JPS6040114B2 - 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 stores information using magnetic bubbles (hereinafter referred to as a magnetic bubble element), in addition to means for generating magnetic bubbles as information and means for storing magnetic bubbles, there is also a means for reading out the presence of magnetic bubbles as information. In other words, a magnetic bubble detector is essential.

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 to compensate for the decrease in detection output caused by 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 a 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. In general, when a detection element is provided using a material that detects magnetic flux, for example, a material that exhibits a magnetoresistive effect such as permalloy, and the length of the elongated magnetic bubble is adjusted, the resistance value changes due to the leakage magnetic flux. The absolute value of increases in proportion to the length of the extension. That is, a large magnetic bubble detection output can be obtained. There are two well-known types of magnetic bubble stretchers:
The first is a paper presented at the Conference on Magnetism and Magnetic Materials by Strauss et al.
．． No. 10, p. 202 (1972)), which gradually stretches magnetic bubbles at stacked portions of soft magnetic chevron patterns such as permalloy. The second is a paper published in the Bell System Technical Journal by Nelson et al. (BGTJ, Vol.
．． 59, p. 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 is mainly used in a magnetic bubble detector section disposed in a magnetic bubble transfer path formed by a continuous circular pattern (hereinafter referred to as a CD pattern) formed by selectively implanting ions into a magnetic bubble material. There are many things. 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 magnetic bubbles at will even just before the magnetic bubbles are stretched. It has the feature that the magnetic bubble can be started and stopped at will compared to the aforementioned Scheffron stretcher.

Furthermore, this hairpin conductor stretcher eliminates magnetic bubbles after they are detected by a detector placed near the stretcher by applying a reverse current pulse to the hairpin conductor if they are not needed. becomes possible. It is also possible to contract an elongated magnetic bubble into a normal diameter magnetic bubble with a similar current pulse. However, when a 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. A hairpin conductor stretcher 2 is provided in this magnetic bubble transfer path 11.
Perm in the hairpin gap. A magnetic bubble detecting element 3 made of a thin film stripe magnetoresistive element or the like is arranged respectively. Here, 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 this hairpin conductor stretcher and the detector section, if a stretching current ls22 is applied to the conductor 2 in the direction shown by the arrow 21, the magnetic bubble will be detected as being stretched. Unwanted magnetic bubbles after detection are current pulses of opposite polarity 23
is applied to the conductor pattern 2 and is annihilated by a magnetic field of opposite polarity generated within 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. Since the bias magnetic field is convex upward in the gap between the hairpin conductors, the position of the elongated magnetic bubble inside is unstable. Therefore, as shown in Figure 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 protrudes outside the hairpin conductor. On the other hand, a portion 40 of the elongated magnetic bubble inside the hairpin will eventually be 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. Also, when contracting an elongated magnetic bubble,
Similarly, a malfunction is likely to occur in which the conductor does not shrink in the gap between the hairpin conductors and instead protrudes outside the conductor and shrinks. The object of the present invention is to provide a magnetic bubble element having a hairpin conductor magnetic bubble stretcher capable of stable erasure and contraction operation, which eliminates the above-mentioned drawbacks and eliminates the instability of the magnetic bubble erasure or contraction operation of the conventional hairpin conductor magnetic bubble stretcher. It is to provide.

The magnetic bubble element according to the present invention includes a thin film of magnetic material capable of holding magnetic bubbles, and a hairpin-like conductor pattern or a reciprocating parallel conductor pattern arranged in a magnetic bubble transfer path provided on the thin film of magnetic material. and the ratio of the distance between the centers of the conductor pattern (2W) and the distance (H) between the center of the thickness of the conductor pattern and the center of the pre-magnetic material thin film (2W/H)4.
It is characterized by being 0 or more.

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

First, the principle of the present invention will be explained with reference to FIGS. 3A to 3C.

In the hairpin conductor pattern 2 shown in FIG. 3A, the distance between the centers of its conductor stripes is increased to some extent by 2W compared to the conventional pattern. When the center-to-center distance 2W increases to a certain extent, the distribution of the magnetic field generated in the hairpin conductor becomes 3rd.
As shown by line 24 in FIG. B, it has been revealed through calculations etc. by the applicant that a small portion of the generated magnetic field (i.e., a minimum potential portion) occurs from both sides of the magnetic field distribution in the conductor gap. Therefore, as shown in FIG. 3A, when the elongated magnetic bubble 4 is located in the center gap of the hairpin conductor 2, if the magnetic field distribution shown in FIG. 3B is applied in the magnetization direction of the magnetic bubble, then the center gap is the minimum magnetic potential portion, so the magnetic bubble does not move away from the conductor gap, and the magnetic potential increases throughout, as shown in Figure 3C.
As shown in the figure, the elongated magnetic bubble at the center gap of the conductor narrows in the magnetic domain and eventually disappears.

In other words, a reliable and stable erasing operation of magnetic bubbles can be performed. Regarding the contraction of long magnetic bubbles, it is similarly clear that the operation will be more stable if the generated magnetic field is weakened and the magnetic field generation is stopped before the magnetic bubbles disappear. FIGS. 4A to 4D are diagrams for explaining the first embodiment of the present invention.

The stripe width and thickness of the hairpin conductor 2 according to this embodiment are 0.5rm and 3.5rm, respectively, as shown in No. 4B.
It is 0 Am. At this time, as shown in FIG. 4A, the hairpin conductor 2 is provided so that the distance between the center of the magnetic material that can hold the 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 that can hold the magnetic bubble. The spacing between the hairpin conductors should be 2W, measured between the centers of both conductor straps. 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, then
In order to generate the minimum magnetic field potential in the central gap of the hairpin conductor, which is necessary for the present invention, a very limited relationship as shown in FIG. 4C or FIG. What was needed was made clear. Hairpin conductor spacing 2W
The maximum distance between the magnetic material conductors that causes a minimum magnetic potential in the central gap of the hairpin conductor when changing is normalized to 2W and is shown in FIG. 4C.

It was shown that H/(2W) increases by 0.25 as 2W increases. Similarly, when the distance days are changed, the minimum conductor spacing 2W that causes the minimum magnetic potential in the central gap is normalized by the distance days and is shown in FIG. 4D. 2W day approaches 4.0 as the day increases.

From the above, in order to stably extinguish or stably contract an elongated magnetic bubble with a hairpin-shaped conductor, 2W/day is required at least 4.5W/day.
It became clear that it was necessary to be greater than 0.
Next, a second embodiment of the present invention will be described with reference to FIGS. 5A to 5D.

In this embodiment, the width and thickness of the hairpin conductor 2 are 2.0 fm and 0.0 m, respectively, as shown in FIG. 5B.
It is 5 m. 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 FIG. 5C. H/(2W) approaches 0.25 as 2W increases. Similarly, the maximum conductor spacing 2W that causes the minimum magnetic potential at the central gap when the distance is changed is shown in FIG. 5D, normalized by the distance. It approaches 4.0 with an increase of 2 W/day.

From the above, it has become clear that in this example as well, in order to stably extinguish or stably shrink the elongated bubbles in the hairpin-shaped conductor, it is necessary that 2 W/day be at least greater than 4.0. As explained above, the present invention provides 2W
This magnetic bubble element is characterized in that the conductor interval of the hairpin conductor is 2W and the distance between the center of the magnetic material for holding the magnetic bubble and the center of the conductor is set in advance so that /day is at least 4.0.

It has been found that by using the present invention, extremely stable operation is possible when the magnetic bubble stretcher conductor of a magnetic bubble element using a CD pattern is used as a magnetic bubble extinguisher.

Further, it goes without saying that even in a general magnetic bubble element, if the present invention is used, a stable magnetic bubble extinguisher can be made. It is clear that the present invention can be easily implemented even if the hairpin-shaped conductor is a simple reciprocating conductor pattern.

[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 explaining the drawbacks of the conventional example, FIGS. 3 A to C are diagrams explaining the principle of the present invention, and FIG. 4 A -D are diagrams showing a first embodiment of the invention, and FIGS. 5A to 5D are diagrams showing a second embodiment of the invention. In the figure, 1 is a magnetic material thin film for holding magnetic bubbles, 2 is a hairpin conductor pattern, 3 is a magnetic bubble detector, 4 is an elongated magnetic bubble, 11' is a magnetic bubble transfer path, and 21 is an arrow indicating the direction of current pulse application. , 22 is a magnetic bubble stretching current pulse, 23 is an extinguishing or contraction pulse, 2
4 is the magnetic field distribution of the hairpin conductor part, 40 is the part where the magnetic bubble disappears, 41' is the part where the magnetic bubble protrudes outside the hairpin conductor, and 42 is the unnecessary magnetic bubble that remains after disappearing. No.l
Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A magnetic material thin film capable of holding a bubble magnetic domain, a bubble magnetic domain magnetic transfer path provided on the magnetic material thin film, and a hairpin-shaped conductor pattern or a reciprocating parallel conductor arranged in the transfer path. pattern, and the ratio (2W/H) of the distance between the centers of the conductor pattern (2W) and the distance (H) between the center of the thickness of the conductor pattern and the center of the magnetic material thin film is 4. A magnetic bubble element characterized in that the magnetic bubble element is 0 or more. 2. The magnetic bubble device according to claim 1, wherein the bubble magnetic domain transfer path is formed by a pattern row in which ions are selectively implanted.