JPS5834904A - Garnet film for contiguous disk magnetic bubble element - Google Patents

Abstract

PURPOSE:To reduce the minimum rotary magnetic field of transfer margin by a method wherein Co<2+> is substituted at the required position of a garnet and the cubic symmetrical crystal magnetic anisotrophy contant of the garnet is reduced. CONSTITUTION:A fused liquid added CoO of 0.037-0.45gr to a raw meterial composed of 0.062gr Sm2O3, 0.426gr Gd2O3, 1.292gr Tm2O3, 0.364gr CaCO3, 2.554gr GeO2, 18.76gr Fe2O3, 178.6gr PbO, 3.57gr B2O3 is used. When LPE growth is done at a temperature of 920 deg.C or higher, smaller cubic symmertrical crystal magnetic anisotrophy constant ¦K1¦ is obtained as addition volume increases (as fused liquid number increased) by comparing with fused liquid number 1 (no CoO is added).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid phase epitaxial (hereinafter referred to as LPE) garnet film for continuous disk magnetic bubble memory elements (hereinafter referred to as CD bubble elements).

The CD bubble element is different from the so-called permalloy bubble element, which is composed of conventional discontinuous permalloy patterns, etc., and is different from the so-called permalloy bubble element, which is composed of conventional discontinuous permalloy patterns. As shown in FIG. 1, this is a new type of bubble memory device that uses a continuous bead-like pattern to drive a bubble T-driven by a Charsite wall to perform a memory operation.

Until now, in the LPE garnet film for CD bubble devices, the journal φ of applied physics (
J-APPI, Phys+,) sg Vol. 50, No. 3, Page 2258 (1979), K, depending on the pattern loop direction with respect to the in-plane direction,
There was a big difference in margin. Also, as stated in EE Trans Transmissions on Magnetics (Ih: EE Trans, Mag) Volume 14, page 494 (1978),
The magnitude of the minimum transferable rotating magnetic field Hr2 was limited by the effective magnetocrystalline anisotropy magnetic field Hic1 of the ion-implanted layer. HKI is 3. /2thαcal”αlK+I/M
a. Hail. Here, α is the rising angle of magnetization from the in-plane direction of the film, and is determined by material characteristics and ion implantation conditions. Therefore, if α is constant and the magnetization Ms is constant, the H illusion is proportional to the cubic symmetric magnetocrystalline anisotropy constant KK. Since K1 is determined by the constituent elements of garnet, by determining the constituent element ratio of the garnet film), the inevitable K K I is fixed at tb, and HKI is fixed. The Kl of garnet is usually negative, and when the proportion of gallium, germanium, or silicon that replaces the iron element is reduced, or in the case of a CD bubble element that uses a large amount of samarium, aeropium, etc. as a rare earth element, lK11 As this increases, the difference in transfer margin due to the pattern loop direction versus the in-plane direction tends to increase, and the minimum rotating magnetic field H
There was a drawback that the weight per ml increased.

An object of the present invention is to solve the above-mentioned drawbacks of the conventional CD
The cubic symmetric crystalline magnetic anisotropy constant of LPE garnet for bubble devices is 1K11 t, and the other magnetic characteristics of the garnet film are made small without changing much.

In order to achieve this objective, the present inventors have found that it is possible to achieve this by adding a small amount of Co2'+ to the 16& position of LPE garnet for CD bubble devices. Accordingly, K1 is in the positive direction tIC11! It changes dramatically, so you can make the + smaller for Garnet's turtle.

Cobalt ions in garnet are in a divalent state (Co”),
Magna can take the trivalent form 1(Co")t-, so Fe"
When substituting '1ico2+, for gallium-based, aluminum-based, scandium-based, or composite garnet, add a charge 1 compensation mark to line 5j5. Ge”.

It is necessary to simultaneously exchange at least one kind of tetravalent ions such as Si'', Ti4++ and Zr'+ with K11ll.
In a-G type garnet, the valence of cobalt ions must be controlled, for example, by the method shown below. The measurement results of LPE garnet film grown from the melt having the composition shown in Table 1 and the cobalt oxide layer added as shown in Table 2 are as follows.
As shown in the figure.

