JPS6116088A - Magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To improve the margin of a bias magnetic field in a start-stop action mode by securing the coincidence between the direction of an intra-face holding magnetic field and the direction of the magnetization easy axis of a magnetic film for transfer and therefore decreasing the holding magnetic field. CONSTITUTION:Coincidence is secured between the direction of an intra-face holding magnetic field HDC that holds stably a magnetic bubble and the direction of an axis (a) easy for magnetization of a magnetic film of a soft magnetic pattern 3 for transfer of the magnetic bubble. As a result, the minimum holding magnetic field is minimized compared with other cases. This improves the margin of a bias magnetic field in a start-stop action mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic bubble memory element with improved start-stop operation characteristics that occur when the density is increased.

[Background of the invention]

As shown in FIG. 1, in order to stably hold the magnetic bubbles of the magnetic bubble memory element 1, the magnetic bubble memory device applies a bias magnetic field HB to the permanent cornerstone 2, 2' and rotates the magnetic bubble to drive the magnetic bubble. A hold magnetic field HDC is applied to stop the magnetic bubble at a position where it is easy to start and stop within the soft magnetic material pattern when the magnetic field is started or stopped. The hold magnetic field HDC is applied using, for example, a permanent magnet in which the magnetic bubble memory element 1 is arranged obliquely as shown in the figure or another permanent magnet.

However, this hold magnetic field HDC is about 1/10 of the value of the rotating magnetic field that drives the magnetic bubbles, and as the density of the magnetic bubble memory element 1 increases,
As the magnetic material pattern becomes smaller, in order to stably hold the magnetic bubble, it is necessary to deepen the magnetic bubble trap well generated under the soft magnetic material pattern generated by this hold magnetic field HD c JfC.

[Purpose of the invention]

Therefore, the present invention has been made in view of the above-mentioned problems, and its object is to provide a magnetic bubble memory element that improves the bias magnetic field margin during start/stop operations by reducing the hold magnetic field. Our goal is to provide the following.

[Summary of the invention]

In order to achieve such an object, the present invention aims to determine the direction of the easy axis of in-plane anisotropy magnetization that occurs after vapor deposition or sputtering on a soft magnetic material pattern that drives magnetic bubbles, and the direction of the easy axis of magnetization in a magnetic bubble memory after forming the soft magnetic material pattern. The direction of the hold magnetic field applied to the element is made to match.

That is, FIG. 2 shows, as an example, the relationship between the amount of magnetization M and the external magnetic field H in the directions of arrows a and b after sputtering a soft magnetic film on a G-G-G substrate. In the figure, it is known that the shape of this MH loop changes depending on conditions such as the value of the substrate bias during sputtering and the thickness of the soft magnetic film to be produced, and it is also known that it changes depending on the substrate temperature during evaporation. . Furthermore, IEEE MAG-15 shows that the direction of the easy axis of magnetization (a direction) and the direction of the hard axis (b direction) can also be controlled by sputtering and vapor deposition conditions.
, N06. P1821-P1823 (1979). In addition, Hc is a coercive force, & is an anisotropic magnetic field, and - for example, HcTho, 4δe+ Hz”5δe
becomes. In addition, after the soft magnetic material pattern is formed, due to the anisotropy caused by the pattern shape, the MK loop described above changes significantly due to the influence of the direction of the rotating magnetic field, the pattern shape, etc. The effect of in-plane anisotropy is preserved. Therefore, if you use the same shape pattern,
When magnetized in the a direction, a larger amount of magnetization can be obtained than in the b direction. That is, by making this direction a coincide with the hold magnetic field of the start-stop operation, the operating characteristics can be improved.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 3 is an enlarged plan view of a main part of a magnetic bubble transfer path for explaining an example of a magnetic bubble memory element according to the present invention. In the figure, 3 is a soft magnetic material pattern called a chevron that constitutes a magnetic bubble transfer path, a is the easy axis direction of magnetization of the soft magnetic material film before forming the soft magnetic material pattern 3, and b is its hard axis direction. , ) IDC indicates the hold magnetic field, and the figure shows the case where the hold magnetic field HDC direction and the easy magnetization axis direction a match, and the case where the hold magnetic field HDC direction and the hard magnetization axis direction a match, respectively. .

Two types of magnetic bubble memory devices were fabricated in this manner and the characteristics of the devices were measured, and as a result, data as shown in FIG. 4 was obtained. That is, in FIG. 4, the vertical axis shows the bias magnetic field margin ΔMu, and the horizontal axis shows the hold magnetic field HDC. In the same figure, when the easy axis direction a of magnetization and the HDC direction of the hold magnetic field are matched as described above, curves A and A' are obtained, and the direction of the hard axis of magnetization and the HDC direction of the hold magnetic field are matched. In this case, curves B and B' were obtained. Therefore, as is clear from the figure, the easy magnetization axis direction a and the holding magnetic field Hp
By configuring the magnetic bubble memory elements so that the c directions coincide with each other, the minimum hold magnetic field HDC can be made the smallest.

〔Effect of the invention〕

As explained above, according to the present invention, since the minimum hold magnetic field can be made the smallest, it is possible to improve the bias magnetic field margin during start/stop operation, and contribute to an increase in the drive margin of the magnetic bubble memory element. Excellent effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross section of a main part of a magnetic bubble memory device for explaining a method of applying a hold magnetic field to a magnetic bubble memory element.
2 is a diagram showing the soft magnetic material #MH loop before pattern formation, and FIG. 3 is a plan view of a main part of a magnetic bubble transfer path for explaining an embodiment of the magnetic bubble memory element according to the present invention. , FIG. 4 is a diagram showing the hold magnetic field characteristics of the magnetic bubble memory element. III+-・Magnetic bubble memory element, 2.2'・Representative: Patent attorney Monto Takahashi...-So Fig. 1 Fig. 4 Ho L), 44i Hoc (oe) Fig. 2

Claims (1)

[Claims] A magnetic bubble memory element characterized in that the direction of an in-plane holding magnetic field for stably holding magnetic bubbles and the direction of the easy axis of magnetization generated after formation of the magnetic film for transferring the magnetic bubbles are made to coincide.