JPS5998376A - Magnetic storage element - Google Patents

Abstract

PURPOSE:To attain easily and sure write of a vertical Bloch line by holding a magnetic bubble to a stripe domain tip section and applying a pulse bias magnetic field to the stripe domain tip section. CONSTITUTION:A magnetic bubble transfer means 9 is provided with the pulse bias applying means 3 and a magnetic bubble fixing means 3' which are provided in common, and a single magnetic bubble transferred from a magnetic bubble transfer means 7 is held at the tip section of the stripe domain 2. Then, when a bias pulse magnetic field is generated to the holding region and the tip section of the domain 2 via the means 3', the vertical Bloch line pair 45 is written easily and surely as magnetic information. The write to a high density magnetic storage element by the Bloch line pair is attained easily and surely through the constitution above.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a perpendicular magnetic field that statically and stably exists within Bloch domain walls that form the boundaries of stripe domains formed in a ferromagnetic film whose easy magnetization direction is perpendicular to the film surface. The present invention relates to a novel magnetic memory element using Ploch lines as a storage unit, which has means for writing vertical Ploch lines in a Bloch domain wall with good controllability.

The development of magnetic bubble elements has been actively carried out in various places with the trend toward higher density, including permalloy devices, ion-implanted contiguous disk devices, current-driven devices, and so-called hybrid devices that combine these devices. It has been said that the limit to the high density of these devices lies in the photophosphorographic 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 increasing density, that is, to what extent the bubble diameter can be reduced, has become a problem. With the garnet materials currently in use, the minimum attainable bubble diameter is said to be 0.3 μm. Therefore, a bubble material that retains bubbles with a diameter of 0.3 μm or less must be found other than garnet material. This is not easy and is even considered to be the limit of bubble density.

On the other hand, a new memory element has been proposed that can significantly improve the density limit based on the characteristics of the bubble retaining layer and can keep the information read time at the same level as conventional elements. This magnetic memory element is equipped with an information reading means, an information writing means, and an information storage means, and has stripe domains existing in a ferromagnetic film (including a ferrimagnetic film) whose easy magnetization direction is perpendicular to the film surface. It is characterized by using a pair of adjacent vertical Proch lines formed in the surrounding Bloch domain wall as a storage information unit, and having means for transferring the vertical Proch line within the Bloch domain wall. When this element configuration is made into a major-minor configuration, the major line uses the nopple domain as the information unit as before, the minor loop consists of the stripe domain, and the vertical Bloch line (hereinafter referred to as V
It's called BL. ) is the information unit.

To show the overall flow of information, first, the information written by the generator (the presence or absence of bubbles) moves down the write major line by -1 from the top. In order to store this information in the minor loop, it is possible to configure the minor loop with a Bloch domain wall that can hold VHL so that the information on the major line indicated by the presence or absence of bubbles can be transferred to the minor loop in the form of VBL. This is a feature of the present invention and is an important key to dramatically improving storage capacity. The information (VBL) transferred to the minor loop by the write line transfer gate can move the striped domain domain wall that constitutes 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 also has a block replicator function.

In this way, by configuring the minor loop with striped domains existing in the bubble material and using VBL instead of the bubble domain as the information unit on the minor loop, it is possible to increase the An order of magnitude increase in storage density can be achieved.

A configuration example 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 forms a bubble on the major line and a minor loop.

It uses interaction with the striped domain head.

When there is a bubble domain on the major line, the heads of the stripe domains forming the minor loop connected to it take advantage of the fact that they move 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 on the stripe domain domain wall of the minor loop. VB
As a means of forming L into a striped domain head, a pulse current is applied to a 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, which 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 stripe domain, and the stripe domain head is separated by two conductors on the stripe domain side, thereby creating two VBLs with the same properties in the stripe domain. make.

VBLs with the same properties stably exist even if they approach each other.

The minor loose stripe domain head corresponding to the area where the bubble exists on the major line is separated from the conductor pattern due to the repulsion with the bubble, so no VBL is formed. As a result, the major line information ``1'' is transferred as if there is no VBL pair in the minor loop.In the minor loop, information is stored with a pair of VBLs with the same properties as 1 bit.Replicator action □VBL pairs are used in consideration of stability.The transfer pattern is set so that one bit can be transferred sequentially to keep the bit period in the minor loop, that is, the VBL interval, constant.-
As an example, a parallel thin line pattern made of a permalloy thin film with a width S0 is formed on the striped domain constituting the minor loop in a direction perpendicular to the longitudinal direction of the striped domain with a period twice the stable interval So between VBLs, It utilizes the interaction between the magnetism induced on both sides of parallel thin wires and VBL. One way to transfer the VBL along the minor loose is to dynamically apply 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 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 a VBL pair is fixed to a stripe domain head by applying an in-plane magnetic field, for example.

