JPH0223588A - Magnetic storage element - Google Patents

Abstract

PURPOSE:To stabilize the reading-out and writing operations of a vertical Bloch line pair by providing the 1st grooves in a striped area holding layer and the 2nd grooves having widths narrower than those of the 1st grooves between the 1st grooves and their adjacent grooves in a state where the 2nd grooves face one ends of the adjacent grooves. CONSTITUTION:The first grooves 4 and 2nd grooves 16 are respectively provided in a (YSmLuCa)3(FeGe)5O12 garnet film 1 on a Gb3Ga5O12 (111) base plate 2 and the reading-out/ writing area 17 of a vertical Bloch line (VBL) pair, with the 2nd grooves 16 being formed on both sides of separating areas. The grooves are formed by performing selective injection of H2 and etching using hot phosphoric acid. Striped areas 14 are stabilized around the grooves 4 by producing local magnetic fields. In order to make the writing and reading out of the VBL pair possible into the surrounding magnetic walls 15 of the areas 14, bias magnetic fields 10 are reduced and the striped areas 14 are elongated straight into the area 17. The heads of the area 14 are stopped at prescribed positions of the gate area 17 by means of magnetic fields produced by electric currents. Thereafter, the lading ends of the areas 14 are cut off and the reading-out/writing of the VBL pair are performed. By making potential wells around the grooves shallower, arbitrary elongation of the leading ends of once stabilized areas into the grooves 4 is prevented. The potential well of a main line 18 can be raised up only when the rading-out/writing gate is actuated.

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-minor-loop configuration, the major line uses bubbles as information carriers, the minor loop is composed of striped domains L, and the VBL pairs existing in the Bloch domain wall around it are used as information carriers. To show the overall flow of information, first, information written by the bubble generator (example of presence or absence of bubbles) moves along the write major line. When one page of information is written on the major line, in order to store it in the minor loop, the information on the major line indicated by the presence or absence of bubbles is transferred to the minor loop in the form of a VBL pair. Therefore, the write transfer gate has a function of converting the presence or absence of a bubble into the presence or absence of a VBL pair. The minor lube is composed of Bloch domain walls that can hold VBL pairs. Further, the minor loop has a function of reading out the VBL pair of the striped domain domain wall that constitutes it 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, it is possible to achieve a storage density of about two orders of magnitude compared to the bubble element. improvement can be achieved.

One of the most important parts of this element is the information writing section and the information reading section. An example of the configuration of this write/read gate (hereinafter referred to as R/W gate) is the IE Transactions on Magnetics (IEEE Trans).

Magn, ) Vol, MAG-22, No, 5.
(1986) pp, 784-789. When writing a VBL pair, the dummy VBL at the tip of the striped domain is moved to the side wall, and the domain tip is cut. When reading the VBL pair, a local in-plane magnetic field is applied to the tip of the stripe domain, and a dummy VB at the tip is
L is moved and the presence or absence of a VBL pair as a bit is replaced with the ease of cutting the domain tip and read out. As described above, since the RJW gate operation involves cutting the minor loop, it is difficult to perform the R/W operation in the center of the minor loop where VBL pairs are accumulated. Therefore, in practical devices, the tip of the stripe domain (minor loop) where a write or read operation is to be performed is stretched,
&W It is necessary to introduce it into the gate area.

In JP-A-62-233844, a domain holding layer 1 and a spacer 3 are arranged on a substrate 2, a major line 18 is provided, a large number of striped magnetic domains are arranged, and the striped magnetic domains are straightened during &W agate production. Groove 4.6 to extend to
．． 16 (Fig. 4(a), (b)). However, in this structure, the trench portion 4 that holds the minor loop and the R
/W Guide domain holding layer 1 provided in gate region 17
Region 2 sandwiched between hollowed out portions 16 (guide grooves 16)
There is a difference in the bias magnetic field that changes the bubble domain to the stripe domain between the region 6 and the region 27 sandwiched between the guide grooves 16. In the region 27, there is a drawback that the domain head fixed in the groove 4 does not extend unless the bias magnetic field is lowered more than in the region 26. When the bias magnetic field is lowered until the domains extend in the region 27 of the guide groove 16, the domains that started to extend first do not extend straight, and the regions 26
It grows horizontally. Therefore, other domains are area 27
This has the drawback that normal reading and writing operations cannot be performed because the data is prevented from being expanded to . 5 is the hollowed out edge,
10 indicates a bias magnetic field.

(Problems to be Solved by the Present Invention) In the above-mentioned element, there was a problem in stably performing read or write operations of the VBL pair held by the magnetic domain wall (minorube). The present invention eliminates these drawbacks, reads out the VBL pair of the minor loop,
Another object of the present invention is to provide an ultra-high-density solid-state magnetic memory element with a 1-D density so that externally applied magnetic field conditions for writing can be simplified.

