JPS5911984B2 - magnetic bubble memory device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bubble memory device, and more particularly to an improvement in a magnetic bubble memory information writer.

5-Generally, magnetic thin films have an easy axis of magnetic domain in the in-plane direction, but certain magnetic materials, such as single crystals such as orthoferrite and magnetic garnet, have a strong axis of easy magnetization only in the C-axis direction. It has uniaxial anisotropy.

When such a material is made into a thin film with 10 planes perpendicular to the C-axis, when no external magnetic field is applied, the upward magnetization direction and the downward magnetization direction are almost equal, as shown in Figure 1a. They are interlaced in stripes in area.
When a downward bias magnetic field is applied to this thin film, the 15 upward magnetic domains decrease and the downward magnetic domains expand, as shown in Figure 1b.
After going through such a state, the upwardly directed magnetic domain finally becomes a small cylinder with a diameter of several μm, as shown in FIG. 1c.

This cylindrical magnetic domain is called a magnetic bubble domain. Moreover, if the bias magnetic field is made stronger by 20 degrees from the state shown in FIG. 1c, the magnetic bubble domain suddenly collapses and disappears from a certain radius. To create a new magnetic bubble domain from this state, several thousand Oe should be applied locally in the opposite direction to the bias magnetic field.
A pulsed magnetic field must be applied. This magnetic field is called New Creation magnetic field (HN). The magnetic bubble memory device utilizes the fact that this magnetic bubble domain can be moved freely within a magnetic thin film by a magnetic field, and is made by forming a permalloy thin film on a substrate using a Taber as shown in FIG. A propagation path is formed by forming a matrix of patterns such as half disks as shown in b, and information is stored as "1" where there is a magnetic bubble and "o" where there is no magnetic bubble.

Therefore, magnetic bubbles must be generated according to the information to be stored. Figure 3 shows a nu-creation type bubble generator, which is one type of bubble generator, which combines a conductor pattern 1 that generates a local magnetic field and a permalloy pattern 2 in the shape of a 1-1 square. It is something that

This bubble generator generates bubbles 3 by passing a pulse current through the conductor pattern 1 to generate a magnetic field in the opposite direction to the bias magnetic field. However, in this method of writing information using nucleation, the crystal has a characteristic that the nucleation magnetic field (HN) decreases as the temperature rises, so bubbles are likely to occur, and two bubbles may be generated at once. Errors may occur. For this purpose, a closed loop with a propagation path including a bubble generator is created, and Ohnopi 1" is written into this closed loop at the optimum temperature, and the bubbles packed in this closed loop are divided and used to write information. However, even in this force method, if the closed loop is cleared once, it is necessary to fill the bubbles in a high temperature state.In such a case, unnecessary bubbles are generated as described above. The present invention was devised to improve this drawback.For this reason, in the present invention, a substrate made of a magnetic material with strong uniaxial anisotropy is used. Above, a closed loop propagation path including a magnetic bubble generator patterned with a thin film metal and a divider, an information storage loop connected to the closed loop propagation path across the divider, and the information storage loop and the closed loop. A magnetic bubble memory device including a chip having a guardrail surrounding a propagation path is characterized in that a propagation path is provided that connects the closed loop propagation path and the guardrail.

Embodiments of the present invention will be described in detail below based on the accompanying drawings.

FIG. 4 shows an enlarged plan view of a part of the chip.

In the figure, 4 is a conductor pattern of a magnetic bubble generator, and 5 is a conductor pattern of a divider, both of which are formed of a thin film of Al or the like on a substrate. 6 is a closed loop propagation path in which half disk patterns 7 for bubble propagation formed of Vermalloy thin film are arranged in a matrix, and in the middle of this closed loop 6 there are conductor patterns 4 and 5 for a bubble generator and a divider.
The permalloy pattern above them is shaped like a pickaxe.

Further, reference numeral 8 denotes a guardrail which surrounds the outer periphery of the chip by arranging T patterns 9 formed of a permalloy thin film.
Two propagation paths 10 and 11 are formed between the guardrail 8 and the closed loop propagation path 6. This propagation path 1
0 and 11 are the main points of the present invention and are provided before and after the bubble generator 12. Note that a propagation path 14 emerging from the divider 13 is a propagation path that guides bubbles to a loop 15 for information storage. In the chip in which each pattern is formed in this way, even if extra bubbles are generated by the bubble generator 12, the bubbles that reach the propagation paths 10 and 11 according to the present invention are guided by the driving magnetic field to the closed loop propagation path 6 as shown by the arrow. He can join the bubble around the loop.

Further, some of the excess bubbles are absorbed directly into the closed loop propagation path 6, or those that reach the guardrail 8 are released outward by the action of the T-pattern 9 of the guardrail. In this way, surplus bubbles are prevented from entering the information storage loop 15. As explained above, the present invention prevents excess bubbles from entering the information storage loop by providing a propagation path between the closed loop propagation path having a bubble generator and the guardrail, thereby improving the reliability of the magnetic bubble memory device. This is an improvement.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the principle of magnetic bubble generation, Fig. 2 is a plan view of a magnetic bubble propagation pattern, Fig. 3 is a plan view of a magnetic bubble generator, and Fig. 4 is a magnetic bubble memory of an embodiment according to the present invention. FIG. 3 is a partially enlarged plan view of a chip of the device. 4...Conductor pattern of magnetic bubble generator, 5.
... Conductor pattern of divider, 6 ... Closed lube propagation path, 7 ... Propagation path permalloy pattern, 8 ... Guardrail, 10, 11 ...・・・
・Propagation path, 12... Magnetic bubble generator, 13.
...Divider, 15...Loop for information storage.

Claims (1)

[Claims] 1. On a substrate made of a magnetic material with strong uniaxial anisotropy,
A closed-loop propagation path including a magnetic bubble generator and a divider patterned with thin film metal, an information storage loop connected to the closed-loop propagation path via the divider, and surrounding the information storage loop and the closed-loop propagation path. What is claimed is: 1. A magnetic bubble memory device comprising a chip having a guardrail, further comprising a propagation path connecting the closed loop propagation path and the guardrail. 2. The magnetic field according to claim 1, wherein the propagation path connecting the closed loop propagation path and the guardrail is formed by two propagation paths that reach the guardrail from before and after the bubble generator. Bubble memory device.