JPH0348403A - Magnetic bubble element - Google Patents

Abstract

PURPOSE:To obtain a magnetic bubble element through high density ion implantation, where crystal magnetic anisotropy of magnetic garnet film for bubble is suppressed while simultaneously magnetostrictive effect due to ion implantation is improved, by employing a garnet film represented by a general formula R3-XSmXFe5-U-V-WMUAVCOWO12. CONSTITUTION:In a magnetic bubble element in which an inner magnetized region is disposed on a desired part of a magnetic garnet film capable of holding magnetic bubble to form a magnetic bubble transfer path on the garnet film and means for transferring magnetic bubble via the path is provided, the garnet film is represented by R3-XSmXFe5-U-V-WMUAVCOWO12 with numerical values in the range of 0<=u<=0.7, 0<v<=0.2, 0<w<=0.15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion implantation type magnetic bubble element. [Prior art] In the development of magnetic bubble memory devices, increasing their density is the most important issue. Compared to conventional permalloy pattern devices that eliminate bubbles, ion implantation devices are being developed that are more suitable for higher densities. This ion implantation type magnetic bubble element is described in A.I.B. Conference Proceedings Vol. 10, p. 339 (1973) (AIPConf, Proc.
．． &10, p. 339 (1973)), H8, He'', and Ne were added to the surface of the garnet film.
By implanting ions such as +, the value of uniaxial magnetic anisotropy energy in the direction perpendicular to the film surface is changed from positive to negative due to the magnetostriction effect, and the magnetization of the surface layer is directed in-plane, and this in-plane magnetization layer causes bubbles to be generated. It is a driving force. Currently, bit period L. using bubbles with a diameter of 0.4 to 1 μm. Development of an ion implantation type magnetic bubble element with S~4 μm and storage density of 4~32 Mb/d is underway. This device has a storage density more than four times that of the permalloy device that uses bubbles with a diameter of 2 μm, which have already been commercialized. One of the important issues in putting such devices into practical use is the development of a garnet film for magnetic bubbles suitable for ion implantation type magnetic bubble devices. In the garnet film used in ion implantation type magnetic bubble elements,
The magnetostriction effect must be sufficiently large to induce a change in uniaxial magnetic anisotropy sufficient to direct magnetization in the plane of the film by ion implantation. In particular, this problem becomes more important as the density of devices increases. In other words, in order to increase the density of devices, it is necessary to miniaturize the magnetic bubbles that serve as information carriers. As is well known, in order to miniaturize magnetic bubbles, it is necessary to increase the saturation magnetization Ms of the garnet film. Additionally, along with this, the uniaxial anisotropy energy K1 for directing the magnetization in the direction perpendicular to the film surface must also be increased. Therefore, the amount of change in uniaxial anisotropy energy required to form the in-plane magnetization layer must be increased.

As a characteristic of the garnet film, the magnetostriction effect must be greater. When the bubble diameter is smaller than 1 μm, the magnitude of the magnetostrictive effect of the garnet film currently being studied is not necessarily sufficient. Furthermore, the magnitude of the magnetocrystalline anisotropy is important for the garnet film used in ion-implanted magnetic bubble devices. In ion implantation type devices, the magnetization direction of the in-plane magnetization layer is controlled by a rotating magnetic field applied within the film plane. If the magnetocrystalline anisotropy energy K1 becomes too large, the rotation of magnetization of the in-plane magnetization layer is disturbed, and bubbles cannot be transferred normally. It is desirable that the absolute value of the magnetocrystalline anisotropy energy K1 be as small as possible. Co"+ is well known as the ion 4 that changes K1 in garnet crystals. Physical Review Vol. 16, No. 39
73 (1977) (Phys. Ray. vol.
