JPH05234358A - Bloch line memory - Google Patents

Abstract

PURPOSE:To avoid that a main stripe magnetic domain creeps to a major line, to surely perform a recording and replay operation and to enhance the reliability of the title memory by a method wherein a protrusion which protrudes toward a guide pattern is installed at a fence pattern. CONSTITUTION:When a bias magnetic field is high, a major line 14 between the tip part 3a on the side of a fence stripe magnetic domain 4 of a guide stripe magnetic domain 3 and a protrusion 4A at the magnetic domain 4 is kept at a wide interval, and magnetic bubbles are transferred surely. When the bias magnetic field is reduced, the protrusion 4A at the magnetic domain 4 protrudes along the extension direction. On the other hand, the tip part 3a of the magnetic domain 3 is extended to the length direction along the protrusion. As a result, the line 14 is made narrow by the protrusion 4A and the tip part 3a, it is possible to avoid that the tip part of a main stripe magnetic domain 2 creeps to this part, and the tip part 2a is extended to its length direction. Thereby, it is possible to obtain a Bloch line memory which performs a recording and replay operation surely and whose reliability is high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Bloch line memory in which a vertical Bloch line existing in a domain wall of a stripe magnetic domain is used as an information carrier.

[0002]

2. Description of the Related Art For a Bloch line memory, see, for example, Nikkei Electronics, August 15, 1983, 141.
The article on pages pp. 167 and Japanese Patent Laid-Open Publication No. 60-113389 disclose the same, and this type of vertical Bloch line memory has come into the limelight as a high-density memory.

This Bloch line memory is shown in FIG.
As shown in, the main stripe magnetic domain M having VBLs (vertical Bloch lines) serving as information carriers in the domain wall.
A plurality of minor loops 31 arranged in parallel,
At one end thereof, there is provided a chopping section 32 formed of, for example, two chopping conductors for cutting out a magnetic bubble depending on the presence or absence of VBL on each minor loop section 31, and a major line 33 for transferring this to a bubble detector 34.

In the Bloch line memory, VBL, which is an information carrier, has an extremely fine magnetized structure and cannot be directly converted into an electric signal. Therefore, as described above, a magnetic bubble is formed depending on the presence or absence of VBL. By detecting the presence or absence of the magnetic bubble, the reading operation of the memory is performed, and the presence or absence of the magnetic bubble corresponding to the information is converted into the presence or absence of VBL to perform the writing.

In this Bloch line memory, as a stabilizing means for regularly arranging the above-mentioned main stripe magnetic domains, a method of providing a groove in a magnetic thin film for stabilizing the magnetic stripe or a magnetic thin film on the magnetic thin film is provided. There is known a method of arranging a perpendicular magnetization film pattern of a pattern corresponding to the main stripe magnetic domain and stabilizing it by a stray magnetic field generated from the perpendicular magnetization film pattern (for example, Japanese Patent Laid-Open No. 60-113390).

[0006]

By the way, in such a Bloch line memory, it is required to surely extend the main stripe magnetic domain linearly toward the major line at the time of recording / reproducing. That is, at the time of recording / reproducing information, the main stripe magnetic domain is stretched (extended) by reducing the magnetic field in the direction opposite to the magnetization direction of the main stripe magnetic domain. It is necessary to control so that it is in the longitudinal direction of the main stripe magnetic domain).

The present applicant has previously filed Japanese Patent Application No. 2-264610.
6 shows a schematic enlarged plan view of an example thereof, the guide stripe magnetic domains 3 are alternately provided on one end side of the main stripe magnetic domain 2 in the extending direction, and the main stripe magnetic domains 2 and the guide stripes are provided. The magnetic domain 3 is configured to be stabilized by a perpendicular magnetization film pattern laminated on a magnetic thin film. By providing the guide stripe magnetic domain 3 in this manner, the extension direction of the main stripe magnetic domain 2 is changed by the magnetic field potential between the guide stripe magnetic domains 3. We proposed a Bloch line memory that regulates its length.

