JPS62119759A - Magneto-optical material - Google Patents

Abstract

PURPOSE:To reduce the variance in the inversion magnetic field in spite of the titled magneto-optical material using a polycrystal by using garnet having specified lambda111 and lambda100 as the polycrystal garnet. CONSTITUTION:A polycrystalline Bi-substituted rare earth iron garnet film having a compensation temp. is formed on an amorphous substrate to obtain the magneto-optical material. The garnet crystal wherein the ratio K (lambda111/lambda100) of the magnetostriction constants in the <111> and <100> directions is adjusted to 1/5-5 is used in the Bi-substituted rare earth iron garnet film. When the K value is lower than 1/5 or higher than 5, the magnetic characteristic in the direction vertical to the film face is widely distributed due to the variance in the crystal axis of the crystal grain. When the ratio K of the two magneto- striction constants is controlled to 1/5-5, or preferably to 1/3-3, the magnetic characteristic in the direction vertical to the film face is not fluctuated even when the crystal axis of the crystal grain is varied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical material, and more particularly to a magneto-optic material using polycrystalline garnet with less variation in magneto-optical properties.

[Conventional technology]

As a magneto-optical material in which a Bi-substituted rare earth iron garnet film having a compensation temperature is provided on an amorphous substrate, for example, Bi,
2 Gd1. A glass substrate is known in which a polycrystalline perpendicularly magnetized film of 1 Fe2.1 A11.6o12 is formed by sputtering. (For example, the gth Japanese Society of Applied Magnetics Academic Lecture Abstracts/IaB-j, PJ4! (/9.r4c)
) [Problems to be Solved by the Invention] The conventional magneto-optical material using Bi-substituted rare earth iron garnet having the compensation temperature described above has a large coercive force and a large rotation angle of 7 Arade. However, the magnetization hysteresis loop is relatively gentle, resulting in a wide distribution of the magnetic field required to reverse the magnetic domain. The wide distribution of this reversal magnetic field causes problems such as a decrease in the S/N ratio when the magneto-optic material is used as a magneto-optical recording film, and sloppy switching when used as an optical shutter. Ta.

[Means for solving problems]

In order to solve the above-mentioned conventional problems, the present invention provides a Bi-substituted rare-earth iron garnet film of a magneto-optical material, which is formed by forming a polycrystalline Bi-substituted rare-earth iron garnet film having a % compensation temperature on an amorphous substrate. Garnet crystal (／／
The ratio K (λ111/λ100) of the magnetostriction constants λ111 and A100 in the /) and (/00':) directions is /5-
j is used.

Generally, the magnetic properties of a garnet crystal are expressed by the properties of the garnet crystal in the <l//> and (/00> directions, and the magnetostriction constant is also expressed by the magnetostriction constants λ111 and A100 in the above two directions.These two The ratio K (λ111/λ100) of magnetostriction constants is preferably /5 to j
/3 to 3, that is, the difference in one magnetostriction constant is required to be small. Is the value of K smaller than //3?
If it is larger, the magnetic properties in the direction perpendicular to the film surface will be widely distributed due to variations in the crystal axes of the crystal grains.

The ratio K of the two magnetostriction constants is /15~5, preferably //3~
If it is 3, it has the effect that the magnetic properties in the direction perpendicular to the film surface do not vary even if there are variations in the crystal axes of the crystal grains.
Bi■R■Fe◎M@012 (R: rare earth element, M:
A13"tGa3++cu2"+Ge"+Cu"+V
5+ trivalent or combination of ions equivalent to trivalent, 0.2
5≦(a)≦2. trr, o, s≦(a)≦3.0,3
．． 0≦◎≦s, o, o, s≦(b)≦8l, to, 2
≦■+(b)≦3.5, Lj≦◎→≦s, r ), and at least 20 mol% or more, preferably 50 mol% or more of the rare earth elements contained are Ho and/or D
Bi-substituted rare earth iron garnet having the composition y1 can be exemplified.

The first half of the above conditional expression indicates the conditions for generating the crystal structure of the garnet crystal, and the second half, including Ho and/or Dy in the Bi-substituted rare earth iron garnet, is the condition for reducing the difference in the magnetostriction constants. shows. If the content of Ho and/or Dy is less than 20 mol%, the ratio of magnetostriction constants tends to fall outside of //j~3.

The above-mentioned Bi-substituted rare earth iron garnet film with a magnetostriction constant ratio K of //j to 5 can be produced on an amorphous substrate such as a glass plate by a vapor phase method such as a sputtering method or a vapor deposition method, or by a method of applying a solution and then baking it. can be created on.

