JPH071635B2 - Method of reading magnetic storage element - Google Patents

Description

The present invention relates to a method for reading a nonvolatile ultra-high density solid-state magnetic memory element.

(Prior Art) One of the most important parts in an element using this method is an information reading section. The magnetic storage element in which the method is used comprises information reading means and information writing 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 reading the information written in the stripe domain domain wall in the form of a VBL pair is indispensable.
Conventionally, when there are three VBL14s (VBL pairs that are data and VBLs that existed at the tip in advance) at the tip of the stripe domain as shown in Fig. 4, gradually extend these three while holding them at the tip. , On the way or after stretching, locally apply an in-plane magnetic field in the longitudinal direction of the stripe domain to the area including the tip, and of the three VBLs, keep only the central one at the tip and the other two To the side walls on both sides,
After separating the books, in the region between the tip and the position where the other two VBLs are held, the upper and lower sidewalls are cut in parallel with each other, and there is only one VBL at the tip. In this case, the mechanism was such that the VBL was moved to one of the side walls sandwiching the tip by the above-mentioned local in-plane magnetic field, and the tip was made into a uni-chiral state and was not cut. (The 61st Annual Meeting of the Institute of Electro-Communications in 1986 (March 1986) 228. Journal of the Applied Magnetics Society of Japan 10 (1986) pp414-418.INTERMAG'86 (198)
6) DD-05.) However, in this method, when the stripe domain tip is stretched, it is necessary that three VBLs are finally held at the tip, so domain stretching is performed with good controllability. This is very important. An error will occur if any of the following occur. In other words, if the domain wall moving speed at the time of stretching the tip portion is high, the gyroscopic force acts, and the VBL at the tip portion may once move to the side wall. After that, one of the right ends of the three VBLs returns to the tip due to the in-plane magnetic field applied along the longitudinal direction of the stripe domain over the entire chip for stabilizing the VBL pair in the information storage unit. If the above-mentioned local in-plane magnetic field is simply applied to this state, the VBL at the tip does not always move to the side wall opposite to the side wall where the remaining two VBLs exist, and the VBL All three may be stabilized on the same side wall. When this happens, VBL is added to the tip, which is the intended purpose.
It becomes impossible to discriminate the cutting of the leading end of the stripe domain by utilizing the difference between placing one or not.

This content is shown in FIGS. 4 (a) to (f) and FIG. 5 (a) to
An explanation will be given using (f). The tip of the stripe domain for storing information at the position 3 in FIG. 4 (a) is extended to the position 3'by applying a current to the conductor pattern 7 in the direction of the arrow. At that time, unless stretching is performed with extreme caution, VBL, which is an information carrier existing at the position (bit position) of the tip 3 of the stripe domain before stretching,
The VBL, which originally exists at the tip of the pair, may move together to the upper side wall by the gyroscopic force as shown in FIG. 4 (a). After that, due to the interaction with the in-plane magnetic field Hip0 which is added in the longitudinal direction of the stripe domain for holding the VBL pair of the information storage unit over the entire chip, only one VBL at the right end is changed as shown in FIG. 4 (b). Return to the tip. In this state, the in-plane magnetic field in the direction opposite to Hip0 generated by applying a parallel current to the conductor patterns 10, 11 and 12
When only Hip is added to the region containing the domain tip of the stretched domain, the VBL at the tip moves in the direction of arrow 15 in FIG. 4 (c) or in the direction of 185 in (e). When the VBL moves in the direction of 18 as shown in Fig. 4 (e), the two VBLs remaining on the upper side wall are also separated by the interaction with Hip, and one in the direction of 19 and another The book moves in 20 directions. If the VBL at the tip of the stripe domain moves in the direction of 18, it collides with the VBL that has moved in the direction of 19 and newly creates a VBL pair indicated by 21 in FIG. 4 (f). In such a state, the side wall magnetizations of the region sandwiched by the cutting conductor patterns 8 and 9 at the domain tip end are opposite to each other on the upper side and the lower side, and the stripe domain tip end 3 described later with reference to FIG. There is no difference in the relative relationship between the upper and lower sidewall magnetizations in the cutting region as compared with the case where there is only one VBL in the above, and there is no difference in the cutting conditions. On the other hand, at the tip
When Hip was added, the VBL at the tip part moved in the direction indicated by 15 in Fig. 4 (c), and the two upper VBLs moved in the directions of 16 and 17, respectively, resulting in Fig. 4 ( When the state of d) is obtained, the upper and lower side wall magnetizations in the cutting region are parallel to each other, which is different from the state of FIG. 5d.
In this case, when there are three VBLs at the tip 3 of the stripe domain and when there is only one VBL, and when there are three VBLs with the same cutting magnetic field, they are cut and a bubble is created. At the time of, there is a difference that it is not cut and bubbles cannot be made. Figure 5 shows one VBL at tip 3
, That is, the VBL pair has not been transferred to the tip 3. In this case, simply move the VBL to either the upper or lower side wall by the conventional method,
The relative relationship of the lower side wall magnetization does not change, and FIG.
As shown in (f), they are antiparallel to each other. From the above, this method has a high probability of causing an error when a VBL pair is transferred to the tip 3.