As shown in FIG. 6, this Bloch line memory is formed by providing a magnetic thin film made of a magnetic garnet film or the like on a base made of, for example, a non-magnetic garnet having a size of 5 mm square. A magnetic domain wall, that is, a minor loop portion 13 formed by arranging minor loops in parallel, and a major line 14 facing both ends thereof, for example, are provided. The major line 14 comprises magnetic bubble transfer means 15 in which, for example, a pair of magnetic bubble transfer conductors (only one is shown in the figure) are arranged. And minor loop part 13 and major line 14
2 and the chopping conductor 16 are formed, for example.

Between the minor loop portion 13 and the major line 14, the guide stripe magnetic domains 3 are alternately provided on one end side of the main stripe magnetic domain 2 in the extending direction as described above. A fence stripe magnetic domain 4 for avoiding the influence of an external magnetic field is provided around the major line 14 as a whole.

To explain the recording method in such a structure, first, magnetic bubbles are transferred by the magnetic bubble transfer means 15 along the major line 14, and the bias magnetic field is reduced to expand the main stripe magnetic domain 2. If there is no bubble, the main stripe magnetic domain 2 extends to the major line 14 and the chopping conductor 16
The magnetic stripe 2 extends downward, but when a magnetic bubble is present, the main stripe magnetic domain 2 is not extended due to the repulsion of the bubble. Therefore, only the stretched main stripe magnetic domain 2 can be cut by the chopping conductor 12, so that only the minor loop portion 13 of the stretched main stripe magnetic domain 2 has VBL.
Can be formed. In this way, binary information such as "0" and "1" obtained by converting the presence / absence of a magnetic bubble into the presence / absence of a pair of VBLs can be written.

As a reading method, for example, the main stripe magnetic domain 2 is extended and the chopping conductor 1 is similarly obtained.
6, VB in the stretched minor loop part 13
A required read current, which is cut off only when L is present, can be applied to convert the presence / absence of VBL into the presence / absence of a magnetic bubble to perform the reading.

As described above, in the Bloch line memory, it is necessary to surely extend the main stripe magnetic domain 2 toward the major line 14 in the longitudinal direction when recording / reproducing the information. In this case, the tip portion 2a of the main stripe magnetic domain 2 stretched as shown in FIG. 7 may wrap around the major line 14. If the width of the major line 14 is made small, this wraparound can be avoided, but in this case, there arises a disadvantage that the transfer of the magnetic bubble becomes difficult.

When stabilizing each of the magnetic domains 2 to 4 by the groove provided in the magnetic thin film, the fence groove for stabilizing the fence stripe magnetic domain 2 is
By providing the protrusion protruding along the extension direction of the main stripe magnetic domain 2, it is possible to stabilize the extension direction of the main stripe magnetic domain 2 and prevent the main stripe magnetic domain 2 from wrapping around the major line 14. Yes (for example, Japanese Patent Application No. 2-3 related to the applicant's application)
No. 07865 application).

However, in the case where the guide stripe magnetic domain 3 and the fence stripe magnetic domain 4 are stabilized by the perpendicular magnetization film pattern made of a TbCo film or the like, it is possible to surely prevent the wraparound when the main stripe magnetic domain is expanded. In some cases, the transfer of magnetic bubbles cannot be performed reliably.

According to the present invention, in the Bloch line memory in which the guide stripe magnetic domain, the main stripe magnetic domain and the fence stripe magnetic domain are stabilized by the perpendicular magnetization film pattern as described above, the main stripe magnetic domain is surely controlled during the gate operation. An object of the present invention is to obtain a Bloch line memory which is reliable in recording / reproducing operation and which has high reliability while extending in the longitudinal direction and surely avoiding its wraparound on the major line.

[0016]

A Bloch line memory according to the present invention has a plurality of main stripes on a magnetic thin film having perpendicular magnetic anisotropy, as shown in FIG. In a Bloch line memory in which magnetic domains are formed in parallel and a vertical Bloch line formed on a domain wall of this main stripe magnetic domain is a storage information unit, a guide stripe magnetic domain is formed on at least one end side in the extension direction of the main stripe magnetic domain, and at least this A fence stripe magnetic domain is formed in a direction blocking the extension direction of the main stripe magnetic domain, and the main stripe magnetic domain, the guide stripe magnetic domain, and the fence stripe magnetic domain are formed by a perpendicular magnetization film laminated on a magnetic thin film. 6 and the fence pattern 7 stabilize each.

