 30 m/sec of ordinary materials, and the dynamic characteristics of magnetic transfer and optical readout technologies can be significantly improved. . Furthermore, if an orthorombic material is used in the laser beam deflection element, the driving frequency can be improved. Materials with orthorombic anisotropy cannot be obtained from (111) garnet films, which are common bubble materials. (110) Orthorombic anisotropy occurs in garnet liquid-phase epitaxial films. Ablide Physics Letters, Vol. 29, No. 12, p. 815 (1976) by Wolfe et al.
As shown in the paper of 2010, in order for the (110) garnet film to have orthorombic anisotropy and to have an axis of easy magnetization perpendicular to the film surface,
The two anisotropic energy constants are the following equations 1 and 2.
It is necessary to satisfy both the relationships shown in the formula and the third formula. K _U >0 (1), K _U +Δ>0 (2) Δ≠0 (3) However, in many garnets,
K _u <0 or K _U +Δ>0, and when grown on a nonmagnetic garnet substrate with a (110) plane, the [110] direction perpendicular to the film plane does not become the axis of easy magnetization. Therefore, it is important to find a garnet film composition and manufacturing conditions that can provide a (110) garnet film having orthorombic anisotropy that satisfies the first and second equations at the same time. This is most important for the practical application of magnetic transfer/optical readout elements with a wide frequency band or laser beam polarization elements that can be driven in a high frequency range. Furthermore, I.E.E. Transactions on Magnetics (I.E.E.
E Trans Mag) Volume 13, page 1087 (1977) and the paper published by Breed et al.
As is known from the paper published by Makino and Hidaka in the Proceedings of the 25th Union of Applied Physics Lectures, Lecture No. 30a-F-5 (1978), page 558, (110) garnet films generally have a The magnetic force (Hc) is large, and stability may not be guaranteed when used as a bubble element. In addition, in the material published by Breed et al.
Both the anisotropy energy Ku perpendicular to the film plane and the anisotropy energy Δ in the film plane are mainly caused by strain-induced anisotropy. For this purpose, the difference in lattice constant between the film and the substrate must be made extremely large. This not only causes coercive force, but also means that the magnetic properties are likely to change due to distortion caused by various element patterns deposited on the garnet film. Localized distortion in the garnet film causes bubble malfunction. The object of the present invention is essential for a double conductor pattern bubble element, a magnetic transfer/optical readout element with a wide frequency band, and a laser beam deflection element that can be driven at a high frequency. It has an axis of easy magnetization perpendicular to the film surface,
Moreover, it has a low coercive force, and can generate the required magnetic anisotropy mainly through growth-induced anisotropy without introducing strain into the film (110).
The object of the present invention is to provide a garnet film. The present inventor has developed (YBi) ₃ (FeGa) ₅ O grown on a (110) nonmagnetic garnet substrate from a flux containing PbO and Bi ₂ O ₃ as main components as disclosed in Japanese Patent Application No. 54-158334. ₁₂ , garnet with a film composition doped with rare earth ions, that is, Y _3-Wxy R _W R′ _x
Bi _y Fe _5-z Ga _z O ₁₂ (However, 0<W≦2.0, 0≦x≦
1.7, 0.05≦y≦0.7, 0.5≦z≦1.45, R is La,
One element or combination of elements selected from the group consisting of Ho, Sm, Eu, Gd, Er, Yb, R' is
It was discovered that a garnet liquid phase epitaxial film with a composition represented by one element or a combination of two elements selected from the group consisting of Tm and Lu exhibits orthorombic anisotropy with an axis of easy magnetization perpendicular to the film surface. It was found that K _U and Δ could be made larger than that of YBi) ₃ (FeGa) ₅ O ₁₂ , and the present invention was completed. The present invention will be explained in detail below using Examples. Example 1 Melt 1 shown in Table 1 was used to deposit Y _2.425 −Sm _0.075 on a (110)Gd ₃ Ga ₅ O ₁₂ substrate at a temperature of 837°C.