(Means for Solving the Problems) The present invention provides a VBL consisting of two adjacent VBLs created in a Bloch domain wall at a stripe domain boundary existing in a ferromagnetic film whose easy magnetization direction is perpendicular to the film surface. In a magnetic memory element that uses a pair of striped domains as a storage carrier, a groove (first groove) is created by selectively scraping the retention layer over a region where the striped domain is desired to be stabilized, and a domain domain wall is formed around the groove around the groove. the first groove forming region at a position corresponding to the middle of adjacent first grooves along the longitudinal direction of the first groove in a region facing one tip region of the groove; By providing an auxiliary groove (second groove) separately from the second groove and reducing the width of the second groove, the VBL pair existing in the striped domain domain wall fixed to the target first groove can be reduced. Read or write operations can be performed with good stability.

(Example) The configuration will be explained in detail below.

FIGS. 1(a) and 1(b) show the structure of the main part of the minor loop portion of the striped domain holding layer in the present invention. A groove 4 (first groove) is formed in the region of the striped domain holding layer 1 on the substrate 2 where the domain is to be held, and the domain (
A groove 16 (second groove) is formed in the area 17 where the VBL pair is read or written, sandwiching a region separated from the groove 4.

This can be obtained, for example, by selectively implanting ions such as H2+ into the region corresponding to the grooved portion of the striped domain holding layer, and then etching with hot phosphoric acid.

As shown in FIGS. 2(a) and 3(b) and FIGS. 3(a) and 3(b), a local magnetic field is generated 1- to stabilize the stripe domain 14 around the groove 4. Write a VBL pair to the surrounding domain wall 15 of the domain 14, or write VB from the domain wall 15.
To read out the L pairs, reduce the bias magnetic field 10;
It extends straight into the R/W gate region 17. In the conventional method, the domains 14 cannot be reliably stretched straight, and there is a high possibility that the domains 14 will get oily on the sides, but with this method, the domains 14 can be reliably stretched straight. The head of the extended domain 14 is the λW agate region 17
is stopped at a fixed position by a conductor current magnetic field. After this, by cutting off the tip of domain 14, VB
Performs L pairs of read and write operations. Also, this groove 1
6 makes the surrounding potential well shallow and prevents arbitrary extension of the domain tip once stabilized in the groove 4. It is sufficient to raise the potential well of the major line 18 by the conductor current magnetic field only during logic gate operation.

A 411 m bubble material (YSmLuCa) 3 (FeGe) 501 □ garnet film was grown by LPE to a thickness of 2 pm on a Gb 3 Ga 50 1 □ (111) substrate. In the structure shown in FIG. 1, grooves (width of groove 4: 311 m, width of groove 16: 2 pm, arrangement pitch: 12 .mu.m) were selectively implanted into the desired portions by ion implantation, and then etched using phosphoric acid. The depth of the groove created was 2°111 m. On top of that, a domain 14 having a closed domain wall surrounding the grooved portion 4 shown in FIGS. On the other hand, writing and reading operations of the VBL pair could be performed reliably.

(Effects of the Invention) As described above, according to the present invention, read and write operations of VBL pairs can be performed with good stability.

[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)
is a diagram showing a state in which domains are maintained in the present invention,
FIGS. 3(a) and 3(b) show that V from the domain according to the present invention is
FIG. 3 is a diagram showing a state in which a domain head is introduced into a λW agate area in order to read or write a BL pair. FIGS. 4(a) and 4(b) are diagrams showing the operation of a conventional magnetic memory element. In the figure, 1. domain retention layer, 2. Substrate, 3. Spacer, 4. Domain holding layer hollowed out part (first groove), 5
゜Drilled edge, 6. Guard domain holding layer hollowed out portion (third groove), 10. Bias magnetic field, 14. Hollow domain, 15. Domain outer domain wall, 16. Groove (second groove) for preventing extension of the domain 14 and guiding the domain to the gate portion; 17. Conversion gate between Bloch line pair and bubble, 18. Major line, 26° region sandwiched between groove 4 and groove 16, 27. This is the area sandwiched between the grooves 16.

Claims (1)

[Claims] In a Bloch domain wall 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 a means for retaining and transferring a pair of two adjacent vertical Bloch lines created within a Bloch domain wall, a first groove is formed in a stripe domain retention layer over a region where a stripe domain is to be arranged. A second groove is provided at a position corresponding to the middle of the first grooves that are adjacent to each other along the longitudinal direction of the first groove in a region opposite to one tip region of the first groove. A third groove is arranged in a peripheral part of the area where the first groove and the second groove are arranged, and the width of the second groove is smaller than the width of the first groove. magnetic memory element.