JPS6040113B2 - magnetic bubble element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bubble element having a hairpin-like conductor, and more particularly to a magnetic bubble element having a hairpin-like conductor for erasing or deflating a magnetic bubble or an elongated magnetic bubble.

In an element that records and stores information using magnetic bubbles (hereinafter referred to as a magnetic bubble element), in addition to means for generating and storing magnetic bubbles as information, there is also a means for reading out the presence of magnetic bubbles as information, i.e. A magnetic bubble detector is an essential functional element.

In recent years, the diameter of magnetic bubbles used in magnetic bubble elements has been becoming smaller as storage density has increased.
As the diameter of the magnetic bubble to be read becomes smaller, the detection output of the magnetic bubble generally decreases accordingly. Various magnetic bubble stretchers have been proposed in order to compensate for the decrease in detection output due to miniaturization of magnetic bubbles. Compensation of the magnetic bubble detection output using the magnetic bubble stretcher is performed as follows.

A magnetic bubble that has been greatly stretched by the magnetic bubble stretcher (hereinafter referred to as an extended bubble) generates leakage magnetic flux that is larger than that generated from a magnetic bubble with a normal diameter. When a magnetic bubble is stretched linearly, the leakage magnetic flux from the stretched bubble increases in proportion to the stretching ratio. Generally, when a material that detects magnetic flux, for example, a material that exhibits a magnetoresistive effect such as permalloy, is provided as a detection element in accordance with the length of extension of a magnetic bubble, the resistance value of the detection element changes due to the leakage magnetic flux. The absolute value of increases in proportion to the elongated length. That is, a large magnetic bubble detection output can be obtained. The following two types of magnetic bubble stretchers are well known.

The first is the paper presented at the Magnetism and Magnetic Materials Conference by Strauss et al.
C. No. 10, 202 (1972), the chevron stretcher gradually stretches magnetic bubbles at the stacked part of a chevron pattern made of a sensitive magnetic material such as permalloy. The second is the literature published by Nelson et al. in the Bell System Technical Journal (already TJ, 59,
229 (1980)), in which a current pulse is passed through a hairpin-shaped conductor, and a magnetic bubble is rapidly expanded by the magnetic potential generated in the gap between the hairpin-shaped conductors. This hairpin conductor stretcher mainly consists of a continuous circular pattern (CD) formed by selectively implanting ions into a magnetic bubble material.
It is often used in a magnetic bubble detector section arranged in a magnetic bubble transfer path formed by a pattern (referred to as a pattern). The hairpin conductor stretcher rapidly stretches magnetic bubbles by applying a current pulse to the conductor, so it is possible to stop the transfer of bubbles at will even just before the magnetic bubbles are stretched. Compared to the above-mentioned chevron stretcher, the bubble can be started and stopped at will.

Furthermore, this hairpin conductor stretcher eliminates magnetic bubbles after they are detected by a detector placed near the stretcher, by applying a current pulse of opposite polarity to the hairpin conductor if they are not needed. Is possible. It is also possible to contract an elongated magnetic bubble into a normal diameter magnetic bubble with a similar current pulse. However, when the conventional hairpin conductor stretcher is used as a magnetic bubble eraser or constrictor, it has a serious drawback of unstable operation, as will be explained below with reference to the drawings.

FIG. 1 is a diagram showing a magnetic bubble detector using a conventional hairpin conductor stretcher.