16, p. 3973 (1977)), when a trace amount of CO is added to a garnet crystal called Y3F6sOxi, the value of K1 changes from negative to positive. Co
By adjusting the amount of , the value of K8 can be made approximately O. Shigashi, Y. Fe. Since O,, does not have the uniaxial magnetic anisotropy necessary to retain the magnetic bubble,
It cannot be used as a magnetic bubble material. Also, Journal Magnetism and Magnetic Materials Volume 35, Page 326 (198
3) (J. Magnetism and M.
agnetic materials vol. 35,
p, 326 (1983)), (YSmLuCa), (FeGe) so
The value of K8 when Co is added to the magnetic bubble material Y. Unlike the case of Fe, O,, it does not show the phenomenon of changing from negative to positive. Furthermore, Japanese Patent Application Laid-Open No. 55503/1983 discloses that a garnet film for magnetic bubbles containing Ge is disclosed in K.I. It is stated that the maximum moving speed of the magnetic bubble can be increased by increasing the value of . [Problems to be Solved by the Invention] The above-mentioned conventional technology did not give sufficient consideration to the magnetostrictive effect and the magnetic anisotropy of the crystal in the magnetic bubble element using the high-density ion implantation method. Conventional magnetic bubble materials have sufficient uniaxial anisotropy to hold magnetic bubbles,
Moreover, a garnet film with K,=O was not obtained. An object of the present invention is to provide a high-density ion implantation type magnetic bubble element that reduces the magnetocrystalline anisotropy of a garnet film for bubbles and at the same time increases the magnetostriction effect due to ion implantation. [! [Means for Solving the Problem] The above object is to (1) arrange magnetic bubbles formed in the magnetic garnet film by arranging an in-plane magnetized region in a desired part of the magnetic garnet film that can hold magnetic bubbles; In a magnetic hub element having a transfer path of
uAwC O wo11 (wherein R is Y.La.Eu,G
d. Tb. Dy, Ho%Er, Tm. Yb, Lu, Bi
At least one element selected from the group consisting of %Pb,
M is Ga. Al, Sc. In. At least one element selected from the group consisting of Cr, A is . represents at least one element selected from Ge and Si, x, u. v,w
are 0.6≦x≦2.5 and 0≦u≦0. 7 Represents a numerical value in the range of 0 < v≦0.2 0 < w≦0.15. ) A magnetic bubble element characterized by being a magnetic garnet film represented by (2) at least L as the element represented by R in the above general formula;
u, and the Lu is 60% or more of the element represented by 5R, (3) as the element represented by R in the general formula, Pb is O. This is achieved by the magnetic bubble element described in item 1 above, which is less than the OS. The above general formula R3,XSm*Feg-u-v-wMuAvcowOB
(In the formula, R, M.A represent the above-mentioned elements, x.u, v.
In the magnetic garnet film having the composition shown by (w represents the above-mentioned value), the effect of the present invention can be obtained even if the amount of W representing the amount of Co and the amount V of the element represented by A is as small as about 0.001. If v) 0,20 or w>0.15, it becomes difficult to set KzmeO. When the element M replacing Fe is Ge or AM, if the amount U exceeds 0.7, the saturation magnetic flux density decreases to 700 G or less, making it difficult to maintain magnetic bubbles with a diameter of 1 μm or less. This makes it unsuitable for high-density magnetic bubble devices. Furthermore, when the element M replacing Fe is Sc, In, or Cr, if the amount exceeds 0.7, the Curie temperature Tc decreases to 150°C or less, and the saturation magnetic flux density, anisotropy magnetic field, etc. This makes it difficult to apply it to magnetic bubble devices because it exhibits large temperature changes. Sm amount X is 0.
If it is less than 6 or more than 2.5, the uniaxial anisotropy energy becomes small, which is not preferable because errors such as generation of unnecessary bubbles occur frequently in the magnetic bubble generator. In order to increase the uniaxial energy and suppress the occurrence of the above error, it is necessary to
More preferably, at least % is Lu. It is preferable to use two or more types of elements represented by R at the same time. By using two or more types of elements, it becomes easy to match the lattice constants of the substrate and the magnetic garnet film. In the magnetic garnet film of the present invention, it is preferable that the value of magnetocrystalline anisotropy energy K1 is approximately O. For example, it is preferable that the absolute value of K is smaller than 2 X I O'erg/d at room temperature, and I X 10 3erg/al
It is especially preferable that the size is smaller. In addition, the ions implanted into the surface of the magnetic garnet film to form a transfer path include H+, Ha+, D+, and Dz+.