In addition, the magnetostriction constant of the above-mentioned garnet crystal changes depending on the temperature, but the magnetostriction constant in the present invention is the temperature at which it is normally used (room temperature).
It represents the magnetostriction constant at .

[For production]

The present invention was made in view of the fact that variations in the magnetic properties of the conventional magneto-optical materials are caused by variations in the direction of the crystal axes of the crystal grains of polycrystalline garnet films. Since a garnet with a small difference in two magnetostriction constants is used, variations in magnetic properties due to variations in the direction of crystal axes are reduced.

〔Example〕

Example-/Bil, 45D'/1.05 Gd0.32 Fe3.
85 AI! A magneto-optical material having a Bi-substituted rare earth iron garnet film having a composition of 1.3301z on a glass plate was prepared by the following operation.

First, a glass plate 32 with a thickness of about /zs is mounted on a stainless steel electrode plate (sample stage) 3/ of a radio frequency (RF) sputtering apparatus as shown in FIG. I installed the plug. Target 3g is Bi2 Gd F'e4.8AA! 1.20
12 disk-shaped sintered bodies 3! on top of B13GdFe4,8
Small disc sintered chip 36 and B of AA'1.2012
13DyFe4. QA! ! A small disk sintered body Tisof 37 of size n, 2 o 12 is placed.

Next, the inside of the sputtering equipment was
After exhausting the gas with Ar and 02 gas (Ar:02-
9:1) was allowed to flow up to O, (188 TOrr).

After the degree of vacuum is stabilized, the glass plate 32 is heated to
While heating to tOO''C using An amorphous film 39 with a film thickness of approximately 7 μm was created.The glass plate 32 with the amorphous film 39 was then held in air for 650″CKj hours and then cooled to crystallize the amorphous film and form a multilayer film. The crystal film was designated as II0.

The polycrystalline film was determined by conductively coupled plasma emission spectroscopy.
, 45 D'11. o5Gd0.32 F193.85
A11.3301g of crystalline film was analyzed.

The magnetostriction constant λ111/λ of the polycrystalline film. . Ha//3~
3 and estimated by the following reason. Here, A111 and A100 of TeDy3Fe5012 are JO
In OK -5,9X/(7-6 and 1/2.!r
x10-6 and A111 and A1 of Gd5Fe5o12
00 is 300KVC ite-3, /x10-6 and O
It is. (Physics of Ferromagnetic Materials (Part 2)/31 pages, written by Satoshi Chikanobu (
Shokabo) Published March 25, 1982) From these values, A111 and A100 at the temperature of JOOK of Dy2.3 Gd0.7Fe5012 are estimated by internal division method, and A111 knee is 3.2! l;×106rλ100 key9.
4X#)-6. Here A111/λ100ki0.
It is 55.

On the other hand, replacing the rare earth of the garnet crystal with Bi+:
(!: The change in the ratio of magnetostriction constants due to (R3-XBix Fe5O12) is not so large as Y3-) (taking BixFe5O12 as an example).

(295K il+ of Y3-X BiX Fe5O12
) The ratio of magnetostriction constants at temperature - λ111/λ100 is -2 when X-O, -2,63 when X-/!
: Teal to some extent.

See Figure 5 Phys, Rev, B, s2660
1C/913')) Also, by somewhat replacing Fe in the garnet crystal with 1 (R3Fe5-zAlz 012.
The ratio of magnetostriction constants of Y3Fe5-XGaXO12 at a temperature of 295 - λ111/λ100 is - when x-o.
2,/l, when X=i, s, it is medium 2.0, and (6th
See figure J, Appl.

phys,, LLJ63IC19711)) A111 by substitution of Al, which has a smaller change in magnetostriction constant than Ga K.
The change in the ratio A111/λ100 of Ga is smaller than the change in the ratio A111/λ100 of Ga. ) So Bil, +s DYx, o5Gd0.32 Fe
The value of A111/λ100 of 3,8511.33012 is Dy2.3 Gd0.7 A11 of Fe5012'λ
It is estimated that there is not much difference from the estimated values O and SS of 100.

Wavelength 632. of the polycrystalline film 110 relative to the magnetic field H in the direction perpendicular to the film surface of the polycrystalline film 110. When the hysteresis characteristics of one rotation angle of 7 nm were measured against light of 1 nm, a loop with good squareness as shown in FIG. 7 was obtained. The maximum value Hmax of the external magnetic field that causes reversal is approximately /20
00e and the minimum value Hmin of the external magnetic field that causes reversal
was approximately goooe.