In the Bloch line memory according to one aspect of the present invention, the fence pattern 7 for stabilizing the fence stripe magnetic domain is formed as a pattern having a projection 7A protruding toward the guide pattern 6.

In a Bloch line memory according to another aspect of the present invention, the guide pattern for stabilizing the above-mentioned guide stripe magnetic domain is formed as a tapered tip pattern.

[0019]

As described above, in the Bloch line memory of the present invention, the guide stripe magnetic domain is provided on at least one end side of the main stripe magnetic domain, and the fence stripe magnetic domain is provided at least in the direction that interrupts the extending direction of the main stripe magnetic domain. The stripe magnetic domain, the guide stripe magnetic domain, and the fence stripe magnetic domain are stabilized by the perpendicular magnetization film pattern, and the shape of the fence pattern or the guide pattern made of these perpendicular magnetization films is appropriately selected. It was possible to control the shape of the magnetic domain to be stabilized and to reliably extend the main stripe magnetic domain and transfer the magnetic bubble during recording and reproduction.

That is, in the Bloch line memory according to one embodiment of the present invention, as shown in FIG. 1, a fence pattern 7 made of a perpendicular magnetization film for stabilizing the fence stripe magnetic domain 4 is replaced by a guide pattern 6 for stabilizing the guide stripe magnetic domain. When the bias magnetic field is high, as shown in FIG. 2, as shown in FIG.
The fence stripe magnetic domain 4 is formed with a contour substantially along the fence pattern 7, and when the bias magnetic field is reduced to extend the main stripe magnetic domain 2 in the longitudinal direction thereof, as shown in FIG. The leading end of the protruding portion of the fence stripe magnetic domain 4 extends along the guide stripe magnetic domain 3 along the main stripe magnetic domain 2 in the major line 14 between the guide stripe magnetic domain 3 and the fence stripe magnetic domain 4. It is possible to prevent the tip end portion 2a of the wraparound from going around, and it is possible to surely extend in the longitudinal direction.

In another Bloch line memory of the present invention, as shown in FIG. 1, the guide pattern 6 for fixing the guide stripe magnetic domain 3 is formed as a tapered pattern, and when the bias magnetic field is high. As shown in FIG. 2, the guide stripe domain 3 is stabilized by this.
The tip portion of the guide pattern becomes a pattern that is retracted inward from the tapered portion of the guide pattern 6, and when the bias magnetic field is reduced, as shown in FIG.
As shown in, the tip of the guide stripe magnetic domain 3 extends reliably in the longitudinal direction of the guide pattern 6.

Therefore, at the time of high bias, since the protruding portion 4A of the fence stripe magnetic domain 4 and the tip portion 3a of the guide stripe magnetic domain 3 on the fence stripe magnetic domain 4 side are separated from each other, the major line 14 has a sufficiently wide width.
The magnetic bubble can be reliably transferred. Further, when the bias is low, the main stripe magnetic domain 2 and the fence stripe magnetic domain 4 are reliably extended in the longitudinal direction, and the major line 14 is narrowed by the tip 3a on the fence stripe magnetic domain 4 side. Can be avoided, and the tip portion 3 can be reliably held without hindering the extension of the main stripe magnetic domain 2 at a position corresponding to each guide stripe magnetic domain 3.
It is possible to extend b toward the main stripe magnetic domain 2 opposite to it.

As described above, in the Bloch line memory of the present invention, the major line 1 is used during bubble transfer.
The width of 4 can be increased to ensure the transfer, and the extension of the main stripe magnetic domain 2 can be controlled in the longitudinal direction at the time of recording / reproducing, that is, at the time of gate operation, so that the reliability can be improved. ..