It is preferable to use at least one type of ion selected from the group consisting of: [Function] Figure 1 shows (YSmLu) with a bubble diameter of 0.8 μm. (
Ge and Ge were simultaneously added to (FeGa), Oi, (Y
SmLu), (FeGa)z-v-wGevCOwOx
Addition amount W of CO in i film and magnetocrystalline anisotropy energy K. This shows the relationship between The three straight lines in the diagram are each
Molar ratio of added G e Jlv and Ge amount W (v/w)
What if is 0.5.1 and 3? This is a straight line that shows the relationship between W and K8. As seen in this figure, by adding Ge and Ge simultaneously, the value of K1 is reduced to the value before addition, K,=-3.
It increases almost linearly from 2×10”erg/d and changes from negative to positive values.The rate of increase is
The larger the ratio, the larger the value. The reason why K1 increases as the ratio of Ge to CO increases. It is thought that this is because the amount of Co'', which has the effect of increasing K1, increases with an increase in Ge'→.In other words, co increases in the amount of Co''+ or Co'' in the garnet crystal.
However, it is C that has the effect of increasing K1.
On the other hand, Ge has a very strong tendency to exist as Ge4J in garnet crystals, and when the amount of Ge is increased, co3+ becomes C due to charge compensation.
It is thought that K
■ can be reduced to almost zero. In the prior art, (YSmLuCa)s(FeG
e) When Co was added to 01, the value of K did not change from negative to positive. This garnet type contains Ge as in the present invention. However, at the same time, it contains a large amount of Ca, which has a very strong tendency to become divalent cations, so Co"+ was not generated, and it is thought that K1 did not change from negative to positive. In the present invention, the value of K1 is made extremely small by simultaneously adding small amounts of CO and Ge to garnet for bubbles in which all the cations present in the rare earth sites and iron sites are trivalent. ni, G
Similar to e, Si has a very strong tendency to become a tetravalent cation.
Almost the same results are obtained when Ge is added simultaneously with Ge.

Figure 1 shows the change in K2 when Co and Ge are added to (YSmLu)3(FeGa)sotz. As for the garnet composition before addition, if the cations present in the rare earth sites (dodecahedral positions) and iron sites (octahedral and tetrahedral positions M) are basically all trivalent ions, the same K. The change is obtained. In fact, ions that exist in rare earth sites include Y, La, Eu'', cd
"+, Tb'Na Dy3+, H03+, Er", T
m"Na, Yb"+Lu30, Bi", Sm", Ga 3 +, AQ", S as ions existing in the iron site
c” In”Ge, Si in garnet containing Cr30
By adding Ge and at least one of the elements shown in Fig. 1, K1 showed a change similar to that shown in Fig. 1. In these experiments, including Figure 1, a liquid phase epitaxial growth method using a solvent mainly containing PbO was used to fabricate the garnet film. Therefore, the obtained garnet film contains Pb, which is present in the solvent. Pb
It is known that K8 tends to become divalent cations, but the amount of the mixed cations is small at less than 0.05 ([child/compositional formula)].
It is thought that this has no particular effect on changes in . As described above, by simultaneously adding Ge and at least one of the elements Ge and Si to the garnet film for bubbles, the crystal anisotropy energy K8 can be made extremely small. As mentioned earlier, in the ion implantation bubble element,
It is necessary to implant ions such as H into the surface of the garnet film to form an in-plane magnetic layer. H! When we investigated the change in uniaxial magnetic anisotropy of the above garnet film implanted with Ge. It has become clear that the addition of at least one element of Si and Co increases the change in uniaxial magnetic anisotropy. Furthermore, it has been revealed that by utilizing this effect, it is possible to create ion-implanted magnetic bubble devices with fewer defects. This effect will be explained below. Figure 2 shows H on a garnet film with a bubble diameter of 0.8 μm.
