JPH04113578A - Magnetic storage element - Google Patents

Abstract

PURPOSE:To arrange a plurality of stripe domains with good stability by arranging a first groove, a second groove and a domain generator at a prescribed position. CONSTITUTION:A groove 4 (the first groove) is formed in an area holding the domain on a stripe domain holding layer 1, and a groove 16 is formed in the area opposed to the one top end area of the groove 4. This groove 16 is a guide groove for preventing the domains arranged around the groove 4 from extending and when stretching the domains to a gate part. A domain generator and means 8 and 20 for generating magnetic flux in a local surface are arranged at the both sides of the groove 4 as well as a conductor 8 is arranged so that its envelope is coincident with a line connecting the tips of the groove 4 and the line connecting the tips of the groove 16. Thus, it is possible to extend the stripe domain along the objective longitudinal direction of a groove dugging part to the prescribed position with the good stability and to stabilize the plural number of stripe domains.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a nonvolatile ultra-high density solid state magnetic memory element.

(Prior art) This magnetic memory element includes an information reading means, an information writing means, and an information storage means, and has a stripe existing in a ferromagnetic material (including a ferrimagnetic film) whose easy magnetization direction is perpendicular to the film surface. It has means for holding and transferring adjacent vertical Bloch lines (hereinafter referred to as VBL) formed in the Bloch domain wall around the domain as a pair within the Bloch domain wall. For example, when the element configuration is a Major-minal loop configuration, in the Major line, bubbles are used as information carriers, the minor loop is configured with striped domains, and VBL pairs existing in the Bloch domain wall around the bubbles are used as information carriers. To show the overall flow of information, first, the information written by the bubble generator (column of bubble presence/absence) moves along the write major line. When one page of information is written on the Meisha Line, in order to store it in the Minor Lube, the information on the Meisha Line indicated by the presence or absence of bubbles is transferred to the Minor Lube in the form of VBL7. Therefore, the write transfer gate has a function of converting the presence or absence of a bubble into the presence or absence of VBL7t. The minor loop is composed of a Bloch domain wall that can hold a VBL pair. Further, the minor loop has a function of reading out the VBL pair of the striped domain domain wall and moving it to the transfer gate as necessary. Information transfer from the minor loop to the read major line involves converting VBL pairs to bubbles. The bubble detector reads the converted bubble presence/absence column. In this way, by configuring the minor loop with striped domains existing in the bubble material and using VBL pairs instead of bubbles as information carriers on the minor loop, storage density can be improved by approximately two orders of magnitude compared to bubble elements. can be achieved.

In this device, an important technique is to stably arrange a large number of magnetic domains at predetermined positions on the chip.

One way to deal with this is to bring the stripe domain domain wall to the outside of the trench boundary boundary layer thickness step (Japanese Patent Application No. 6O-079658). The reason for this is that when a stripe domain is set to include the trench and the outside of its boundary, the film thickness step at the trench boundary generates a demagnetizing field that prevents the domain wall outside the boundary from approaching the film thickness step. This is because the magnetic domain wall can respond to the VBL pair drive driving stray magnetic field applied from the outside without being hindered, and the response of the magnetic domain wall can be reversible. This is a necessary condition for VBL versus retaining stone wall stabilization. On the other hand, when striped domains are confined within the grooved portion, the difference in film thickness generates a demagnetizing field that strongly suppresses the striped domains from moving outside the grooved boundary. For this reason, the domain wall cannot freely act in response to an externally applied magnetic field. Therefore, it is necessary to initially set the stripe domain so that the stripe domain domain wall is located outside the trench boundary boundary film thickness step part.

(Problems to be Solved by the Invention) Figures 6(a) and 6(b) show the main parts of the structure.

