JPH0782744B2 - How to read the Brochure line pair - Google Patents

Description

The present invention relates to a method for reading information from a non-volatile ultra-high density solid magnetic memory element.

(Prior Art) This magnetic memory element comprises information reading means and information writing means, and has means for transferring a pair of vertical Bloch lines (hereinafter referred to as VBL) in a Bloch domain wall. In such a magnetic storage element, a means for reading the information stored in the stripe domain domain wall in the form of a VBL pair is indispensable. Regarding this method, in the conventional method, when there are three VBLs (VBL pair 8 as data and VBL7 that was previously at the tip) at the tip 6 of the stripe domain in the reading, the tip portion is read out, as shown in FIG. By applying an in-plane magnetic field locally in the stripe domain longitudinal direction to the region including, the three VBLs are separated so that one VBL is formed on each of the domain tip and the sidewalls on both sides of the VBL. Gradually stretch the three wires while holding them at the tips, and in the middle of that or in the area including the tips after stretching, for example, use the conductor lines 19, 21, 22 to locally localize the in-plane magnetic field in the stripe domain longitudinal direction. As shown in Fig. 4 (b) after adding Hip, only one of the three VBLs is kept at the tip and the other two are moved to the sidewalls on both sides to separate the three. Then, the tip and the other two VBLs are retained. Conductor wires in a region where the magnetization of the upper and lower side walls of both sides are parallel to each other sandwiching the tip between a position that is
Using 20,20 ', cut as shown in Fig. 4 (c),
Further, as shown in FIG. 4 (d), when there is only one VBL at the tip 5 (there is no VBL pair of data and only 7 exists), either VBL is sandwiched by the above-mentioned local in-plane magnetic field. To the side wall of FIG. 4 (e), the tip end is in a unichiral state, that is, the magnetizations of the upper and lower side walls are antiparallel to each other. As shown in FIG. 6F, a bubble domain is generated corresponding to each of the cases where there is a VBL pair and the case where there is no VBL pair using the mechanism of not being disconnected, and the stored information is read by utilizing that fact. (Japanese Patent Application Sho 60
−089321, 1986 General Conference of The Institute of Electrical Communication (198)
3.3) Lecture No. 228. Journal of Japan Society of Applied Magnetics 10 (1986) pp414
−418.INTERMAG′86 (1986) DD-05.) However, even if the directions of magnetization at the centers of the sidewalls on both sides of the domain tip can be controlled to be parallel or anti-parallel to each other, the next domain cutting process will cause a conductor pattern. Since it is sensitively dependent on the arrangement of the two, it was a very difficult technique to take out a large tolerance in the difference in the cutting process between the two.

(Problems to be Solved by the Invention) In the conventional reading method, the magnetization directions at the centers of the side walls on both sides sandwiching the domain tips obtained by separating the three VBLs in a predetermined manner are parallel or one. In the case of VBL, the difference in the domain cutting process depending on the anti-parallel also sensitively depends on the arrangement of the conductor pattern for domain cutting, and the stable position of the extension domain is given by 9 and the shape of the potential well and the material Due to the combination of coercive force and the like, the relative position of 9 is slightly different for each gate, and the cutting conditions are individually different, so it is difficult to obtain reliable results. Eliminating these defects is important for improving the read reliability of VBL pairs.

It is an object of the present invention to provide a reading method that eliminates such conventional problems.

(Means for Solving the Problem) In the present invention, the conventional method of leading both the domain having a VBL pair at the tip and the domain not having the VBL pair to the domain cleavage site is newly used, and when there are three VBLs at the tip (there is a VBL pair). ) And one VBL (there is no VBL pair), the difference in the moving speed of the domain tip is used, and the moving speed is high, that is, only the domain in which one VBL exists at the tip is the domain breaker. I am trying to lead to. By doing so, even if the directions of magnetization at the centers of the side walls on both sides of the domain tip are controlled to be parallel or antiparallel, the next domain cutting process is sensitive to the placement of the conductor pattern, and VBL We removed the disadvantage of the conventional method that it is quite difficult to convert the presence / absence of a pair into the presence / absence of a bubble, that is, it is quite difficult to reliably extract the difference in the cutting process between the two. As an example of a specific method, a groove is formed in the stripe domain holding layer as shown by 10 in FIG. 1 in order to separate the areas extending each stripe domain in a part of the area where the stripe domain tip is extended. . As a result, the potential well in the region sandwiched by the grooves 10 is shallower than the region between the line connecting the tips 11 of the grooves 10 and the line connecting the stripe domain stable positions 5, 5 in FIG. That is, a barrier against domain extension is formed in the region sandwiched by the grooves 10. In such a state, the domain tip gives a driving force to the domain tip so that the domain tip can overcome this barrier if it takes time. What is important in the present invention is that the time during which the driving force is applied is controlled so that the domain wall moving speed is high, that is, only the tip 5 of the domain having one VBL at the tip is sandwiched between the adjacent grooves 10. It is to overcome barriers and grow. After overcoming the boundary, the domain tip 6 that has not crossed over the boundary barrier has a weak driving force that does not overhang the barrier, and only the domain tip 5 extending to the region sandwiched by the grooves 10 is guided to the domain cut portion.

Therefore, the domain tip having three VBLs extends only to the line connecting the tips 11 of the grooves 10, that is, before the barrier. On the other hand, VB at the tip of the domain that extends to the region sandwiched by each groove 10
L is finally stabilized at the tip of the extended domain by the in-plane magnetic field Hip0 applied to the entire chip. When this domain is cut, the same type of VBL that was cut with the bubble is duplicated at the tip of the domain after the bubble was cut. Further, this cutting has an advantage that it can be reliably performed in a wide cutting magnetic field range. Of course, the replicated VBL does not cause instability even when the tip of the stripe domain is pushed back to its original position.

Writing and erasing of the VBL pair can be performed by wiring the read gate portion of the VBL pair of the present invention and applying the method described in Japanese Patent Application No. 61-002399, for example. At the time of writing, the method of erasing the already written information is such that the application time of the magnetic field for stretching the domain tip used in the read operation is lengthened and the number of VBLs at the tip is one After the domain tip is also crossed under the domain cutting conductor pattern 12, the domain tip is cut off using the domain cutting conductor pattern to make one VBL at the new domain tip, and then the above write operation is performed. Just go.

(Example) Below, the Example of this invention is described.

FIG. 1 shows the basic configuration of the VBL pair read section formed at the tip of the stripe domain. 2 and 3 are stripe domains, and VBL7 at the tip 5 is already included in the initial state of the storage domain. Data VBL on tip 6
Pair 8 exists. Reference numeral 9 is a conductor pattern used to extend the tip of the stripe domain when reading the VBL pair. Reference numeral 12 is a conductor pattern for cutting the domain tip. It is a conductor pattern that gives a pulse bias magnetic field. Next, the operation will be described. First, the conductor pattern 9
A pulse current is applied to the leading edge of the stripe domain to lead it to the reading section. Then, VBL7 at the tip moves to the side wall due to the gyroscopic force. As a result, the tip end is in a state where there is no VBL, and the side wall moving speed can be kept high. When the domain is completely extended, VBL7 is stabilized at the tip 5 by interaction with Hip0 in FIG. On the other hand, the tip 6 with the VBL pair moves only up to 6'between. This works in such a direction that the in-plane magnetic field component due to the current of the domain extending conductor pattern 9 holds one of the three VBLs at the tip 6 at the tip of the extending domain, and the VBL interferes with the motion of the domain wall. This is because Therefore, only the tip 5 where the VBL pair does not exist at the tip crosses the domain cutting conductor pattern 12 of the gate portion 13 which performs conversion between the VBL pair and the valve. When a pulse current is applied to 12 to cut the domain, a bubble is generated and a VBL of the same type as that cut with the valve is replicated on the tip of the newly formed stripe domain.

Referring to FIG. 3, VBL is added to the domain tip used in the present invention.
The mechanism by which the stretching speed of the domain tip is different between the case where there is one and the case where there are three will be explained.

The positions of the tips of the stripe domains when the gate portion 13 is not operated are set to 5 and 6. 5 has no VBL pair as data, but only VBL7 placed at the tip of the initialized domain. There are 3 VBLs in 6 including VBL pair 8 which is a gater and 7 in total. A pulse current for stretching the domain tip is applied to the conductor pattern 9 in the direction of the arrow. Then, VBL existing in domain tip 5
Due to the in-plane component of the conductor current magnetic field of 9 and the gyro force associated with the domain wall movement, VBL7 deviates from the domain tip and becomes a domain wall without VBL. On the other hand, at the tip 6, due to the in-plane magnetic field component due to the conductor current of 9, one VBL on the right side of the VBL pair 8 extends while being held at the domain tip. Therefore, the stretching speed of the domain tip 6 is 1-2 orders of magnitude smaller than that of 5. This mechanism is used in the present invention. That is,
When the position of the line connecting the tips 11 of the grooves 10 of the domain tip 6 is reached, the domain tip 5 extends to the region sandwiched by the grooves 10.

In the conventional method, in order to prevent the VBL from being injected during the process of extending the domain tip at the time of writing and reading, the speed at which the domain tip is extended must be kept low. First, even if the domain tip is stretched as specified, the difference in the difficulty of domain cutting depends on whether the magnetization directions of the center of the side walls sandwiching the domain tip are parallel or antiparallel. Dependently, it was difficult to obtain reliable results.
As one means for improving the read reliability, it is conceivable that only one type of domain extends in the domain cutting portion.

In the present invention, in order to improve the separation between the domains in the region where the domain tip is extended, a groove 10 is placed, and a barrier for domain extension is formed in the region sandwiched between the grooves, and the extraction speed of the domain tip is Utilizing the dependence on the number of Bloch lines existing at the tip, a control mechanism is attached so that only one type of domain (domain having only one VBL at the tip) can reach the conductor pattern for domain cutting. ing. As a result,
Disconnect all domains that have reached the domain disconnection section,
All you have to do is generate a valve. By adopting this method, the read reliability of the VBL pair is dramatically improved compared to the conventional method. Writing and erasing VBL pairs can also be done using this area.

(Effects of the Invention) According to the present invention, a stable information read / write method is established in a Bloch line memory using a stripe domain barrier as an information storage unit, and the conventional domain cutting characteristic of the stripe domain tip portion has VBL of 1 at the tip. The reliability is dramatically improved as compared with the method using the fact that it differs depending on whether or not there is a book.

[Brief description of drawings]

1 and 2 are block diagrams of the VBL pair reading unit in the present invention. FIG. 3 is an illustration of the mechanism used in the present invention. FIG. 4 is a diagram showing an example of a conventional method relating to the reading method. 1 ... Stripe domain holding layer, 2, 3 ... Stripe domain, 4 ... Domain domain wall, 5, 6 ... Domain tip, 5 ', 5 "5,6', 6", 6, ... Stretching process , And the domain tip of the domain tip after stretching, 7 ……
VBL, 8 ... VBL pair at the tip of domain, 7 ', 7 ", 7 ... VBL position in domain extension process, 8', 8", 8 ...
… Position of VBL pair in the process of domain extension, 9 ... Domain extension conductor pattern, 10 ... Groove for separating each extension domain, 11 ... Tip of groove, 12 ... Domain cutting conductor pattern, 13 ... Read gate section, 14 ……
Major line, 15 ... Domain magnetization, 16 ... Domain wall centerline magnetization, 17 ... Conductor pattern for strengthening separation from adjacent bit positions, 18 ... Stretching domain tip holding conductor pattern, 19, 21 , 22 …… Local plane magnetic field applying conductor pattern, 20 …… Domain cutting conductor pattern.

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. Information reading of a magnetic storage element using a stripe domain in the ferromagnetic film having means for transferring a pair of two adjacent vertical Bloch lines formed in the Bloch domain wall at the boundary of the stripe domain in the Bloch domain wall Regarding the method, by fixing the stretching magnetic field application time of the stripe domain and providing a groove barrier for domain extension, it is possible to extend the domain tip only when the number of Bloch lines existing at the domain tip is one. Characteristic Bloch line pair reading method.