JPH035987A - Bloch line memory device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD The present invention relates to Bloch line memory devices using vertical Bloch line pairs as storage units.

[Prior art]

With the development of high-density storage devices, Bloch line memory devices have recently attracted attention due to their large storage capacity and non-volatility.

A Bloch line memory device consists of an information storage section consisting of a domain wall surrounding a stripe magnetic domain made by elongating bubble magnetic domains, and vertical Bloch line pairs (V
This is to store information in the form of presence/absence of BL pairs). This Bloch line memory device is basically (
It consists of three elements: i) writing section, (note) recording transfer section, and (iii) reading section.

When constructing a Bloch line memory device using these elements, the prerequisite technology is the technology to stably exist striped magnetic domains, and in the operations (i) and (iii), a bias magnetic field H, perpendicular to the film surface is applied. A position control technique is required when changing (decreasing) the stripe magnetic domain head portion and moving (stretching) it to a desired position.

For this reason, conventional methods have been to (a) group the magnetic film into bar-shaped groups to stabilize the striped magnetic domains around the groups, and (b) form a high magnetic force in-plane magnetized film pattern on the magnetic film to stabilize the striped magnetic domains. to stabilize it. (C) Methods have been proposed in which ions are implanted into the surface of the magnetic film to stabilize striped magnetic domains within the implanted region, among which method (a) is currently widely adopted. However, this method requires chemical etching using phosphoric acid, physical etching using ion milling, etc. to form the groups, which complicates the manufacturing process and has the disadvantage that the device is likely to be damaged.

On the other hand, regarding the stabilization of striped magnetic domains by the high magnetic force film in (b), for example, J. Appl. Phys., 63 (
8), 3171 (1988), the structure and principle for stabilizing the stripe magnetic domain and stretching the head portion of the stripe magnetic domain are shown. However, this method uses a film that is magnetized in the in-plane direction as the high magnetic force film, so there is a part formed in the domain wall surrounding the striped magnetic domain at a position that overlaps with the high magnetic force film, and a part that is formed at a position that does not overlap with the high magnetic force film. This causes a difference in the behavior of the domain walls between the two sections, which is disadvantageous for smooth transport of the VBL pair.

Figure 1 shows this situation. In the figure, 1 is a high magnetic force film pattern, 2 is a striped magnetic domain stabilized by this high magnetic force film, and 3-a is a domain wall formed at a position overlapping the high magnetic force film. , 3-b show domain walls formed at non-overlapping positions. Also, in Fig. 2, the bias magnetic field H is changed from the state shown in Fig. 1.
In Figure 1, which shows the state of stretching of the striped magnetic domain head section when B is decreased, 1-1 is the area necessary for the stable existence of the striped magnetic domain (hereinafter referred to as pattern A), and 2-2. is a region (hereinafter referred to as pattern B) necessary for controlling the position of the striped magnetic domain head section when the stripe magnetic domain head section is stretched by decreasing the bias magnetic field H8.

Regarding stabilization of striped magnetic domains using a high magnetic force perpendicular magnetization film (b) or stabilization of striped magnetic domains by ion implantation (c) as described above, please refer to JP-A-59-96589.
No., I E E E Tran, Magn.

MAG-22, 5, 799 (1986), etc., but there is only a description regarding pattern A, and there is no description regarding pattern B, that is, position control of the striped magnetic head portion.

[Problem to be solved by the invention]

The purpose of the present invention is to solve the above-mentioned problems in the prior art, and to provide a Bloch line memory device that can stably hold striped magnetic domains and accurately control the position of the striped magnetic domain head section when changing the bias magnetic field. The goal is to provide the following.

