JPS5996590A - Formation of stripe domain minor loop - Google Patents

Abstract

PURPOSE:To form simply a minor loop by using paired adjoining vertical Bloch lines made in the Bloch magnetic wall at the boundary of a stripe domain as a storage information unit and providing a transferring means in the magnetic wall. CONSTITUTION:The curie temperature TcII of a vertical magnetized film II is made higher than the curie temperature TcI of a vertical magnetized film I , and the vertical magnetized film II is saturated first by applying a bias magnetic field. When the temperature of this memory element chip is kept higher than TcI and lower than TcII, the vertical magnetized film becomes paramagnetic and all magnetic domains are erased. When the temperature of this memory element chip is lowered to a temperature lower than TcI, the vertical magnetized film I becomes a ferromagnetic body and magnetic domains are formed. At this time, it is subjected to a magnetic field made by the vertical magnetized film II, and the stripe domain minor loop is formed in the shape of copied stripes under the vertical magnetized film II worked to the form of stripes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention stores a pair of vertical Proch lines formed in Bloch domain walls at the boundaries of striped domains existing in a ferromagnetic film whose easy magnetization direction is perpendicular to the film surface. The present invention relates to a method of forming a stripe domain in each minor loop portion in a magnetic memory element (Plochline memory element) which is used as an information unit and is characterized by having means for transferring within the domain wall.

The development of magnetic bubble elements is actively being carried out in various places with the aim of increasing 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 photolithography technology used to form the bubble transfer path.

However, in recent years, the technology has advanced rapidly.

As a result, the question of how small the bubble diameter, that is, the material needed to increase the density, 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 in a material 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 retention layer and keep the information read time at the same level as conventional elements. There is. This magnetic memory element is equipped with an information reading means, an information writing means, and an information storage means, and has a stripe domain 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 a bubble domain as an information unit as before, the minor loop consists of a stripe domain, and the vertical Bloch line (hereinafter referred to as VB
It's called L. ) is the information unit. To show the overall information flow, first, the information written by the generator (presence or absence of bubbles)
moves the write major line. In order to store this information in the minor loop, change the minor loop to V] so that the information on the major line indicated by the presence or absence of bubbles can be transferred to the minor loop in VBLO form.
The feature of the present invention is that it is constructed with a Bloch domain wall that can hold 3L, and is an important key to dramatically improving the Q1 storage capacity. Line transfer gate including meeting,
Information transferred to minor loop (VBL)
It is possible to move the striped domain domain wall that makes up the U 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.

An example of the structure of this element will be explained. The major line uses a current drive method for both writing and reading. 4
The write transfer gate, which consists of book parallel conductors, uses the interaction between a bubble on the major line and a striped domain head that constitutes a minor loop. 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 strike domain domain wall of the minor loop. As a means of forming a VBL into a striped domain head, a pulse current is applied to a conductor pattern in contact with the striped domain head to dynamically move the striped domain head, thereby dynamically converting the head domain wall. In this way, VB
Two L's are formed, 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 stripe domain, and the stripe domain head is separated by two conductors on the stripe domain side. Create VBL. VBL with the same properties
remain stable even when they get close to each other. Major line (
The stripe domain head of the minor loop corresponding to the location where the C bubble exists is separated from the above conductor pattern due to the repulsion with the bubble.
VBL is not formed.

As a result, the information "1" on the major line is transferred with no VBL pair in the minor loop. Within the minor loop, 11i7 information is stored with each pair of VBLs having the same properties as one bit. The evBL pair is used in consideration of the stability of the replicator action. The bit period in the minor loop is '), V B L
A transfer pattern is provided so that one bit can be transferred sequentially to keep the rIIJ interval constant. - As an example, on the striped domain constituting the minor rubo, there is a stable interval [S] between VBL in the direction perpendicular to the longitudinal direction of the striped domain.

The period is twice that of the width S. A parallel thin wire pattern was formed using a Permalloy thin film, and the interaction between the magnetic poles and VBL induced on both sides of the parallel thin wire was utilized.