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the Bloch line memory of the present invention will be described below.
This will be described in detail with reference to FIGS. In this example, as in the example described with reference to FIG. 6, a magnetic thin film made of a magnetic garnet film or the like is provided on a substrate made of, for example, a non-magnetic garnet of 5 mm square, and the main stripe magnetic domain 2 A minor loop portion 13 in which domain walls, that is, minor loops are arranged in parallel, and a major line 14, for example, facing both ends thereof are provided. The major line 14 is provided with a magnetic bubble transfer means 15 in which, for example, a pair of magnetic bubble transfer conductors (only one is shown in the figure) are arranged. Then, for example, two chopping conductors 16 are formed between the minor loop portion 13 and the major line 14.

Minor loop part 13 and major line 1
4, the guide stripe magnetic domains 3 forming the gate portion are alternately provided on one end side in the extension direction of the main stripe magnetic domain 2, and the minor loop portion 13 and the major line 14 are entirely surrounded. Fence stripe domain 4 to avoid the influence of external magnetic field around
And the fence stripe magnetic domain 4 is provided in a direction that interrupts the extending direction of the main stripe magnetic domain 2.

In this example, the fence pattern 7 for stabilizing the fence stripe magnetic domain is shown in FIG. 1 which shows the perpendicular magnetization film pattern configuration of the main portion from the minor loop portion of this Bloch line memory to one major line. Is configured as a pattern having a rectangular protrusion 7A protruding toward the guide pattern 6 for stabilizing the guide stripe magnetic domain. In this case, the width W ₁ of the fence pattern 7 is 5 μm, the width W ₂ of the protrusion 7A is 5 μm, and the length L ₁ of the protrusion 7A is 20 μm. In addition, narrow rectangular protrusions are provided on the tip portions 6a and 6b of the guide pattern 6 to be tapered, and the width W _{3 of the} middle portion thereof is 5 μm and the overall length L ₂ is 20 μm. Width W ₄ is 3μ
Each pattern 6, 7 was formed with m and length L ₃ of 5 μm.

In FIG. 1, five main stripe magnetic domains are formed in parallel for the sake of convenience. However, in a general Bloch line memory, several hundred to several thousand main stripe magnetic domains 2 are formed in parallel. Is.

FIG. 4 shows an enlarged schematic sectional view taken along the line AA in FIG. In this case, a magnetic thin film 1 made of, for example, magnetic garnet having perpendicular magnetization is deposited by epitaxial growth or the like on a base made of non-magnetic garnet, and Al and Cr each having a thickness of 1000 Å are laminated thereon. The resulting bit pattern 22 is patterned by applying photolithography or the like. The Cr film of the bit pattern 22 generates a bit potential that stabilizes the position of the Bloch line generated on the domain wall of the stripe domain by the inverse magnetostriction effect generated by the stress, while the Al film relaxes the stress of Cr, The amplitude of this bit potential is adjusted. Then, an insulating layer 2 made of, for example, SiO _{2 having} a thickness of 3000 Å is formed on this.
3 is deposited and flattened, and then a main pattern 5, a guide pattern 6 and a fence pattern 7 made of TbCo or the like and made of a perpendicularly magnetized film having a thickness of, for example, 2000 Å are deposited, and then photolithography or the like is performed. Depending on the application, the pattern described in the plan view of FIG. 1 is formed.
Then, a magnetic bubble driving conductor or a chopping conductor, for example, a Ti film having a thickness of 200 Å is formed on the Ti film with an insulating layer 23 having a thickness of about 3000 Å interposed therebetween.
First and second conductor layers 24 formed by stacking 0Å Au films
And 25 are adhered and formed.

As shown in FIG. 2, a main pattern 5, a guide pattern 6 and a fence pattern 7 made of a perpendicularly magnetized film stabilize the main stripe magnetic domain 2, the guide stripe magnetic domain 3 and the fence stripe magnetic domain 4, respectively. When the magnetic domains 2 to 4 are stabilized by the perpendicular magnetic film patterns 5 to 7, it is necessary to initialize the magnetic domains 2 to 4. As a method of initializing this magnetic domain, as in the above-mentioned Japanese Patent Application No. 2-264610, for example, the magnetic field potential under the perpendicular magnetization film patterns 5, 6 and 7 is reduced by uniformly applying an external magnetic field. After that, the external magnetic field is increased to eliminate unnecessary magnetic domains outside the potential, or the fence stripe magnetic domain 4 is initialized by reducing the uniform magnetic field, and then the main pattern 5 and the guide pattern 6 A bubble magnetic domain is generated by the initialization conductor provided between the two, and the bubble magnetic domain is extended along the main pattern 4 and then cut to form the main stripe magnetic domain 2 and the guide stripe magnetic domain 3, and various methods are employed. You can In this way, each perpendicular magnetization film pattern 5,
The stray magnetic fields of 6 and 7 can stabilize the magnetic domain state so that the magnetization directions of the magnetic domains 2, 3 and 4 are aligned with the directions of the patterns 5, 6 and 7.

