JPS5864692A - One-layered conductor type current driving magnetic bubble element - Google Patents

Abstract

PURPOSE:To decrease a driving current by providing a condutor layer which has a perforated pattern for transfer on a magnetic film, and also arranging a nonmagnetic thin-film layer, which has a perforated pattern shifting from said perforated transfer pattern slightly, on the opposite surface. CONSTITUTION:On a magnetic film which has a constant of magnetic strain that is not ''0'', a tensile conductor layer 15 having a perforated pattern for transfer is provided, and a nonmagnetic thin-film layer 16 having a perforated pattern is arranged oppositely. When current pulses 12 are applied to the conductor 15 between time points 50 and 51, a bias magnetic field due to the disorder of the current due to the perforated pattern for transfer is produced, and a bubble has a stable point 30. The magnetic field is erased and the bubble moves to a position 31 between time points 51 and 52. Between 52 and 53, it moves to a point 32 again with a magnetic field gradient. Similarly, the bubble is transferred as shown by an arrow 20. Consequently, the simple peripheral circuit transfers bubbles with a fine current.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current-driven magnetic bubble element. In a storage device that uses magnetic bubbles (hereinafter simply referred to as bubbles) as information carriers, the bubble transfer method is to transfer a chevron-shaped or Y3-shaped pattern made of soft magnetic tears such as permalloy using an in-plane rotating magnetic field applied externally. A so-called magnetic field drive method, in which bubbles are attracted to magnetic poles generated by sequential magnetization and transferred, has been common. However, with this magnetic field drive method, as the bubble diameter is reduced to increase storage density, the in-plane rotating magnetic field required for bubble transfer increases rapidly, so the voltage applied to the in-plane rotating magnetic field generation coil increases. However, it is well known that it has the major drawback of not being able to perform high-speed transfers. In order to overcome these drawbacks of the magnetic field drive system, it is necessary to realize a bubble transfer system that does not use a coil for generating an in-plane rotating magnetic field.

As a bubble transfer method that does not use a coil for generating an in-plane rotating magnetic field, there is a current drive method (hereinafter referred to as a pole to which the present invention relates) in which an alternating current is passed through a meandering conductor line formed on a magnetic thin film to drive a bubble. (referred to as the initial current drive method to distinguish it from the newer current drive method) has become publicly known.

Although some improvements have been made to this initial current drive method, the shape of the conductor wrap is too complicated, and the shape of the conductor entanglement is too complicated, and it is necessary to use a filter that is essential for giving directionality to the bubble motion. Attempts to increase the storage density result in an increase in the power consumption of the device due to factors such as the fact that the bubble must be transferred against the trapping force caused by the magnetic interaction between the bubble and the P layer. It wasn't practical.

In order to overcome these drawbacks that were inevitable with the magnetic field drive method and the initial current drive method, a new current drive method called a two-layer conductor type current drive method has been proposed in recent years. This two-layer conductor type current drive method requires the use of a much simpler opening pattern than the initial current drive method, so it is possible to dramatically improve storage density. However, the two-layer conductor type current drive system has serious drawbacks in that the two conductor layers must each be driven independently, resulting in very high power consumption and the peripheral circuitry becoming extremely complex. There is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a single-conductor current-driven magnetic bubble element that can transfer bubbles with as little current as possible using a very simple peripheral circuit. Another object of the present invention is to provide a corner pattern for changing the transfer direction that is suitable for such a single-conductor current drive system.

Before explaining the present invention in detail, the general properties of magnetic materials will be described first. For example, El Sherta (,t,,5
In October 1979, the Journal of Applied Physics (Journal of Applied Physics) was published by
of Appli@d Physles, Vol. 50, No. 11, pp. 7862-7864, a tensile thin film pattern on a bubble material exhibiting a magnetostrictive effect is At the edge, the domain wall energy changes as shown in Figure 1 due to the inverse magnetostriction effect. In FIG. 1, the horizontal axis 1 indicates the position of the domain wall, the vertical axis 2 indicates the domain wall energy, 3 indicates the domain wall energy distribution, and 4 indicates the tensile thin film pattern.

The present invention is based on the following principle that utilizes the properties of the above-mentioned magnetic materials, and eliminates the serious drawbacks of conventional current drive systems such as the initial current drive system and the two-layer conductor type current drive system. This provides a new corner slam.

FIG. 2 is a diagram showing the basic principle of the present invention.

#! In FIG. 2, 5 is a bubble, arrows 6 and 7 are directions of driving force applied to the bubble domain wall, and 8 is a boundary 14 of the tensile thin film pattern 4 in the direction of a bias magnetic field. When the bubble is in the position shown in FIG. 2(a), the domain wall energy shown in FIG. 1 and 3 on the right side of the thin film pattern boundary decreases as it approaches the thin film pattern boundary. It receives a driving force in the direction indicated by 7.

