JPS598905B2 - Cylindrical domain expander - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic domain expander in an expanded solid magnetic domain detection device in which a magnetic domain transfer circuit and a magnetic domain detection device are formed simultaneously in a cylindrical magnetic domain storage device, and particularly to The present invention relates to a magnetic domain expansion device with improved operating characteristics.

As shown in Fig. 1, the conventional expanded solid magnetic domain detection device is constructed by stacking a large number of chevron transfer elements 1, each having an L-shaped shape, made of a soft ferromagnetic thin film such as permalloy, at right angles to the direction of magnetic domain movement. Magnetic domain expanders (hereinafter simply referred to as expanders) 2, 3, and 4 are constructed with a predetermined period T, and between the expanders 2 and 3, magnetoresistive elements are connected alternately to both ends of Chevron transfer elements. A detector (hereinafter simply referred to as detector) 5 was arranged to transfer and detect magnetic domains.

In the magnetic domain expansion device configured in this way, the expansion devices 2, 3, and 4 are repeatedly arranged in multiple stages as shown in FIG. ) at right angles to several hundred times and introduced into the detector 5,
Perform magnetic domain detection.

In this case, the detector 5 is required not only to produce a magnetoresistive effect, but also to have characteristics as an expander capable of holding and transferring the expanded magnetic domain. Therefore, the characteristics of the expanded solid magnetic domain detection device largely depend on the characteristics of the expanders 2, 3, and 4. However, in the magnetic domain expansion device with the above configuration, the expansion devices 2, 3, 4 configured by the Chevron transfer element 1 are G, P, Vella-Cole.
iro and T, J, Ne1s0n (App1, Phys0
Le, V01.24, N0.8, 397-398
, 15 April 1974), there is a problem in that the movement of the enlarged magnetic domain is non-uniform.

That is, the relationship between the rotation angle increment of the in-plane rotating magnetic field and the moving distance of the enlarged magnetic domain changes greatly depending on the position of the magnetic domain on the enlargers 2, 3, and 4. FIG. 2 shows a state in which the enlarged magnetic domain moves, for example, on the enlarger 4. As shown in FIG. In these figures, figure a shows, for example, a state in which the enlarged magnetic domain 6 jumps from the enlarger 3 to the enlarger 4 in FIG. Here, as the in-plane rotating magnetic field Hr rotates, the enlarged magnetic domain 6 is further expanded to the magnetic domain 7 in FIG.
The magnetic domain 3 is gradually moved on the enlarger 4. During this time, although the rotating magnetic field Hr rotates by about 180 degrees, the enlarged magnetic domain 8 remains at almost the same position as a in the figure. Next, when the rotating magnetic field Hr rotates slightly, the expanded magnetic domain 8 suddenly moves a large distance, crosses the apex (center) of the expander 4, and becomes the magnetic domain 9 shown in d of the same figure.
The state will be as follows. Here, the magnetic domain 9 expanded beyond the apex of the expander 4 is rotated by the rotation of the rotating magnetic field Hr as shown in FIG.
As shown in f, the magnetic domain 10 and magnetic domain 11 move relatively uniformly, and when the rotating magnetic field Hr rotates 360 degrees, it returns to its original state, that is, the state shown in a in the figure. The discontinuous movement that occurs when a magnetic domain expanded to -4 jumps the gap between the expanders, moves to the next expander, and then moves to the apex of this expander is caused by a V-shaped transfer element. commonly observed in magnifiers. The non-uniformity of the movement of the magnetic domain expanded in this manner has been a cause of significant characteristic deterioration of the expander, that is, the magnetic domain detection device, especially when the diameter of the cylindrical magnetic domain is 3 μm or less.

