JPS62283481A - Bloch line memory and its production - Google Patents

Abstract

PURPOSE:To satisfactorily form a desired pattern on a magnetic thin film surface and to effectively record and reproduce by forming an area having a different magnetic characteristic from an area except a magnetic domain on a part in the vicinity of the surface of the magnetic domain. CONSTITUTION:A magnetic garnet film 4 is applied on a substrate 2, an iron film 11 is formed on the film 4 and the film 11 is patterned so as to retain the same part as the place form of the object magnetic domain 6. Iron ion is diffused in the area in the vicinity of the surface of the film 4 from the film 11 heated and patterned in a vacuum atmosphere to substitute gallium ion or the like for the iron ion and the magnetic characteristic of a diffused area 6a is made different from other part to enhance a saturated magnetization. After the diffusion of the iron ion, the film 11 is removed, the pattern of a line shape conductive layer 9 is formed at the prescribed position of the surface of the film 4, an upward bias magnetic field HB is externally impressed and a magnetic domain wall is moved so as to form a stripe magnetic domain 6 correspondingly to the area 6a.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial use! ? ] The present invention relates to a Bloch line memory. The Bloch line memory is a memory capable of recording information at extremely high density and can be applied to various child devices.

[Prior Art] At present, memories such as external memory for computers, memory for electronic files, memory for image files, etc.
Various memory devices are used, such as magnetic tape, Winchester disks, floppy disks, optical disks, magneto-optical disks, and magnetic bubble memories. Among these memory devices, other than the RA magnetic bubble memory, it is necessary to move the recording/reproducing head relative to the memory when recording information or producing l'T. That is, with such relative movement of the head,
The head permanently records an information string on the information track 2 and reproduces the information string fixedly recorded on the information track.

However, in recent years, as there has been a demand for increasingly higher recording densities, tracking control to make the head accurately follow the information track has become more complex, and this control has become more complicated, resulting in the quality of the recorded + Ig raw signal being lower. The quality of the recorded rIf raw signal may deteriorate due to vibration of the head moving mechanism or dust "W" adhering to the memory surface. Furthermore, the quality of the recorded rIf raw signal may deteriorate due to vibration of the head moving mechanism or dust "W" attached to the memory surface. Furthermore, the quality of the recorded rIf raw signal may be degraded due to the vibration of the head moving mechanism or dust "W" attached to the memory surface. In the case of a memory that performs recording without contact with the optical disk head, it is necessary to use force song control for focusing, and this control is insufficient. A problem has arisen in that the quality of recording, reproduction, and transmission deteriorates.

On the other hand, a magnetic bubble memory is capable of recording information at a predetermined position t and transferring the recorded information. It is believed that the relative movement with the head during ILT production is not 6 yellow, and therefore the above-mentioned problems do not occur even when recording density is increased, and it is possible to achieve uniformity at high C. There is.

However, magnetic bubble memory is magnetic garnet I1
A circular magnetic domain (
bubbles) are used as information bits, the minimum bubble (diameter 0
．． Even if 3gm) is used, the limit of recording density is several 1 Mbit/CrrI', and it is difficult to further increase the density.

Therefore, recently, Bronhollein memory has been attracting attention as a memory with a recording density that exceeds the recording density limit of magnetic bubble memories. This Bloch line memory uses a pair of Neel 11 wall structures (Pro 7 Hole line) sandwiched between Bloch domain wall structures existing around a magnetic thin film as an information beat. , compared to the above-mentioned magnetic bubble memory, the Q density is improved by nearly two orders of magnitude.For example, /Hepple diameter 0.5
When using pm garnet film, 1.6Gbit/
The recording density of crrf is 1! [Nikkei Electronics 4 August 1983, 150]
P141-1678].

4. [1] A schematic perspective view of an example of a magnetic material structure constituting the Pronholline memory is shown.

In the figure, 2 is GGG, NdGGA? A magnetic Carnet thin film 4 is sealed on the substrate. The film can be formed by, for example, a liquid phase epitaxial growth method (LPE method). The thickness is, for example, about 5ILm. 6 is magnetic garnet) t'! A striped magnetic domain is formed in the Ii film 4, and a domain wall 8 is formed as a boundary region between the inside and outside of the magnetic domain.

The width of the striped magnetic domain 6 is, for example, about 5 gm, and the length is, for example, about 10 gm. Further, the thickness of the domain wall 8 is, for example, about 0.5 gm. As shown by the arrow, the direction of magnetization is in the direction G within the magnetic domain 6,
On the other hand, the direction of magnetization outside the magnetic domain 6 is the F direction.