On the left side of the thin film pattern boundary, the domain wall energy decreases as the distance from the thin film pattern boundary increases, so the pebble domain wall on the left side of the thin film pattern boundary receives a driving force in the direction shown by arrow 6. Therefore, the bubble as a whole receives a driving force that directs it toward the inside of the thin film pattern. Therefore, if no external force is acting on the bubble, the bubble will be 11
It is not possible to stop at the position shown in Figure 12 (a),
The position where the domain wall energy is minimum, that is, Fig. 2 (b)
Move to the stable position shown by .

Next, the operating principle of the single-layer conductor type current-driven magnetic bubble element of the present invention based on the above-mentioned basic principle will be explained in the 3rd v! This will be specifically illustrated using an example of implementation shown in P. The third figure shows an example of the waveform of the current flowing through the conductor layer, and FIG. 3(b) shows an example of the corner pattern of the present invention.

In FIG. 3(a), the vertical axis 11 is the current value, the horizontal axis 10 is the time, 12 is the current waveform, 50, 51, 52°ss, 54,
55, 56, 57.58-. 59.60 indicates each time on the horizontal axis lO. $1!3 In Figure (b)', the arrow 13 indicates the positive direction of the current, the direction 14 of the bias magnetic field, 15 the perforated pattern for transfer provided in the tensile conductor layer, 1
6 is a perforated pattern provided in a tensile non-magnetic thin film layer formed facing the conductor layer, 30, 31, 82, 33,
8° 4, 35° 36.37, 38.39 indicates the bubble position %20 arrow indicates the bubble transfer direction.

When a bipolar current pulse such as 12 in Figure 3(a) is applied to the conductor layer, at the time between 50 and 51 in Figure 3(a), the bias caused by the current disturbance due to the perforated pattern for transfer occurs. A magnetic field distribution (hereinafter simply referred to as magnetic field distribution) is generated and the position indicated by 30 becomes a stable point of the bubble. next 51
During the period between -52 and 52, current flows through the conductor layer and the magnetic field distribution disappears, so the bubble moves to position 31 based on the basic principle explained using FIG. During the next time period 52-53, the magnetic field distribution expands again and the bubble moves to the position indicated by 32 under the driving force of the magnetic field gradient. In the next time period 53-54, the magnetic field distribution disappears and the bubble moves to position 33 based on the basic principle described above. During the next time period 54-55, the bubble at position 33 is moved to position 34 due to the magnetic field distribution due to the bias magnetic field gradient directed towards position 34. next 55-5
Since the magnetic field distribution has disappeared during the time period of 6, the magnetic field is moved to the position of the bubble 35 based on the above-mentioned basic principle.

In the next time between 56 and 57, a magnetic field distribution occurs such that both positions 32 and 36 become stable points for the bubble, but 3
Since the distance between 5 and 36 is smaller than the distance between 35 and 32, the bubble at position 35 receives the magnetic field gradient toward position 36 and moves to position 36. During the next time period 57-58, the magnetic field distribution disappears and the bubble moves to position 37 based on the basic principle described above. During the next time p between 58 and 59, a magnetic field distribution occurs, so the bubble moves to position 38 as it receives a magnetic field gradient from position 37 to position 38. In the next time between 59 and 60, the magnetic field distribution disappears and the bubble moves to position 39 based on the basic principle. Therefore, at the time between 50 and 60, Bab /I/ is 30, 31, 32, 33 degrees 34. 35, 36, 37, 3
8. Transferred through position 39 and changes its transfer direction by 180° as shown by arrow 20.

That is, the single-layer conductor type current-driven magnetic bubble element of the present invention is provided by forming a single layer of a perforated conductor layer for transfer on a magnetic thin film having a non-zero magnetostriction constant capable of retaining magnetic bubbles, and A perforated pattern or perforated pattern is formed in this nonmagnetic thin film layer so as to be slightly misaligned with respect to the perforated pattern for transfer. It is characterized by having an island pattern and a corner pattern that can change the direction of bubble transfer by a time-modulated magnetic field gradient generated by an alternating current flowing through the conductor layer.

Next, some other embodiments of the present invention will be shown. FIG. 4 shows an embodiment of the present invention in which the shape of the pattern is changed. In Figure 4, 5 is the bubble%, 13 is the direction of the current flowing through the conductor layer, and 14
is the direction of the bias magnetic field, 15 is the perforation pattern for transfer in the tensile conductor layer, 16 is the perforation pattern provided in the tensile non-magnetic thin film layer, and 20 is the transfer direction of the bubble.