In the Bloch line memory of the present invention, as shown in FIG. 2, in the fence stripe magnetic domain 4 which is stabilized under the fence pattern 7, the fence stripe magnetic domain 4 is formed along the projection 7A provided on the fence pattern 7. The protrusion 4A is formed on the.

Further, in this case, the tip portions 3a and 3b of the guide stripe magnetic domain 3 which is stabilized under the guide pattern 6 are provided.
Has a small magnetic potential under the tips 6a and 6b of the guide pattern 6, so that the stripe magnetic domain does not extend under the tips 6a and 6b in a high bias magnetic field.
The magnetic domains 3 are formed as a slightly reduced pattern.

That is, when the bias magnetic field is high, the major line 8 between the tip 3a of the guide stripe magnetic domain 3 on the fence stripe magnetic domain 4 side and the projection 4A of the fence stripe magnetic domain 4 is kept sufficiently wide. As a result, the magnetic bubbles can be reliably transferred.

Then, when the bias magnetic field is reduced, as shown in FIG. 3, the projections 4A of the fence stripe magnetic domain 4 become
The tip portion further projects toward the guide stripe magnetic domain 3 along the extending direction, while the tip portion 3a of the guide stripe magnetic domain 3 extends in the longitudinal direction along the tapered protrusion. Therefore, it is possible to avoid that the major line is narrowed by the protrusion 4A and the tip 3a and the tip 2a of the main stripe magnetic domain 2 wraps around this portion, and the tip 2a of the main stripe magnetic domain 2 is surely lengthened. It extends along the direction, that is, toward the region sandwiched between these protrusions 4A.

Further, the other tip portion 3b of the guide stripe magnetic domain 3 also extends in the longitudinal direction along the tapered projection, without disturbing the extending direction of the main stripe magnetic domain 2 at a position corresponding to each guide stripe magnetic domain 3. , Surely extends toward the main stripe magnetic domain 2 facing the tip portion 3b.

In FIG. 3, the main stripe magnetic domain 2 opposed to the guide magnetic domain 3 is restrained from being stretched by the guide magnetic domain 3, but is stretched in the opposite direction along the longitudinal direction at the other end, It goes without saying that it is stretched on the major line provided on the edge side.

With such a structure, the recording / reproducing operation can be performed in the same manner as the conventional Bloch line memory. That is, the magnetic bubble transfer conductor provided on the major line 14 transfers the magnetic bubble corresponding to binary information, for example, "0" and "1" information, and the main stripe magnetic domain extended to the portion where the magnetic bubble does not exist. 2 can be cut by a chopping conductor to form VBL in the main stripe magnetic domain 2, and the presence or absence of a magnetic bubble can be converted into the presence or absence of a pair of VBLs for writing.

At the time of reproduction, the bias magnetic field is reduced to extend the main stripe magnetic domain 2 and VB is applied to the chopping conductor formed across the guide stripe magnetic domain 3.
A required read current, which is cut only when L is present, is applied to cut the magnetic domain 2 to form a magnetic bubble.
The presence or absence of the magnetic bubble can be converted into the presence or absence of the magnetic bubble to read it.

As described above, in the Bloch line memory of the present invention, the major line 1 is used during bubble transfer.
The width of 4 can be increased so that the transfer can be performed reliably, and the extension of the main stripe magnetic domain 2 can be controlled in the longitudinal direction at the time of recording / reproducing so as to surely extend to the gate portion. The reproduction can be surely performed, and the reliability can be improved.

In the above embodiment, the fence pattern 7 is provided with the projection 7A and the guide pattern 6 is a tapered pattern. However, the same effect can be obtained when either one is applied. It goes without saying that the Bloch line memory of the present invention is not limited to the above-mentioned embodiment, and various other material configurations can be adopted.