When grown at a temperature of 920°C or higher, the melt number l
Compared to , melt number 2 has a smaller value of 1K11, melt number 3 has a smaller value of 1K11, and melt number 3 has a smaller value of 1K11. This is the Co"O effect at the 16m position. At a growth temperature Tg of 935°C, the saturation magnetization 4πMg is 710 gausi.

At Tg 920°C, 4rMm is 6501 auam,
The l-axis magnetic anisotropy constant Ku is approximately 2500 at Tg935°C.
0erg/j, about 3300 for T1920 C
At 0 erg/d, no change due to cobalt substitution was observed.

The composition in Table 1111 is [CaCOm)/([:CaC
0a: ] 10[Ge0z'))O molar ratio (Ri parameter) is 0.13, but when the Ri parameter is 0.23, only a small amount of Co''+ was substituted in the garnet film. Furthermore, when the Ri parameter was smaller than 0.13, a large amount of Co'' was substituted. In this way, by selecting the ratio of the amount of Ca and Ge in the melt and the growth temperature, the Co't16a position is substituted in the Ca-G-based LPE garnet film, and Kl is replaced with the other 4KMs.
, Ku, etc. can also be controlled independently. Ca-8
In i-based and Ca-Ge-8t-based garnet films,
In the same manner, Co Z+ could be substituted at the 16a position.

On the other hand, when cobalt ions are replaced, the coercive force Hc increases, so if too much is replaced, a good transfer margin cannot be obtained. From this point of view, it is better to select a slightly smaller amount of cobalt to replace. CD
In order to reduce the IKIIt of garnet for bubble devices, it varies somewhat depending on the film composition, but in any case, 0.02 per molecular formula weight was sufficient.
The amount of Co''+ inserted into the 16& position is limited to 0.02 or less.

This will be explained in detail below using examples.

Example I Ca ass Smo, ss Lutye B i
aa Feo4m Geo, si 012 composition, t = 0.11μm, 4πM @-690g Ku
A bubble retaining layer garnet film having a magnetic property of a B rKu = 55000 erg/- was prepared in advance at a temperature of 0.
(111) Gd s grown to 85 μm
A Gl+ Oss substrate was added to the raw material having the composition shown in Table 1.
Cao with the following characteristics t was immersed at 935°C in a melt containing cobalt oxide in the amount shown in melt number 2 in the table, and epitaxial growth was performed for 1 minute and 30 seconds.
oGdo,・obam OJ@ Tm oss Feas
ts C06JOI G@rums Oss film second
A double epitaxial layer was obtained.

The thickness of the second layer is 0.4μm+4'M I =710
g & u II * Ku = 25040 erg
/j, Kl=-5800erg/cd. Add to this acceleration energy 120 @V, 2X1011
/- H.+ ion implantation was performed, and the good loop transfer margin of the 4 μm periodic circular contiguous and ast pattern film surface was measured, and a margin curve as shown in curve 4121 in Figure 2 was obtained. As a reference example, K11 above the bubble retaining layer
The raw materials with the compositions shown in Table 1 were epitaxially grown from the melt without CO2+ as shown in Table 2 Melt No. 1 at 935°C for 1 minute and 30 seconds. 0.4μm, 4@Mg = 720gauss
, Ku = 25400・rg/j, ni1=-64
90erg/j) to 120ke, 2X
10"/aj It is also shown in the good loop transfer margin curve 22' when H.+ ion implantation is performed.Second
As is clear from the figure, Hrmf could be lowered by about 70e by lowering lK11 by cobalt substitution.

Table III Raw material composition 8mzOm O,062gr GdxOm 0.426 grTm*Ox
1.292 grCaCOs O,
364gr G・02 2.554grF・203
18.76 grPbo 178.6
grB2ss 3.570 grl
0 Hr 2 0.037 Hr 3 0.075 Hr 4 0.150 Hr 5 0.225 Hr 6 0.450 gr Example 2 The raw materials having the composition shown in Table 1 were added to the raw materials shown in Table 2, melt number 6. A substrate with a bubble retaining layer similar to that shown in Example IK was prepared using a melt containing cobalt oxide as shown in 93! F:
Ca (1,4@Gd o *
18mg1.1 Tm us F@oss CO
@JIG@o, uOu film was obtained. The film thickness is 0.4μm,
4πMm==710 gauge.

