JPH0459710B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stripe domain generating means for a magnetic memory element.

Magnetic valve elements are being actively developed in various places with the aim of increasing their density, including permalloy devices, ion-implanted continuous disk devices, current-driven devices, and so-called hybrid devices that combine these devices. It has been said that the limit to the sophistication of these devices lies in the photolithography technology used to form the bubble transfer path.
However, in recent years, the technology has advanced rapidly.
As a result, the issue of materials for sophistication, that is, to what extent the bubble diameter can be made smaller, has become an issue. With the garnet materials currently in use, the minimum bubble diameter that can be achieved is said to be 0.3 μm. Therefore, it is necessary to find a bubble material other than garnet material that retains bubbles with a diameter of 0.3 μm or less. This is not easy and is even considered to be the limit of bubble density.

On the other hand, as a memory element, information reading means and information writing means can be used as a memory element, which can significantly improve the density limit based on the characteristics of the storage layer and keep the information read time at the same level as conventional elements. In a magnetic memory element comprising an information storage means, a magnetic field exists in a Blotsho domain wall around a stripe domain existing in a ferromagnetic film (including a ferrimagnetic film) whose easy magnetization direction is perpendicular to the film surface. A magnetic memory element has been proposed that uses the created pair of adjacent vertical Bloch lines as a storage information unit and has means for transferring the vertical Bloch lines within the Bloch domain wall. Although this device can have both a shift register configuration and a major-minor configuration, one type of vertical block line memory will be described here using the major-minor configuration as an example. In this embodiment, the major line uses bubble domains as the information unit as before, the minor loop consists of stripe domains, and the information unit is the vertical Blotsho line (hereinafter referred to as VBL) existing in the surrounding Blotsho domain wall. FIG. 1 is an overall view of the chip. To show the overall information flow, first, the information written by the generator 1 (bubble presence/absence 5) moves the write major line from top to bottom.In order to store this information in the minor loop 2, the bubble 3 The minor loop can be transferred to the minor loop in the form of VBL, indicating the presence or absence of the information on the major line.
The feature of the present invention is that it is composed of Blotzho domain walls that can maintain VBL, and is an important key to dramatically improving storage capacity. The write line transfer gate 4 allows the information (VBL) transferred to the minor loop to move on the stripe domain magnetic wall forming the minor loop. Information transfer from the minor loop to the read major line involves conversion from VBL to bubble. Note that this read transfer gate 5 also has a block replicator function.

In this way, the minor loop is composed of striped domains existing in the bubble material, and the information unit on the minor loop is replaced by the bubble domain.
By using VBL, storage density can be improved by about two orders of magnitude compared to devices using conventional bubble domains.

The configuration example and operation of this element will be explained in more detail. The major line uses a current drive method for both writing and reading. A write transfer gate consisting of four parallel conductors uses the interaction between a bubble on the major line and a striped domain head forming a minor loop. When there is a bubble domain on the major line, the head of the stripe domain that forms the minor loop connected to it takes advantage of the fact that it moves away from the bubble due to the repulsive interaction between the bubble and the stripe domain. When there is no bubble on the write major line, write VBL to the stripe domain domain wall of the minor loop.
As a means of creating a VBL in a striped domain head, a pulse current is applied to the conductor pattern in contact with the striped domain head to dynamically move it, thereby dynamically converting the head domain wall. This method creates two VBLs, but
These have different properties and are easy to recombine.
Therefore, in order to stabilize the information, an in-plane magnetic field is applied in the longitudinal direction of the striped domain, and the striped domain head is separated by two conductors on the striped domain side. Create VBL.
VBLs with the same properties remain stable even when they are close to each other. Since the stripe domain head of the minor loop corresponding to the major bubble exists is away from the conductor pattern due to the repulsion with the bubble, no VBL is formed. As a result, the information of the major line is “1”
is transferred as if there is no VBL pair in the minor loop.