A magnetic material 1 capable of holding magnetic bubbles is provided with a magnetic bubble transfer path 11 capable of transferring magnetic bubbles using an in-plane rotating magnetic field formed by, for example, ion implantation. This magnetic bubble transfer path 11 includes a hairpin conductor stretcher 2.
A magnetic bubble detection element 3 made of a permalloy thin film stripe magnetoresistive element or the like is arranged in the hairpin gap.
It is assumed that the direction of the bias magnetic field is applied in the direction indicated by arrow HB. When the magnetic bubble is transferred to the hairpin conductor stretcher and the detector section, when a stretcher current ls22 is passed through the conductor 2 in the direction shown by the arrow 21, the magnetic bubble is detected as being stretched. After detection, the unnecessary magnetic bubble passes through the conductor pattern 2 with a current pulse 23 of opposite polarity.
It is annihilated by the reverse polarity I magnetic field generated inside the hairpin. At this time, a phenomenon occurs in which unnecessary magnetic bubbles 42 remain around the magnetic bubble transfer path. The presence of unnecessary magnetic bubbles around the transfer path causes major malfunctions of the magnetic bubble element. The cause of the presence of unnecessary magnetic bubbles when the magnetic bubbles disappear will be explained with reference to FIGS. 2A to 2C.

As shown in FIG. 2A, the magnetic bubble 4 extended by the hairpin conductor 2 exists inside the hairpin. Next, when a reverse polarity current pulse for eliminating the elongated magnetic bubble is applied to the hairpin conductor 2, a bias magnetic field shown in FIG. 2B is distributed in the vicinity of the hairpin conductor. In the gap between the hairpin conductors, the bias magnetic field is convex upward, so the internal elongated magnetic bubble becomes unstable in position. Therefore, as shown in FIG. 2C, a part of the elongated magnetic bubble in the hairpin gap moves in the direction where the magnetic field distribution is more stable (in this case, the direction outside the hairpin), and a part of the elongated magnetic bubble 41 It protrudes outside the hairpin conductor. On the other hand, a portion of the elongated magnetic bubble inside the hairpin is finally cut off at that portion due to the increase in the bias magnetic field. As a result, unnecessary magnetic bubbles are generated outside the hairpin conductor, that is, in the vicinity of the transfer path 11. Furthermore, when an elongated magnetic bubble is contracted, a similar malfunction easily occurs in which the bubble does not contract in the gap between the hairpin conductors, but instead protrudes to the outside of the conductor and contracts. An object of the present invention is to provide a magnetic bubble element having a hairpin conductor magnetic bubble eliminator that is capable of stable erasure and contraction operations that eliminate the instability of the magnetic bubble erasure and contraction operations of conventional hairpin conductor magnetic bubble stretchers. It is in. The magnetic bubble element according to the present invention includes a thin film of magnetic material capable of holding magnetic bubbles;
a magnetic bubble transfer path provided on the thin film of magnetic material; and a first hairpin-shaped conductor pattern with a magnetic bubble detection means disposed in the transfer path in the vicinity thereof; A second hairpin-shaped conductor pattern having a common gap with the gap of the hairpin-shaped conductor pattern is provided near the first conductor pattern.

Next, the principle of the present invention will be explained in detail with reference to the drawings.

First, the basic concept of the present invention will be explained with reference to FIG.

The hairbin-shaped conductor pattern 5 shown in FIG. 3A has a distance 2W between the centers of its conductor stripes that is somewhat larger than that of the conventional pattern. Center distance 2W
When becomes large to a certain extent, the generated magnetic field distribution generated in the hairpin-shaped conductor part will become smaller in the central part of the magnetic field distribution in the conductor gap part (i.e., the minimum potential part) from both sides, as shown in 24 in Figure 3B. ) has been revealed through calculations etc. by the applicant. Therefore, the third
As shown in Figure A, when the elongated magnetic bubble 4 exists between the central sections of the hairpin-shaped conductor 5, when the magnetic field distribution shown in Figure B is applied in the magnetization direction of the magnetic bubble, the magnetic potential increases in the central gap. Because it is extremely small, the magnetic bulb does not move away from the conductor gap, and the magnetic potential increases throughout, and as shown in Figure 3C, the elongated magnetic bubble has a narrow width at the conductor center gap. and eventually disappear. In other words, a reliable and stable erasing operation of magnetic bubbles can be performed. It is similarly clear that the contraction of the elongated magnetic bubble can be stably operated by weakening the generated magnetic field and stopping the magnetic field generation before the magnetic bubble disappears. Part 4 about the principle of the present invention
Further details will be described with reference to Figures A to D.

The stripe width and thickness of the hairpin-shaped conductor 5 according to the present invention are 0.6 m and 0.3 m, respectively, as shown in FIG. 4B. At this time, as shown in Figure 4A,
The hairpin-shaped conductor 5 is provided so that the distance between the center of the magnetic material 1 capable of holding a magnetic bubble and the center of the conductor is equal to the distance between the center of the conductor and the center of the magnetic material 1 capable of holding a magnetic bubble. The spacing between the hairpin-shaped conductors is set to 2W as measured between the centers of both conductor stripe widths. If the magnetic field from the conductor that the magnetic bubble feels is represented by the central magnetic field of the magnetic material mentioned above, in order to generate the minimum magnetic potential in the central gap of the hairpin conductor, which is necessary for the present invention, it is necessary to It has become clear that a very specific relationship as shown in FIG. 4D or D is required. When the hairpin conductor spacing 2W is changed, the maximum distance between magnetic material conductors that causes a minimum magnetic potential in the center gap of the hairpin conductor is normalized by 2W and is shown in Figure 4C. The ratio H/(2W) becomes 0.2 as 2W increases.
It is shown that there are 5 hills. Similarly, when the distance day is changed, the minimum conductor spacing 2W that causes the minimum magnetic potential in the center gap is normalized by the distance day, and the fourth
Shown in Figure D. The ratio 2W/day approaches 4.0 as the day increases. From the above, it has become clear that in order to stably extinguish or stably shrink an elongated magnetic bubble in a hairpin-shaped conductor, the ratio needs to be greater than 4.0, even if the ratio is not 2 W/day. Furthermore, even if the pattern width and thickness of the hairpin-shaped conductor 5 are changed to 2.0 French m and 0.5 French m, respectively, the ratio of at least 2 W/day is required to generate the minimum magnetic potential in the central gap. It became clear that a value greater than 4.0 was still necessary.

Therefore, the structure of the magnetic bubble element according to the present invention will be described in more detail as follows.

That is, a second hairpin-like conductor for magnetic bubble erasure having a common central gap is provided near the first hairpin-like conductor pattern forming the magnetic bubble stretcher, and the conductors on both sides of the second hairpin-like conductor pattern are The ratio (2W/H) of the center-to-center distance (2W) to the center-to-center distance (H) between the center of the magnetic material thin film for bubble domain retention and the film thickness of the second hairpin-shaped conductor is 4.0.
This is a magnetic bubble element characterized by the above. An example of this invention will be described below.

FIGS. 5A to 5C are diagrams illustrating a first embodiment of the present invention. As shown in the plan view of FIG.
A second hairpin-shaped conductor pattern 5 is arranged around the magnetic bubble detecting means 3 and the magnetic bubble stretcher 2 so that the central gap is in common with the magnetic bubble stretcher 2. FIG. 5B shows a cross-sectional view of the magnetic bubble element according to this example.

In this embodiment, the level difference caused by the first hairpin-shaped conductor 2 is eliminated by a smoothing process, and the second hairpin-shaped conductor pattern 5 is formed.
is provided in the bubble magnetic domain holding material thin film 1. Second
The ratio (2W/H) between the hairpin-shaped conductor gap 2W and the center of the hairpin-shaped conductor layer and the center of the bubble magnetic domain material thin film is 4.
．． It is configured to be 0 or more. The bias component magnetic field distribution generated by these hairpin conductor patterns is the fifth
It will look like Figure C. Since the first hairpin-like conductor pattern has a sufficiently smaller pattern gap than the second,
4' shows a magnetic field distribution with one valley. From this, the magnetic bubble is extended, and then a current pulse for erasing the extended magnetic bubble is applied to the second hairpin-shaped conductor pattern. Since the magnetic field distribution due to the second hairpin-shaped conductor pattern has a minimum part at the center gap of the hairpin as shown in 24, the elongated magnetic bubble disappears stably without causing positional deviation. Next, a second embodiment of the present invention is shown in FIG.

In this embodiment, the second hairpin-like conductor pattern 5
It is provided on the same surface as the hairpin-shaped conductor pattern.
Therefore, conductor patterns 2 and 5 can be constructed from the same conductor layer. Further, the ratio 2W/day is sufficiently larger than 4.0. A third embodiment of the invention is shown in FIG.

In this example, the spacer of the bubble magnetic domain material thin film 1 of the first hairpin-shaped conductor pattern 2 is dug down around the first hairpin-shaped conductor pattern to determine the distance between the second hairpin conductor and the bubble magnetic domain material thin film 1. further reduce the ratio to 2W/
A magnetic bubble element with an enlarged structure is shown.
A fourth embodiment of the invention is shown in FIG.

In this example, it is provided between the second hairpin-shaped conductor 2 for magnetic bubble erasure and the bubble magnetic domain material thin film 1. By doing this, you can make the days extremely small. When the number of days is reduced, the generated magnetic field strength per unit current becomes stronger, and the erasing current of the elongated magnetic bubble can be reduced. As described above, by using the present invention, a magnetic bubble element having a magnetic bubble eraser capable of stably erasing or shrinking a long elongated magnetic bubble can be realized.

Furthermore, new effects arise by implementing the present invention. That is, when the first hairpin-shaped conductor pattern and the second hairpin-shaped conductor pattern are connected in series externally as necessary and used as a magnetic bubble stretcher, sufficient stretching can be achieved with an extremely small current pulse. It becomes possible to emit a magnetic field of In this case, it is clear that the ratio of 2W/day in the second hairpin conductor pattern does not necessarily need to be 4.0 or more. Furthermore, in the description of the present invention, as an example of the transfer path of magnetic bubbles, a pattern array formed by selective ion implantation is given, but a path formed by a pattern of soft magnetic material may also be used. It does not specify how to form a transfer path.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional example according to the present invention, FIGS. 2 A to C are diagrams for explaining the drawbacks of the conventional example, FIGS. 3 A to C are diagrams illustrating the concept of the present invention, and FIG. A to D are diagrams showing the principle of the invention, FIGS. 5A to C are diagrams showing the first example of the invention, and FIGS. 6 to 8 are diagrams showing the second to fourth examples of the invention, respectively. It is a figure showing an example. In the figure, 1 is a magnetic material thin film for holding magnetic bubbles, 2 is a first hairpin-shaped conductor pattern, 3 is a magnetic bubble detector,
4 is an elongated magnetic bubble, 5 is a second hairpin-shaped conductor pattern, 11 is a magnetic bubble transfer path, 21 is an arrow indicating the current pulse application direction, 22 is a magnetic bubble stretch current pulse, 23 is an extinction or contraction pulse, Reference numerals 24 and 24' indicate the magnetic field distribution of the hairpin conductor, 40 the magnetic bubble extinguished area, 41 the area where the magnetic bubble protrudes outside the hairpin conductor, and 42 the unnecessary magnetic bubble remaining after the extinguishment. Figure 6: Measures 7: Figure 8: Younger brother's figure: Figure 2: Tsutomu 3: Curtain 4: Hair S figure

Claims (1)

[Scope of Claims] 1. A magnetic material thin film capable of retaining a bubble magnetic domain, a bubble magnetic domain transfer path provided on the magnetic material thin film, a bubble magnetic domain detecting means disposed in the transfer path, and the vicinity thereof. First
a hairpin-like conductor pattern, and a second hairpin-like conductor pattern having a common gap with a gap of the first hairpin-like conductor pattern is provided in the vicinity of the first conductor pattern. magnetic bubble element. 2 The distance between the centers of both side conductors of the second hairpin-shaped conductor pattern (2W) and the distance between the center of the film thickness of the bubble domain holding magnetic material thin film and the second hairpin-shaped conductor (
2. The magnetic bubble element according to claim 1, wherein the ratio (2W/H) to H) is 4.0 or more.