This striped domain head is then cut out into bubbles using a conductor pattern. Then, the same VBL as the cut VBL is configured in the striped domain head after the bubble is cut. This kind of VBL replication effect is a VBL with a minus sign.
Occurs only for The bubble cut from the striped domain head of the minor loop is transferred on the major line toward the detector. Here, striped domain heads are cut depending on whether the striped domain head has VBL or not.

It takes advantage of the fact that the pulse current values are different. If there is no VBL on the striped domain head, it will be difficult to cut. Therefore, if there is a VBL in the stripe domain, 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 (i, o) on the minor loop is converted to the presence or absence of a bubble on the read major line.

The elimination method for VBL pairs will be described. VBL you want to delete
Write the pair 3 to the position closest to the stripe domain head of the minor loop on the major line side. Next, by applying an in-plane magnetic field Hip, bring the VBL pair to be erased and one half of the VBL pair next to it to the stripe domain head, and use the parallel conductor used to cut off the positive VBL when writing information. Use it to cut out the striped domain head. After the bubble domain is cut out, the VBL brought along with the VBL pair to be deleted is replicated in the striped domain head. in the end,
Only the VBL pair that is desired to be erased will be erased. In addition, when clearing the entire minor loop, first erase all stripe domains by increasing the bias magnetic field, and then form a minor loop drive domain from the S21 bubble to clear all bits without VBL being completely heated.

It is possible to create a state of zero.

In the magnetic memory element described above, it is essential to write information in a controllable manner.In other words, injecting the VBL pair into the Bloch domain wall of the striped magnetic domain with good controllability is essential for controlling the VBL. It is indispensable for magnetic memory elements that serve as storage information units.

In a magnetic memory element in which the VH2 pair as described above is a unit of storage information, unlike the above-described configuration example, the present invention controls the VBL pair on the Bloch domain wall of a stripe domain as storage information in response to the presence of a magnetic bubble. The present invention provides a magnetic memory element having a means for writing data with high performance.

That is, the present invention includes an information reading means, an information writing means, and an information storage means, and the present invention provides information on the periphery of 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 that uses a vertical Proch line pair consisting of two adjacent vertical Proch lines formed in a Bloch domain wall as a storage information unit, and has means for transferring the vertical Proch lines within the Bloch domain wall, A magnetic bubble information generation means having a domain wall structure of single rotation magnetization, a magnetic bubble transfer path connected to the information generation means and provided near the stripe domain, and from the transfer path to the vicinity of the tip of the stripe domain. It is characterized by having means for transporting magnetic bubbles, means for holding magnetic bubbles near the tips of the striped domains, and means for applying a magnetic baffle Nihals bias magnetic field to the tips of the striped domains and the vicinity thereof. It is a magnetic memory element.

Next, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram showing an embodiment of the device of the present invention. A ferromagnetic thin film 1 with an easy magnetization direction perpendicular to the film surface that can hold magnetic bubbles is used as a medium, and stored information is stored on a Bloch domain wall 2.
2, a striped magnetic domain 2 stored as a pair of vertical Proch lines 45, a magnetic bubble information generating means 8 having a single-rotation magnetization domain wall structure, and a magnetic bubble information generating means 8 provided near the striped magnetic domain almost perpendicularly to the longitudinal direction of the striped magnetic domain. a magnetic bubble transfer path 7 connected to a generating means; a means 9 for transferring the information magnetic bubbles from the magnetic bubble transfer path to the tips of the striped magnetic domains; and a means for transferring the magnetic bubbles near the tips of the striped magnetic domains. It is characterized by comprising means 3' for holding, and means 3 for generating a pulse bias magnetic field at the predetermined position.

FIG. 2 is a diagram showing a means for writing VBL pairs into Bloch domain walls of striped domains according to the present invention. The VBL pair write of the present invention is performed as follows.

As shown in FIG. 2(A), the direction of magnetization within the domain wall at the tip U of the striped domain 2, which has a Bloch domain wall 22 that can store VBL pairs as information units, is the direction shown by the arrow 40. Domain wall 51 near the column
A magnetic bubble 5 having a domain wall structure with a single rotational magnetization whose inner magnetization direction is shown by an arrow 50 opposite to the arrow 40 is arranged, and a local pulse bias magnetic field is applied so as to surround the stripe domain tip U and the magnetic bubble 5. Application means 31 are provided. The pulse bias magnetic field applying means 31 in the writing means is a hairpin-shaped conductor button, which also serves as a channel for setting so that the positions of the stripe domain tip U and the nearby magnetic bubble do not deviate.