As one method, transfer along the VBL minor loop was performed dynamically 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 stripe 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 pit formed by a VBL pair is fixed to a stripe domain head by applying an in-plane magnetic field, for example.

The striped domain head is then cut into bubbles using a conductor pattern.

Then, the same VBL as the VBL that was cut out is configured in the striped domain head after the bubble is cut out. Such a replication effect of VB and L occurs only for VBL with a minus sign.

The bubble cut from the striped tome of the minor loop is transferred toward the detector on the major line. Here, VBL is applied to the striped domain head.
It takes advantage of the fact that the pulse current value that cuts out the stripe domain head is different depending on whether it is present or not.

If there is no VBL on the striped domain head, it will be difficult to cut. Therefore, if there is a position on the striped domain head, you can send a bubble to the major line, but VB
If there is no L, there is no bubble. In other words, the presence or absence (1, 0) of VBL 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. Place the VBL pair to be erased at the position closest to the minor loose stripe domain head on the writing major line side. Next, an in-plane magnetic field ■ip is applied to bring the VBL pair and one half of its neighboring VBL pair to the stripe domain head, which is used to cut off the positive VBL when writing information. Cut out the striped domain head using the parallel conductor.

After the bubble domain is removed, the striped domain head is replicated with the VBL pair to be deleted. In the end, only the placement pair that you want to delete will be deleted. In addition, when clearing the entire minor loop, first raise the bias magnetic field to erase all the stripe domains, and then form the minor loop drive domain from the S = 1 bubble.
It is possible to create a state in which the VBL has no heat and all pits are zero.

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 method for forming a stripe domain minor loop in a magnetic memory element (Ploch line memory element) that uses Gabloch lines as information units is S=1.
A method of forming a striped domain from bubbles is known, but in this case, forming a striped domain involves generation of bubbles, discrimination of S=1 bubbles, transfer of S=1 bubbles, and transfer of S=1 bubbles. A complex procedure is required to transfer the material from the main loop to the minor loop.

An object of the present invention is to provide a simpler method for forming stripe domains and minor loops in a magnetic memory element that uses the vertical prompt line as an information unit. That is, the present invention provides a ferromagnetic material (including a ferrimagnetic material) which has an information reading means, an information writing means, and an information storage means, and whose easy-to-destruct direction is perpendicular to the film surface.
A porcelain device that uses a vertical Ploch line pair consisting of two adjacent vertical Pronovo lines formed in a Pronovo domain wall at the boundary of a stripe domain existing in a film as a storage information unit, and has means for transferring the vertical Ploch line within the Pronovo domain wall. The ferromagnetic film (hereinafter referred to as perpendicular magnetization film I) of the memory element
That's what it means. ), a striped ferromagnetic material whose easy magnetization direction is the same direction as the perpendicular magnetization film ■, directly or through a nonmagnetic layer on the perpendicular magnetization film ■. This is a striped domain minor loop forming method characterized by forming a film (hereinafter referred to as perpendicular magnetization film (2)) and copying the floating magnetic field of the perpendicular magnetization film (2) to perpendicular magnetization film (I).

The present invention will be described above with reference to Examples.

FIG. 1 is a diagram showing an example of an embodiment of the present invention.

Reference numeral 11 is a perpendicularly magnetized film (2) processed into a stripe shape.

12 is a perpendicular magnetization film (2). 13 indicates a stripe domain formed below 11.

(The direction of magnetization is usually the direction shown by the arrow in Figure 1, but if the exchange coupling at the boundary between films 11 and 12 is large, the direction of magnetization of film 12 is opposite to that shown in Figure 1. ) The temperature TcI of the perpendicularly magnetized film ■! is higher than the temperature Tc1 of the perpendicularly magnetized film I. As a procedure for forming striped domains, first a bias magnetic field is applied to saturate the perpendicularly magnetized film (1). next,
When the temperature of this memory element chip is maintained at a temperature higher than T C+ and lower than Te1I, the perpendicularly magnetized film I becomes paramagnetic and all magnetic domains are completely erased. If the temperature of this memory element chip is then lowered to a temperature lower than Tc1, the perpendicularly magnetized film l becomes a ferromagnetic material and a magnetic domain is formed.
As a result, a stripe domain minor loop is formed by copying the stripes under the perpendicularly magnetized film (2), which has been processed into a stripe shape.