(Problems to be Solved by the Invention) In the conventional reading method, VB is added to the stripe domain tip portion 3.
If there is an L pair, 3 together with one VBL at the tip beforehand
It is necessary to control the current waveform applied to 7 with high accuracy so that the VBL of the book does not come off the tip. Because, when the domain wall moves fast, the VBL at the tip moves to the side wall due to the gyroscopic force. Then, it may cause a problem as shown in FIG. 4 (f). Finding means to solve this point is important for improving this reliability. The present invention presents a new method to solve this problem.

(Means for Solving Problems) The present invention has a ferromagnetic material (ferrimagnetic) that has an information reading means, an information writing means, and an information storing means, and has a direction perpendicular to the film surface as an easy magnetization direction. A pair of vertical Bloch lines adjacent to each other formed in the Bloch domain wall at the boundary of the stripe domain existing in the film (including the body). In the magnetic storage element using the stripe domain, a part of the outer peripheral domain wall at the tip of the stripe domain is stretched, 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. , And at the same time after pushing the tips of the stretched stripe domains in the direction opposite to the stretched direction, the area in which the local in-plane magnetic field is applied Then, the stripe domain is cut off.

(Operation) In the present invention, three VBs at the tip 3 of the minor loop
After extending the tip of L, 3 for the intended purpose
The process of separating books will be described. FIG. 2 (a) shows that when a domain having three VBL14s at the tip 3 is applied to the conductor pattern 7 and stretched to the right, the three VBLs come to 14 'due to the gyroscopic force. There is. FIG. 2 (b) shows that only one of the three VBLs on the stretched domain on the right side is added to the entire chip due to the in-plane magnetic field Hip0 (here, it is added to the left), and the domain tip is added. It shows a moved state. For this state, the conductor pattern 10,1
When an in-plane magnetic field in the direction opposite to Hip0 is applied in the longitudinal direction of the domain using 1,12, a pulsed current is applied to the conductor pattern 13 or 7 almost at the same time to dynamically push the tip 3'of the domain to the left. The VBL existing at 3'moves toward the lower side wall by the gyroscopic force, and a new 14 'is formed at the tip.
The VBL in the middle of is moving to the tip for Hip. As a result, after the domain of the VBL14 at the tip shown in FIG. 2 (a) is stretched, the local in-plane magnetic field Hip and the action of the additional pulse bias magnetic field applied to the tip 3'are used to cause the 3 shown in FIG. 2 (c). It separates into books. In this state, two conductor patterns 8 and 9 are arranged on the film surface, and a pulse current is applied to the conductor pattern so as to generate a magnetic field in the same direction as Hz in a region sandwiched by the conductor patterns. Then, the stripe domain is finally cut into the two domains shown in FIG. 2 (d). Negative VBL is injected into each domain by cleavage. In other words, the negative VBL removed along with the bubble by cutting is replicated at the tip of the newly created stripe domain. In addition, in the method that does not use the wide conductor pattern shown in the existing method, the probability that a horizontal Bloch line exists at the cut part by cutting off the current other than 10 and 12 of the Hip applying conductor pattern when cutting the domain. Can be made smaller.

