JPS6348690A - Bubble magnetic domain stretching device - Google Patents

Abstract

PURPOSE:To obtain a strong bubble stretching capability and a stable bubble transfer characteristic by adopting an asymmetrical structure to the inlet side element chip of a chevron pattern shorter than an exit side element chip. CONSTITUTION:The asymmetrical structure is adopted in which the length l1 of the inlet side element chip 11 of the chevron pattern 10 is shorter than a length l2 of the exit side element chip 12. The length of the inlet side element chip 11 of the chevron pattern 10 where the pattern width W1 at peaks is wider than the pattern width W2 at troughs is made shorter than the length of the exist side element chip 12 in this way, then the shape anisotropy of the inlet side element chip 11 is not increased to prevent the deterioration in the bubble transfer characteristic at the inlet side element chip. Moreover, a deep potential is formed at the tip of the exit side element chip 12 is formed to increase the bubble expansion capability.

Description

[Detailed Description of the Invention] [Summary] This is a bubble magnetic domain stretcher in which a chevron pattern having a curvature such that the pattern width at the crest is wider than the pattern width at the trough is connected to an element on the entrance side and an exit side. In a bubble domain stretcher in which the fragments are arranged in the direction of bubble propagation, the chevron pattern has an asymmetric structure in which the entrance side fragments are shorter than the exit side fragments, resulting in strong bubble expansion ability and stable bubbles. This makes it possible to obtain transfer characteristics.

[Industrial application field]

The present invention relates to a bubble magnetic domain expander for a magnetic bubble memory element used in a storage device such as an electronic computing bag W.

A magnetic bubble memory device is a thin film of magnetic garnet (magnetic bubble crystal) formed by liquid phase epitaxial growth on a single crystal substrate of gadolinium, gallium, and garnet, for example.
A bubble transfer path is formed using a soft magnetic thin film such as permalloy and has a matrix of half-disk or asymmetric chevron patterns on it, and the bubbles generated by a bubble generator according to the information are If there is a bubble in the pattern, it is set as "1", and if there is no bubble, it is set as "O", and the rhyme is stored. In addition, information is read by stretching the bubbles using a bubble domain stretcher to form striped magnetic domains, and then extracting them as electrical signals using a detector that utilizes the magnetoresistive effect to detect the presence or absence of bubbles.

The density of such magnetic bubble memory elements continues to increase, and the bubbles used tend to become smaller. For this reason, there is a problem in that bubbles are not sufficiently expanded in the bubble domain expander, resulting in a decrease in detection ability.

[Conventional technology]

FIG. 5 is a diagram showing a bubble domain expander using a conventional chevron pattern. This bubble domain expander has multiple rows 2 in which a large number of chevron patterns 1 of soft magnetic thin films are arranged at regular intervals, and an outlet side element 3 in the previous stage.
are arranged so as to be intertwined with the inlet side element piece 4 at the rear stage. FIG. 6 is a diagram showing the pattern period dependence of the bias margin of this bubble domain expander. In the figure, the vertical axis represents the bias magnetic field, the horizontal axis represents the drive magnetic field, and the curve A (×
), the pattern pitch P = 15μ, B (white circle), P = 13.5μ, C (black circle), P = 12μ,
The case of P=10.5μ is indicated by D (triangle mark). As can be seen from the figure, as the pattern period P increases, the upper limit of the bias margin is improved and the expansion ability is increased. On the other hand, on the low bias side, the lower limit of the bias margin tends to deteriorate as the pattern period increases. This is because in order to effectively extend the bubble, it is necessary to lengthen the pattern period and form a deep potential at the toe of the chevron pattern. This is because the shape anisotropy increases and the bubble driving force from point a to point b shown in FIG. 5 becomes weaker. For this reason, in order to compensate for the bubble-driven deterioration, an improved chevron pattern with a curvature that widens the pattern width at the peaks of the chevron pattern, as shown in FIG. 7, has come to be used.

[Problem that the invention seeks to solve]

Even in the bubble domain expander using the above-mentioned improved pattern, as the bubble becomes smaller, as shown in FIG. There is a problem in that they tend to separate and cause malfunctions due to entanglement.

The present invention was created in view of these points, and an object of the present invention is to provide a bubble magnetic domain expander with strong expansion ability and stable bubble characteristics.

[Means for solving problems]

Therefore, in the present invention, a plurality of chevron patterns 10 having a curvature such that the pattern width W1 between the peaks of the chevron patterns is wider than the pattern width W2 of the valleys of the chevron patterns 10 are arranged at regular intervals. , in a bubble magnetic domain expander in which a plurality of rows thereof are arranged in multiple stages, and the outlet side element piece 12 at the front stage and the inlet side element piece 11 at the rear stage are arranged in the bubble traveling direction, the entrance side element of the chevron pattern 10 It is characterized by having an asymmetric structure in which the length of the piece 11 is shorter than the length of the outlet side element piece 12.

[For production]

By making the entrance-side elemental piece 11 of the chevron pattern 10, in which the pattern width at the peak part is wider than the pattern width at the trough part, shorter than the exit-side elemental piece 12, an increase in the shape anisotropy of the entrance-side elemental piece 11 is suppressed, and This prevents deterioration of the bubble transfer characteristics at the side elemental piece, and furthermore, a deep potential is formed at the tip of the exit side elemental piece 12, increasing the bubble expansion ability.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention.

As shown in the figure, in this embodiment, a plurality of chevron patterns 10 having a curvature wider than the pattern width W1 at the crests than the pattern width W2 at the troughs are arranged in a row, and the plurality of the pattern rows are formed into bubbles. The inlet side elemental piece 11 on the side where the bubble enters and the exit side elemental piece 12 on the side where the bubble exits are arranged in multiple stages in a complicated manner, as in the conventional case, and the key point of this embodiment is to create a chevron pattern. 10 is formed asymmetrically so that the length 11 of the inlet side elemental piece 11 is shorter than the length 7!2 of the outlet side elemental piece 12.

In this embodiment configured as described above, since the entrance side elemental piece 11 is shorter than the exit side elemental piece 12, the increase in shape anisotropy of the artificial side elemental piece 11 is suppressed, and the transfer of bubbles in the entrance side elemental piece 11 is suppressed. Deterioration of characteristics is prevented. Furthermore, at that time, the exit side element 1
Since the length of the chevron 2 is longer than that of the conventional symmetrical chevron, a deeper potential is formed at its tip, and the bubble expansion ability is increased.

FIG. 2 is a diagram showing another embodiment of the present invention.

In this embodiment, as shown in the figure, the entrance side pieces 11 of two adjacent chevron patterns 10 are connected.

In this embodiment configured in this way, since the triple exit of the outlet side elemental piece 12 is farther away from the mountain position, the outlet side elemental piece 12
The magnetic poles generated on the side surfaces of the tube are weakened, and malfunctions due to entanglement of bubbles as explained in FIG. 7 are prevented.

Furthermore, 1st U3. In the chevron pattern shown in Figure 2,
The length 11 of the entrance side elemental piece 11 is 1 according to the results shown in FIG.
Since a chevron pattern with a period of 2μ shows almost no lower limit deterioration, it is desirable to set the maximum to about 6μ.

Further, it is sufficient to set the length 12 of the outlet side piece 12 to about 10 μ at the maximum based on the experimental results described below.

FIG. 3 shows the results of measuring the pattern length of the bar pattern and the potential generated at its tip.

The figure shows the length l of a bar pattern with a width of 1 μ on the horizontal axis and the bias magnetic field on the vertical axis.
600e on curve B, 400e on curve VAC, 2 on curve
Each case of 00e is shown. As can be seen from the figure, the potential of the bar pattern begins to be saturated at about 1=10μ, so the length 12 of the outlet side element 12 may be about <10μ as described above.

FIG. 4 is a diagram showing the bias margin of the embodiment of the present invention in comparison with the conventional example. In the figure, the horizontal axis represents the driving magnetic field, the vertical axis represents the bias magnetic field, and curve A (black circle) represents the embodiments shown in FIG. 1 (P = 13μ, 11-4μ, 12-
7μ) in the conventional example (
P = 13μ, Nj = 112 = 6.5μ) by curve C (
Conventional example (P=9.6μ, 11
=12 =4.8μ). It can be seen from the figure that this embodiment (curve A) exhibits better characteristics in both the upper and lower limits of the bias margin than the conventional examples (curve &iB, C).

〔Effect of the invention〕

As described above, according to the present invention, strong bubble expansion ability and stable bubble transfer characteristics can be obtained with an extremely simple configuration, and it is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing another embodiment of the invention, Fig. 3 is a diagram showing the bar length dependence of the potential depth of a bar pattern, and Fig. 4 is a diagram showing an example of the present invention. The figure shows the bubble transfer characteristics of the embodiment of the present invention in comparison with the conventional example. Figure 5 shows the conventional bubble domain expander. Figure 6 shows the bias margin of the conventional bubble domain expander. FIG. 7, which is a diagram showing pattern period dependence, is a diagram showing a bubble domain expander using a conventional improved pattern. In FIGS. 1 and 2, 10 is a chevron pattern, 1 is an inlet side piece, and 12 is an outlet side piece. ] 1 FIG. 10 showing an embodiment of the present invention... Chevron pattern] ]... Entrance side piece] 2... Outlet side piece FIG. 2 Showing another embodiment of the present invention; Master? Figure 3 shows the dependence of tensile depth on the knob length Figure 3 shows the transmission characteristics of the embodiment of the present invention in comparison with the conventional example Figure 4 shows the conventional bubble domain expander Figure 1...chevron pattern 2... Nog turn row 3... Outlet side elemental piece 4... Inlet side elemental piece driving magnetic field HD (Oe) Figure 6 shows the pattern period dependence of the bias margin of a conventional bubble domain expander.

Claims (1)

[Claims] 1. The pattern width of the chevron pattern mountain portion (W_1 is
The chevron pattern (
10) In the bubble stretcher in which the inlet side elemental piece (11) and the outlet side elemental piece (12) are arranged in the bubble traveling direction so as to be intertwined, the inlet side elemental piece (11) of the chevron pattern (10) is arranged.
A bubble magnetic domain expander characterized in that it has an asymmetric structure in which the length of the bubble is shorter than the length of the outlet side element (12). 2. The bubble domain expander according to claim 1, characterized in that two adjacent chevron patterns (10) are connected to each other at their inlet side pieces (11). .