JPS6338797B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a memory element of a magnetic bubble memory device used as a memory of a terminal of an electronic computing device.

(2) Background of the technology Magnetic bubble memory devices, which have recently come into use, are nonvolatile, capable of large-capacity, high-density storage, low power consumption, small size, and light weight, and furthermore, they do not require any mechanical elements. Since it is a solid-state device that does not contain any metal, it has various characteristics such as high reliability, and is therefore expected to have a promising future as a large-capacity memory.

The memory element used in this magnetic bubble memory device is made by forming a thin film of magnetic garnet on a gadolinium-gallium-garnet single-crystal substrate by liquid phase epitaxial growth, and then forming a permalloy thin film or forming bubbles by ion implantation on top of the thin film of magnetic garnet. A transfer pattern is formed in advance, and if there is a bubble at a specific location in the transfer pattern, information is recorded as "1", otherwise as "0".

The bubble magnetic domain detector that detects the presence or absence of bubbles in such magnetic bubble memory devices has a structure that stretches bubbles onto a strip-shaped magnetic thin film and detects the bubbles using the magnetoresistance effect produced in the magnetic thin film. It is being

(3) Prior art and problems Figure 1 is a diagram for explaining a conventional bubble magnetic domain detector, in which 1 indicates a transfer pattern;
2 shows a conductor pattern for bubble extension formed in a hairpin shape. Note that the band-shaped magnetic pattern is provided within the loop of the hairpin-shaped conductor pattern, but is not shown in the figure.

In the conventional bubble magnetic domain detector, the conductor pattern 2 is arranged so that the bubble extends in a direction perpendicular to (or parallel to) the bubble transfer direction indicated by arrow A, as shown in Fig. 1. If it is perpendicular or parallel to the bubble transfer direction, there is a drawback that the detection efficiency becomes low during high-speed driving.

(4) Object of the Invention In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a magnetic bubble memory element having a bubble magnetic domain detector with high bubble magnetic domain detection efficiency.

(5) Structure of the Invention According to the present invention, this purpose is to detect bubbles using a driving magnetic field that rotates in a plane by passing current through a conductor pattern to locally lower the magnetic field and elongate the bubble magnetic domain. In a magnetic bubble memory device having a bubble magnetic domain detector that utilizes the magnetoresistive effect, the bubble magnetic domain detector has a conductor pattern arranged so that the bubble magnetic domain extends in a direction that is not perpendicular to or parallel to the bubble transfer direction. This is achieved by providing a magnetic bubble memory device characterized by the following.

(6) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a diagram showing the structure of a bubble magnetic domain detector of a magnetic bubble memory device according to the present invention.

In the figure, 3 indicates a transfer pattern for transferring bubbles, and 4 indicates a conductor pattern for expanding bubbles. Note that illustration of the magnetic thin film pattern for bubble detection is omitted.

In this embodiment, as shown in FIG. 2, the conductor pattern 4 for bubble expansion has a hairpin shape, and its longitudinal direction is not perpendicular or parallel to the bubble transfer direction indicated by arrow B of the transfer pattern 3. .

The operation of this embodiment configured in this way will be described next. The bubble is transferred on the transfer pattern 3 as the driving magnetic field rotates. At the phase when this bubble enters the cusp 3a of the transfer pattern 3, a pulse current is applied to the conductor pattern 4 so that the local magnetic field of the cusp becomes low. The bubble is the cusp 3a
When the bubble exists in the conductor pattern, the bubble extends into a striped magnetic domain and is detected by a magnetoresistive sensing element (not shown) such as a permalloy thin film placed in the center of the conductor pattern. Here, the signal V of the detection element is proportional to the detection efficiency, which is determined by the length l of the striped magnetic domain and the direction of the driving magnetic field at the time of detection. By the way, the stripe length l increases in proportion to the pulse application time T, but the maximum T that can be applied depends on the driving frequency.

Therefore, the inclination angle θ (θ=
The angle of inclination of the conductor pattern with respect to a line perpendicular to the bubble transfer direction may be selected such that the maximum detection efficiency is obtained at the end of pulse application.

FIG. 3 shows the experimental results of the relationship between the inclination angle θ of the conductor pattern for bubble expansion and the detected voltage in the bubble magnetic domain detector of the magnetic bubble memory device of the present invention. In this case, the experiment was conducted under the following conditions: the frequency of the driving magnetic field was 100 KHz, the bias magnetic field was 340 Oe, the driving magnetic field was 50 Oe, and the pulse for bubble expansion was θ = -135° and the pulse width was 10 μs. Under these conditions, the peak of the detected voltage is around θ=45°, but this value varies depending on the conditions.

(5) Effects of the Invention As explained in detail above, the magnetic bubble memory element of the present invention has a bubble magnetic domain detector in which the direction of the conductor pattern for bubble extension is tilted in a direction that is not perpendicular to or parallel to the bubble transfer direction. By providing this, a great effect is that high detection efficiency of bubble magnetic domains can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining a conventional bubble magnetic domain detector of a magnetic bubble memory device, FIG. 2 is a diagram showing the structure of a bubble magnetic domain detector of a magnetic bubble memory device according to the present invention, and FIG. 3 is a diagram of the present invention. FIG. 2 is a diagram showing the relationship between the inclination angle of a conductor pattern for bubble expansion and the detected voltage of a magnetic bubble memory element according to the present invention. In the drawings, 3 indicates a bubble transfer pattern, and 4 indicates a conductor pattern.

Claims (1)

[Claims] 1. Bubble magnetic domain detection using magnetoresistive effect, in which bubbles are driven by a driving magnetic field that rotates in-plane, and current is passed through a conductor pattern to locally reduce the magnetic field and detect by elongating the bubble magnetic domain. A magnetic bubble memory element having a conductor pattern, wherein the bubble domain detector has a conductor pattern arranged so that the bubble magnetic domain extends in a direction that is not perpendicular to or parallel to the bubble transfer direction.