Ku = 23500 erg/d, K1--6
00 erg/aj.

This K 120Kev, H@” 2X 10”/a
i Perform a super pad roof injection.
When we measured the transfer margin of the good loop, we found that the third
As shown in 32.33 of the figure, there was an effect that the transfer was improved. As comparative data, super bad loop transfer merge 7 with a drive layer that does not contain cobalt
Song @31t - shown at the same time. (Material parameters are from Example 1.
This is the same as the reference example. ) Example 3 A double 1[cD bubble element was prepared by adding cobalt oxide to the raw material having the composition shown in Table 1, as shown in Table IIEZ, melt number 4. Drive layer Kl'=-3970
・rg/j and other material parameters were the same as in Example 1. Due to the effect of lowering lK11 by C62+ substitution, Hr- was lowered by about 100.compared to the case without CO2+. It also had the effect of reducing the anisotropy of the transfer margin.

Example 4 A double film CD bubble element was prepared using a melt obtained by adding cobalt oxide as shown in Melt No. 5 in Table 2 to the raw materials having the composition shown in Table 1. Drive layer Kl = -2910e
rg/−Other material parameters were the same as in Example 1. Due to the effect of lowering Kl due to the addition of CO2+, Hr- was lowered by about 120· compared to the case without Cg2+. It also had the effect of reducing the anisotropy of the transfer margin.

Example 5 (jo, 5Yo1i Smo, txLutAs Bl
o, s F@a, aG@ o, 5olz In a single-layer CD bubble element with the composition, Co2+t16a position KO
,005 mol/molecular formula weight substitution, Hrl, &I
The effect of reducing f about 1000 is 9. Improvements were also seen in the anisotropy of the transfer margin.

Example 6 Smo, s4TmLls Bi (L40 Fe 44
A single-layer CD bubble device was fabricated using an LPE garnet film having the following composition: 1 GauxCoonosGeO, OOIolm. By replacing the Co needle, Hrsll will be reduced to about 8
0. It had the effect of reducing it.

There was also an effect of improving the anisotropy of the transfer margin.

As described above, the present invention provides an LPE garnet film for a CD bubble device, where CO1 is located at the 161st position of garnet.
+ f substituting K, other materials x C4K
MmTKu, etc.), K, the cubic symmetric magnetocrystalline anisotropy constant IKt I t- of garnet decreases with almost no change in K, and thus the minimum rotating magnetic field Hr- of the transfer margin decreases.
and also reduce the transfer anisotropy, CD
This improves the performance of the bubble element.

[Brief explanation of drawings]

This is an example of a seven-line diagram showing the growth temperature dependence of the cubic symmetric magnetocrystalline anisotropy constant Kl of the jllEFica-Go-based LPE garnet. The numbers in the figure correspond to the melt numbers in the Calendar 2 table, # line 1 indicates the case where Kobal) is not included in the melt, and 2 to 6 indicate the case where it is included. It is shown that when the growth temperature is 920° C. or higher, KIKll decreases significantly as cobalt is added. Figure 2 shows that by replacing cobalt, the minimum rotating magnetic field Hr-
This is an example of a diagram showing a decrease in . Number 21 is the case where cobalt is included, and number 22 is the case where cobalt is not included. FIG. 3 is an example of a diagram showing that the transfer anisotropy is reduced by substituting cobalt. Number 31 is a super-bad loop margin curve when Cobal)t is not included, and numbers 32 and 33 are a super-bad loop margin curve when Copal)t is included, and a good-loop margin curve 11t-, respectively. '#, 2 figures 1 figure 8, & temperature figure 3 tiger rotary chess world

Claims (1)

[Claims] A garnet film for a continuous fist disk magnetic (pull) memory element, characterized in that it contains 0.002 to 0.02 mol of C02+ per molecular weight of garnet at the 16& position of the garnet.