An example of a formation technique for hollowing out the center 4 of the region in the domain holding layer 1 on the substrate 2 where the domain is desired and arranging a closed domain domain wall so as to surround it is I.
E.E. Transaction on Magnet
Iris (IEEE Trans, Magn,...
MAG-22°784 (1986)). Here, 3 is a spacer, 6 is a hollowed out portion of the guard domain holding layer, and 8 is a conductor for generating magnetic domains. conductor 8
A region 23 where the notch 13 is sandwiched between the groove 4 and the groove 16
When the magnetic field enters the range, the bias magnetic field range in which magnetic domains can be generated is interposed as shown in FIG. Also,
As shown in FIGS. 8(a) and 8(b), when the conductor 8 does not overlap the grooves 4 and 16, that is, when it is separated from the grooves 4 and 16, the area where the grooved portions are arranged in parallel There is a considerable difference in the magnitude of the bias magnetic field at which the bubble domain changes to a stripe domain between the region 23 and the region 28 where there is no grooved portion, and the bias magnetic field in the trenched region 23 must be lowered compared to other regions. It turns out that there is a drawback that the domain does not grow. When the bias magnetic field is lowered until the domain extends in the region 23 between the grooves in the region including the grooved portions, the domain extends in one of the grooved portions and becomes the side where the bubble generator 8 is located. As soon as it reaches the opposite side, that is, the area 28 where the conductor button 20 for domain coupling is located, the domain expands, and a stray pattern domain is formed over the entire area 28 where the conductor button 20 is located. The domains that are extending through the grooved region 23 behind the already extending domains are obstructed by the stray domain and cannot extend to the point where they cross under the conductor batten 20 for domain joining. As a result, a domain surrounding the groove 4 cannot be generated. In other words, even if the conductor overlaps the grooves 4 and 16 or is apart from the grooves 4 and 16, there is a drawback that a domain surrounding the groove 4 cannot be generated.

As mentioned above, conventional magnetic memory elements have had problems in stably arranging a large number of magnetic domains. An object of the present invention is to eliminate these drawbacks and provide an ultra-high-capacity solid-state magnetic memory element in which the conditions for applying an external magnetic field for stably arranging striped domains can be simplified.

(Means for Solving the Problems) The present invention provides a ferromagnetic (including ferrimagnetic) film having an information reading means, an information writing means, and an information storage means, and whose easy magnetization direction is perpendicular to the film surface. In a magnetic recording element having a means for holding and transferring a pair of two adjacent perpendicular Bloch lines formed in a Floch domain wall at the boundary of a striped domain existing in a Bloch domain wall,
A first groove is provided in the striped domain holding layer over a region where the striped domain is to be arranged, and each adjacent groove is provided in one tip region of the first groove along the longitudinal direction of the first groove. A second groove is arranged at a position corresponding to the middle of the groove of node 1, a means for generating a magnetic domain is arranged in a region sandwiched between the first groove and the second groove, and the envelope of the generator is It is characterized in that it coincides with a line connecting the tips of the first grooves and a line connecting the tips of the second grooves.

(Function) By arranging the first groove, the second groove, and the domain generator at predetermined positions, striped domains can be stably extended to a predetermined position along the longitudinal direction of the target groove digging, and a large number of striped domains can be produced. Striped domains can now be stabilized.

(Example) FIG. 1 is a diagram showing an example of the present invention. The present invention will be explained using FIG. Grooves 4 (first grooves) are formed in regions on the striped domain retention layer 1 where domains are desired to be retained. 5 is a hollowed out edge. A groove 16 (second groove) is formed in a region opposite to one tip region of the groove 4. The groove 16 is a guide groove arranged around the groove 4 shown in FIG. 5(a) to prevent the domain 14 from elongating and to extend the domain to the gate portion. A domain generator and means 8 for generating a local in-plane magnetic field are provided at both ends of the groove 4,
20 are placed. The conductor 8 is arranged so that its envelope coincides with a line connecting the tips of the grooves 4 and a line connecting the tips of the grooves 16. The conductor 8 can generate domains with good controllability so that the comb-shaped comb shown by 11 in FIG.
This is a domain generator shaped like an edge 12 and a notch 13. 6 is a hollowed out part of the guard domain holding layer; 28
is the exit area of area 23.