This figure shows the relationship between the H, f dose and the anisotropic magnetic field change amount ΔHk when . The two curves in FIG. 2 show the K. (YSmLu) i (FeG a G e C O
)sons film and Ge and Ge-free (YSm
Lu). These are the results for the (FeGa)sons film. These two types of films have the same saturation magnetic flux density 4πMm, the value (=97
The amount of Ga was adjusted so that it was 0G). Also, Y of the rare earth site? m. The amount of Lu is the same in each case. H! + accelerating voltage is 63kV, and after implanting H1+, about 1000 Si
Laminated with O2 membrane. Thereafter, in order to stabilize the characteristics of the ion-implanted layer, heat treatment was performed in N2 gas for 380 minutes for 30 minutes, and ΔHh was measured. As shown in Figure 2, Co and Ge were added ( Y S
m L u ) 3 ( F e G a G e C
o) The absolute value of ΔHh for the same dose is larger for the 501g film. Since the magnitude of 4πMs is the same, it is thought that the absolute value of the magnetic fecal constant λ,1■ is larger in the film containing Co and Ge. This effect was also observed when Ge and Si were added. This suggests that Co plays an essential role. However, the physical review No. 16
As shown in Vol. 3973 (1977). Y
It is known that when Ge is added to 3Fa,01■, the λ111M pair value decreases, contrary to the above effect. The reason for this difference is not yet clear. Since this effect is particularly noticeable in garnet, which contains a large amount of Sm, it is considered important that Sm and Ge coexist. As shown in Figure 2, by adding CO and Ge, the H8+ dose can be reduced to obtain the same ΔHh. This is extremely advantageous in realizing ion implantation type magnetic bubble devices with low defect density, as described below. Generally, there is a large amount of He” in the crystal,
It is known that when H, F, etc. are implanted, tiny cavities are generated in the crystal. This cavity is thought to be created by He or H2 condensing in the region where the bonds between atoms are broken by ion implantation. As a result of detailed examination of the sample prepared in the experiment shown in FIG. As shown in FIG. 3, in the sample with a large + dose, it became clear that a cavity 3 was generated inside the ion implantation region 2 covered with the SiO layer 1. In the vicinity of this cavity 3, the magnetic properties of the ion implantation layer are similar to those of other regions, and it is thought that the rotational motion of in-plane magnetization is disturbed. actually,
It has been confirmed that when such a cavity 3 exists near the bubble transfer path, an error occurs in which bubbles are not transferred normally, resulting in a defect in the ion implantation element. Therefore, in order to realize a device with good characteristics, it is necessary to suppress the occurrence of such cavities as much as possible. Figure 4 shows H! implanted at an accelerating voltage of 65 keV! This is a diagram showing the relationship between the dose of m'' and the density of cavity defects.As seen in this diagram, the dose of H,+ is 4×10'' (!
m-'', the density of cavity defects increases rapidly.
Therefore, in order to realize a bubble element with fewer defects, it is necessary to set the dose amount to a value of 4×10"01-" or less. By the way, as the dose amount is reduced, the absolute value 1Δakl of the anisotropic magnetic field variation becomes smaller, as shown in FIG. Generally, if 1ΔHk1 is too small, it becomes difficult to transfer bubbles in the ion implantation transfer path. (YS
mLu)3 (F e Ga) song membrane or (YSmLu)a (F e Ga Ga
Co) When an ion implantation transfer path with a bit period of 3 μm was formed using an sOti film, 1ΔHk1 had to be 47,000e or more in order to obtain good transfer characteristics. As can be seen from Figure 2, it does not contain Co and Ge (
YSmLu). In the case of (FeGa),O,, film, 4
In order to obtain 1ΔHbl of 70,000 or more, the H2 dose is 4. It must exceed 5 x 10"cm-". At this dose, several cavity defects occur per 1aI, as shown in FIG. In contrast to this. (YSmLu) a (FeGaGeCo
). In the case of Oo film, 1ΔHhl can be set to 47000e with a dose of 3.5×10"01-", and an ion-implanted magnetic bubble device without cavity defects can be realized. [Example] Examples of the present invention are shown below. (Example 1) Using the melt of the composition shown in Table 1, (Y@, 4-S m,
,. L ul,4@P b@,6g) (F 64,
,,Q 6,. .

Gas,. ,G o,,,,)01,G da G a 5 on the (1 1 1) plane
Ebitaxial growth was performed on the 012 substrate. The saturation temperature of this melt is 900°C, and the garnet film is 889°C.
