JPS6235184B2 - - 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 bubbles become smaller, the bias magnetic field area that can stretch and drive the bubbles decreases relative to other parts of the bubble element, so various measures are being 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.

Since the lower limit of the bias magnetic field of the bubble element is determined by the maximum value of the lower limits of the drive bias magnetic field of various functional parts including the stretcher, major loop, minor loop, etc., the drive bias magnetic field of the bubble element is This is because when the lower limit is the maximum value of the lower limits of the drive bias magnetic field of the constituent 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 driving 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 an adjacent pattern column with low potential, and the stretched domain ends up spanning 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 pattern pillars should have several tiers on both the top and bottom sides of the pattern pillars or at one end. The shape may be arranged such that the stretching force of the domain is small. The present invention has a pattern shape at the end of a pattern column, in which the length of the pattern in the bubble transfer direction of both upper and lower surfaces or one end is shorter than the length of the pattern in the bubble transfer direction of the pattern in the center of the pattern column. In this way, the domain stretching force at the end face of the pattern column is weakened, and even in a low bias magnetic field, the domain stretching force is reduced.
The domains do not extend from the pattern pillars out 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. (YSmLuCa) on GGG as bubble material ₃
(FeGe) ₅ O ₁₂ (film thickness: 1.7 μm, characteristic length: 0.18 μm, saturation magnetization: 565 Gauss) by growing a YIG conductive film to a thickness of 700 Å to suppress hard bubbles. Pitch P ₁ 12μ
A stretcher with a thickness of 4000 Å is made by stacking 300 chevron patterns in the direction of domain extension, with a gap G _{of 1} 1 μm, a pattern width of W ₁₃ μm, and an apex angle of 90°.
Figure 2 shows the transfer margin at a driving frequency of 100 KHz for the stretcher section of the magnetic bubble element provided through Al ₂ O ₃ .

EXAMPLE A stretcher part ( _pattern column central part ₃₀₀ The steps have the same shape as the comparative example, 10 steps each at the top and bottom ends of the pattern column,
The pattern shape is the pattern length at 11 in the center of the pattern column.
10.5 μm for μm, that is, the gap G ₂ in the domain transfer direction at both the upper and lower ends of the pattern column is 1.5 μm for the gap G ₁ at the center of the pattern column 1 μm.
Figure 4 shows the transfer margin at a driving frequency of 100 KHz. In this embodiment, a chevron pattern is used as the stretcher pattern shape, but a chevron shape in which the shape of the pattern is changed can also provide the same effect. As is clear from this example, according to the present invention, the lower limit of the drive bias magnetic field can be lowered without lowering the upper 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. P ₁ is the pattern pitch of the stretcher in the comparative example and the example, W ₁ is the pattern width of the stretcher in the comparative example and the example, G ₁ is the pattern gap of the stretcher in the comparative example and the domain transfer at the center of the pattern pillar of the stretcher in the example. _G2 is a pattern gap in the domain transfer direction at both the upper and lower ends of the pattern column of the stretcher in the example.

Claims (1)

[Claims] 1. 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 so that the magnetic bubble domains can be extended in a direction perpendicular to the transfer direction of the magnetic bubble domains. In a stretcher consisting of pattern columns in which patterns are arranged in the domain extension direction, the length of the pattern in the bubble transfer direction of the pattern at both upper and lower ends or one end of the pattern columns arranged in the domain extension direction is defined as the pattern column. A magnetic bubble element characterized in that the length of the central pattern in the bubble transfer direction is shorter than the length of the pattern in the bubble transfer direction.