When a Bi _0.5 Fe _4.3 Ga _0.7 O ₁₂ garnet liquid phase epitaxial film was grown, the film thickness was 1.8 μm, and it became an orthorombic anisotropic bubble material with the [110] axis perpendicular to the film surface as the axis of easy magnetization. Ta. The magnetic properties of this LPE film are shown in Table 2, and the anisotropic energy K U between the easy magnetization axis [110] and the intermediate magnetization axis [001] and the anisotropic energy K _U between the magnetization intermediate axis and the hard magnetization axis When we measured the anisotropic energy Δ using a ferromagnetic resonance device, we found that K _U =
It was determined that 12000erg/cm ³ and Δ=40000erg/cm ³ . These values are disclosed in Japanese Patent Application Laid-Open No. 158334/1983. (YBi) ₃ (FeGa) ₅ O ₁₂ was larger than either value. These were attributed to growth induction since the difference in lattice constant between the film and the substrate was almost zero. The bubble diameter in this material was 1.7 μm, and no hard bubbles were present. The coercive force of the material is sufficiently small that the minimum driving magnetic field ΔH=
I was able to make a bubble work with 20oe. The saturated moving speed of the bubble is 140 m/soc, and the domain wall mobility is 25
It was m/sec-oe. When we made a double conductor pattern element using this material, we found that the bubble was 10MHz.
It was possible to drive at a frequency of Even when this material was used in conventional devices using permalloy patterns, the yield of devices was improved because the process of suppressing hard bubbles could be omitted. In addition, the maximum domain wall movement speed is required in conventional bubble elements. There was no breakdown in transfer speed during stripe magnetic domain transfer in some areas. When this material is used as a laser beam deflection element, not only is high-speed driving possible, but the ^Faraday rotation angle is large (-
4000deg/cm) The S/N ratio of the signal has been improved. When this material was used in an element that magnetically transfers information in a magnetic recording medium moving at a speed of 40 m/sec and reads it out using laser light, the saturation domain wall movement speed of this material is 140 m/sec, so the magnetic It is possible to sufficiently follow the moving speed of recorded information, and the recording and playback frequency can be
I was able to expand it to 7MHz. Furthermore, since Bi ³⁺ is substituted in this material, the Faraday rotation angle can be increased and the S/N ratio of the signal can be increased.
I was able to increase it to over 45dB. Note that similar results were obtained when a portion of Ga in the garnet composition formula was replaced with Al. Example 2 Melt 2 shown in Table 1 was used to deposit Y _2.91 E _U0.04 Bi _0.05 on a (110) Dy ₃ Ga ₅ O ₁₂ substrate at 953°C.
When a Fe _3.55Ga 1.45O ₁₂ garnet liquid phase epitaxial film was grown, it became an orthorombic material whose axis of easy magnetization was perpendicular to the film surface, as shown in Table 2. In this material, the magnetization intermediate axis [110]
Therefore, Δ<0. Example 3 Using melt 3 shown in Table 1, Y _2.24 Sm _0.03 Gd _0.03 Bi _0.7 was deposited on a (110) Sm ₃ Ga ₅ O ₁₂ substrate at 790°C.
When a Fe _3.8 Ga _1.2 O ₁₂ garnet liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained. Example 4 Using melt 4 shown in Table 1, Y _2.53 Gd _0.07 Bi _0.4 Fe _4.4 was deposited on a (110) Gd ₃ Ga ₅ O ₁₂ substrate at 850°C.
When a Ga _0.6 O ₁₂ garnet liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained. Example 5 Using melt 5 shown in Table 1, Y _2.27 Sm _0.02 Eu _0.01 Bi _0.7 was deposited on a (110) Sm ₃ Ga ₅ O ₁₂ substrate at 760°C.