With conventional expanders, this unevenness of movement is unavoidable;
It has the disadvantage that high-speed operation characteristics are worse than half-disk or asymmetric Sipron transfer paths.
Furthermore, in the magnetic domain expansion device of FIG.
The margin for the gap length between the two is small, which poses a major problem in manufacturing the expander pattern, especially when the magnetic domain diameter is miniaturized. In an attempt to improve this problem, as shown in FIG. 3, the gap length margin can be greatly increased by using a magnetic domain expander 13 in which the asymmetric Sipron transfer element 12 is used as an expander component. can be improved. However, according to the magnetic domain expansion device using the asymmetric Sipro 7 transfer element 12, good characteristics can be obtained up to a cylindrical magnetic domain diameter of about 2 μm, but as the magnetic domain diameter becomes further finer, the characteristics deteriorate. That is, the strength of the in-plane rotating magnetic field required to operate the enlarging device increases significantly, and the power consumption required to drive the enlarging device increases. As described above, conventional magnetic domain expansion devices have the drawback that as the diameter of the magnetic domain becomes smaller, the characteristics deteriorate, particularly the strength of the rotating magnetic field increases significantly. Therefore, the object of the present invention is to
By eliminating the drawbacks of the conventional magnetic domain expansion device described above and shifting the apex of the expansion device to the side where the expanded magnetic domain to be transferred enters the expansion device, the expanded magnetic domain can be uniformly distributed on the expansion device. The object of the present invention is to provide a magnetic domain expansion device that realizes movement at 300 degrees and has excellent high-speed operation characteristics.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 4 is a block diagram of essential parts showing an embodiment of a cylindrical magnetic domain expansion device according to the present invention.

In the same figure, 14, 15, 16 are magnetic domain expanders, and 17 is a magnetic domain detector. It is formed from a thin film. The magnetic domain expanders 14, 15, and 16 are constituted by an expander component 18 in which the apex t of the asymmetric Sipron transfer element is shifted in the direction of magnetic domain entry. In addition, the magnetic domain detector 17 is constructed by alternately connecting the apex portion of an asymmetric Sipron transfer element whose apex portion t is shifted in the magnetic domain ingress direction and the magnetic domain egress side, similarly to the magnetic domain expanders 14 to 16. . In this case, the apex t of the magnetic domain expanders 14, 15, 16 and the magnetic domain detector 17 is 1/16 to 1/16 of the repetition period T on the side where the magnetic domain enters.
It is configured within a Z-shifted range. Reference numeral 19 denotes a cylindrical magnetic domain transfer path consisting of an asymmetrical apron or half-disk transfer element; 20 and 21 the cylindrical magnetic domain transfer path 19, in which the domain length gradually increases from a state where the domain length is approximately the magnetic domain diameter at right angles to the direction of movement. Therefore, a state in which the number of expander elements including the expander component 18 is increased is shown.

According to the magnetic domain expander configured in this way, the asymmetric Sieprus transfer element 14,1 consisting of the expander component 18
By shifting the apex portions t of 5 and 16 in the direction of magnetic domain entry, which is different from that of a normal siebron or an asymmetric siebron transfer element,... The enlarged magnetic domain is e.g. enlarger 1
The moving distance from the left end of 4 to the apex t is reduced, and the movement of the magnetic poles on the magnifying device during that time due to the rotation of the in-plane rotating magnetic field becomes uniform.

Finally, the discontinuous magnetic domain movement explained in FIG. 2 is greatly reduced in FIG. 4, and excellent operating characteristics are obtained not only in terms of operating margin but also in terms of high-speed operation. In addition, because the movement of the magnetic domains expanded in this way is uniform,
A further advantage is that the repeating period T in the direction of movement of the expanders 14, 15, and 16 domains can be made larger than in the conventional case. That is, the repetition period T can be increased without impairing high-speed operation characteristics, and the operating margin can be improved. In addition, the magnetic domain detector 17 configured in the same manner as the expander 14 has both ends or apex portions of the expander and the entry side of the expanded magnetic domain, which is the conventionally known siebron transfer pattern. Compared to a detector in which the detectors are connected alternately, an effect similar to that of a magnifying device is produced, and the transfer characteristics can be greatly improved. Here, if the apex is shifted to the side where the magnetic domain exits, the transfer characteristics will be worse than in the case of a conventional expander where the apex is in the center.
This is clear from the explanation from line 4 to page 4, line 15.

Therefore, the amount by which the apex is shifted is 1A6 of the repetition period T.
If it is below, the desired effect of the present invention cannot be obtained, and the characteristics will be the same as a conventional enlarger having a vertex at the center. In addition, if the apex is shifted by 1/3 or more of the D repetition period T, the moving distance from the side where the magnetic domain enters to the apex will be shortened, but the permalloy pattern length will also be shortened accordingly, causing expansion. This results in a decrease in the magnetic domain driving force of the device, and the transfer characteristics deteriorate. Therefore, the amount of deviation of the apex portion is preferably in the range of 1/16 to 1/3 of the repeating cycle of the expander. FIG. 5 is a block diagram of main parts showing another embodiment of the magnetic domain expansion device according to the present invention.

Note that this figure shows only the portions corresponding to the magnifying devices 14, 15, and 16 in FIG. 4. In this figure, the expander components 18 of the above embodiment are combined in pairs as shown to constitute an expander component 22, and a magnetic domain expander 23 is constructed. According to such a configuration,
Expander components 18 are combined in pairs and expander 23
By configuring this, the driving force for the expanded magnetic domain of the expander increases, and even if the inter-expander gap becomes large, there is less change in the operating margin of the expander. The degree of margin can be significantly improved compared to the above embodiment.

FIG. 6 shows the operating margins of a conventional expander (curve 1) having the apex at the center, as well as an expander (curve 1) configured with the apex shifted in the magnetic domain entry direction of the expander.

In this case, the domain medium is (YSmLuCa)3(FeGe
) 5012, the material constants of the medium are film thickness 17 μM, magnetic domain width 15 μM, characteristic length 0.15 μM, and saturation magnetization 49
, 0G1 domain demagnetization field is 2800e. Note that the operating margin shown in the figure was measured at a rotating magnetic field frequency of 200 KHz. As is clear from the figure, the magnifying device configured by shifting the apex shown by curve 1 in the direction of entry of the magnifying device has a stronger effect on the rotating magnetic field than the conventional expander which has the apex shown by the curve at the center. Characteristics have been significantly improved in the low range. As described above, according to the magnetic domain expansion device of the present invention, there is little deterioration in characteristics due to miniaturization of the magnetic domain diameter, and excellent high-speed operation characteristics can be obtained.

In addition, the gap margin between the expanders is large, and variations in characteristics due to variations in manufacturing conditions can be minimized, and an improvement in manufacturing yield can be expected. Furthermore, even if the magnetic domain diameter is miniaturized, there is only a small increase in the strength of the rotating magnetic field required. Therefore, an extremely excellent effect can be obtained in that the increase in power consumption that occurs due to the miniaturization of the magnetic domain diameter can be minimized. It will be done.

[Brief explanation of the drawing]

Fig. 1 is a main part configuration diagram showing →u of a conventional cylindrical domain expanding device, and Fig. 2 shows the relationship between the position of the expanded magnetic domain on the conventional magnetic domain expanding device and the direction of the in-plane rotating magnetic field. Main part configuration diagram,
FIG. 3 is a block diagram of main parts showing an example of an expander using an asymmetric Sipron transfer element as a component of the enlarger, FIG. 4 is a block diagram of main parts showing an embodiment of a magnetic domain expansion device according to the present invention, and FIG. 6 is a diagram showing the main part of a magnetic domain expander showing another embodiment of the magnetic domain expander according to the present invention, and FIG. 6 is a measurement result of the operational margin of the conventional hexagram and the magnetic domain expander according to the present invention. DESCRIPTION OF SYMBOLS 1... Siepron transfer element, 2, 3, 4... Magnetic domain expander, 5... Magnetic domain detector, 6-11... Magnetic domain, 12
...Asymmetric Siepron transfer element, 13, 14, 15,
16... Magnetic domain expander, 17... Magnetic domain detector, 18.
... Enlarger component, 19, 20, 21... Magnetic domain transfer path, 22... Enlarger component, 23... Magnetic domain expander.

Claims (1)

[Claims] 1. A magnetic domain expander, which is constructed by arranging asymmetric V-shaped domain transfer elements made of a soft ferromagnetic thin film in multiple stages on a magnetic thin film capable of holding cylindrical magnetic domains, is repeatedly arranged in multiple rows in the same direction as the magnetic domain traveling direction. In the cylindrical magnetic domain expanding device that expands the cylindrical magnetic domain in a direction perpendicular to the magnetic domain advancing direction and transfers the expanded magnetic domain, the expanded magnetic domain is transferred and enters the magnetic domain expander. A cylindrical magnetic domain expansion device comprising an asymmetrical V-shaped magnetic domain transfer element whose apex is shifted by a range of 1/16 to 1/3 of the repetition period of the magnetic domain expansion device.