JPH05347090A - Bloch line memory element and method for operating it - Google Patents

Abstract

PURPOSE:To realize the practical read of a Bloch line. CONSTITUTION:This element is provided with means 9, 11 holding a stripe magnetic domain 2 having a Bloch line pair 4 in the required area of a magnetic film, a means moving the Bloch line pair 4 to the end part of the stripe magnetic domain 2, a stripe magnetic domain cutting means 7 provided in the vicinity of the end part of the stripe magnetic domain and a means 12 impressing intrasurface magnetic field HC to the magnetic film. By impressing the magnetic field DELTAHB of the reverse direction of vertical bias magnetic field HB vertical to the magnetic film and the intrasurface magnetic field a pair of Bloch lines in the vicinity of the center line of the end part of the stripe magnetic domain is separated and the end part of the stripe magnetic domain is expanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid magnetic memory,
In particular, the present invention relates to a Bloch line memory device suitable for realizing a large capacity solid magnetic memory and an operating method thereof.

[0002]

2. Description of the Related Art A Bloch line memory device uses a magnetic garnet as a storage medium like a magnetic bubble memory device. However, the storage system is very different. That is, in the conventional magnetic bubble memory, the presence / absence of bubbles is associated with "1" and "0" of information, whereas in the Bloch line memory device, the vertical Bloch existing in the domain wall around the stripe magnetic domain in which the bubble is extended. The presence / absence of line pairs is made to correspond to “1” and “0”. This is shown in FIG. In the figure, the upward arrow in the stripe domain 2 is the direction of magnetization in the domain, the arrow 101 on the center line of the domain wall 1 is the direction of magnetization at the center of the domain wall, and the arrow 102 perpendicular to the center line of the domain wall 1 is The magnetization directions at the centers of vertical Bloch lines (hereinafter simply referred to as Bloch lines) are shown. In addition, a portion where two Bloch lines are present as a pair corresponds to "1" of information and a portion where there is no information corresponds to "0".

The Bloch line used as an information carrier is a fine magnetic structure existing in the domain wall 1 surrounding the magnetic domain. The Bloch line stably exists in the domain wall and can freely move in the domain wall. Therefore, if a large number of stripe magnetic domains are arranged at a predetermined position and a Bloch line is present in the domain wall, it behaves just like a bubble moving in a minor loop of a magnetic bubble memory. Therefore, the Bloch line memory becomes a shift register type memory like the magnetic bubble memory.

The existence of the Bloch line has long been known,
It has been proved from the experiment and the analysis that the existence thereof makes the moving speed of the magnetic domain slow. Therefore, in the magnetic bubble memory that has to move the magnetic domain,
Bubble magnetic domains including Bloch lines are called hard bubbles, and measures have been taken to prevent them. In contrast,
The Bloch line memory positively utilizes the existence of this Bloch line.

The physical size of the Bloch line is about 1/10 of the width of the stripe magnetic domain in which the Bloch line exists.
As a result, a large number of Bloch lines can exist in one stripe magnetic domain. For example, stripe magnetic domain width 1 currently developed for magnetic bubble memory
In the case of a magnetic garnet of μm, about 5 × 10 ⁶ Bloch lines can be present in 1 cm ² . Therefore, 256 Mbit when two pairs are used as an information carrier.
/ Cm ² of memory can be created.

Further, the Bloch line has a reason that it can be increased in capacity in addition to its fine size. That is, the magnetic bubble memory rotates an in-plane magnetic field to transfer an information carrier, whereas the Bloch line memory uses a vertical magnetic field to transfer information. For this reason, the transfer pattern is simple in plan view, which facilitates high density of the device.