When a Fe _4.5 Ga _0.5 O ₁₂ garnet liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained. Example 6 Using melt 6 shown in Table 1, Y _2.89 Yb _0.06 Bi _0.05 Fe _3.55 was deposited on a (110) Dy ₃ Ga ₅ O ₁₂ substrate at 950°C.
When a Ga _1.45 O ₁₂ garnet liquid phase epitaxial film was grown, it became an orthorombic anisotropic material whose easy magnetization axis was in the [110] direction perpendicular to the film surface, as shown in Table 2. In this material, the intermediate axis of magnetization was at [110], so Δ<0. Example 7 Using melt 7 shown in Table 1, Y _2.00 Yb _0.15 Ho _0.15 Bi _0.7 was deposited on a (110) Sm ₃ Ga ₅ O ₁₂ substrate at 810°C.
When a Fe _4.3 Ga _0.7 O ₁₂ garnet liquid phase epitaxial film was grown, the characteristics shown in Table 2 were obtained. Example 8 Using melt 8 shown in Table 1, Y _2.90 Er _0.05 Bi _0.05 Fe _3.55 was deposited on a (110) Dy ₃ Ga ₅ O ₁₂ substrate at 946°C.
When a Ga _1.45 O ₁₂ garnet liquid phase epitaxial film was grown, it became an orthorombic anisotropic material whose axis of easy magnetization was perpendicular to the film surface, as shown in Table 2. In this material, the intermediate axis of magnetization is [11
0], therefore Δ<0. Example 9 Using melt 3 shown in Table 1, Y _2.00 Er _0.17 Ho _0.13 Bi _0.7 was deposited on a (110) Sm ₃ Ga ₅ O ₁₂ substrate at 803°C.
When a Fe _4.3 Ga _0.7 O ₁₂ garnet liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained. Example 10 Using melt 10 shown in Table 1, Y _0.2 Yb _0.4 Lu _1.7 Bi _0.7 was deposited on a (110) DyGd ₂ Ga ₅ O ₁₂ substrate at 770°C.
When a Fe _4.5 Ga _0.5 O ₁₂ garnet liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained. Example 11 Y 0.1 Er _2.0 Tm _0.2 Bi _0.7 was deposited on a (110)Gd ₃ Ga ₅ O ₁₂ substrate at 770°C using the melt 11 shown in Table 1 _.
When a Fe _4.5 Ga _0.5 O ₁₂ garnet liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained. Example 12 Using the melt 12 shown in Table 1, Y _1.95 La _0.08 Tm _0.02 was deposited on a (110) Gd ₃ Ga ₅ O ₁₂ substrate at 828°C.
When a LU _0.35 Bi _0.6 Fe _4.50 Ga _0.50 O ₁₂ liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained.

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[Table] As described above, by using the present invention, a bubble magnetic domain element using a double conductor pattern that can be driven in the MHz region can be obtained when used as a bubble element material, and when used as a conventional permalloy element. Since there are no hard bubbles, the process of suppressing them can be omitted. When used as a magnetic transfer/optical readout element, an element with a wide frequency band can be obtained. When used with a laser beam polarizer, high frequency driving becomes possible.

Claims (1)

[Claims] 1. In a single crystal garnet film for magnetic and magneto-optical elements, which is formed on a non-magnetic garnet substrate, has the same crystallographic orientation as the substrate, and has an axis of easy magnetization perpendicular to the film surface, the film composition is Y _{3- WXy} R _W
R′ _X Bi _y Fe _5-Z Ga _Z O ₁₂ (However, 0<W≦2.0, 0≦X
≦1.7, 0.05≦y≦0.7, 0.5≦Z≦1.45, R is La,
One element or combination of elements selected from the group consisting of Ho, Sm, Eu, Gd, Er, Yb, R' is
(one element or a combination of two elements selected from the group consisting of Tm and Lu), and the film surface orientation is (110).
A single crystal garnet film for magnetic and magneto-optical elements, characterized in that: