JPS6252394B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current access type bubble magnetic domain device. More specifically, the present invention relates to a bubble magnetic domain element in which a bubble magnetic domain is transferred by passing a current pulse train through a perforated conductor layer provided on a bubble material.

In a storage device that uses bubble magnetic domains as information carriers, the bubble magnetic domain transfer method uses an in-plane rotating magnetic field that externally applies a chevron-shaped or Y-shaped pattern made of a soft magnetic film such as permalloy. The so-called field access method, in which bubble magnetic domains are attracted and transferred to magnetic poles generated by sequential magnetization, has been common.

However, with this field access method, as the bubble domain diameter is reduced to increase information storage density, the in-plane rotating magnetic field required for cylindrical domain transfer increases rapidly, resulting in increased power consumption and in-plane It is well known that this method has a major disadvantage in that the voltage applied to the rotating magnetic field generating coil increases, making it unsuitable for high-speed transfer. Furthermore, as the bubble magnetic domain diameter becomes smaller, the minimum dimension required to form a permalloy pattern becomes smaller.
It is extremely difficult to manufacture an element using a bubble magnetic domain with a diameter of 2 μm or less.

A bubble magnetic domain element with a current access method as a bubble magnetic domain transfer method that overcomes the drawbacks of the conventional field access type bubble magnetic domain element was developed by AH Bobeck in August 1979 at The Bell. System Technical Journal (The Bell System)
Technical Journal) Vol. 58 No. 6 No. 1453~
Published on page 1540.

The essence of this current access type bubble magnetic domain element is that a rectangular or elliptical through-hole array is formed in a conductor layer provided on a bubble material, and when a current is passed through this conductor layer, a bias magnetic field is generated due to the current distribution around the hole. The aim is to drive the bubble magnetic domain using the distribution.

Therefore, this bubble domain drive method does not require an in-plane rotating magnetic field and is suitable for high-speed access. As described in the above-mentioned literature, the current access type bubble magnetic domain transfer method includes a method using one conductor layer and a method using two conductor layers. In either method, there are factors that deteriorate the operating characteristics of the bubble magnetic domain element. That is, when a driving current is passed through this bubble magnetic domain driving conductor layer (hereinafter referred to as the driving conductor layer), a large bias magnetic field component is generated near the circumference parallel to the current of the driving conductor layer, and the bubble element operating bias magnetic field is generated. This is a phenomenon in which the margin is extremely reduced around the driving conductor layer. For this reason, only a narrow, limited area at the center of the driving conductor layer can be used for bubble domain transfer. In other words, this current access type bubble magnetic domain element is not very efficient in terms of chip area.

SUMMARY OF THE INVENTION An object of the present invention is to provide a current access type bubble magnetic domain element which eliminates the above-mentioned drawbacks.

That is, the present invention is a current access bubble magnetic domain element having a bias magnetic field component compensating conductor layer (hereinafter referred to as a compensating conductor layer) that reduces a large bias magnetic field component generated from the peripheral portion of a driving conductor layer. Another object of the present invention is to facilitate the manufacture of the bubble magnetic domain element having a compensating conductor layer.

Next, the present invention will be explained in detail while comparing it with a conventional example using the drawings.

FIG. 1A shows a conventional current access type bubble magnetic domain element described in the above cited document.

A bubble material 1 capable of holding a bubble magnetic domain is grown on a substrate material 2, on which a first driving conductor layer 31 is provided, and an insulating layer (not shown) is provided on top of the first driving conductor layer 31. A second driving conductor layer 32 is provided. Drive conductor layers 31, 32
is provided with an oval hole pattern 30. 4
1 and 42 are currents flowing through the first layer and second layer, respectively, and J ₁ and J ₂ represent the respective current densities. 1
1 is a bubble magnetic domain, and the arrow in the bubble material 1 represents the magnetization direction.

Looking at the driving conductor layer 31, the current 41
(J ₁ =1 mA/μm), a bias magnetic field component 10 shown in FIG. 1B is generated. As can be seen from FIG. 1B, the peripheral portion of the driving conductor layer 31 has an extremely large magnetic field component. This bias magnetic field component has a large value except in the vicinity 5 of the center of the driving conductor layer.

In the case of a bubble magnetic domain with a diameter of 2 μm, the bias magnetic field margin where the bubble magnetic domain exists is about 40 to 50 oersteds (Oe), and it is necessary to suppress the decrease in the drive bias margin to about 10%, so the magnetic field due to the current is ±4 to 50 Oe. Must be less than 5 oersted. That is, the bias magnetic field component Hg shown in FIG.
Only a region where the value of is less than ±1 oersted can be used as an actual device. In this example, this region 5 is only about 30% of the width of the driving conductor layer.