As described above, the Bloch line can freely circulate around the stripe magnetic domain and store information. However, in order to make a memory device, it is necessary to write and read information as necessary. Basically, writing is performed by passing a current through a conductor near the end of the stripe magnetic domain to generate a local magnetic field and reverse the magnetization of the domain wall by 180 °. That is,
As shown in "0" in Fig. 3, the magnetization direction of the domain wall is reversed and becomes "1".
It can be considered that the direction of magnetization is in the region. At this time, the magnetization of the boundary between the reversed region and the non-reversed region is continuously changed, and a region in which the magnetization is changed by 90 ° with respect to the domain wall is formed. This is the Bloch line. The Bloch line is always made in pairs. Therefore, 1
A memory is constructed by associating a pair with one piece of information.

The reading of information is performed after converting the existence of Bloch lines into the presence or absence of bubble magnetic domains. To convert Bloch line to bubble magnetic domain, Konishi will
EE Transaction on Magnetics (IEEE Trans. Mag) -19, No. 5 (1983) p. 1
The method described in 838-p1840 and p1841-p1843 is used. That is, when the Bloch line exists, the direction of magnetization of the domain wall is as shown in FIG.
Reverse at the Bloch line. Due to this change in the magnetization structure, when one Bloch line moves to the end of the stripe magnetic domain, the ease of cutting out the end of the magnetic domain changes. Therefore, the bubbles can be cut out only when one Bloch line exists at the end of the stripe magnetic domain under the predetermined cutting conditions. Then, the cut-out bubble is transferred in the same manner as the major line of the bubble memory and converted into an electric signal, whereby the existence of the Bloch line can be read.

The principle of conversion from Bloch lines to bubble magnetic domains will be described in detail with reference to FIG. In FIG. 1A, when a predetermined current is applied to the hairpin-shaped conductor 7 that overlaps with the stripe magnetic domain 2 and a magnetic field in the collapse direction is applied to the portion sandwiched between the left and right conductors 7, the magnetic domain walls 1 on both sides of the stripe magnetic domain 1 Approach each other. At this time, paying attention to the magnetization 5 of the approaching domain walls, since the magnetization is reversed at the Bloch line, the upper and lower domain walls have the same direction. Therefore, the influence of the exchange interaction acting on the oxides 5 is small, and the domain walls are united by a small magnetic field in the Collapse direction.
As a result, a new bubble magnetic domain 8 is formed. In this case, the Bloch line is easy to cut. On the other hand, in the case of FIG. 7B where there is no Bloch line, the magnetization 5 does not reverse because there is no Bloch line, and the magnetizations 5 are opposite in the upper and lower domain walls. Therefore, even if the above cutting operation is performed,
The effect of the exchange interaction acting on the magnetizations becomes remarkable, and it becomes difficult to combine the domain walls. Therefore, the bubble magnetic domain is not cut out. That is, it is difficult to cut the Bloch line.

In order to detect whether the Bloch line is easy to cut, it is necessary to set the magnetic field strength in the collapse direction within a certain range. That is, if the magnetic field is too strong, the stripe magnetic domain ends are cut out regardless of the presence or absence of Bloch lines. Conversely, if the magnetic fields are too weak, even one Bloch line is present at the ends. Even if it exists, the magnetic domain cannot be cut out. Therefore, it is necessary to select the magnetic field strength within this range. For this selection, a current value may be selected. To give a concrete example, in the case of a material having a stripe domain width of 5 μm, if the gap between the conductors is set to 5 μm, the presence or absence of the Bloch line in the range of about 120 to 150 mA. Can be converted with or without bubbles.

A Bloch line memory can be realized by forming the above-mentioned writing, storing and reading functional units on the same element.

[0012]

As described above, one piece of information in the Bloch line memory is represented by the presence / absence of a pair of Bloch lines. Therefore, in an actual memory device, it is necessary to convert the presence or absence of Bloch line pairs into the presence or absence of bubbles. FIG. 5A shows a case where the Bloch line pair 4 has moved to the end of the stripe magnetic domain 2. FIG. 5B shows a state where there is no Bloch line pair.
Comparing the directions of the magnetization 5 of the domain wall 1 under the two states, it can be seen that they are the same. That is, it can be seen that the magnetization of the domain wall changes depending on the presence or absence of one Bloch line, but does not change depending on the presence or absence of a pair of Bloch lines. The reason for this is that the magnetization reversed in one Bloch line is further reversed in the other Bloch line, and eventually returns to the original magnetization direction. Therefore, it can be understood that the presence or absence of the Bloch line pair cannot be converted into the bubble magnetic domain only by the conventional method, because the direction of the magnetization 5 does not change depending on the presence or absence of the Bloch line pair.

