JPS598901B2 - Magnetic bubble expansion transfer pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved magnetic bubble expansion transfer pattern for expanding and transferring magnetic bubbles, referred to as cylindrical magnets or the like, upstream of a detector pattern.

When a bias magnetic field of an appropriate magnitude is applied perpendicularly to the surface of a magnetic thin plate such as garnet or orthoferrite having uniaxial magnetic anisotropy, magnetic bubbles are generated.

Magnetic bubble utilization devices that use magnetic bubbles to store information, perform logical operations, etc. are non-volatile, non-mechanical, have relatively high storage density, and can have large capacities. Its practical application is rapidly progressing due to the fact that it is relatively high speed, etc. Such magnetic bubble utilization devices require various functions such as generating, transferring, dividing, enlarging, detecting, and erasing magnetic bubbles. Among these functional units, the present invention particularly relates to a magnetic bubble enlargement transfer pattern for enlarging magnetic bubbles in a stage upstream of a magnetic bubble detector. A common method for driving magnetic bubbles is to use a rotating magnetic field and a soft magnetic pattern such as permalloy formed on the surface of a magnetic bubble chip.

This is a method in which, for example, a T permalloy pattern or a chevron permalloy pattern is formed on the surface of a crystal in which magnetic bubbles can exist by a method such as vapor deposition or sputtering, and a rotating magnetic field is applied from the outside in the in-plane direction of the crystal. It is.
The rotating magnetic field is obtained by passing sine wave currents, triangular wave currents, trapezoidal wave currents, etc. whose phases differ by 90 degrees through the x coil and the Y coil, which are arranged orthogonally to each other. As the rotating magnetic field rotates, the magnetic bubble propagates along the permalloy pattern, and when the rotating magnetic field comes to rest, the magnetic bubble also comes to rest at a corresponding location. As mentioned above, T-bar patterns, chevron patterns, etc. are commonly used as magnetic bubble transfer patterns, but when forming these patterns on a crystal, the gaps between the patterns (hereinafter referred to as pattern gaps) are It is small, about 1/3 of the magnetic bubble diameter, and has large restrictions on pattern creation. For example, if the magnetic bubble diameter is 3 [μm], the pattern gap must be set to about 1 [μm], and this value is This is close to the limit of current photolithography technology.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to obtain a magnetic bubble expansion transfer pattern which allows a large pattern gap and is therefore easy to form. Another object of the present invention is to realize a magnetic bubble expansion transfer pattern in which the minimum driving magnetic field is low and the operating margin is sufficiently wide. An object of the present invention is to create a modified chevron pattern in which protrusions are added to the ends and intermediate parts of a conventionally known chevron pattern, stacked in multiple stages perpendicular to the magnetic bubble transfer direction. This can be achieved by creating a magnetic bubble expansion transfer pattern.

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows an enlarged transfer pattern according to the present invention. In the figure, P is a deformed Sipron pattern made of a soft magnetic material such as permalloy formed by vapor deposition or the like on a magnetic bubble crystal.

As shown in the figure, the enlarged transfer pattern of the present invention is constructed by stacking a plurality of modified chevron patterns P perpendicularly to the magnetic bubble transfer direction, and is arranged, for example, in the preceding stage of the magnetic bubble detection pattern.

Note that the numbers shown in the figure represent the pattern size ratio to the melon magnetic bubble diameter. FIG. 2 is an operating margin characteristic curve diagram for comparing the operating margins of the present invention and a conventional enlarged transfer pattern.

In Figure 3, the horizontal axis shows the driving magnetic field, the vertical axis shows the bias magnetic field, and the curve in the figure shows the magnetic bubble as a crystal (YEuY
The operating margin characteristics for each pattern are plotted when a magnetic valve with a diameter of 3 [μ] using bCa) 3 (FeGe) 5012 is operated at a measured drive frequency of 300 [KHz].

Curve a in the figure is an operating margin characteristic curve of an enlarged transfer pattern consisting of a conventional chevron pattern having a pattern gap of 1/3 of the magnetic bubble diameter, that is, a pattern gap of 1 [μ]. 2 of the same curve b&mu magnetic particle diameter
3 is an operating margin characteristic curve of an enlarged transfer pattern consisting of a conventional chevron pattern having a pattern gap of /3, that is, a pattern gap of 2 [μ]. Curve A9
As can be seen by comparing curve b, in the conventional chevron pattern, when the pattern gap is doubled, the operating margin is significantly reduced as shown by curve b. However, even if the enlarged transfer pattern shown in FIG. 1 according to the present invention is set to 1 and the pattern gap is set to twice that of the conventional chevron pattern, the operating margin does not decrease as shown by curve c, but rather increases. I understand. Furthermore, a feature of the enlarged transfer pattern of the present invention is that it has a sufficient operating margin even under a low driving magnetic field, as can be observed from the figure.
The fact that the minimum driving magnetic field is low can have various practical effects such as reduction in power consumption, reduction in heat generation, and ease of designing a driving circuit. As described above, the enlarged transfer pattern of the present invention, which is favorable under a low driving magnetic field, has a weakened holding force of the magnetic bubble under a low driving magnetic field.

For example, the attractive magnetic force between the center and end portions of the pattern is
As shown in the figure, it is thought that good characteristics were obtained as a result of increasing the thickness by adding protrusions. Figure 3 A, b
FIG. 2 is a diagram for comparing and explaining potential wells related to the expansion and contraction of magnetic bubbles in each enlarged transfer pattern consisting of a conventional sheapron pattern and a modified chiapron pattern of the present invention.

In each figure, the horizontal axis indicates the driving magnetic field phase, and the vertical axis indicates the bias magnetic field. In each figure, A shows the region where the magnetic valve contracts, B shows the region where the magnetic valve is stably held without contracting or expanding, and C shows the region where the magnetic valve expands. There is. The magnetic bubbles transferred under the permalloy pattern tend to contract and are difficult to expand at the center and ends of the permalloy pattern, that is, when the driving magnetic field phase angle is 00180 parts. Particularly in the conventional siebron pattern, this tendency is remarkable as shown in Figure a, and therefore the region A in which magnetic bubbles are stably transferred is very narrow.
On the other hand, in the modified Sipron pattern according to the present invention shown in FIG. Therefore, the modified sheapron pattern of the present invention transfers smoothly extended magnetic bubbles, unlike the conventional chiapron pattern in which the magnetic bubbles tend to be transferred while being greatly expanded and contracted during one cycle of the driving magnetic field. be able to. As described above, according to the present invention, it is possible to obtain a magnetic bubble enlarged transfer pattern that has a large pattern gap and is therefore easy to form.

Further, it is possible to realize a magnetic bubble enlarged transfer pattern with a low minimum driving magnetic field and a sufficiently wide operating margin.

[Brief explanation of drawings]

FIG. 1 shows the shape of the enlarged transfer pattern of the present invention.

Claims (1)

[Claims] 1 A modified chevron pattern in which protrusions are added to the ends and intermediate parts of the chevron pattern is stacked in multiple stages perpendicular to the magnetic bubble transfer direction, and the magnetic bubbles are extended in the stacked direction. Magnetic bubble expanding transfer pattern.