JPH039080B2 - - 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 that has orthorone pick anisotropy, whose axis of easy magnetization is 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 devices using normal permalloy patterns instead of conductor patterns, the hard bubble control process can be omitted.
(2) It has advantages such as 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 MR-80-6 (1980), as long as conventional materials are used, there is a limit to the domain wall motion speed of the magnetic recording medium. cannot follow. 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 in magnetic transfer and optical readout techniques 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) Orthorone pick anisotropy occurs in garnet liquid phase epitaxial films. Wolfe et al., Ablide Physics Letters, Vol. 29, No. 12, page 815 (1976)
As shown in the paper of It is necessary to satisfy any of the relationships shown in Equation 2, Equation 2, and Equation 3. Ku＞0 (1), Ku＋△＞0 (2), △≠0 (3) However, in many garnets,
Ku<0 or Ku+Δ<0, and when grown on a nonmagnetic garnet substrate with a (110) plane, the [110] direction perpendicular to the film surface 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 simultaneously satisfies the first and second equations for double conductor pattern bubble elements and 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 (IEEETrans
Mag) Paper published by Breed et al. in MAG Volume 13, Page 1087 (1977) and Proceedings of the 25th Applied Physics Association Lecture Conference Lecture No. 30a-F-
5 (1978), page 558, generally (110), as known from the paper published by Makino and Hidaka.
A garnet film has a large coercive force (He), so stability may not be guaranteed when used as a bubble element. The object of the present invention is to have an easy axis of magnetization perpendicular to the film surface, which is essential for double conductor pattern bubble elements, magnetic transfer/optical readout elements with a wide frequency band, and laser beam deflection elements that can be driven at high frequencies. An object of the present invention is to provide a (110) garnet film having a low coercive force and a low coercive force. In the present invention, R _3-xy R _{′ x} Bi _{y Fe 5-z} Ga _z O ₁₂ (where 0≦ x
≦2.0, 0.05≦y≦0.7, 0.5≦z≦1.45, R is Ho,
A garnet liquid phase epitaxial film having a composition where R' is one element or a combination of two elements selected from the group consisting of Er and Yb, and R' is one element or a combination of two elements selected from the group consisting of Tm and Lu, is a rare earth It has orthorombic anisotropy with an axis of easy magnetization perpendicular to the film surface due to growth-induced isomerism due to pair ordering of ions and Bi ions and strain-induced anisotropy due to the difference in lattice constant between the film and substrate. This discovery led to the present invention. The present invention will be explained in detail below using Examples. Example 1 Melt 1 shown in Table 1 was used to deposit Er _2.5 Bi _0.5 Fe _3.95 Ga _1.05 on a (110) Dy ₃ Ga ₅ O ₁₂ substrate at 826°C.
When an O ₁₂ garnet liquid phase epitaxial film was grown, the film thickness was 1.8 μm, and it became an orthorombic anisotropic bubble material whose easy magnetization axis was the [110] axis perpendicular to the film surface. The magnetic properties of this LPE film are shown in Table 2, and the anisotropic energy Ku between the easy axis of magnetization [110] and the intermediate axis of magnetization [001] and the anisotropic energy Ku between the intermediate axis of magnetization and the hard axis of magnetization are as follows. When the anisotropy energy Δ was measured using a ferromagnetic resonance device, it was determined that Ku=7300erg/cm ³ and Δ=15000erg/cm ³ , respectively. The bubble diameter in this material was 1.6 μm, and no hard bubbles were present. The coercive force of the material was sufficiently small that the bubble could be moved with a minimum driving magnetic field ΔH = 1.8oe. The saturation moving speed of the bubble was 138 m/sec, and the domain wall mobility was 4.3 m/sec-Oe. When a double conductor pattern element was made using this material, it was possible to drive a bubble at a frequency of 6MHz. 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, there was no breakdown in the transfer speed during stripe magnetic domain transfer in the stretcher section, which requires the maximum degree of domain wall motion in conventional bubble devices. When this material is used as a laser beam deflection element, it is not only possible to drive at high speed, but also 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 with laser light, the saturation domain wall movement speed of this material is 138 m/sec, so the magnetic recording information It was able to sufficiently follow the moving speed of the robot, and was able to extend the recording and reproducing frequency to 7MHz. Furthermore, since Bi ³⁺ is substituted in this material, the Faraday rotation angle can be increased and the signal S/N ratio can be increased to over 45 dB. Note that similar results were obtained when a portion of Ga in the garnet composition formula was replaced with Al. Example 2 Melt 4 shown in Table 1 was used to deposit Er _0.83 Tm _1.51 Lu _0.42 on a (110)Gd ₃ Ga ₅ O ₁₂ substrate at 865°C.
When a Bi _0.24 Fe _3.67 Ga _1.33 O ₁₂ garnet liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained. Example 3 Using the melt 5 shown in Table 1, Er _0.89 Lu _1.66 Bi _0.45 Fe _3.70 was deposited on a (110) Dy ₃ Ga ₅ O ₁₂ substrate at 830°C.
When a Ga _1.30 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, Yb _0.92 Er _0.84 Tm _1.00 was deposited on a (110) Gd ₃ Ga ₅ O ₁₂ substrate at 860°C.
When a Bi _0.24 Fe _3.55 Ga _1.45 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, Yb _2.5 Bi _0.5 Fe _3.95 Ga _1.05 was deposited on a (110) Gd ₃ Ga ₅ O ₁₂ substrate at 857°C.
When an 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, Yb _1.19 Lu _1.35 Bi _0.46 was deposited on a (110) Dy ₃ Ga ₅ O ₁₂ substrate at 830°C.
When a Fe _3.70 Ga _1.30 O ₁₂ garnet liquid phase epitaxial film was grown, the properties shown in Table 2 were obtained. Example 7 Using melt 7 shown in Table 1, Ho _0.1 Yb _0.2 Lu _2.0 Bi _0.7 was deposited on a (110) Gd ₃ 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 8 Using melt 8 shown in Table 1, at 948°C,
(110) Ho _2.89 Yb _0.66 Bi _0.05 on Dy ₃ Ga ₅ O ₁₂ substrate
When a Fe _3.55 Ga _1.45 O ₁₂ garnet liquid phase epitaxial film was grown, the [110] direction perpendicular to the film surface was the axis of easy magnetization, as shown in Table 2. The intermediate axis of magnetization in this case was at [110]. Therefore, Δ<0.

【table】

[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 range can be obtained. When used as a laser beam deflection element, high frequency driving becomes possible.

Claims (1)

[Claims] 1 In a single-crystal garnet film for magnetic and magneto-optical elements formed on a non-magnetic garnet substrate, having the same crystallographic orientation as this substrate, and having an axis of easy magnetization perpendicular to the film surface, the film composition is R _{3- xy} R′ _x Bi _y
Fe _5-z Ga _z O ₁₂ (However, 0≦x≦2.0, 0.05≦y≦0.7,
0.5≦z≦1.45, R is one element selected from the group consisting of Ho, Er, and Yb, or a combination of multiple elements;
A single crystal garnet film for magnetic and magneto-optical elements, characterized in that R' is one element or a combination of two elements selected from the group consisting of Tm and Lu, and the film plane orientation is (110).