As means for solving this problem, Japanese Patent Laid-Open No. 59-59
There is a method shown in -101092. In this method, a current is passed through a conductor different from the cut conductor to hold the position of the Bloch line pair, and a cutting operation is performed between the Bloch line pairs to perform reading. According to this method, the presence / absence of a pair of Bloch lines can be converted into the presence / absence of a bubble magnetic domain, and reading by the conventional method is realized. However, this method alone cannot provide a sufficient operation margin. That is, since the distance between the pair of Bloch lines is about 0.2 times the stripe magnetic domain width, it is almost impossible to provide a cut conductor between them.

Further, since this method reads the Bloch line pair existing on the side surface of the stripe magnetic domain, two reading positions are formed on the domain walls facing each other.
Further, there is a drawback that the information existing at the end of the stripe magnetic domain is lost when the magnetic domain is cut out at the time of reading.

Incidentally, as a document relating to another Bloch line memory element, Nikkei Electronics 1983 8-
No. 15, p141 to p167, "Bloch line memory capable of realizing high density solid state magnetic storage of 1 Gbit / cm ² grade", JP-A-61-248296.

An object of the present invention is to provide a practical Bloch line memory device in which a Bloch line pair is used as 1-bit information and an operating method thereof.

[0017]

As described above, if 1-bit information is cut out at the time of reading, the presence or absence of information cannot be detected. Based on this knowledge, if the Bloch line pair corresponding to 1-bit information is separated and only one of the separated Bloch lines is cut out, the above problem can be solved and reading can be performed.

Further, by performing this operation at the end of the stripe magnetic domain, it is possible to save the information existing at the end of the stripe magnetic domain.

In the present invention, in order to convert the Bloch line pairs located at the ends of the stripe magnetic domains into magnetic bubbles, the following structure is adopted. That is, the Bloch line pair has a domain wall surrounded by the pair between the pair. In the present invention, means for applying an in-plane magnetic field substantially parallel to the magnetization direction of the domain wall is provided near the end of the stripe magnetic domain. The direction of the in-plane magnetic field is, for example, parallel to and opposite to the direction (Y axis) in which the stripe magnetic domain extends.

By applying this in-plane magnetic field, a force acts on the region surrounded by the Bloch line pair so as to reduce the magnetization energy. Therefore, this force expands the area and widens the interval between the two Bloch lines forming the Bloch line pair.

As a result, one Bloch line is kept away from the end of the stripe magnetic domain, and the other Bloch line is stably held at the end of the stripe magnetic domain.

Further, while the above-mentioned in-plane magnetic field is being applied, the stripe magnetic domain cutting means provided in the vicinity of the stripe magnetic domain end portion detects the magnetic bubble by the same detecting means as the magnetic bubble memory element.

Here, as the stripe magnetic domain cutting means, there is a hairpin-shaped conductor provided at right angles to the extending direction of the stripe magnetic domain, or two parallel conductors. As a bubble detector, for example, there is a bubble detector using a soft magnetic material and utilizing a magnetoresistive effect.

Next, consider the case where there is no Bloch line pair at the end of the stripe magnetic domain. In this case, even if the domain walls of the striped magnetic domains are brought close to each other by the pulse bias magnetic field provided by the striped domain cutting means, the magnetization directions of the upper and lower domain walls are reversed, so that the striped magnetic domains are not cut.
As described above, the presence or absence of the Bloch line pair at the end of the stripe magnetic domain corresponds to whether or not the stripe magnetic domain is cut, and further to whether or not the stripe magnetic domain is converted into a magnetic bubble. Therefore, by using the present invention, a Bloch line memory device can be practically used.

[0025]

As described above, when the Bloch line is present at the end of the stripe magnetic domain, the magnetization of the domain wall is inverted by 180 ° (direction) at the Bloch line. Therefore,
When the Bloch line pair exists at the end of the stripe magnetic domain, the magnetization further rotates 180 °. Therefore, there is a difference in easiness of cutting the magnetic domain even when the pair exists and when the pair does not exist. Does not happen.

Therefore, if the pair of Bloch lines is separated and one of the Bloch lines is necessarily included to try to cut the magnetic domain, one state is created when there is a pair, and zero state is created when there is no pair. .. Therefore, it is possible to read the presence / absence of a pair by the conventional technique.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The basic structure of the Ploch line memory device is a stripe magnetic domain stabilizing pattern 11 and a stripe magnetic domain 2.
Consists of. In this embodiment, a pattern in which a magnetic film of about 1 μm is dug is used as a means for stabilizing the stripe magnetic domain. By the way, the Ploch line pair (or Ploch line) can freely move in the domain wall. Two methods are considered to move the pair of Bloch lines. One is a method of applying a magnetic field in a direction perpendicular to the film surface, which utilizes a gyroscopic force acting on the magnetization. Another means is to use an in-plane magnetic field parallel to the plane where the magnetic film is present. The Ploch line pair can be freely moved by any of these means, but in order to use the Ploch line as memory information, it is necessary to stabilize the Ploch line pair at a specific address position in correspondence with the driving cycle. In this embodiment, the pattern 9 shown in FIG. 1 is used as this means. As the pattern 9 for holding the pair of Ploch lines, a 4 × Ms, 1000 G in-plane magnetized film processed by photoetching was used.

FIG. 1A shows a state before reading. A Ploch line pair 4 exists at the end of the stripe magnetic domain 2. This corresponds to the case where the information of "1" has been transferred to the end.

Next, as shown in FIG. 2B, a current Ic ₁ is passed through the conductor 10 to generate a strong in-plane magnetic field Hc in the -Y-axis direction (applied in-plane magnetic field: bias in-plane magnetic field HiP is in the Y-axis direction). ). Then, the space between Ploch lines 4-1 and 4-2 expands. This movement can be explained by the fact that the magnetization reacts with the in-plane magnetic field and the energy in the domain wall becomes low as described above. One of the separated Bloch lines (4-1) moves to the outside of the conductor 10 by the magnetic field generated by the conductor 10. The other Ploch line (4-
2) is stably located at the end of the stripe magnetic domain. This separation requires different time depending on the travel distance of the Ploch line. Normally, if the width of the conductor 5 is about 40 μm, it is 50
About 0 nsec is required.

After that, when a predetermined current is applied to the conductor 7 shown in FIG. 1C, the magnetic domain is easily cut and a new magnetic domain 8 is cut out. The cut-out bubble magnetic domain 8 can be detected by a method similar to the ordinary bubble memory technology, and the Bloch line pair can be read as digital information.

The matters described above are for the case where the "1" information is transferred to the end. In the case of so-called '0' information, where the Bloch line is not transferred to the end,
The Ploch line pair 4 shown in FIG. 1 does not exist. This state is shown in FIG.

If there is a conductor at the end of the stripe domain,
(When the current Ic ₁ is applied to the conductor of FIG. 2A and the conductor thereof, there is no change in the movement of the stripe magnetic domain 2 in FIG. 2B). Since there is no Bloch line pair at the end of the stripe magnetic domain, the directions of the magnetization 5 are different between the magnetic films above and below the stripe magnetic domain, as shown in FIG. In such a state, it is difficult to cut out the magnetic domain and the cutting out current Ic ₂
If you select, the magnetic domain will not be cut out.