The direction of magnetization within the domain wall 8 gradually rotates from the inner surface (that is, the side facing the magnetic domain 6) to the outer surface in a twisted manner.

The direction of this rotation is reversed on both sides of the domain wall 6 at the +'Q7 (pro, horai/IO existing in the f direction) as a boundary. The direction of magnetization is indicated by an arrow, and the direction of magnetization at Bloch line 10 is also indicated.

Incidentally, a bias magnetic field HB in the negative direction is applied from the outside to the magnetic structure described above.

As shown in t, 4, there are two types of Bloch lines IO with different magnetization directions, and the presence or absence of a pair of these Bloch lines corresponds to information "l" and "0". The blow and Holline pairs are regular C- in the domain wall 8.
rl1 exists in any one of the potential wells. Further, each Bloch line pair is sequentially transferred to an adjacent potential well by applying a pulsed magnetic field perpendicular to the substrate surface. Thus, the recording of information in the Bloch line memory (incorporating one Bloch line pair into the domain wall 8) and the reproduction of the information recorded in the Bloch line memory (reading out the Bloch line pair in the Fii wall 8) are performed using the Bloch line memory. This can be carried out at predetermined positions while transferring the line pairs within the domain wall 8. The above information can be recorded and reproduced by applying a pulsed magnetic field of a predetermined strength perpendicular to the substrate surface to a predetermined portion. As a means for applying a pulsed magnetic field for reproduction, conductive patterns for pulsed current application are formed on the surface of the magnetic thin film 4 at predetermined positions relative to the striped magnetic domains 6, respectively.

Problems that 1-shot 11 attempts to solve] In the Bloch line memory as described below, in order to properly occupy, read out, and transfer the Pro7 Hole line pair, the position of the domain wall 8, that is, the position of the stripe magnetic melody, must be adjusted. It is necessary to keep it stable.

Therefore, grooves have been conventionally provided on the surface of striped magnetic domains.

FIG. 5(a) is a t-plane view showing such a striped magnetic domain, and FIG. 5(b) is a BB cross section [;4] thereof.

In the figure, 2 is a nonmagnetic garnet substrate, 4 is a magnetic garnet thin film, 6 is a striped magnetic domain formed in the dollar film, and 8 is a domain wall. On the surface of the striped magnetic domain 6, l+W having a width about half of the width of the magnetic domain is formed.
l 2 is formed.

The direction of magnetization within the magnetic domain 6 is the do direction, and the direction of magnetization of the +1!24 portion of the magnetic line outside the magnetic domain 6 is upward.

Such a striped magnetic domain numbered No. 11 is manufactured, for example, in the following manner. That is, as shown in the cross-sectional view in FIG. A resist mask 14 having a transparent portion having a shape corresponding to +1!l2 above is applied!j. After that, ion milling (Ar ion,
Acceleration' [approximately 500 V of pressure] [Figure 6 (a)]
As a result, li 12 is formed, and then the resist mask 14 is removed. Then, by applying an upward external bias magnetic field HB perpendicular to the substrate surface, striped magnetic domains 6 are formed in the magnetic thin film portions corresponding to the grooves 12. This magnetic domain 6 is stably positioned due to the presence of the groove 12 [FIG. 6(b)].

However, the Bloch line memory having one or more grooved striped magnetic domains has the following problems.

That is, as mentioned above, the position t of the Bloch line pair within the domain wall 8
For stabilization, a regular potential well is created. For example, this potential well is formed by forming a line-shaped conductor layer or magnetic material layer on the surface of the magnetic thin film 4 in a direction transverse to the magnetic domain 6. This is done by forming a pattern by attaching a large number of ions in rows at a predetermined pitch, or by implanting ions into such a pattern. It is difficult to form a good pattern due to the existence of
! I don't know.

Also, Iji sex thin It! Horizontal stripe magnetic domain 6 for application of pulsed magnetic field for Bloch line pair transfer on the surface of 124! , lJ, the conductor pattern may not be formed well (in severe cases, it may cause disconnection), which may impede the transfer of Bloch line pairs.

Furthermore, in order to increase the density of recording, it is necessary to make the width of the magnetic domain 6 as narrow as possible and arrange a large number of magnetic domains in a medium area. Therefore, in response to higher density, precise pressurization is required, making it difficult to perform groove processing with sufficient accuracy.

Therefore, the present invention solves the problems of the conventional Bloch line memory, such as one or more, and solves the problems of the conventional Bloch line memory. The purpose of this invention is to improve the positional accuracy of Bloch line pairs by forming stable magnetic domains and 1a walls with good accuracy and accuracy.

[Means for Solving the Problems] According to the present invention, information is recorded using Bloch lines in domain walls formed around magnetic domains in a magnetic thin film, in order to achieve the above objects. In the Bloch line memory, there is provided a Pro7 Hole line memory characterized in that a region having different magnetic properties from a portion outside the magnetic domain is formed at least in a portion near the surface of the magnetic domain.

Further, according to the present invention, as a method suitable for manufacturing such Bloch lines, a Bloch line memory is manufactured in which information is recorded using Bloch lines in domain walls formed around magnetic domains in a magnetic thin film. In this method, a substance for changing magnetic properties is partially diffused in the vicinity of the surface of a magnetic thin film, and then a bias magnetic field is applied to diffuse the magnetic property so as to substantially correspond to the diffusion region of the substance changing magnetic properties. A method of manufacturing a Bloch line memory is provided, which is characterized by forming magnetic domains in a thin film portion.

[Example] Hereinafter, specific examples of the present invention will be described with reference to the drawings.

FIG. 1(a) is a partial plan view of the Bloch line memory according to the present invention, and FIG. 1(b) is a sectional view taken along line B--B.

In FIG. 1, 2 is a non-magnetic garnet substrate, and 4 is a non-magnetic garnet substrate.
is a magnetic garnet ftj film. magnetic garnet)%
During I film removal, a magnetic domain 6 having a striped one-sided shape is formed. 8 is a domain wall around the striped magnetic domain 6. A region 6a having different magnetic properties from other parts of the magnetic thin film 4 (including other parts within the striped magnetic domain 6) is formed in the vicinity of the surface of the striped magnetic domain 6 due to the diffusion of iron (ions or atoms). ing. The saturation magnetization of this region 6a is higher than that of other parts, and on the surface of the magnetic thin layer 1i4, there are many parallel conductor layers 9 extending in the direction crossing the striped magnetic domain 6, that is, in the B-B direction. They are arranged in a pattern. The conductor layer is made of, for example, Cr, A1.
It is made of Au, Ti, etc., and its width is, for example, about 0.5 gm, and the arrangement pitch is, for example, about Igm. 1
Due to the strain caused by the formation of the patterned conductor layer, the poten wells within the domain wall 8 can be arranged regularly and periodically.

The direction of magnetization in the striped magnetic domain 6 is downward, and the direction of magnetization in the magnetic 01 anti-40 portion outside the magnetic domain is in the E direction. Further, HB is a bias magnetic field applied from the outside and has an ox direction.

In the magnetic field F8, a pair of Bloch lines stably exists at a position corresponding to one of the patterned conductor layers 9.

In the Bloch line memory of the present embodiment as described above, the striped magnetic domain 6 is stable due to the existence of the iron diffusion region 6a with high saturation magnetization, and therefore is stable even if some external factors change.
The domain wall 8 is not easily moved by the ribs, and Bloch line reading, reading, and transfer can be carried out stably.

The Bloch line memory of this embodiment as described above can be manufactured, for example, in the following manner.

FIGS. 2(a) to 2(d) are process diagrams showing an example of a method for manufacturing the Bloch line memory of the above embodiment. These figures show the same parts as in FIG. 1(b) above.

First, a magnetic garnet thin film 4 is formed on a nonmagnetic garnet substrate 2 by liquid phase epitaxial growth.

Then, an iron film 11 is deposited on the entire surface of the thin film 4 by sputtering or vapor deposition to a thickness of about 100 mm, leaving only a portion that is the same as the one-sided shape of the striped magnetic domain 6 intended for the iron film. Then, patterning is performed using photolithography technology [Fig. 2(a)].

Next, it is heated at 500 to 600'C in a vacuum atmosphere for about 30 minutes to 1 hour. As a result, iron ions diffuse from the patterned iron+1211 into the region near the surface of the magnetic thin film 4. At this time, if the heating temperature is 1000°C or higher, the perpendicular magnetic anisotropy of the magnetic thin film 4 will disappear, and if the heating temperature is about 200 to 300°C, diffusion will not occur. The heating temperature is set so that the gas anisotropy does not disappear and diffusion occurs. Generally, when forming the magnetic garnet thin film 4, a part of the iron ions are replaced with gallium ions, germanium ions, etc. so that the direction of magnetization is perpendicular to the film surface in order to reduce the saturation magnetization. Due to the diffusion of iron ions from 1211, the gallium ions and germanium ions are replaced with iron ions, and the magnetic properties of the diffusion region 6a become different from other parts.
The saturation magnetization increases [Fig. 2(b)].