If a hard magnetic film is used as the perpendicularly magnetized film (2), apply a bias magnetic field to saturate the hard magnetic film and then perform the procedure described above. When a soft magnetic film is used as the perpendicularly magnetized film (2), the above procedure is carried out while applying a bias magnetic field.

As shown in Figure 1, if no spacer is provided between the perpendicularly magnetized films I and , a domain wall is formed at the boundary between the perpendicularly magnetized films I and . Since Ploch lines are difficult to form in the live domain, it has the advantage of creating a state in which all Ploch lines in the minor loop are erased. However, since this is disadvantageous in terms of the formation, retention, and transfer of Ploch lines, it is desirable that after the formation of the minor loop, the perpendicularly magnetized film is oxidized or, in the case of a metal film, oxidized to lose its magnetism.

Also, as shown in Figure 2, perpendicular magnetization 1i122 and [21
If a non-magnetic spacer 24 is provided between them, there is no need to remove the perpendicular magnetization film 1121, but since the formed strike domain minor loop 23 includes a Ploch line, the Ploch line can be erased. You need to initialize it by doing this.

Even if the bias magnetic field is simply increased to saturate the perpendicularly magnetized film I and ■ while the Ploch line memory element is kept at room temperature, and the bias magnetic field is then lowered, a striated domain power minor loop cannot be formed. can. This is because the magnetic field of the perpendicularly magnetized film H is copied to the stripe domain of the perpendicularly magnetized film I in a manner that the demagnetizing field is reduced.

In order to prevent the stripe domain from splitting into a plurality of parts and the minor loop from splitting, it is effective to simultaneously apply an in-plane magnetic field in the stripe direction when forming the stripe domain.

The present invention has been described above in detail regarding a method for forming a striped domain minor loop in a Plochline memory. Examples are given below.

Example 1 On a GdgGasO+2 substrate, Y2. O5tT1o,I
TJ IJ o, + Ca o, 8Fe4,2Ge(
A 4 μm thick garnet film with a composition of ,,80,2 was grown by LPE. On top of that, an amorphous GdCo film is sputtered!
1l12000X was formed. Thereafter, the Gd0o film was processed into stripes with lines and spaces of 4 μm. The Curie temperature of the garnet film is 195°C, and the G
The compensation temperature of the cl-Co film was 300°C. The external view is shown in Figure 1.
After raising the temperature to 200°C while applying a bias magnetic field of 00e, the bias magnetic field was reduced to zero and the chip temperature was returned to room temperature. Observation with a polarizing microscope showed that good striped domains and minor loops were formed. After confirmation, the GdC0 film was removed using hot dilute nitric acid.

Example 2゜(Y Eu Trn )3 on Gd5Ga50+2 substrate
Garnet film with (FeGa)5012 composition is 3 μm thick.
LPEμm exceeded.

On top of that, 7oooXuff was vapor-deposited, and then CO□2 Ni 24 Mn H was deposited by electroless plating.
A perpendicularly magnetized film having a P 3 composition was formed to a thickness of 3 μm and processed into a stripe shape with a width of 3 μm. The Curie temperature of the garnet film is 170°C, and Co 72 Ni 24 Mn l
The Curie temperature of the Ps film is a sufficiently high temperature of 400'C or higher. An external view is shown in Figure 2. A bias magnetic field of 20,000 e was applied to the Bronholline memory element chip having this configuration to saturate it, and then the chip temperature was raised to 175° C. and then returned to room temperature. As is already well known, in addition to Gd0o, there are also Gd -Fe, Ho
It is known that in many BE-'I'M systems such as -Fe, a perpendicular magnetization film is formed by the svart method or vapor deposition method, and even if these methods are used, striped domains and minor loops can also be formed. Can be formed. The same is true for Tr, q-T 1 systems such as co-Or, as well as the R E -T hr system.