The operation of stripe domain stabilization will be explained using FIGS. 2(a) and (b) to FIGS. 5(a) and (b). First, the magnetization of the striped domain holding layer is saturated in the same direction as the magnetization in the domain stabilized around 4 by applying a bias magnetic field. Thereafter, a current is applied to the domain generator 8 in the direction of the arrow, and the resulting magnetic field generates the domains shown at 11 in FIG. 2(a). after that,
As the absolute value of the bias magnetic field is decreased, the domain extends past the grooved portion 23 to the region 28, as shown in FIG. 3(a). Thereafter, a current is applied to the domain-coupled conductor 20 in the direction of the arrow shown in FIG. 4 to form domains as shown in FIG. 4(a).

Due to these magnetic fields, the domains 11 are joined to each other at both ends of the grooved portion, and conversely, a domain 14 surrounded by a closed domain wall 15 surrounding the grooved portion is formed. When the externally applied magnetic field is reduced to zero, its direction is reversed, and the strength of the magnetic field is increased to the direction shown by 10, a domain with domain walls surrounding the groove is formed as shown in Figure 5(a). be done. This domain is used for VBL pair maintenance. In the figure, 16 is a groove for preventing the domain from popping out and for kiting, 17 is a conversion gate, and 18 is a major line.

A 5 pm bubble material (YSmLuCa) 3 (FeGe) 5012 garnet film was grown by LPE to a thickness of 2 pm on a Gd5Ga5012 (111) substrate. The stripe domain width of this film is 5/im. Figure 1 (a), (b)
After selectively implanting ions such as He+ into the desired portions of the structure, trenches of 2 □m width and 14 □m pitch were etched using phosphoric acid. The depth of the groove created is 2
．． It was 1□m.

On top of that, a domain generator is placed at a predetermined position via a 5i02 spacer of 0.5 pm, and by a series of operations starting from the above-mentioned domain generation, the groove digging portion shown in FIGS. 5(a) and (b) is formed. Domain 1 with a closed domain wall 15 surrounding 4
I was able to successfully form 4.

(Effects of the Invention) As described above, according to the present invention, by arranging the first groove, the second groove, and the domain generator at predetermined positions, it is possible to arrange a large number of striped domains with good stability. be.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are diagrams showing examples of main structures for holding domains in the present invention, and FIGS. 2(a) and (b)
5(a) and 5(b) are diagrams showing the domain formation process of the present invention. FIGS. 6(a) and 6(b) are diagrams showing an example of a conventional domain stabilization method using a closed domain wall surrounding a grooved portion. FIG. 7 is a diagram showing domain generation conditions when the conventional method shown in FIG. 6 is used. Figure 8(a),
(b) is a diagram showing another example of the conventional domain stabilization method having a closed domain wall surrounding a grooved portion. In the figure, 1 is a domain holding layer, 2 is a substrate, 3 is a spacer, 4 is a domain holding layer hollowed out part (first groove), and 5
Hollowed out edge, 6 hollowed out part of the domain holding layer for guide, 8 and 19 are conductor patterns for domain generation, 10 is a bias magnetic field, 11 is a magnetic domain generated by the domain generator 8, 12 is a conductor pattern for domain generator 8 edge, 13 notch of domain generation conductor pattern 8, 1
4 is a hollow domain, 15 is a domain outer domain wall, 16 is a groove for preventing the domain 14 from elongating and guiding the domain to the gate portion, and 17 is a groove for guiding the conversion gate portion between the Bloch line pair and the bubble. , 17 is a conversion gate between a pair of Bloch lines and a bubble, 18 is a major line, 23 is a region sandwiched between grooves 4, and 28 is an exit region of region 23 sandwiched between grooves 4. .

Claims (1)

[Claims] (1) Bloch at the boundary of a stripe domain existing in a ferromagnetic (including ferrimagnetic) film that has information reading means, information writing means, and information storage means and whose easy magnetization direction is perpendicular to the film surface. In a magnetic memory element having means for retaining and transferring a pair of two adjacent perpendicular Bloch lines formed in a domain wall within a Bloch domain wall, a stripe domain holding layer is provided with a a groove is provided, and a second groove is arranged in one tip region of the first groove at a position corresponding to the middle of each adjacent first groove along the longitudinal direction of the first groove. A means for generating a magnetic domain is disposed in a region sandwiched between the first groove and the second groove, and the envelope of the generator is located between a line connecting the tips of the first groove and the second groove. A magnetic memory element characterized by a line connecting the tips of the magnetic memory element.