Next, the iron film 11 is removed by etching, and the magnetic thin film 4 is removed.
A pattern of a line-shaped conductor layer 9 is formed at a predetermined position t on the surface [FIG. 2(c)].

Next, by applying an upward bias magnetic field HB from the outside, a stripe I is applied corresponding to the iron diffusion region 6a.
The domain walls move so as to form a magnetic field 6 [Fig. 2(d)].

FIGS. 3(a) to 3(d) are process diagrams showing another example of the method for manufacturing the Bloch line memory according to the embodiment described in -, and are similar to FIG. 2 above.

First, a magnetic garnet (Qfl124) was applied on a non-magnetic garnet substrate 2 by liquid phase epitaxial growth.
do. Then, in the same manner as in the case of FIG. 2, the thin film 4
An iron film 11 is formed over the entire surface [FIG. 3(a)].

Next, a laser beam (for example, an argon ion laser, output approximately IW) is focused and spot irradiated from above the iron film 11 . And this laser beam sub+7! To! By scanning the irradiation position, the portion of the target striped magnetic domain 6 that is the same as the mo-plane shape is heated. As a result, an iron diffusion region 6a with high saturation magnetization is formed in the vicinity of the surface of the magnetic thin film 4 corresponding to the heated portion in the same manner as in g1 (see Fig. 3(b)). ].

Thereafter, in the same manner as in FIG. 2, the iron film 11 is removed and a pattern of the linear conductor layer 9 is formed [FIG. 3(C)].
Furthermore, the domain walls are moved to form striped magnetic domains 6 [FIG. 3(d)].

According to the method described above, it is possible to accurately and stably form striped magnetic domains 6 at positions corresponding to regions in which iron has been diffused in advance.

In the above embodiment, an example is shown in which the iron diffusion region 6a is formed only in the vicinity of the surface of the striped magnetic domain 6, but in the present invention, the different magnetic property region is the entire region of the magnetic domain. Good too.

[Effect of the Invention J According to the present invention as described above, stable magnetic domains and domain walls can be easily and accurately formed at desired positions of a magnetic thin film, and since the surface of the magnetic thin film is Y-flat, the surface It is possible to form a good sentinel pattern, and furthermore, it is possible to maintain a stable relationship between the writing means, readout stage 7 stages, transfer means, etc. of the Bloch line pair formed in this way, and the domain wall 71, thereby achieving good recording and reproduction. It's a monkey if you do it.

[Brief explanation of drawings]

FIG. 1(a) is a partial molecular plan view of an undeveloped II Bloch line memory, and FIG. 1(b) is a sectional view thereof taken along line B--B. 2(L)-(d) and FIG. 3(a)-(d) are manufacturing process diagrams of the Bloch line memory of the present invention. FIG. 4 is a schematic perspective view of the magnetic structure constituting the Bloch line memory. :FI5(a) is a partial cross-sectional view showing the magnetic domains of a conventional Bloch line memory, :FI5(b) is its B
-B sectional view. FIGS. 6(a) and 6(b) are process diagrams for manufacturing striped magnetic domains of a conventional Bloch line memory. 2:)＾plate, 4: Magnetic thin film, 6: Magnetic domain, 6a: Iron diffusion region, 8: Domain wall, 10: Bloch line. Agent 5 is buried in the earth. Yamashita Minoru Mo 1st cause (b) Figure 2 Figure 6 Ar ion

Claims (4)

[Claims] (1) In a Bloch line memory that records information using Bloch lines within a domain wall formed around a magnetic domain in a magnetic thin film, at least a portion near the surface of the magnetic domain is magnetically different from a portion outside the magnetic domain. Bloch line memory is characterized by the formation of areas with different properties. (2) The Bloch line memory according to claim 1, wherein the magnetic thin film is a magnetic garnet thin film and the heteromagnetic region within the magnetic domain is an iron diffusion region. (3) In a method for manufacturing a Bloch line memory that records information using Bloch lines within a domain wall formed around a magnetic domain in a magnetic thin film, a change in magnetic properties occurs partially near the surface of the magnetic thin film. A method for manufacturing a Bloch line memory, comprising: diffusing a substance for the purpose of the invention, and then applying a bias magnetic field to form a magnetic domain in the magnetic thin film portion so as to substantially correspond to the region in which the magnetic property-changing substance is diffused. . (4) The method for manufacturing a Bloch line memory according to claim 3, wherein the magnetic thin film is a magnetic garnet thin film and the magnetic property changing substance is iron.