The above situation is exactly the same for the second driving conductor layer 32.

In order to expand the effective area for this bubble magnetic domain drive, it is effective to provide another compensation conductor layer through which current can flow so as to cancel the bias magnetic field component generated from the drive conductor layer 31 or 32.

The following two methods can be considered for providing the compensation conductor layer.

First, a compensating conductor layer of the same width is provided over the driving conductor layer, and a current is passed through the compensation conductor layer in the opposite direction to that of the driving conductor layer, thereby reducing the bias magnetic field component generated from the driving conductor layer. This is a method to reduce

The second method is to provide a compensation conductor layer on both sides of the drive conductor layer in parallel with it, and to pass a current with an appropriate density in the same direction as the drive conductor layer through the compensation conductor layer, thereby creating a gap between the compensation conductor layers. This is a method of reducing the bias magnetic field component generated from the driving conductor layer using the opposite component magnetic field.

When applying the bias magnetic field component compensation method described above to a bubble magnetic domain element having two driving conductor layers as shown in FIG. This is not preferable because it complicates the process of manufacturing the bubble magnetic domain element.

According to the present invention, it is not only possible to easily expand the driving conductor layer area that is effective for driving bubble magnetic domains and usable as an element, but also to expand the area of the driving conductor layer that can be used as a bubble magnetic domain. Manufacture of magnetic domain elements can be facilitated.

The invention is based on the following principle. The distribution of the bias magnetic field component in the driving conductor layer region that occurs when a bubble drive current is passed through each of the two driving conductor layers is the sum of the magnetic field distributions that occur when current is passed through each drive conductor layer separately. equal. Therefore, even if the compensating conductor layer is one layer, if the compensating current flowing through it is the sum of the currents that can compensate for the bias magnetic field generated by the current of the individual driving conductor layers, then the two-layer driving conductor layer can be used. The bias magnetic field components from the layers can be compensated by the magnetic field from one compensating conductor layer.

The bubble magnetic domain element of the present invention is composed of a bubble magnetic domain material, at least two driving conductor layers provided thereon, and one compensation conductor layer provided in the vicinity thereof. is characterized in that a total combined current flowing through all of the drive conductor layers is passed.

Next, embodiments of the present invention will be described using the drawings.
FIG. 2A shows a first embodiment of the invention. In this embodiment, the bubble magnetic domain element includes a bubble material 1 grown on a substrate material 2, a first driving conductor layer 31 provided thereon, and a second driving conductor layer 3 provided thereon.
2. It is composed of a compensation conductor layer 33 and an electrical insulating layer 36 provided between each conductor layer.

In this element, the bubble magnetic domain is driven by drive currents 41 and 42 that pass through drive conductor layers 31 and 32. Drive currents 41 and 42 are J ₁ and J ₂ respectively
It is given as a sequence shown by . The bias magnetic field component generated in the bubble material 1 by the drive currents 41 and 42 is applied to the compensating conductor layer 33 in the opposite direction (opposite sign) to the sum of the drive currents J ₁ +J ₂ in the direction J of cell B in FIG. The sequence shown in ₃ [J ₃ = - (J ₁ +
J ₂ )], it is compensated to almost 0.

FIG. 3 shows a second embodiment of the invention. This embodiment has the same element structure as the first embodiment, but three conductor layers, namely, driving conductor layers 31 and 32 and compensation conductor layer 33, are electrically connected to the portion 3 on the element. Keeping in touch. In this embodiment, the compensation conductor layer 33 is replaced by the drive conductor layers 31 and 32.
By setting the common current path to the current path, the density J ₃ of the current 43 in the compensation conductor layer 33 is automatically changed to the density J ₁ of the current 41, 42 in the drive conductor layers 31, 32,
The relationship J ₂ and J ₃ =-(J ₁ + J ₂ ) is satisfied. That is, the compensation conductor layer 33 compensates for the bias magnetic field component for the drive conductor layers 31 and 32.

FIG. 4 shows a third embodiment of the invention. This embodiment has a structure in which the embodiment shown in FIG. 3 is turned upside down, and the compensating conductor layer is attached so as to be in contact with the bubble magnetic domain element chip support substrate 6.

The driving conductor layers 31 and 32, which are connected at one end while maintaining electrical contact, are connected to the compensation conductor layer 33 and the portion 3.
and has an electrical contact at one end. At this time, the compensation conductor layer 33 is replaced by the drive conductor layers 31 and 32.
Similarly to the second embodiment in which a common current path is provided for the two, the compensation conductor layer 33 compensates for the bias magnetic field component.

In the above three embodiments, even if the compensation conductor layer is between the drive conductor layers or between the first drive conductor layer and the bubble material, the bias magnetic field component compensation effect is not achieved. Needless to say, they are the same.

FIG. 5 shows a fourth embodiment of the invention. In this embodiment, the compensation conductor layer 33 is provided on both sides of the drive conductor layers 31 and 32 substantially parallel to them. In this embodiment, the compensation conductor layer 33 is provided on the support substrate 6 of the bubble magnetic domain element chip, which has the substrate material 2, the bubble material 1, and the driving conductor layers 31 and 32 provided thereon. . Also,
It goes without saying that even if the compensation conductor layer 33 is provided on the bubble magnetic domain element chip, the same compensation effect for the bias magnetic field component can be obtained.

Compensation for the bias magnetic field component in this embodiment is performed as follows. Now the first driving conductor layer 31
The bias magnetic field component generated through the bubble magnetic domain driving current 41 having a density J ₁ causes a compensating current 43 having a density J ₃ to flow into the compensating conductor layer 33 on both sides of the current 41.
This is compensated for by leading in the same direction as. At this time, if J ₃ = aJ ₁ , the bias magnetic field component in the bubble magnetic domain material 1 due to the current 41 and the bias magnetic field component in the bubble magnetic domain material 1 due to the current 43 are in opposite directions, and the total bias magnetic field component is extremely becomes smaller. This constant a is the width of the driving conductor layer 31.
Depends on W ₁ and the width W ₃ of the compensation conductor layer 33, approximately a
As a result of the study, it became clear that there is a relationship of =k(W ₁ /W ₃ )1/2. Here, k is a constant of 0.5 to 2.0. It has also been found that a suitable range for the ratio (W ₁ /W ₃ ) is 5 to 20.

When a bubble magnetic domain drive current 42 with a density J ₂ is also passed through the second driving conductor layer 32, the bubble material 1
The bias magnetic field component at is the sum of the currents 41 and 42. Therefore, if the sum of the compensation currents aJ ₁ and aJ ₂ for each of them J ₃ =a(J ₁ +J ₂ ) is passed through the compensation conductor layer 33, one compensation conductor layer can be used to generate a voltage from two driving conductor layers. The bias magnetic field component of is compensated.

In the above embodiments, we have described the case where there are two drive conductor layers, but it is clear that even in the case of three or more layers, the bias magnetic field component can be compensated for by providing one compensation conductor layer. .

As described above, by using the present invention, a current access type bubble magnetic domain element with a large effective usable area can be easily realized with a small number of manufacturing processes.

[Brief explanation of the drawing]

FIG. 1A is a perspective view showing a conventional current access type bubble magnetic domain element, FIG. 1B is a diagram showing a bias magnetic field component due to its conductor layer, and FIG.
FIG. 2B is a diagram showing current waveforms passing through each conductor layer, FIG. 3 is a perspective view of the second embodiment of the present invention, and FIG. 4 is a third embodiment of the present invention. FIG. 5 is a perspective view showing the fourth embodiment. 1 is a bubble magnetic domain material, 11 is a bubble magnetic domain, 2 is a substrate made of bubble magnetic domain material, 31 and 32 are drive conductor layers, 30 is an opening pattern provided in the bubble drive layer, 33 is a compensation conductor layer, 41, 42 and 43 are currents flowing through the conductor layers 31, 32, and 33, respectively;
6 and 37 are insulating layers, 5 is an effective use area of the bubble magnetic domain element, 6 is a bubble magnetic domain element chip support substrate, 1
0 is the distribution of the bias magnetic field component due to the driving conductor layer, J ₁ , J ₂ , J ₃ is the current density flowing in each conductor layer, 3
indicates an electrical connection between the driving conductor layers 31 and 32 and the compensation conductor layer 33.

Claims (1)

[Claims] 1. In a bubble magnetic domain element composed of a bubble magnetic domain material, at least two conductor layers for driving bubble magnetic domains provided thereon, and one conductor layer for bias magnetic field component compensation provided in the vicinity thereof, A current access type bubble magnetic domain element, characterized in that a total combined current flowing through all of the drive conductor layers is passed through the bias magnetic field component compensation conductor layer.