It was grown at ℃. The substrate was rotated at a rotational speed of 6 Orpm and epitaxial growth was performed for 4 minutes while reversing the direction of rotation every 5 seconds, resulting in a film with a thickness of 0.81 μm.
Stripe magnetic domain 1111y (ct bubble diameter) of this film
is 0.80 μm, the saturation magnetic flux density 4πMm is 970G, and the uniaxial anisotropy energy Ku is 1. 0 2 X I O
'erg/aj. Moreover, the magnetocrystalline anisotropy energy K1 is -3. 2
About one order of magnitude smaller than X 103erg/aj<. −
3 X 10"erg/aj. 63 keV: 3.4X101H,/at and 25
Double ion implantation was performed at keV: 1.5×10”→H, /d to provide an ion implantation region 2 having the shape shown in FIG. A disk-type ion implantation magnetic bubble transfer path was formed. ?In order to thermally stabilize the characteristics of the on-implantation region 2, after ion implantation, a garnet film with a thickness of 10 mm was deposited on the surface of the garnet film.
0000 SiO layer was formed and heated at 380℃ in N gas.
Heat treatment was performed for 30 minutes. Uniaxial anisotropic magnetic field H k ( = 2 ・K u
/ Ms) is Hm before ion implantation = 26400e
It changed from -2 1 8 0 0 e (ΔHk=-
482000). As a result of a detailed examination of the ion implantation area, no cavity defects were found.The above garnet film was placed between two orthogonal coils,
When we evaluated the characteristics of the above ion-implanted magnetic bubble transfer path using a magnetic bubble element, we obtained good results in that it had a margin against the bias magnetic field of more than 10% in the range of in-plane rotating magnetic fields from 400e to 700a. Contains no Co or Ge (YSmLuPd). (Fe
When the *Ot* film is used, the minimum value of the in-plane magnetic field that provides a margin of 10% or more for the bias magnetic field is 450e, which is 50e larger than the above result. This is thought to be because the magnetocrystalline anisotropy of the film containing CO and Ge is small, so that the movement of magnetization in the in-plane magnetization layer can smoothly follow the movement of the in-plane rotating magnetic field. Table 1? Example 2) Using a melt having the composition shown in Table 2, (Bi,,,,S m
．． 、． L u,. ,,P b. 、． ．． ) (F a.,
．． ．． A n. 、． ．． G1! @,. Coo,. )01■
A garnet film with a composition of (111) plane (GdCa)
, (FeMgZr), was grown epitaxially on a 013 substrate. The saturation temperature of this melt was 870°C, and the garnet film was grown at 852°C. When the substrate was rotated under the same conditions as in Example 1 and ebitaxially elongated for 1 minute and 10 seconds, a film with a thickness of 0.46 μm was obtained. The stripe magnetic domain width W of this film is 0.45 μm, and the saturation magnetic flux density is 4πMs.
is 1780G, uniaxial anisotropy magnetic field H, is 32900e, and crystal magnetic anisotropy energy K1 is -2
It was rg/cd. This garnet film has 33 keV
:2, QX10”DI/csf and 13keV: 3.
After performing double ion implantation of 5X10"p,"/d (D: deuterium), heat treatment similar to that in Example 1 was performed to form a continuous disk type ion implantation magnetic bubble transfer path with a bit period of 1.5 μm. was formed. The change ΔHk in the uniaxial anisotropic magnetic field due to ion implantation was -4600δe. The ion implantation area was examined in detail, but no cavity defects were found. Evaluation of the transfer characteristics of magnetic bubbles. Good results were obtained in the range of in-plane rotating magnetic fields from 40 Oe to 700 e, with a margin against bias magnetic fields of more than 10%. Table 2? Example 3) Using a melt having the composition shown in Table 3, (Bi@, vsS m
1 11Lu'*. pb,,. ) (F 6 4,
ffs SO llj@Si,,. ．． Ge. ．． 1■)
A garnet film with a composition of 082 is made of (111) Nd,
Ga, O,. It was grown epitaxially on the substrate. The saturation temperature of this melt is 820°C, and the garnet film is 78°C.
