JPH02235283A - Method for driving magnetic storage element - Google Patents

Abstract

PURPOSE:To stably execute the reading/writing operation of the pairs of vertical Bloch lines (VBL)s by impressing a local magnetic field to an area on the side facing to the 2nd grooves to guide the head of a stripe domain up to the entrance of the area held between the 2nd grooves and then reducing a bias magnetic field to introduce the head of the stripe domain into the area held between the 2nd grooves. CONSTITUTION:A local magnetic field is generated to stabilize the stripe domain 14 around the grooves 4 and then the pairs of VBLs are written on the peripheral magnetic wall 15 of the domain 14, or in the case of extending the domain 14 into an R/W gate area 17 to read out the VBL pairs from the magnetic wall 15, the head of the domain 17 is temporarily guided up to the entrance of the R/W gate area 17 by a local magnetic field generating conductor 8. Then, the bias magnetic field 10 is reduced and the domain 14 is straightly extended into the area 17. Then the VBL pairs are read out/written by cutting off the head of the domain. Consequently the reading/writing operation of the VBL pairs can be stably executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a Bloch line memory, and relates to a method of stretching a striped domain serving as a Bloch line transfer path.

(Prior art) This brosopholine memory element includes an information reading means, an information writing means, and an information storage means, and exists in a ferromagnetic material (including a ferrimagnetic film) whose easy magnetization direction is perpendicular to the film surface. Adjacent vertical Bloch lines (hereinafter referred to as V
(referred to as BL) as a pair within the Blodscho domain wall. For example, when the element configuration is a Major-Minal-Lube configuration, the Major line uses bubbles as information carriers, the minor loop consists of striped domains, and the VBL pairs existing in the surrounding Proch domain wall serve 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's worth 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 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 pairs on the striped domain domain walls constituting the minor loop and moving them 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 to carry information on the minor loop,
Compared to bubble devices, storage density can be improved by about two orders of magnitude.

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 given by IE. IEEE Trans.Mag
n. ) Vol. MAG-22, No. 5, (1
986) pp. 784-789. VB
When writing L pairs, the dummy VBL at the tip of the stripe domain is moved to the side wall and the domain tip is cut. When reading a VBL pair, a local in-plane magnetic field is applied to the tip of the stripe domain, a dummy VBL at the tip is moved, and the presence or absence of a VBL pair as a bit is read out by converting the ease of cutting the domain tip. In this way, since the R/W gate operation is accompanied by a minor loop cutting operation,
~W in the center of the minor loop accumulating VBL pairs
It is difficult to operate. Therefore, in an actual device, it is necessary to extend the tip of the stripe domain (minor loop) on which write and read operations are to be performed and introduce it into the R/W gate region.

In the patent application No. 63-174738, Figs. 6(a) and (b)
As shown in FIG. 2, a domain holding layer 1 and a spacer 3 are arranged on a substrate 2, a major line 18 is provided, and a large number of striped magnetic domains are arranged. Groove 4, 6. 16 were arranged (Fig. 6(a), (b)). However, in this structure, the region 26 sandwiched between the grooved portion 4 that holds the minor loop and the hollowed out portion 16 (guide groove 16) of the guide domain holding layer 1 provided in the R/W gate region 17, and the guide groove There is a difference in the bias magnetic field at which the bubble domain changes to the stripe domain in the region 27 sandwiched between the regions 16 and 16. In the region 27, there is a drawback that the domain head fixed in the groove 4 will not extend unless the bias magnetic field is lowered by 6 degrees compared to the region 26. Region 27 whose domain is the guide groove 16
If the bias magnetic field is lowered until the region 26 is elongated, the domain that started elongating first will not extend straight, but will extend laterally in the region 26. For this reason, other domains are prevented from extending into the area 27, resulting in a drawback that normal read and write operations cannot be performed. Reference numeral 5 indicates a hollowed-out edge, and reference numeral 10 indicates a bias magnetic field.

(Problems to be Solved by the Present Invention) The above-described method has a problem in stably performing a read or write operation of the VBL pair held in the magnetic domain wall (minor loop). The present invention eliminates these drawbacks, reads out VBL pairs of minor lube,
Alternatively, it is an object of the present invention to provide a method for stretching a stripe domain that allows simplifying externally applied magnetic field conditions for writing.

(Means for Solving the Problems) The present invention provides a VBL consisting of two adjacent VBLs created in a Ploch 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 along a region in which the stripe domain is desired to be stabilized, and a groove (first groove) is formed around the groove. to stabilize the domain domain wall, and place the first groove at a position corresponding to the middle of adjacent first grooves along the longitudinal direction of the first groove in a region opposite to one tip region of the groove. An auxiliary groove (second groove) is provided separately from the groove-forming region, and a local magnetic field is applied to a region of the tip end region of the first groove facing the second groove. By guiding the tip of the striped domain fixed in the first groove to the entrance of the region sandwiched by the second groove, and then introducing it into the region sandwiched by the second groove by decreasing the bias magnetic field, It is possible to stably perform a read or write operation of the VBL pair existing in the striped domain domain wall fixed to the target first groove.

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

FIGS. 1(a) and 1(b) show the configuration of the main part of the minor loop portion of the stripe domain holding layer in the present invention. A groove 4 (first groove) is formed in the region of the striped domain holding layer on the substrate 2 where the domain is to be held, and the domain (minor groove) is stretched and separated from this groove 4 in the region 17 where the VBL pair is read or written. A groove 16 (second groove) is formed across the area. For example,
It is obtained by selectively implanting ions such as He into the region corresponding to the trench portion of the striped domain holding layer, and then etching with hot phosphoric acid. A zigzag conductor pattern 8 as shown in FIG. 5 was used as an example of the local magnetic field applying means. 12 is an edge portion, and 13 is a notch portion.

As shown in FIGS. 2(a) and 2(b), a local magnetic field is generated to stabilize the striped domain 14 around the groove 4.

Next, as shown in Figures 3(a) and (b), domain 1
When extending the domain 14 into the &W gate region 17 in order to write a VBL pair to the surrounding domain wall 15 of the domain wall 15 or to read a VBL pair from the domain wall 15, the local magnetic field generating conductor 8 is used to extend the domain 14 into the &W gate region 17. The head of domain 17 is guided to the entrance of domain 17. After that, Figure 4 (a
), (b), the bias field 1o is decreased to extend the domain 14 straight into the R/W gate region 17. In the conventional example, it was not possible to reliably stretch the domain 14 straight, and there was a high possibility that it would bend sideways, but with this method, the domain 14? You can definitely stretch it straight. The head of the extended domain 14 is stopped at a defined position of the ~W gate 17 by the conductor current magnetic field. Thereafter, read and write operations of the VBL pair are performed by cutting off the tip of the domain l4. The groove 16 also makes the surrounding potential well shallow and prevents the domain tips, once stabilized in the groove 4, from extending out arbitrarily. It is sufficient to raise the potential well of the major line 18 by the conductor current magnetic field only during the R/W gate operation.

A 4 pm bubble material (YSmLuCa) 3 (FeGe) 50 12 garnet film was grown by LPE to a thickness of 2 pm on a Gd3Ga501 (11l) substrate. Grooves in the structure shown in Figure 1 (groove 4 width 3 μm, groove l6 width 2 pm, arrangement period 12
pm) was selectively implanted into the desired area, and then etched using phosphoric acid. The depth of the groove formed was 2.1 pm. On top of that, S102 spacer 0
．． A domain 14 having a closed domain wall surrounding the grooved portion 4 shown in FIGS. 2(a) and 2(b) is formed with a distance of 5 pm, and VBL pairs are written and read from the domain domain wall 15 by the method described above. It worked reliably.

(Effects of the Invention) As described above, according to the present invention, reading and writing operations of VBL pairs can be performed with good stability. Here, a zigzag conductor is used as the local magnetic field applying means, but similar effects can be obtained with conductors of other shapes.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are diagrams showing examples of main structures for holding domains in the present invention, and Figures 2 (a) and (
Fig. 3(a) and (b) are diagrams showing a state in which the domains according to the present invention are maintained. Figure 4(a) shows a state in which the domain tip held by is guided to the entrance of the R/W gate region by a local magnetic field.
(b) the domain head to read or write VBL pairs from the domain according to the present invention;
FIG. 3 is a diagram illustrating a state where it is introduced into a W gate region. Fifth
The figure is a diagram showing an example of a conductive button for applying a local magnetic field in the present invention. FIGS. 6(a) and 6(b) are diagrams showing the state of domains obtained by the conventional striped domain stretching method. In the figure, 1... domain holding layer, 2... substrate,
3...Subasa, 4...Domain retaining layer hollowed out part (first groove), 5...Drilled part edge, 6...Ga.
- domain holding layer hollowed out portion for domain (third groove), 8...
- Conductor button for local magnetic field generation, 10... Bias magnetic field, 12... Edge of conductor 8, 13... Notch of conductor 8, 14... Hollowed out domain, 15. ... Domain outer peripheral domain wall, 16 ... Groove (second groove) for preventing extension of domain l4 and guiding the domain to the gate part, 17
...Conversion gate between Bloch line pair and bubble,
18...Major line, 26...A region sandwiched between the grooves 4 and 16, 27...A region 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. A method for driving a magnetic memory element having a means for holding and transferring a pair of two adjacent vertical Bloch lines created within a Bloch domain wall, the magnetic memory element having a domain wall surrounding a first groove provided in the ferromagnetic film. A second groove in which the stripe domain is arranged at a position corresponding to the middle of two adjacent first grooves along the longitudinal direction of the first groove in a region opposite to one tip region of the first groove. When stretching the region between the grooves, the stripe domain is moved by a local magnetic field to the entrance of the region between the second grooves, and then moved into the region between the second grooves by a bias magnetic field. 1. A method for driving a magnetic memory element, comprising: