JPS608551B2 - Cylindrical domain element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic memory element that utilizes cylindrical magnetic domains.

When a uniform bias magnetic field of an appropriate magnitude is applied to a magnetic film such as garnet, which has an axis of easy magnetization in the direction perpendicular to the film surface, a cylindrical magnetic domain consisting of a single domain wall whose magnetization direction is opposite to that of the periphery is created in the magnetic film. It is known that it can be done.

When a magnetic field gradient is applied to this cylindrical magnetic domain, the cylindrical magnetic domain moves along the magnetic field gradient. By using this property, it is possible to realize a magnetic storage device. The most commonly used method for moving the cylindrical magnetic domain is to arrange European magnetic thin film patterns such as the letters T and 1 on a magnetic film and apply a rotating magnetic field in the in-plane direction of the magnetic film.

In order to realize a cylindrical magnetic domain element used in a magnetic storage device, a means for generating, detecting, and erasing the cylindrical magnetic domain is required in addition to the simple movement of the cylindrical magnetic domain.

Furthermore, in cylindrical magnetic domain elements, a method is generally used in which two types of transfer paths, called major loops and minor loops, are provided to shorten the access time.

This method is called a major-minor one-way method (M/m method). In the M/m type cylindrical element, a transfer gate for transferring and receiving the cylindrical area between the major loop and the minor loop or a replicator for dividing the cylindrical area is required. An example of a replicator is IE Transactions on Magnetics (mEET).
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This is illustrated in Fig-8 of Volume G-9, page 477 (1973). However, in the replicator in the above-mentioned document, the cylindrical magnetic domains in the replicator portion travel in opposite directions.

Therefore, the interaction between the cylindrical magnetic domains increases in this part, and the transfer margin of the cylindrical magnetic domains decreases. Further, in this replicator, it is necessary to stretch the cylindrical magnetic domain with a conductor loop, and after the stretched cylindrical magnetic domain intersects the conductor loop, a current for cutting the cylindrical magnetic domain must be applied. However, because it takes a long time for the cylindrical magnetic domain to intersect with the conductor loop,
When the bias magnetic field becomes high, the elongated cylindrical magnetic domain contracts, making it impossible to divide the cylindrical magnetic domain, resulting in a reduction in operating margin. An object of the present invention is to provide a replicator which is different in type from conventionally known replicators and has a sufficient operating margin.

This will be explained in detail below using examples.

FIG. 1 shows a replicator section according to an embodiment of the present invention.

First cylindrical domain transfer path 11 and second cylindrical domain transfer path 12
A first conductor 14 for enlarging the cylindrical magnetic domain and a second conductor 15 for cutting the cylindrical magnetic domain are arranged near the applicator center 13.

Here, it is essential that the first conductor and the second conductor are formed of different layers with an insulating layer interposed therebetween, which is also a difference from conventional known examples. Normally, it is required to reduce the number of steps in the manufacturing process as much as possible, so for example, if the first conductor is formed of the first thin film layer, the second conductor is formed of the same layer as that forming the cylindrical domain transfer path. It is preferable to form it with two thin film layers.

The thin film layer forming the cylindrical magnetic domain transfer path is usually a magnetic film layer such as a permalloy film, but a film of gold, aluminum, copper, etc. may be superimposed on the magnetic thin film to increase electrical conductivity. Of course, the second conductor may be formed from the first thin film layer, and the first conductor may be formed from the second thin film layer. Furthermore, in the embodiment according to FIG. 1, the first conductor! 4 and the second conductor 15 are arranged so as to intersect near the replicator central portion 13. Here, the first conductor 14 and the second conductor 15 are arranged with an insulating layer interposed therebetween so as not to be electrically short-circuited. First or second cylindrical domain transfer path】6
When the cylindrical magnetic domain entering from either of the cylindrical magnetic domains 717 reaches the first conductor loop section 14 for enlarging the cylindrical magnetic domain, when a current is passed through the first conductor loop, the cylindrical magnetic domain is divided into the first and second cylindrical magnetic domains. It can be stretched to span both transfer paths. Generally, when the bias magnetic field for holding the cylindrical magnetic domain becomes strong, the cylindrical magnetic domain becomes difficult to expand, so when the current in the first conductor loop is cut off, the cylindrical magnetic domain shrinks again and the cylindrical magnetic domain transfers into the first or second cylindrical magnetic domain transfer path. It tends to exist only on one side. All of the replicators that have been reported so far are designed to operate only within a bias range in which the once expanded cylindrical magnetic domain does not contract even when the current for enlarging the cylindrical area is turned off. On the other hand, in the replicator according to the present invention, a first conductor for enlarging the cylindrical magnetic domain and a second conductor for cutting the cylindrical magnetic domain are used.
Since the conductors are arranged so as to intersect, it is possible to simultaneously flow a current for cutting the cylindrical magnetic domain while a current for expanding the cylindrical magnetic domain is flowing. Therefore, the replicator of the present invention can be operated up to a higher bias magnetic field than the conventional replicator, resulting in a wider operating margin.

In the embodiment shown in FIG. 1, the first and second cylindrical domain transfer paths near the center of the replicator each consist of three layers of chevron patterns, but the number of layers may be other than this. Of course~Y
It may also be composed of patterns of other shapes, such as a semicircular shape or a semicircular shape.

Although the conductor patterns 14 and 15 are shown to be straight in the figure, they may of course be curved, and the thickness does not need to be uniform.

[Brief explanation of drawings]

The figure is a plan view showing a ribricator section in an embodiment of the present invention. 11 is a first cylindrical domain transfer path, 12 is a second cylindrical domain transfer path, 13 is the center of the replicator, 14 is a cylindrical domain expansion conductor, 15 is a cylindrical domain cutting conductor; It is the direction.

Claims (1)

[Claims] 1. In a magnetic storage device having a magnetic film capable of holding a cylindrical magnetic domain, a magnetic means for stably existing the cylindrical magnetic domain in the magnetic film, and a magnetic means for moving the cylindrical magnetic domain, a first cylindrical magnetic domain A transfer path, a second cylindrical magnetic domain transfer path, a first conductor for expanding the cylindrical magnetic domain, and a second conductor for cutting the cylindrical magnetic domain are formed in separate layers at a close portion of these two types of transfer paths, and A cylindrical magnetic domain element comprising: replicators arranged to intersect with each other.