Example 3 A Plochline memory element chip having the same configuration as Example 1 was kept at room temperature (or at a temperature higher than room temperature and lower than the Curie temperature of the garnet film), and the bias magnetic field was simply set to 1.0.
After increasing the magnetic field to OOOe, striped domain minor loops were still able to be formed even when the magnetic field was returned to zero. In this case, there is a high probability that defective loops will occur due to the domain being divided into multiple parts, so it was necessary to repeatedly raise and lower the bias magnetic field to select a pair with fewer defective loops. Furthermore, at this time, when an in-plane magnetic field in the stripe direction of JO~500e and an AC bias magnetic field with an amplitude of 1~100e were superimposed, defective loops were reduced.

As described above, the present invention uses bubble generation, S=1 bubble discrimination, transfer without changing the bubble state, and transfer procedures to form a striped domain minor loop in a Plochline memory device. It is possible to form a striped domain minor rubo without any problems.

[Brief explanation of drawings]

FIG. 1 is an external view showing the configuration of an embodiment of the present invention. 1
1 is a perpendicular magnetization film (1), 12 is a perpendicular magnetization film I holding a minor loop, and 13 is a copied stripe domain. FIG. 2 is an external view showing the configuration of another embodiment of the present invention. Reference numeral 21 indicates a perpendicular magnetization film (1), 22 a perpendicular magnetization film I holding a minor loop, 23 a copied stripe domain, and 24 a spacer. Representative Fi 1 Patent Attorney Susumu Uchihara I Figure f 2nd Procedural Amendment (Spontaneous) 9.22.1 Showa Date Commissioner of the Japan Patent Office 1, Indication of Case 1988 Patent Application No. 20573
No. 8 No. 2, Title of the invention: Striped domain/minor loop formation method 3, Relationship with the amended case Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4 , Agent Address: Sumitomo Sanda Building, 37-8 Shiba 5-chome, Minato-ku, Tokyo 108 (Contact address: NEC Corporation Patent Department) 5. Claims column specification of the specification to be amended - Detailed description of the invention Explanation column 6, Contents of amendment 1) 9 amendments are made to the scope of claims as per the attached sheet. 2) In the first line of page 11 of the specification, the word “vessel” is replaced with “ki”.
and correct it. Attachment Scope of Claims A stripe existing in a ferromagnetic material (including ferrimagnetic material) film having an information reading means, an information writing means, and an information storage means, and whose easy magnetization direction is perpendicular to the film surface. The ferromagnetic material of the magnetic storage element uses a vertical Proch line pair consisting of two adjacent vertical Proch lines formed in a Bloch domain wall at the boundary of a domain as a storage information unit, and has means for transferring the vertical Proch lines within the Bloch domain wall. In the method of forming a striped domain minor loop in a film (hereinafter referred to as perpendicular magnetization film I), the same direction as the perpendicular magnetization film is set as the direction of easy magnetization on the perpendicular magnetization film I through a surface or a nonmagnetic layer. Striped domain minor loop formation characterized by forming a striped ferromagnetic film (hereinafter referred to as perpendicular magnetization film ■), and copying the stray magnetic field of the perpendicular magnetization film to the perpendicular magnetization film. Method.

Claims (1)

[Claims] Boundary of a stripe domain existing in a ferromagnetic material (including a ferromagnetic material) having an information reading means, an information writing means, and an information storage means and whose easy magnetization direction is perpendicular to the film surface. The ferromagnetic film (hereinafter referred to as vertical In the method of forming a striped domain minor loop in a magnetized film (referred to as "magnetic film"), a striped domain minor loop is formed on the perpendicularly magnetized film I, either directly or through a nonmagnetic layer, with the direction of easy magnetization being the same as that of the perpendicularly magnetized film I. 1. A method for forming a striated domain minor loop, which comprises forming a ferromagnetic film (hereinafter referred to as perpendicular magnetization film (2)), and copying the stray magnetic field of the perpendicular magnetization film (2) to a perpendicular magnetization film (I).