JPS6235185B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cylindrical magnetic domain (hereinafter simply referred to as a bubble).
The present invention relates to a bubble element having a stretcher-type bubble detection section in a bubble transfer path that transfers a bubble using an in-plane magnetic field.

Currently, the mainstream method for reading out signals from such field access type bubble elements is based on the magnetoresistive effect. In order to facilitate signal detection, it is common to extend the bubble at right angles to the transfer direction, and for this purpose, a plurality of chevron patterns or the like are lined up in the direction of bubble extension in a part of the transfer path of the detection section. A stretcher configuration is adopted.

As the bubble becomes smaller, it expands,
Since the bias magnetic field area that can be driven is relatively reduced compared to other parts of the bubble element, various measures have been taken, such as improving the pattern shape of the stretcher part. These were mainly intended to raise the upper limit of the bias magnetic field that can drive stretched bubbles (hereinafter referred to as stretched domains).

However, as a stretcher, it is also necessary to lower the lower limit of the driving bias magnetic field of the stretched domain.

The lower limit of the bias magnetic field of the bubble element is determined by the maximum value of the lower limit of the drive bias magnetic field of various functional parts including the stretcher, major loop, minor loop, etc. This is because when the lower limit of the magnetic field is the maximum value of the lower limits of the drive bias magnetic field of the component parts of the element, the lower limit of the drive bias magnetic field of the bubble element can be lowered by lowering the lower limit of the drive bias magnetic field of the stretcher.

The present invention has been made in view of these points, and its purpose is to lower the lower limit of the drive bias magnetic field of the stretcher without lowering the upper limit of the drive bias magnetic field. To provide a bubble element that can be expanded laterally.

Whereas the upper limit of the stretcher drive bias magnetic field is determined by the contraction of the stretched domain,
The lower drive bias field limit is often due to errors in which the stretched domains extend outside the pattern columns of the stretcher and into adjacent pattern columns from outside the pattern.

That is, under a low bias magnetic field, the tip of the stretched domain extending outside the pattern column moves toward the pattern end of the adjacent pattern column, which has a low potential, and the stretched domain straddles the two pattern columns.

Therefore, in order to suppress such errors, the shape of the pattern pillars constituting the stretcher should be the same except for the ends, and the shape of the pattern pillars should be the same on both the upper and lower sides of the pattern pillars, or in several steps at one end. The pattern shape may be arranged in such a shape that the stretching force of the domain becomes small.

The present invention is characterized in that the pattern shape of the upper and lower ends or one end of the pattern column has a pattern width smaller than that of the pattern at the center of the pattern column. is weakened, and even in a low bias magnetic field, the stretched domains do not extend from the pattern pillars to the outside of the pattern, and in a high bias magnetic field, there is sufficient domain stretching force except at the ends of the pattern pillars.

A more detailed explanation will be given below with reference to Examples. A YIG thin film was grown on (YSmLuCa) ₃ (FeGe) ₅ O ₁₂ (film thickness 1.7 μm, characteristic length 0.18 μm, saturation magnetization 565 Gauss) grown on GGG as a bubble material.
A conventional chevron pattern with pitch P ₁ 12 μm, gap G ₁ 1 μm, pattern width W ₁ 3 μm, and apex angle 90° as shown in Figure 1 was formed on a thin film grown to 700 Å to suppress hard bubbles. ,
Figure 2 shows the transfer margin at a driving frequency of 100 KHz in the stretcher section of a magnetic bubble element in which 300 stages of stretchers are stacked in the direction of domain extension with 4000 Å of Al ₂ O ₃ interposed therebetween.

Example A stretcher section (300 _{steps at the center of the pattern column) according} to the structure of the present invention as shown in FIG. is the same shape as the comparative example, with 10 steps on each of the upper and lower ends of the pattern column,
The pitch, gap, and apex angle of the pattern are the same as those of the comparative example, and the pattern width W2 is a series of chevron patterns of 2.5 μm), and the driving frequency is 100 KHz.
Figure 4 shows the transfer margin.

In this embodiment, a chevron pattern is used as the stretcher pattern shape, but a chevron shape in which the pattern shape is deformed can also be used to obtain the same effect. As is clear from this embodiment, the present invention makes it possible to lower the lower limit of the drive bias magnetic field in the stretcher section, which greatly contributes to expanding the drive margin of the magnetic bubble element.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the configuration of a conventionally known Chevron stretcher, Fig. 2 is a diagram showing the drive margin at 100KHz of the stretcher section of the configuration shown in Fig. 1, and Fig. 3 is a diagram showing the stretcher according to the present invention. FIG. 4 is a schematic diagram showing an embodiment of the structure, and FIG. 4 is a diagram showing a driving margin of the stretcher section in the embodiment of the present invention. P1 is the pitch of the stretcher pattern of the comparative example and the example, G1 is the gap of the stretcher pattern of the comparative example and the example, W1 is the stretcher pattern width of the comparative example and the center part of the pattern column of the stretcher of the example pattern width, W
2 is the pattern width at both the upper and lower ends of the stretcher pattern column in the example.

Claims (1)

[Claims] 1. Magnetic bubble domains can be extended in a direction perpendicular to the transfer direction of magnetic bubble domains on a part of the transfer path where magnetic bubble domains are transferred by an in-plane rotating magnetic field on a magnetic material capable of holding magnetic bubble domains. In a stretcher consisting of pattern pillars in which patterns are arranged in the domain extension direction, the pattern width of the pattern at both upper and lower ends or one end of the pattern pillars arranged in the domain extension direction is equal to that of the pattern in the center of the pattern pillar. A magnetic bubble element characterized in that it is configured to be smaller than a pattern width.