[0040]

As described above, in the Bloch line memory of the present invention, the fence pattern 7 and the guide pattern 6 are provided.
By providing the projection 7A projecting toward the guide stripe 4A and the projection 4A projecting toward the guide stripe magnetic domain 3 in the fence stripe magnetic domain 4 which is stabilized under the projection 7A, the width of the major line is sufficiently widened during the magnetic bubble transfer. The magnetic bubble is satisfactorily transferred, and when the main stripe magnetic domain 2 is extended on the major line during the gate operation, the extension of the protrusion 4A narrows the major line and the tip 2a of the main stripe magnetic domain 2 is extended. It is possible to avoid wraparound in the lateral direction.

In another Bloch line memory of the present invention, by making the guide pattern 6 a tapered pattern, similarly, at the time of the magnetic bubble transfer, the major line is made wide and the transfer of the magnetic bubble is favorably performed. During operation, the guide stripe magnetic domain 3 which is stabilized below this can be reliably extended in the longitudinal direction thereof, and the major line can be made narrow to avoid the wraparound of the tip portion 2a of the main stripe magnetic domain 2.

[Brief description of drawings]

FIG. 1 is an enlarged schematic plan view of a main part of an example of a Bloch line memory of the present invention.

FIG. 2 is an enlarged schematic plan view of a main part of an example of a Bloch line memory of the present invention.

FIG. 3 is an enlarged schematic plan view of a main part of an example of a Bloch line memory of the present invention.

FIG. 4 is an enlarged schematic cross-sectional view of a main part of an example of a Bloch line memory of the present invention.

FIG. 5 is a configuration diagram of an example of a Bloch line memory.

FIG. 6 is a schematic enlarged plan view of an example of a Bloch line memory.

FIG. 7 is a schematic enlarged plan view of an example of a Bloch line memory.

[Explanation of symbols]

 1 Magnetic Thin Film 2 Main Stripe Magnetic Domain 3 Guide Stripe Magnetic Domain 3a Tip 3b Tip 4 Fence Stripe Magnetic Domain 4A Protrusion 5 Main Pattern 6 Guide Pattern 6a Tip 6b Tip 7 Fence Pattern 7A Protrusion 13 Minor Loop 14 Major Line 15 Magnetic Bubble Transfer means 16 Chopping conductor

Claims (2)

[Claims] 1. A Bloch line memory in which a plurality of main stripe magnetic domains are formed in parallel on a magnetic thin film having perpendicular magnetic anisotropy, and a vertical Bloch line formed on a domain wall of the main stripe magnetic domain is a storage information unit. Guide stripe magnetic domains are alternately formed on at least one end side of the extension direction of the main stripe magnetic domain, at least fence stripe magnetic domains are formed in a direction that interrupts the extension direction of the main stripe magnetic domain, the main stripe magnetic domain, the guide stripe magnetic domain and the The fence stripe magnetic domains are each stabilized by a main pattern, a guide pattern and a fence pattern made of a perpendicularly magnetized film laminated on the magnetic thin film, and the fence pattern that stabilizes the fence stripe magnetic domains faces the guide pattern. hand Bloch line memory, characterized in that it is a pattern having a leaving protrusions. 2. A Bloch line memory in which a plurality of main stripe magnetic domains are formed in parallel on a magnetic thin film having perpendicular magnetic anisotropy, and a vertical Bloch line formed on a domain wall of the main stripe magnetic domains is a storage information unit. Guide stripe magnetic domains are alternately formed on at least one end side of the extension direction of the main stripe magnetic domain, at least fence stripe magnetic domains are formed in a direction that interrupts the extension direction of the main stripe magnetic domain, the main stripe magnetic domain, the guide stripe magnetic domain and the The fence stripe magnetic domains are each stabilized by a main pattern, a guide pattern, and a fence pattern, each of which is composed of a perpendicularly magnetized film laminated on the magnetic thin film, and the guide pattern for stabilizing the guide stripe magnetic domain has a tapered tip. What is done Bloch line memory which is characterized.