If this is detected by a method similar to the magnetic bubble technique described above, it can be read that the Ploch line pair was not present at the end of the stripe magnetic domain. By the above method, it is possible to detect whether or not the Bloch line pair exists at the end of the stripe magnetic domain, that is, "1" or "0" of information.

In the above embodiment, a width of 40 μm is used as means for generating an in-plane magnetic field for separating the Ploch line pair.
Was used. The width of this conductor is selected in order to efficiently generate an in-plane magnetic field, and it is generally considered to be good to be several times to 100 times the stripe magnetic domain width. If it is wider than that, the effective area of the device is reduced and it is not efficient. Further, when the width is narrow, it is not preferable for efficiently generating the in-plane magnetic field.

As a means for applying the in-plane magnetic field in the minus Y-axis direction, there is a method of using a high coercive force material magnetized in the in-plane direction other than using a conductor. An in-plane leaking magnetic field (in-plane magnetic field) is generated from the high coercive force film magnetized in the plane. When the direction of this leakage magnetic field and the direction of magnetization between the separated Bloch line pairs are made to coincide with each other, the Bloch line pairs are separated and read becomes possible. FIG. 6 shows this configuration. It is made of Tb-Fe-Co or the like near the end of the stripe magnetic domain. A pattern 12 having an easy magnetization direction in the plane (hereinafter referred to as "in-plane magnetization film pattern") is provided. When the magnetization direction of the in-plane magnetized film is set to the right direction shown in FIG. 6, the in-plane magnetic field leaking from the in-plane magnetized film is in the Hc ′ direction. After that, as shown in FIG. 7B, a magnetic field (-ΔHs) opposite to the vertical bias magnetic field Hs is applied to extend the stripe magnetic domain ends. At this time, when the Ploch line pair is present at the end of the stripe magnetic domain, the Ploch line pair feels the in-plane magnetic field and separates, as in the case of using the previous conductor, and it becomes possible to read out (FIG. 11C).

Further, in the state shown in FIG. 7 in which there is no pair of Ploch lines, the magnetic domain is not cut out for the reason described above. Therefore, even when the in-plane magnetized film is used as the in-plane magnetization applying means, the Bloch line pair can be separated as in the case where the in-plane magnetic field is generated by the conductor, and thus the Bloch line pair can be read.

Next, a second embodiment of the present invention will be shown. In this embodiment, the magnetization structure of the stripe magnetic domain is different from that in the first embodiment. FIG. 8A shows the stripe magnetic domain 2. There are two Ploch line pairs 4 around one stripe magnetic domain 2. The directions of magnetization between the Ploch line pairs are opposite to each other. This is the third
This is because the magnetization continuously rotates along the domain wall, as is apparent from the figure. Under this state, as shown in FIG. 8A, when a magnetic field H in the same direction as the magnetization of the region surrounded by the Ploch line pair existing in the lower domain wall is applied,
The lower Bloch line pair separates and moves to both ends of the stripe magnetic domain. Therefore, the information possessed by this Ploch line pair disappears (FIG. 8B).

As a means for preventing this problem, an improvement measure for inserting one Bloch line at each stripe magnetic domain end has been considered. This state is shown in FIG. As shown in the figure, if the Bloch lines 3 are present at both ends of the stripe magnetic domain 2 and an in-plane magnetic field HiF is applied, the magnetization of the domain wall of the stripe magnetic domain is in the HiF magnetic field direction on both sides.
The Ploch line 3 can be stably present at the end. If the Ploch line pair is written in this state, the magnetization between the Ploch line pairs is always opposite to the HiF magnetic field (applied in-plane magnetic field) due to the continuity of the magnetization direction described above (FIG. 8D). Therefore, no matter whether the Ploch line pair exists on the upper or lower domain wall, the Ploch line pair is not separated and can be stably present.

A reading method at the end portion of the stripe magnetic domain having this structure will be described with reference to FIG. FIG. 10A shows the case where the above-mentioned Bloch line 3 and the Bloch line pair 4 corresponding to the information "1" are present at the end portions of the stripe magnetic domain. After that, a current I is applied to the conductor 10 as in the first embodiment.
If c ₁ is flown, the Ploch line pair 4 is 4-1 and 4-2.
To separate. At this time, since the region between the Ploch line 3 and the Ploch line pair 4 is also enlarged, as shown in FIG. 9B, the three Ploch lines include the end portion (4-1) of the stripe magnetic domain and the end portion of the conductor 10. It is stable at (3,4-2). After that, when the tip portion of the striped magnetic domain is cut out, the magnetization directions of the domain walls are the same, so that the bubbles 8
Is cut out.

On the other hand, the case of information "0" will be described with reference to FIG. FIG. 10A shows a state in which only the Bloch line 3 exists at the end of the stripe magnetic domain. After that, if a current Ic ₁ is applied to the conductor 10, the Ploch line 3 will move to the position shown in FIG.
Move to the position shown in (b). At this time, even if the Ploch line moves along either of the upper and lower domain walls, the magnetization of the domain wall after the movement is reversed in the upper and lower domain walls. Therefore, the magnetic domain is not cut out even by the cutting operation shown in FIG. Therefore, as in the case of the first embodiment,
Information can be read by detecting the presence or absence of the cut out magnetic domain by the same means as in the conventional bubble memory technology.

[0041]

According to the present invention, reading can be realized in a Ploch line memory device in which 1-bit information is associated with a pair of Ploch lines.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a plan view showing an embodiment of the present invention.

FIG. 3 is a perspective view showing stripe magnetic domains and Ploch lines existing on the magnetic domain walls.

FIG. 4 is a plan view for explaining the conventional principle of converting the presence or absence of a Ploch line into the presence or absence of a magnetic bubble.

FIG. 5 is a plan view for explaining a problem when converting the presence / absence of a Ploch line pair into a magnetic bubble by a conventional method.

FIG. 6 is a plan view showing an embodiment of the present invention.

FIG. 7 is a plan view showing an embodiment of the present invention.

FIG. 8 is a plan view for explaining a relationship between a pair of Ploch lines and an in-plane magnetic field and for stably holding the pair of Ploch lines at a predetermined position.

FIG. 9 is a plan view showing the principle of converting the presence / absence of a pair of Ploch lines into the presence / absence of a magnetic bubble.

FIG. 10 is a plan view showing the principle of converting the presence / absence of a pair of Ploch lines into the presence / absence of a magnetic bubble.

[Explanation of symbols]

1 ... domain wall, 2 ... stripe domain, 3 ... Ploch line,
4 ... With Ploch line, 4-1 ... Ploch line (one side of pair separated), 4-2 ... Ploch line (one side of pair separated), 5 ... Magnetization, 6 ... Perpendicular magnetization garnet, 7 ... Hairpin conductor (for magnetic separation) Conductor), 8 ... Magnetic bubble, 9 ... Pattern (pit pattern) for holding Ploch line pairs, 10 ... Conductor, 11 ... Pattern for stabilizing stripe magnetic domain, 12 ... In-plane magnetized film pattern.

Claims (19)

[Claims] 1. A means for holding a stripe magnetic domain having a Bloch line pair in a desired region of a magnetic film, a means for moving the Bloch line pair to an end of the stripe magnetic domain, and a stripe magnetic domain cutting means provided near the end of the stripe magnetic domain. In the Bloch line memory element having the above, the in-plane magnetic field applying means is provided in the vicinity of the end of the stripe magnetic domain. 2. A Bloch line memory device according to claim 1, wherein the direction of the in-plane magnetic field generated by said in-plane magnetic field applying means is substantially parallel to the extending direction of said stripe magnetic domains. 3. The Bloch of claim 1 or 2, wherein the in-plane magnetic field applying means uses a conductor having a predetermined width, and the conductor is stored so as to overlap the stripe magnetic domain. Line memory device. 4. The Bloch line memory device according to claim 3, wherein means for supplying a predetermined current is connected to the conductor. 5. A Bloch line according to claim 2, further comprising the stripe magnetic domain extending means for extending the stripe magnetic domain by applying a bias magnetic field and a reverse magnetic field perpendicular to the magnetic film surface. Memory device. 6. The in-plane magnetic field applying means is a high coercive force film having a predetermined width, and the high coercive force film is provided on the magnetic film so as to overlap the stripe magnetic domain. 5. The Bloch line memory device described in 5. 7. A Bloch line memory device according to claim 1, wherein one Bloch line is provided at each of both ends of the stripe magnetic domain. 8. The Bloch line memory device according to claim 1, wherein the magnetic film is a magnetic garnet film. 9. A Bloch line memory device according to claim 1, wherein the magnetic bubbles cut out by said stripe magnetic domain cutting means are detected by magnetic bubble detection means. 10. The Bloch line memory device according to claim 1, wherein said stripe magnetic domain cutting means is a hairpin-shaped conductor provided in a direction substantially perpendicular to the extending direction of the stripe magnetic domains. 11. A method of operating a Bloch line memory device, comprising the following steps. (1) A step of holding a stripe magnetic domain having a pair of Bloch lines in a desired region of a magnetic film. (2) A step of moving the Bloch line pair to the end of the stripe magnetic domain. (3) A step of applying an in-plane magnetic field in a plane parallel to the plane on which the magnetic film exists and in a direction of separating the Bloch line pairs. (4) A step of converting the presence or absence of a Bloch line existing at the end portion of the stripe magnetic domain into the presence or absence of a bubble magnetic domain by bringing the upper and lower domain walls of the stripe magnetic domain close to each other by using the stripe magnetic domain cutting means. (5) The step of stopping the application of the in-plane magnetic field. 12. The means for applying the in-plane magnetic field is a conductor having a predetermined width, the conductor is arranged so as to overlap the stripe magnetic domain, and the in-plane magnetic field causes a current to flow through the conductor. 12. The method of operating a Bloch line memory device according to claim 11, wherein the operation is caused by the above. 13. A method of operating a Bloch line memory device according to claim 11, wherein one Bloch line is provided at each of both ends of the stripe magnetic domain. 14. A method of operating a Bloch line memory device according to claim 11, wherein said stripe magnetic domain cutting means is a hairpin-shaped conductor provided in a direction substantially perpendicular to the extending direction of the stripe magnetic domains. 15. A method of operating a Bloch line memory device, comprising the following steps. (1) Step of preparing a high coercive force film having a predetermined width on the magnetic film. (2) A step of holding a stripe magnetic domain having a pair of Bloch lines in a desired region of a magnetic film. (3) The high coercive force film is generated. With an in-plane magnetic field parallel to the surface where the magnetic film is present, by applying a magnetic field that is in the opposite direction to the bias magnetic field that is perpendicular to the surface where the magnetic film is present, the edges of the stripe magnetic domains are kept high. Separation of Bloch line pairs while stretching on the magnetic film. (4) A step of converting the presence or absence of a Bloch line existing at the end of the stripe magnetic domain into the presence or absence of a magnetic bubble by utilizing the ease of cutting out the stripe magnetic domain. (5) A step of stopping application of a magnetic field in a direction opposite to the vertical bias magnetic field. 16. The method of operating a Bloch line memory device according to claim 15, wherein the direction of the in-plane magnetic field is substantially parallel to the extending direction of the stripe magnetic domain and opposite to the extending direction. 17. The method of operating a Bloch line memory device according to claim 15, wherein the in-plane magnetic field is a leakage magnetic field generated by a high coercive force film provided near an end portion of the stripe magnetic domain. 18. A method of operating a Bloch line memory device according to claim 15, wherein one Bloch line is provided at each of both ends of the stripe magnetic domain. 19. The ease of cutting out the striped magnetic domains is
16. A hairpin-shaped conductor provided in a direction substantially perpendicular to the extending direction of the stripe magnetic domains.
A method for operating the described Bloch line memory device.