It was grown at 6°C. When the substrate was rotated under the same conditions as in Example 1 and epitaxial growth was performed for 1 minute and 30 seconds, a film with a thickness of 0.36 μm was obtained. The stripe magnetic domain Illw of this film is 0.35 μm, and the saturation magnetic flux density 4πMS is 19
80G, uniaxial anisotropy magnetic field Hk is 33000s, magnetocrystalline anisotropy energy K1 is -4×10”erg/d
Met. 25kV to this garnet film: 2. OXIO”D,/
d and 13kaV: 3. After double ion implantation of OXIO"D,"/j+, the same heat treatment as in Example 1 was performed to form a continuous chip with a bit period of 1.3 μm.
A disk-type ion implantation magnetic bubble transfer path was created.
The change ΔHk in the uniaxial anisotropic magnetic field due to ion implantation is -4
It was 3000e. The ion implantation area was examined in detail, but no cavity defects were found. Evaluation of the transfer characteristics of magnetic bubbles. 400e to 700
Good results were obtained, with a margin of more than 10% against the bias magnetic field in the range of the in-plane rotating magnetic field of e. Table 3 (Example 4) Table 4 shows other examples of garnet films used in the magnetic bubble element of the present invention. By adding Ge and Ge or Ge and Si at the same time, the crystal anisotropy energy of these garnet films is about one order of magnitude smaller than when these elements are not included. Using these garnet films, ion implantation transfer paths were formed in the same manner as in Examples 1 to 3, and the transfer characteristics of magnetic bubbles were evaluated. The characteristics of each garnet film, the ion implantation conditions for each garnet film, and the bit period of the transfer path are shown in Table 5. A layer of 1000 layers of Sin was formed on the surface of the ion-implanted garnet film, and a transfer path was formed by processing in N gas at 380°C for 30 minutes. As a result of detailed examination of the ion implantation area, no cavity defects were found in any of the samples. Furthermore, the minimum value of the in-plane rotating magnetic field required to transfer the magnetic bubble was approximately 50 g smaller than that in the case of Ge and no Ge or Si. Margin Table 4 Below Table 5 Margins [Effects of the Invention] According to the present invention, it is possible to reduce the magnitude of the magnetocrystalline anisotropy energy of the garnet film for magnetic bubbles, so that The magnitude of the in-plane rotating magnetic field is 50
This has the effect of reducing the size by about a. Furthermore, since the magnetostriction effect can be increased, the dose of ion implantation required to obtain the same change in the anisotropic magnetic field can be reduced by about 20%, which has the effect of keeping the density of cavity defects low.

[Brief explanation of drawings]

Figure 1 shows the relationship between the amount of Ge and the crystal magnetic anisotropy energy in the garnet film, and Figure 2 shows the relationship between the amount of Ge and the crystal magnetic anisotropy energy in the garnet film.
Figure 3 is a cross-sectional view of a garnet film with cavity defects in the ion-implanted layer. Figure 5 is a diagram showing the relationship between the amount of H2 naps and the cavity defect density in a garnet film that has been subjected to implantation and heat treatment. 1...S i O, layer 2... ion implantation region 3... cavity 4... non-ion implantation region

Claims (3)

[Claims] 1. By arranging an in-plane magnetized region in a desired part of a magnetic garnet film capable of holding magnetic bubbles, a transfer path for magnetic bubbles formed in the magnetic garnet film and a means for transferring magnetic bubbles by the transfer path are provided. In the magnetic bubble element having the above, the magnetic garnet film has the general formula
_vCo_wO_1_2 (in the formula, R is Y, La, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi
, at least one element selected from the group consisting of Pb,
M represents at least one element selected from the group consisting of Ga, Al, Sc, In, and Cr; A represents at least one element selected from Ge and Si;
represent numerical values in the ranges of 0.6≦x≦2.5, 0≦u≦0.7, 0<v≦0.2, 0<w≦0.15, respectively. ) A magnetic bubble element characterized by being a magnetic garnet film represented by: 2. The element represented by R in the above general formula has at least Lu, and the Lu is 6 of the element represented by R.
The magnetic bubble element according to claim 1, wherein the magnetic bubble element is 0% or more. 3. Pb as the element represented by R in the above general formula
2. The magnetic bubble device according to claim 1, wherein is 0.05 or less per said general formula.