The VBL pair is written in the Bloch domain wall 22 of the stripe domain as follows. An arrow 3 shown in FIG. 2(B) is attached to the hairpin conductor 31 which is a pulse bias magnetic field applying means.
Apply current in two directions. A bias magnetic field in the direction shown by the arrow 21 is generated in the portion 6 surrounded by the hairpin conductor,
The magnetic bubble and stripe domain try to expand.

However, since the conductor 31 is also a fixed position channel,
The respective magnetic domains do not extend outside the hairpin, but the tip portion 24 of the stripe domain and the magnetic bubble approach each other within the hairpin portion 6, and the domain walls 51 and 22 touch each other as shown at 52. In the joint portion 52 where the domain walls are in contact, the rotation of magnetization inside and outside the magnetic domain of the stripe domain tip row and the rotation of magnetization inside and outside the magnetic bubble 5 are rotations in opposite directions with respect to each domain wall. The rotation of magnetization is easily released, and the joint part 5
The domain walls of No. 2 disappear as shown in FIG. 2(C) and merge into one striped domain.

However, the structure of the domain wall is such that the initial magnetization direction 4 at the center of each domain wall is
0 and 51, the magnetization direction at the center of the domain wall is 41°42.40 in the Bloch domain wall 22 corresponding to the joint portion 52.
VBL with positive value rotated as 42 and 41°43
．． A VBL43 having negative magnetism rotated by 40" is generated.

When the current 32 for applying the pulse bias magnetic field is stopped, ji
g 2 Figure (J) H Nis-like VBL 42 , VBL
43 (D different null magnetism attracts each other and is stable VBL pair 4
Five matches against Yang will be completed.

That is, the VBL pair of the storage information unit is written to the Bloch domain wall 22 of the striped magnetic domain 2.

As a magnetic memory element, it is necessary to controllably write (VBL pairs) according to storage information into the domain walls of multiple striped domains.To do this, a single rotation magnetization domain wall structure is required at the tips of the striped domains. A means for generating and transferring magnetic bubbles in accordance with stored information is essential.Next, the generation and transfer means will be explained using an embodiment.

FIG. 3 shows a first embodiment of the magnetic bubble generation and transfer means according to the present invention. In this embodiment, a soft magnetic material button array 73 that is sequentially magnetized by the rotation of the in-plane magnetic field Hn70 is used as the magnetic bubble transfer means. As the soft magnetic material baton row, the already known 1゛-bar chevron,
The magnetic bubble transfer path 7 can be formed using any one of an asymmetric chevron, a half disk, a Y-Y type, etc. The magnetic bubble as information is produced by a nucleation type magnetic bubble generation means 8 provided in the transfer path.
1 selectively generated. In this embodiment, the bubble generating means 81 is constituted by a hairpin-shaped conductor button.

The domain wall structure of the nucleated magnetic bubble 5 is not necessarily a single rotation magnetization domain wall structure. In order to apply the VBL pair injection method of the present invention, it is necessary to arrange the domain wall structure of the magnetic bubble 5 into a single rotation magnetization structure. For this purpose, domain wall adjusting means 80 is provided in the middle of the transfer path 7. The domain wall adjusting means 80 is configured as follows. Local in-plane magnetic field generation means 80a (this uses a leakage magnetic field from a soft magnetic material baton 73 or an in-plane rotating magnetic field), a pulse bias magnetic field generation means 80c (this uses a hairpin conductor batten), and ion implantation or exchange interaction. It is composed of in-plane magnetized film portions 80b which are bonded together on the surface of a soft magnetic material.

To adjust the domain wall structure to single rotation magnetization, proceed as follows. First, a magnetic bubble 5' having an arbitrary domain wall structure is transferred to a domain wall adjusting means (equipment). Next, under the control of the write control unit 12, a pulse bias magnetic field is applied to the magnetic bubble while applying an in-plane magnetic field. Then, the domain wall structure of the magnetic bubble transforms into σ- or σ-, which has two VBLs, as is already known. Next, when the in-plane magnetic field is set to O and a pulse bias magnetic field is applied, the magnetic bubbles in the σ- or σ- state become χ- or χ- bubbles with a single rotation magnetization domain wall structure.
have different magnetization directions within the domain wall. Next, when a short pulse bias magnetic field is further applied, the horizontal Ploch line punch-through generated from the bottom surface on the opposite side due to the in-plane magnetized film due to the polarity of the magnetic field causes the magnetic field to move within the domain wall ° of either χ or χ-. The magnetization is reversed and the domain wall states align to one state. It is already known that this final state can be controlled by the polarity of the pulsed bias magnetic field.

