JPS6043584B2 - magnetic bubble element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bubble element having a bubble lattice structure.

In recent years, various research and development efforts have been made to increase the density of magnetic bubble elements.

As a result, bubble latex was proposed as a higher density magnetic bubble element with the same magnetic bubble domain (hereinafter referred to as bubble) size (Institute of Engineering, IP Conference Proceedings (AIPC0nf, Pr()C,) 2nd
(See No. 4, pages 617-619 (1975lf-))
. Initially, a method using electric current was proposed to access bubbles and lattice, but recently a method using rotating magnetic fields has been proposed (Applied Physics, Letters).
pl, Phys, Letters) Volume 2, No. 3, No. 16
(See page 6 (197 hours)). These magnetic bubble elements having a bubble lattice structure are characterized by coding depending on the domain wall state of the bubble (ie, 5=1 or 5=0).

In the magnetic bubble element using carbubble lattice,
A practically applicable mechanism for reading out this information has not yet been found.

The only way is that the deflection angle θ of the moving direction of the bubble with respect to the magnetic field gradient is sin θ = 85 due to the difference in the domain wall state of the bubble.
V/γdΔH2 (where S is the state of the bubble domain wall,
It has only been proposed to utilize the fact that V is the velocity of the bubble, γ is the gyromagnetic ratio, d is the bubble diameter, and ΔL is the bias magnetic field gradient between the bubble diameters. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic bubble element having a new and superior information readout mechanism in a bubble lattice structure, particularly in a bubble lattice accessed by a driving rotating magnetic field.

In other words, by utilizing the fact that the deflection angle θ of the bubble with respect to the magnetic field gradient direction differs due to the difference in the bubble domain wall state, a difference occurs in the transferable region of the bias magnetic field, and the transfer is performed normally in the S=0 bubble. We propose an element that takes advantage of the fact that if S=1 bubble is made to disappear, information can be read out in subsequent states depending on the presence or absence of the valve. More specifically, the present invention provides that when the bubble domain wall state is S = 1, the bubble transferable region of the bias magnetic field is smaller than in the S = 0 state, and disappears quickly in a high bias magnetic field, and the bubble domain wall state is is S=1 or S=0
The object of the present invention is to obtain a magnetic bubble element that has a mechanism that can clearly identify and detect which of the following is the case. When a magnetic bubble is transferred by a driving rotating magnetic field, a bubble supporting film,
In other words, a transfer path (hereinafter referred to as a pattern) made of soft magnetic material (permalloy is often used) is provided at an appropriate distance from the magnetic material such as garnet that holds the bubble.
The magnetic charges induced in this pattern by the driving rotating magnetic field cause the bubbles to be transferred.

Various patterns have been proposed for the shape of the pattern, but when the bubble domain wall state is S = 1 and there is a bias in the bubble traveling direction with respect to the magnetic field gradient, this bias is either clockwise or counterclockwise with respect to the bubble traveling direction. We have discovered that the stability against this bias differs depending on the direction, although the degree varies depending on the shape of the pattern.

In other words, when viewed so that the direction of the bias magnetic field is facing you,
When the rotation direction of the driving rotating magnetic field is counterclockwise, S=
It is stable even against the deviation of a bubble in one state, but if the rotation direction of the driving rotating magnetic field is rotated clockwise. When the bias is increased, the S=1 bubble becomes unstable with respect to the bias of the bubble, and especially when the bias magnetic field is increased and the bubble diameter becomes small, the S=1 bubble disappears quickly.

This effect is especially noticeable in the Y-shape (shape 1,
This is noticeable in patterns such as a U-shape 2, a V-shape 3, an X-shape 4, or a shape 5 in which a protrusion is added to the bottom of a U-shape.

The present invention takes advantage of this effect by providing the bubble detection mechanism with a transfer path having a pattern as described above, and changing the direction of the driving rotating magnetic field clockwise when viewed so that the direction of the bias magnetic field faces toward you. By setting the bias magnetic field to an appropriate value, bubbles with domain wall state S = 1 will disappear during this pattern transfer, bubbles S = 0 will be transferred normally, and bubble domain wall state will become S = 1 or 0 is identified and detected based on the absence or presence of bubbles.

The present invention will be explained in more detail by way of examples.

Figure 2 shows (YSnlLuCa)3(GeFe)501
. (h=3.28μM, l=0.44μM, 4πm=2
89GaL! A YIG film of 800 A was grown in contact with the bubble support film of SO) to suppress hard bubbles, and a bubble domain wall state detection mechanism having a Y-shaped pattern was provided with a spacing of 1.5 μm. 370KH
This figure shows the drivable region of the bubble in the S=1 and S=0 states when driven by z. The shaded area in the diagram is S=0
This is a region where only bubbles can be driven, S=1 bubbles disappear, and the bubble domain wall state can be detected. Figure 3 shows 250e
, 370 KHz drive rotating magnetic field shows the bubble domain wall state detectable region, where the spacing is 1.5 μm or more, there is a margin of 50 e or more, and the spacing 2.5 μm or more has a margin of 50 e or more.
At 1 μm, there is a margin of 70e. FIG. 4 shows an embodiment of the bubble element detection mechanism of the present invention.

The interval between the permalloy pattern and the bubble support layer made of garnet is 1.8 μm, and the bubbles sent from the bubble storage area 6 toward the detection unit rotate clockwise when viewed with the direction of the bias magnetic field facing you. As explained in FIG. 2, the S=1 bubble disappears while being transferred through the transfer path 8 of the Y-shaped pattern by the driving rotating magnetic field, and the S=0 bubble disappears.
Only the bubbles are transferred to the stretcher section 9, and S=
O-bubble is detected as an output signal. Therefore S=
One bubble is identified as having a detection output of 0. The shape of the transfer path 8 of the detection unit is other than Y-shape, for example, ■-shape, U-shape, etc.
Similar results can be obtained in the case of a letter shape or an X shape. As described above, the present invention provides a magnetic bubble element having an effective detection mechanism for a field access bubble lattice configuration.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing some examples of pattern shapes used in the transfer path of the detection mechanism in the present invention. FIG. 2 is a diagram illustrating the operation of an embodiment of the present invention, and shows a normally drivable region of the bubble domain wall state detection mechanism, with the shaded area being the domain wall state detectable region. FIG. 3 is also a diagram illustrating the operation of the same embodiment, and shows the domain wall state detectable region (shaded area) when the rotating magnetic field is fixed at 260e and the spacing of the domain wall state detection mechanism and bubble support layer is changed. This is what is shown. FIG. 4 is a route map showing one embodiment of the detection mechanism used in the present invention. 1...Y-shaped pattern,
2... U-shaped pattern, 3... ■-shaped pattern, 4... X-shaped pattern, 5... U-shaped pattern with a protrusion at the bottom, 6... Storage area, 7.
... Bubble traveling direction, 8... Transfer path, 9... Stretcher section, 10... Detector.

Claims (1)

[Claims] 1. In a magnetic bubble element that is provided on a magnetic material holding magnetic bubble domains and has a mechanism capable of transferring magnetic bubble domains by an in-plane driving rotating magnetic field, a bias magnetic field is set to a predetermined intensity. 1. A magnetic bubble element having a mechanism for detecting a domain wall state of a magnetic bubble domain by setting S=1 bubbles to disappear but allowing S=0 bubbles to remain. 2 The mechanism for detecting the domain wall state of magnetic bubble domains is Y
The magnetic bubble element according to claim 1, comprising a soft magnetic film having a shape such as a U-shape, a V-shape, an X-shape, or a U-shape with a protrusion at the bottom. 3. The magnetic bubble element according to claim 1, wherein in the mechanism for detecting the domain wall state of the magnetic bubble domain, the direction of rotation of the drive rotating magnetic field is clockwise when viewed so that the direction of the bias magnetic field is directed toward the front. 4 The distance between the mechanism that detects the domain wall state of the magnetic bubble domain and the magnetic material that holds the magnetic bubble domain is 1.5
The magnetic bubble element according to claim 1, which has a diameter of μm or more.