FIG. 5 shows an example of an implementation using an island pattern 17 in a compressible non-magnetic thin film layer. When a compressible nonmagnetic thin film layer is used, the domain wall energy distribution near the pattern boundary is
The distribution becomes like the porcelain energy distribution shown in 3 in the figure folded back about the vertical axis 2.

Therefore, when using a compressible non-magnetic thin film layer, by providing an island pattern that is inversely symmetrical to the perforated pattern, the bubble transfer direction can be controlled based on the same operating principle as explained using FIG. It can be changed.

In FIG. 5, 5 is a bubble, 13 is the direction of the current flowing through the conductor layer, 14 is the direction of the bias magnetic field, 15 is a transfer perforation pattern in the tensile conductor layer, and 17 is an island in the compressible non-magnetic thin film layer. The pattern %20 is the bubble transfer direction.

FIG. 6 is an example in which the present invention is applied to a part of a corner where the bubble transfer direction is changed by 90'. jI6 In figure 5, 5 is a bubble, 13 is the direction of the current flowing through the conductor layer, 14 is the direction of the bias magnetic field, 15 is the perforated pattern for transfer in the tensile conductor layer, and 16 is provided in the tensile nonmagnetic thin film. In the Taanaaki pattern, 20 is the bubble transfer direction.

Various shapes of patterns in the conductor layer and nonmagnetic thin film can be considered in addition to the examples shown in FIGS. 3, 4, 5, and 6, but these will be explained using FIG. 83. Any shape that can transfer bubbles based on the operating principle described above is included in the present invention.

Methods for forming perforated patterns for transfer in conductor layers and perforated patterns in non-magnetic thin films include wet chemical etching, plasma etching, anodic etching, etc.; It goes without saying that any forming method that causes stress is included in the present invention.

[Brief explanation of drawings]

Figure 181 is 11M of the explanatory diagram shown in the paper by El-Shinaru et al. FIG. 2 is a diagram illustrating the basic principle of weak original firing. FIG. 3 is a diagram specifically illustrating the operating principle of the present invention using an example of implementation. FIG. 4, FIG. 15, and FIG. 6 are diagrams showing embodiments of the present invention. 1 is the horizontal axis showing the position of the domain wall, 2 is the vertical axis showing the domain wall energy, 3 is the domain wall energy distribution, 4 is the tensile thin film pattern, 5 is the company bubble, 6. The direction of the driving force received by the IFI bubble magnetic wall, 8 the boundary of the thin film pattern, 10 the horizontal axis representing time, 11 the vertical axis representing the current value, 12 the current waveform, and the arrow 13 the direction of the current flowing through the conductor layer. ,50,51,
52,53°54.55,56,57.5B,59.6
0 is each time on the horizontal axis 10, 30, 31, 32, 33, 3
4°35.36, 37, 38.39 are bubble positions W1.
．． 14 is the direction of the bias magnetic field, 15 is a perforated transfer pattern provided in the tensile conductor layer, 16 is a perforated turn provided in the tensile nonmagnetic thin film layer, and 17 is a compressible nonmagnetic The island-shaped turf provided in the thin film layer, 20 is the bubble transfer direction. Figure 1 Figure 3

Claims (1)

[Claims] 1. On a magnetic thin film having a magnetostrictive gravity other than O capable of holding magnetic bubbles, a perforated pattern for transfer is arranged such that a line connecting the centers exhibits a bend at at least 1t11 points. A single conductor layer is formed, and a non-magnetic N film layer is formed facing the conductor layer so as to be separated from each other by Kg4 and electrically insulated. A single-layer conductor current-driven magnetism, characterized in that a perforated pattern or an island-like pattern is provided with a slight positional shift with respect to the perforated pattern, and has means for applying a substantial alternating current to the conductor layer. bubble element. B Arrange the above perforation patterns for transfer in a substantially V-shape, and apply perforation patterns or island-like patterns in the non-magnetic thin film to the conductor layer for transfer perforation patterns at the apex of the V-shape. In a direction parallel to the direction of the flowing alternating current,
In addition, regarding other perforated transfer patterns, the layer structure described in item 1 of the scope of patent I is characterized in that the perforated pattern for transfer is provided with a slight positional deviation in the direction perpendicular to the direction of the alternating current flowing through the conductor layer. Conductor-type current-driven magnetic bubble element. λ The perforated transfer patterns described above are arranged in a substantially L-shape, and the perforated patterns or island-like patterns in the nonmagnetic thin film are arranged in a conductor layer for the perforated patterns for transfer on one side of the L-shape. The conductor layer is arranged in a direction parallel to the direction of the alternating current flowing through the conductor layer, and with a slight positional shift in the direction perpendicular to the direction of the alternating current flowing through the conductor layer with respect to the perforated pattern for transfer on the other side. A single-layer conductive current-driven magnetic bubble element according to claim 1 of the patent, characterized in that: