JPH06103590B2 - Writing method of magnetic memory element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a nonvolatile ultra-high density solid-state magnetic memory element.

(Prior Art) One of the most important parts in this device is an information writing part. The magnetic storage element comprises information reading means, information writing means, and information storage means, and has means for transferring the pair of Bloch lines (hereinafter referred to as VBL) in the Bloch domain wall.

In such a magnetic memory element, a means for writing information in the stripe domain in the form of VBL pairs is indispensable.
Conventionally, the tip end of the stripe domain is dynamically pushed as shown in FIG. 3, and the domain wall magnetization is inverted only at the tip end by utilizing the moving speed of the domain wall caused by the push, and the two ends are
VBLs were formed and these two VBLs were paired.

However, the two Bloch lines formed by this method have different signs, and because they have the drawback of being easily recombined with each other due to disturbance, an operation to change the sign of one of the two VBLs Was needed. This procedure will be described with reference to FIG. The tip end of the stripe domain for storing information at the position 3 in FIG. 3 (a) is extended to the position 3 '. At that time, VBL4 is moving to the 3'position.

In this state, parallel currents are applied to the conductor patterns 10, 11 and 12 and a pulse current is applied to the conductor pattern 24 while applying a rightward in-plane magnetic field to the domain tip, and VBL4 at the 3'position is set. Dynamically move to the left. Then, first, VBL4 is held at the left end of the conductor pattern 10 by the interaction with the local in-plane magnetic field. after that,
The domain wall magnetization at the tip of the stripe domain at the 3'position is reversed, and positive and negative two VBLs 25 and 26 are placed at both ends of the third
It is written as shown in FIG.

In this state, when the current of the conductor patterns 11 and 12 is cut off, the negative VBL26 approaches VBL4 as shown in FIG. 3 (c). Then, a VBL pair 27 composed of VBL4, 26 is formed. After that, the positive VBL, 25 remaining at the tip of the stripe domain at the 3'position is connected to the conductor patterns 8, 9
A parallel current is applied to the edge of the domain to cut it off, so that it is removed together with the cut out bubble domain, and at the same time, a new negative VBL is written to the edge of the stripe domain at the 3'position. By the series of operations up to this point, the writing of 1 bit is completed.

(Problems to be Solved by the Invention) In the conventional writing method, it is necessary to accurately control the magnitude of the magnetic field that dynamically moves the domain wall at the tip of the stripe domain. This is because the allowable range of the magnetic field for writing VBL stably is narrow. Therefore, it is very important to keep a constant distance between the conductor pattern 24 for generating the magnetic field shown in FIG. 3 and the stripe domain tip domain wall and the tip of the stripe domain at the position of 3 '.

However, although the stripe domain tip is an essential characteristic, it shrinks irreversibly with respect to the increase or decrease of the static magnetic field Hz applied in the direction perpendicular to the film surface to control the stripe domain shape, and extend.

Therefore, it is extremely difficult to control the distance between the tip domain wall and the conductor pattern to be constant, and finding a means for solving this point was important for practical use of this element.
The present invention presents a new method to solve this problem.

(Means for Solving Problems) The present invention has a ferromagnetic material (ferrite) having an information reading means, an information writing means, and an information accumulating means, and having a direction perpendicular to the film surface as an easy magnetization direction. (Including the magnetic substance), a means for transferring pairs of two adjacent vertical Bloch lines formed in the Bloch domain wall at the boundary of the stripe domain existing in the film, in the Bloch domain wall, In the magnetic storage element using the stripe domain, a part of the outer peripheral magnetic wall at the tip of the stripe domain is stretched and stabilized toward the major line portion, and the stripe is locally formed at the tip of the stretched stripe domain. A horizontal Bloch line is generated by applying an in-plane magnetic field in the longitudinal direction of the domain, and in the region where this local in-plane magnetic field is applied, By applying a pulse magnetic field in the direction of cutting the stripe domain, the horizontal Bloch line is punched through, and then the stripe domain is cut.

(Operation) In the present invention, a stripe domain having no VBL (hereinafter, referred to as X-stripe) is cut to obtain VBL.
The process of injecting is explained. FIG. 2 (a) shows an X-stripe. The figure shows changes in the film thickness direction of the magnetization of the center plane of the domain wall. 13 is the upper surface of the film, 5 is the center of the film, and 14 is the lower surface of the film. Hz is a bias magnetic field for holding the stripe domain.

Next, the in-plane magnetic field Hi is set along the longitudinal direction of the X-stripe.
p is added as shown in FIG. 2 (b). Then Hip
On the side wall 20 having the opposite magnetization, horizontal Bloch lines 15 and 16 are generated from both upper and lower surfaces of the film, and the state shown in FIG. 2 (b) is obtained. In this state, as shown in FIG. 2 (c), two conductor patterns 8 and 9 are arranged on the upper surface of the film, and a magnetic field having the same direction as Hz is generated in the region sandwiched by the two conductor patterns. Thus, a pulse current is applied to the conductor pattern.
Then, the domain wall dynamically moves, and the gyro force Fgl indicated by the arrow acts on the horizontal Bloch line accordingly, and the horizontal Bloch line 15 punches through from the lower surface of the film. Then, as shown in FIG. 2 (d), two VBL21,
A transient state with 22 is obtained.