On the other hand, FIG. 3 shows the operation when there is no VBL pair at the bit position of the tip 3 of the minor loop. VBL4 moves to 4 ', as shown in Fig. 3 (a), by stretching the tip of the domain. After that, Hip0 moves to the tip 3 ', as shown in FIG. 3 (b). After that, while giving Hip by the conductor pattern of 10, 11, 12 and at the same time, by applying the pulse bias magnetic field of the same direction as the bias magnetic field Hz to the domain tip portion 3 ′ by the conductor pattern 13 or 7, the tip portion 3 ′ is left. VBL at the tip when pressed dynamically toward
Moves to the lower side wall, and the state of FIG. 3 (c) is obtained. In this state, the second conductor pattern 8 and 9
The same pulsed magnetic field as in the figure is applied to the domain. In this case, the magnetization directions at the centers of the upper and lower side walls are opposite to each other in the region sandwiched by 8 and 9, and therefore the regions are not cut (FIG. 3 (d)). The above is the mechanism for converting the information stored in the presence or absence of the VBL pair on the stripe domain domain wall into the presence or absence of the bubble and reading the information.

In addition, as shown in Japanese Patent Application No.
After separating the three VBLs, turn off the current in the Hip applying conductor patterns 10 and 11 other than 12, collect all the VBLs on the right side of the conductor pattern 9, and then cut the domain in the region sandwiched between 8 and 9. Good.

(Example) The content of this invention is demonstrated using an Example. FIG. 1 shows the basic configuration of the VBL pair read section formed at the tip of the stripe domain. 3 is the tip of the stripe domain,
VBL4 at the tip is already in the initial state of the memory domain. Reference numeral 7 is a conductor pattern used to extend the tip of the stripe domain when reading the VBL pair. Reference numerals 10, 11 and 12 are conductor patterns for generating a local in-plane magnetic field in the domain longitudinal direction so as to include the tip portion 3'at the tip portion of the stripe domain. Reference numerals 8 and 9 are conductor patterns for cutting the domain tip. Reference numeral 13 is a conductor pattern which gives a pulse bias magnetic field to the domain tip.
Next, the operation will be described. First, a pulse current is applied to the conductor pattern 7 to guide the tip of the stripe domain to the reading section. Then, the VBL 14 once moves to the upper side wall due to the gyroscopic force in this case. Then Hip0
It is stabilized at the tip 3'by interaction with. After that, a parallel current is applied to the conductor patterns 10, 11 and 12 to give a rightward in-plane magnetic field Hip in the longitudinal direction so that the stripe domain tips include the domain tips 3 ′, and at the same time, the conductor patterns 13 are simultaneously applied. Alternatively, a pulse current is applied to 7 and a pulse bias magnetic field in the same direction as the static bias magnetic field for stabilizing the stripe domain is applied to the tip portion 3 ', and the tip 3'is moved to the left to the dynamics. The VBL is moved to the lower side wall and trapped on the left side of the conductor pattern 10 where the hip exists, and then pulsed currents antiparallel to each other are applied to the conductor patterns 8 and 9 to sandwich the region between them. A pulsed magnetic field with the same direction as Hz is applied to and the domain is cut.

(Effect of the Invention) According to the present invention, a stable information reading method is established in a Bloch line memory using a stripe domain domain wall as an information storage unit, and operation is performed as compared with a conventional method of simply applying an in-plane magnetic field to the tip of the stripe domain. Was stabilized.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a VBL pair reading unit in the present invention. FIG. 2 is a diagram showing a reading process when there is a VBL pair in the present invention. FIG. 3 is a diagram showing a reading process when there is no VBL pair. Fig. 4 shows VBL in the conventional method
The figure which shows the error mode which may occur when there is a pair. FIG. 5 is a diagram showing a reading process when there is no VBL pair in the conventional method. 1 ... Stripe domain, 2 ... Domain wall, 3 ... Domain tip, 3 '... Domain tip after stretching,
4 ... VBL, 5 ... Magnetization on center line of domain wall, 6 ... Magnetization in domain, 7 ... Conductor pattern for domain extension, 8,9 ... Conductor pattern for domain cutting, 10, 11, 12 ...
… Conductor pattern for in-plane magnetic field application, 13 …… Conductor pattern that gives a magnetic field that dynamically moves the extended domain tip, 14,14 ′ …… VBL pair and VB that exists in front of the tip
Three VBLs with L together, 15,16,17,18,19,20…
… The direction in which each VBL moves by the application of Hip, 21 …… VBL
versus.

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. Magnetic storage using the stripe domain in the film of the ferromagnetic material, 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 the element,
A part of the outer peripheral domain wall at the tip of the stripe domain is stretched, an in-plane magnetic field is locally applied to the tip of the stretched stripe domain in the longitudinal direction of the stripe domain, and the tip of the stripe domain is stretched almost at the same time. Is read in the direction opposite to the stretched direction, and then the stripe domain is cut in the region to which the local in-plane magnetic field is applied.