A second embodiment of the magnetic bubble generation and transfer means 8 of the present invention will be described with reference to FIG. In this embodiment, as the magnetic bubble transfer path 7, a current-driven transfer path consisting of a perforated two-layer conductor pattern 74, which is already known, is used. This driving method is suitable for coronal speed driving, in which driving currents 71 and 72 are alternately applied to the two-layer conductor pattern, and magnetic bubbles are transferred by the magnetic field generated around the conductor hole. In this embodiment, magnetic bubble information of a single rotation magnetization domain wall structure is generated as follows. First, as in the previous embodiment, magnetic bubbles are continuously generated using a magnetic bubble generating means 81 composed of a hairpin-shaped conductor button or the like. Next, the domain wall structure adjusting means 80 as described above
All of them are converted into magnetic bubbles with a single rotation magnetization domain wall structure.

Finally, the magnetic bubbles are transferred to the magnetic bubble erasing means 82 to erase the magnetic bubbles corresponding to unnecessary information. This erasing means 82 usually comprises a hairpin-shaped conductor button and means for applying a current thereto. All of these means are connected to and controlled by the write control section 12.

Next, according to the present invention, the magnetic bubble of the stripe single magnetization rotating domain wall structure is transferred from the magnetic bubble transfer path through the transfer path 7 according to the information, and comes to the transfer button 73' corresponding to the tip 24 of the stripe domain 2. At this time, a current indicated by T in FIG. 5(B) is applied to the magnetic bubble transfer means 9, which is made of, for example, a hairpin conductor and is provided in the vicinity thereof. Since the transfer means 9 has a common part with the magnetic bubble position holding means 3', the magnetic bubbles are transferred to the holding means 3'. Since the position holding means 3' is common to the pulse bias magnetic field applying means 3, when the current shown in FIG. A VBL pair is written in the Bloch domain wall 22.

As described above, by using the present invention, VBL pairs can be easily written on the Bloch domain wall of a stripe domain.

Therefore, the present invention is excellent as a high-density magnetic memory element that uses VBL pairs as information units. Furthermore, if the present invention is used, since a VBL pair corresponds to one magnetic bubble, it is possible to directly correspond to magnetic bubble information (convert it to VBL pair information. In the above explanation, magnetic The means for generating bubbles is not limited to a hairpin conductor, but may also be a divided type using a soft magnetic material pattern.

Further, as the magnetic bubble transfer path, it goes without saying that a contiguous disk batten formed by ion implantation may be used.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing an embodiment of a vertical Ploch line pair writing means, and FIG. 3 is a diagram showing a first embodiment of a magnetic bubble generating means according to the present invention. FIG. 4 is a diagram showing a second embodiment of the magnetic bubble generating means, and FIG. 5 is a diagram showing an embodiment of the magnetic bubble transporting and fixing and pulse bias magnetic field generating means. 1 is a ferromagnetic thin film, 2 is a striped domain, 3.3'
5.5' is a magnetic bubble, 6 is inside the conductor pattern, and 7 is a pulse bias applying means and a magnetic bubble fixing means, respectively.
Reference numeral 8 indicates a magnetic bubble transfer means, 8 a magnetic bubble generation means having a single rotation magnetization domain wall structure, and 9 a magnetic bubble transfer means. 11
is the magnetization direction outside the magnetic domain, 12 is the write control section, 21 is the direction within the magnetic domain, 24 is the tip of the stripe domain, 31 is the hairpin conductor, 32 is the current direction, 40, 40
', 40'' are magnetization directions within the domain wall, 42 and 43 are vertical Proch lines, 45 is a pair of vertical Proch lines, 50 is the magnetization direction of the magnetic bubble, 51 is the domain wall, 52 is the domain wall junction, 70 is the rotating magnetic field, and 71°72 is the magnetization direction in the domain wall. 73 is a transfer button, 74 is a two-layer conductor transfer button, 8OA is an in-plane magnetic field generation means, 80b is an in-plane magnetization layer, and 80c is a pulse bias application means.

Claims (1)

[Claims] Ferromagnetic film (
A vertical Proch line pair consisting of two adjacent vertical Proch lines created in a Bloch domain wall around a stripe domain (including a ferrimagnetic film) is used as a storage information unit, and the vertical Proch line is transferred within the Bloch domain wall. A magnetic memory element characterized by having a magnetic bubble information generating means having a domain wall structure of single rotation magnetization, and a magnetic bubble transfer means connected to the information generating means and provided in the vicinity of the stripe domain. a means for transporting a magnetic bubble from the transfer path to the vicinity of the tip of the stripe domain; a means for holding the magnetic bubble near the tip of the stripe domain; and a means for transporting the magnetic bubble from the transfer path to the vicinity of the tip of the stripe domain; 1. A magnetic memory element comprising means for applying a bias magnetic field.