In this state, the central magnetizations of the upper and lower sidewalls of the stripe domain are parallel to each other. By subsequently applying a pulsed magnetic field in this state, the stripe domain is finally cut into two domains shown in FIG. 2 (e). Negative VBL2 in each domain domain wall
Two 1,2 or VBLs 23 ', 22 with different signs are injected. It is the essence of the present invention that the mechanism for injecting two negative VBLs into one domain domain wall found here was used for writing a VBL pair in this element.

(Example) The content of this invention is demonstrated using an Example. Fig. 1 (a)
(D) shows the basic configuration of the VBL pair write section formed at the tip of the stripe domain. 3 is the tip of the stripe domain, and VBL4 at the tip is necessarily in the initial state. Reference numeral 7 is a conductor pattern used for extending the stripe domain when writing the VBL pair. 10, 11 and 12 are conductor patterns for generating a local in-plane magnetic field in the domain longitudinal direction at the tip of the stripe domain. Reference numerals 8 and 9 are conductor patterns for cutting the domain tip.

Next, the operation will be described. First, in order to move the VBL4 at the tip to the side wall at the time of writing information, the conductor patterns 10, 11,
A parallel current is applied to 12 and a pulse current is applied to the conductor pattern 7 while applying a longitudinal rightward in-plane magnetic field Hip to the tip of the stripe domain to guide the tip of the stripe domain to the write section. Then, in this case, the VBL4
It moves to the left end of the conductor pattern 10 along the upper side wall, and is stabilized at that position by the interaction with the hip.

The domain wall structure on the right side of the conductor pattern 10 is the first
It is as shown in FIG. Currents antiparallel to each other are applied to the conductor patterns 8 and 9 in the directions indicated by arrows in this domain, and a pulse magnetic field in the same direction as Hz is applied to a region sandwiched between 8 and 9 to punch through the horizontal Ploch line 15. Then, as shown in Fig. 1 (c), two VB
A transient state in which L17 and L18 are written in the domain wall is formed. Against this state, the magnetic field due to the current of 8 and 9 is continuously applied, and the domain is disconnected. As a result, two negative VBLs 17 and 19 are written at the tip of the stripe domain.

(Effects of the Invention) According to the present invention, a stable information writing method is established in a Bloch line memory in which a stripe domain domain wall is used as an information storage unit. And, the movement was remarkably stabilized.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a portion in which a VBL pair of the present invention is written at the tip of a stripe domain. FIG. 2 is a diagram showing the basic configuration of the write operation of the VBL pair used in the present invention.
FIG. 3 is a diagram showing an example of a conventional VBL pair writing method. 1 ... Stripe domain, 2 ... Stripe domain domain wall, 3, 3 '... Stripe domain tip, 4 ... VB
L, 5 ... Magnetization at the domain wall center in the film thickness, 6 ... Magnetization in the stripe domain, 7 ... Conductor pattern for extending the tip of the stripe domain, 8, 9 ... Conductor pattern for cutting the tip of the stripe domain , 10,11,12 …… Local in-plane magnetic field generating conductor pattern, 13 …… Domain wall magnetization on the upper surface of the film, 14 …… Domain wall magnetization on the lower surface of the film, 15, 16 …… Horizontal Bloch line, 17 …… Negative VBL , 18 …… Positive VBL, 19,19 ′ ……
Negative VBL entered by domain disconnection, 20 …… sidewall, 21
…… Negative VBL, 22 …… Positive VBL, 23,23 ′ …… Negative VBL entered by domain cutting, 24 …… VBL vs. write conductor pattern, 25 …… Positive VBL entering domain tip , 26
…… Negative VBL that entered the domain tip, 27 …… VBL pair consisting of negative VBL.

Claims (1)

[Claims] 1. A ferromagnetic material (including a ferrimagnetic material) film having an information reading means, an information writing means, and an information storage means, and having a direction perpendicular to the film surface as an easy magnetization direction. A magnetic memory element using the stripe domain in the ferromagnetic film, having means for transferring pairs of two adjacent vertical Bloch lines formed in the Bloch domain wall at the boundary of the stripe domain in the Bloch domain wall. In, a part of the outer peripheral domain wall of the tip of the stripe domain is stretched and stabilized toward the major line portion, and an in-plane magnetic field is locally applied to the stretched tip of the stripe domain in the longitudinal direction of the stripe domain. A horizontal Bloch line is generated by adding it, and the stripe domain is cut in the region where the local in-plane magnetic field is applied. By applying a pulse magnetic field in the direction, the horizontal Bloch lines After punchthrough, writing method of the magnetic memory device characterized by cutting the stripe domain.