Example-2 Bil, 5 Dy1.5F'83.8 A11.201
A magneto-optical material having a Bi-substituted rare earth iron garnet film having the composition No. 2 on a glass plate was prepared by the following operations.

Bismuth nitrate, dysprosium nitrate, ferric nitrate, aluminum nitrate in a molar ratio of 85: /, j: 3, g
It was weighed so that the total amount was O and OS moles. Add these nitrates to 10ml of 3N nitric acid aqueous solution! Add ethyl alcohol after dissolving it! It was made into a solution of Oml. This solution was dropped onto a glass plate 2 cm thick and 1 cm square, and then coated on the glass plate using a method of rotating the glass plate (spin cord method). This coating film is approximately IIo o
After drying in step C, the operation of forming a coating film on the dried film was repeated to finally form a uniform dry film with a thickness of about 220 nm.

This glass plate with a dry film was heated in the air for 630 minutes.
After being kept at ℃ for 3 hours, it was cooled. The dried film was thermally decomposed and then crystallized to become a polycrystalline film.

The polycrystalline film is Bil, 5 DYl, 5F83.8 A1
1.2012 polycrystalline garnet film. Further, the optical loop of the polycrystalline film was measured in the same manner as in Example 7, and the results are shown in FIG.

As described in Example 1, the ratio of the magnetostriction constants of the polycrystalline film is 0.0 out of the value A111/λ100 of Dy3Fe5012. '1
7(A111=-!r, 9×10-6, λIQQ
--/2.5×1O-6).

The maximum value Hmax of the external magnetic field that causes reversal is approximately /6000
e, and the minimum value of the external magnetic field that causes reversal is approximately 1roo
It was oe.

Comparative Examples Bil, 2Gdl, I Fe4. l AA'1.60
A Bil-exchanged rare earth iron garnet film having a composition of No. 12 was prepared on a glass plate in the same manner as in Example.

The results of measuring the magnetic hysteresis of the above-mentioned polycrystalline film having a thickness of approximately 10 μm are shown in FIG.

Bil, 2 Gd1. of this comparative example. l F'64.1 A
The ratio of magnetostriction constants of 11.6o12 garnet is Gd3
λ111/λ1oo of Fe+ 012=-oo(λ1
ll--3. /X10-6. λ100-”).

As shown in FIG. 3, the maximum value Hmax of the external magnetic field causing reversal of the polycrystalline film of the comparative example was about / j 00 Qe %, and the minimum value Hmin of the external magnetic field causing reversal was about 1oooe. Hmin/)Imax medium 0.07 ``?'' It can be seen that reversal occurs with a small magnetic field compared to Hmin/Hmax -0.5 of Example-Noyohi 2.

〔Effect of the invention〕

According to the present invention, since a garnet with λ'ill and A100 values of /15 to j is used as the polycrystalline garnet, the variation in the reversal magnetic field is small even though it is a magneto-optical material using polycrystals. It has become.

The above improvement in magnetic properties is preferable because it increases the S/N ratio when the magneto-optical material is used as a magneto-optical recording film, and increases the switching speed when it is used as an optical shutter.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the magneto-optical properties of the magneto-optical materials obtained in Example 1 and 2. Figure 3 is a sectional view schematically showing the sputtering apparatus used in Example 1, and Figure is a diagram showing the magneto-optical properties of the magneto-optical material obtained in Comparative Example 1, and FIG.
The magnetostriction constant λ1ilyλ1o of 2. FIG. 6 shows the magnetostriction constant λ111. of Y3Fe5-xGaxoxz. λ1
00 and λIll/λ100. Figure 1 Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) In a magneto-optical material formed by forming a polycrystalline Bi-substituted rare-earth iron garnet film having a compensation temperature on an amorphous substrate, <111> and <100> of the garnet crystals of the Bi-substituted rare-earth iron garnet film Magnetostriction constant λ_ of direction
The ratio K of 1_1_1 and λ_1_0_0 (λ111/λ
100) is 1/5 to 5. (2) The Bi-substituted rare earth iron garnet film contains Bi(a)
R(b)Fe(c)M(d)O_1_2{R: rare earth element, M: trivalent or combination of ions equivalent to trivalent, 0.
25≦(a)≦2.88, 0.5≦(b)≦3.0, 3
．． 0≦(c)≦5.0, 0, 5≦(d)≦1.4, 2.
2≦(a)+(b)≦3.5, 4.5≦(c)+(d)
≦5.8}, and at least 20 mol% of the rare earth elements contained therein have a composition of Ho and/or Dy.