In the minor loop, information is stored using a pair of VBLs with the same properties as one bit. VBL pairs are used considering replicator action and stability.
A transfer pattern is set so that the bit period in the minor loop, that is, the VBL interval, can be kept constant and selectively transferred one bit at a time. As an example,
On the striped domain constituting the minor loop above, a parallel fine line pattern made of permalloy thin film with a width S _{0 is formed in the direction perpendicular to the longitudinal direction of the striped domain, with a period twice the stable interval S 0 between} VBL, and parallel It utilizes the interaction between the magnetic poles induced on both sides of the thin wire and VBL.

One way to dynamically transfer VBL along the minor loop is by applying a pulsed bias magnetic field to the stripe domain. A readout transfer gate consisting of three parallel conductors converts the information stored as VBL in the striped domain domain wall forming the minor loop into a bubble and transfers it out to the major line, and also transfers the information on the minor loop. It also functions as a replicator to prevent destruction. The operating principle will be explained. One bit formed by the VBL pair is fixed to the striped domain head by applying an in-plane magnetic field, for example. The striped domain head is then cut out into a bubble using a conductor pattern. Then, after the bubble is cut, the same VBL as the cut VBL is regenerated at the stripe domain head. Such a VBL replication effect occurs only for VBLs with a minus sign. Bubbles cut from the striped domain head of the minor loop are transferred along the major line toward the detector. Here, we utilize the fact that the pulse current value for cutting off the stripe domain head is different depending on whether the stripe domain head has VBL or not. If there is no VBL on the striped domain head, it will be difficult to cut.
Therefore, VBL on the striped domain head
If there is, a bubble can be sent to the major line, but if there is no VBL, there is no bubble. In other words,
The presence or absence of VBL (1, 0) on the minor loop is converted to the presence or absence of a bubble on the read major line.

We will discuss the elimination method for VBL pairs. I want to delete
Place the VBL pair at the position closest to the stripe domain head of the minor loop on the write major line side. Next, I want to add an in-plane magnetic field Hip and erase it.
Bring the VBL pair and one half of the VBL pair to the striped domain head, and cut off the striped domain head using the parallel conductor used to cut off the positive VBL when writing information. After cutting out the bubble domain, the striped domain head contains the information you want to erase.
The VBLs brought with the VBL pair are replicated. In the end, only the VBL pair that you want to erase will be erased. In addition, when clearing the entire minor loop, first erase all the stripe domains by increasing the bias magnetic field, and then form the minor loop stripe domain from the S=1 bubble to create an all-bit zero with no VBL. can create a state.

In this magnetic memory element, the most fundamental problem in this element is how to generate striped domains that form minor loops. In other words, it is known that irregular labyrinth-like striped domains can exist in ordinary ferromagnetic films without an applied magnetic field, but there is no effective means to generate them by regularly arranging any number of striped domains. is still not well known.

An object of the present invention is to provide a magnetic memory element having means for aligning and generating stripe domains in each minor loop of the magnetic memory element.

According to the present invention, a stripe domain exists in a ferromagnetic film (including a ferrimagnetic film), which includes an information reading means, an information writing means, and an information storage means, and whose easy magnetization direction is perpendicular to the film surface. A magnetic storage element having a major-minor configuration, which uses a vertical Blotsho line pair consisting of two adjacent vertical Blotsho lines formed in a Blotsho domain wall around the periphery of the block as a storage information unit, and has means for transferring the vertical Blotsho lines within the Blotsho domain wall. In this method, there is obtained a magnetic memory element characterized in that a bubble domain generator conductor pattern and a periodic bubble domain transfer pattern are provided in a minor loop region constituted by striped domains.

Hereinafter, the present invention will be explained in detail using examples.

Embodiment 1 FIG. 2 is a schematic diagram showing an embodiment of the configuration of a minor loop region of a magnetic memory element of the present invention. FIG. 2 partially shows the minor loop region of FIG. Minor loop region 2 in Figure 2
A feature of this embodiment is that a hairpin-shaped conductor 21 is formed in a portion of the conductor 0, followed by two-layer conductor opening patterns 22 and 23. Bubbles 24 are generated using the conductor pattern 21 under a constant vertical bias magnetic field, and the bubbles 24 are further transferred to each minor loop position by a current driving method of the two-layer conductor patterns 22 and 23. That is, bubbles are transferred by alternately flowing two-layer conductor currents 27 and 28 in a direction perpendicular to the transfer direction. Thereafter, by decreasing the perpendicular bias magnetic field while applying an in-plane magnetic field in one direction, a row of striped domains 25 is obtained. The pattern 26 is a soft magnetic material pattern or a metal pattern for holding the striped domain at a constant length in one direction. Note that even without the pattern 26, it is possible to align the striped domains to some extent by controlling the in-plane magnetic field.

Embodiment 2 FIG. 3 is a schematic diagram showing another embodiment using a two-layer conductor transfer pattern similar to the first embodiment.
The difference from the first embodiment is that the opening patterns 22, 2
3 and by providing striped two-layer conductors 22' and 23' instead of a full-surface two-layer conductor, current consumption is reduced. In the case of this example,
The two-layer conductor currents 27 and 28 are caused to flow parallel to the bubble traveling direction. In this case as well, striped domains can be generated regularly as in the embodiment.

Embodiment 3 FIG. 4 is a schematic diagram showing another embodiment of the present invention. This embodiment is characterized in that a hairpin conductor pattern 21 using the magnetic field of a permalloy pattern 41 is provided as a seed bubble generator, and a permalloy pattern 42 is provided as a bubble transfer pattern.
After transferring the bubble 24, striped domains 25 are formed using an in-plane applied magnetic field and a permalloy striped domain holding pattern 26.

Embodiment 4 FIG. 5 is a schematic diagram showing another embodiment of the present invention. This embodiment is characterized in that a bubble transfer pattern is provided using ion implantation. In FIG. 5, transfer pattern 51 represents a non-ion implantation pattern of the bubble retention layer. Here, seed bubbles are generated at the ends of the pattern 51 by the hairpin-shaped conductor magnetic bubble generator 21, and the bubbles 24 are transferred along the pattern 51. The bubble in the ion-implanted region can be easily formed into a stripe domain 25 by using the feature that it can easily expand by applying an in-plane magnetic field in the direction of difficult magnetization of the ion-implanted layer.
can be formed. Pattern 52 is a striped domain retention pattern. Here, pattern 52 is a non-ion implantation pattern. In this case as well, regularly aligned striped domains are obtained.

As explained above, according to the present invention, a means for generating stripe domains in each minor loop row can be obtained, and
This is highly effective in realizing a large-capacity magnetic storage element that uses VBL pairs as storage information units. Furthermore, it is easily inferred that the stripe domain record generation means of the present invention can be applied to the case where block points are used as storage information units instead of VBLs of stripe domains.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a magnetic memory element chip using VBL pairs on striped domains. 2 to 5 are schematic diagrams showing one embodiment of the present invention. 1...Bubble generator, 2...Minor loop, 3...
Bubble, 4...Write transfer gate, 5...
Read transfer gate, 20... Minor loop region, 21... Bubble generator conductor pattern, 2
2, 23... Two-layer conductor opening pattern, 24... Bubble domain, 25... Stripe domain, 26... Stripe domain retention pattern, 27, 28... 2
Layer conductor current, 22', 23'...two-layer conductor, 41...permalloy pattern, 42...permalloy transfer pattern, 51...non-ion implantation transfer pattern, 52...stripe domain holding non-ion implantation pattern.

Claims (1)

[Claims] 1. A ferromagnetic film (including a ferrimagnetic film) that is equipped with an information reading means, an information writing means, and an information storage means, and whose easy magnetization direction is perpendicular to the film surface.
A major miner that uses a vertical Blotsho line pair consisting of two adjacent vertical Blotsho lines created in a Blotsho domain wall around a striped domain existing in the area as a storage information unit, and has means for transferring the vertical Blotsho lines within the Blotsho domain wall. 1. A magnetic memory element according to the present invention, characterized in that a bubble domain generator conductor pattern and a periodic bubble domain transfer pattern are provided in a minor loop region constituted by stripe domains.