[Structure and operation of the invention]

The Bloch line memory device of the present invention has vertical Bloch lines (
In a Bloch line memory device having a magnetic film for storing VBL) pairs, a pattern A is used to stably hold the stripe magnetic domain in a state where a bias magnetic field perpendicular to the magnetic film surface is applied within the stripe magnetic domain. A pattern B for controlling the position of the striped magnetic head part that moves when the bias magnetic field is changed is provided adjacent to the pattern B, and the patterns A and B are ion-implanted, and a high-magnetic perpendicular pattern is placed on the pattern A. It is characterized in that magnetized films are laminated.

To explain the principle of the device of the present invention with reference to the drawings, the third
In the figure, 5 is a magnetic film provided on the substrate 15, in which the VBL pair 4 indicated by the arrow is stored.
The L pair 4 is formed around the striped magnetic domain 2 surrounded by the domain wall 3. 6 is used to stably hold the stripe magnetic domain 2 while applying a bias magnetic field HB perpendicular to the film surface of the magnetic film 5, and to control the position of the stripe magnetic domain head portion that moves when H3 is changed. It is a pattern. First, let's divide this pattern into two parts. In other words, these patterns include (1) a region provided to stably hold the stripe magnetic domain (pattern A), and (2)
) A region provided to control the position of the striped magnetic domain head portion that moves when Ha is changed (pattern B
). For a certain size H of N, a striped magnetic domain stably exists along the shape of pattern A, and by reducing this perpendicular magnetic field by ΔHB, the striped magnetic domain head part is aligned along the pattern B region. When the area is stretched to the area where the pattern A and pattern B are stretched, the effective magnetic field felt by the striped magnetic domains formed at the bottom of the pattern A and pattern B areas (in the opposite direction to He,
Heff^, He
ffg, and the effective magnetic field felt by the striped magnetic domain formed in the area without a pattern is Heffo, then Heffo I < l Heff+, l < l
A relationship HeffA1 is established.

4(a) and (b) (
As shown in (a) is a front view, (b) is a cross-sectional view, and the same applies hereafter, first, in order to form Heff^, a magnetic film 5 is formed on a substrate 15, and a pattern A (1- 1) and ion implantation into the pattern B (1-2) region. Suitable ions for implantation are H+, He, Ne'', etc.

In addition, when Hl is used as the injection amount, IXl015
/C♂ or higher is desirable. The effect of this ion implantation is a reduction in vertical field orientation, which makes it easier for striped magnetic domains to exist stably. Next, as shown in FIGS. 5(a) and 5(b), a high magnetic force perpendicular magnetization film 8 is laminated on top of pattern A (1-1) of the ion-implanted pattern A and B pattern regions. At this time, they may be laminated with a nonmagnetic spacer interposed therebetween. Suitable materials for the high magnetic force perpendicular magnetization film include amorphous TbFeCo alloy and CoCr alloy. In addition, the material for the spacer is SiO2, SiN
etc. are suitable. Note that the high magnetic force perpendicularly magnetized film is used by being magnetized in the opposite direction to that of Hg, and as a result, a stray magnetic field is generated from the film, which contributes to stabilizing the striped magnetic domain as an effective magnetic field.

In the device of the present invention, patterns A and B can also be configured as shown in FIGS. 6 and 7. That is, FIG. 6 is a diagram showing the configuration of a device when patterns A and B are formed only with high magnetic force perpendicular magnetization films, and the pattern A section (1-1
) is thicker than 3528 parts (1-2), the effective magnetic field in the pattern A part can be made larger than the effective magnetic field in the 3528 parts. Further, FIG. 7 is a cross-sectional view of the implanted portion when pattern A (1-1) and pattern B (1-2) are formed by ion implantation alone in the magnetic film 5, and the implantation amount in the pattern A portion is 3528. 6, the effective magnetic field at the pattern A section can be made larger than the effective magnetic field at the 3528 section, as in the case of FIG.

In any case, in the device of the present invention, the stripe magnetic domain exists stably under the pattern A normally (except when writing and reading signals).

A feature is that the stripe magnetic domain head portion moves to the bottom of pattern B by changing Hg during signal writing and reading.

The present invention will be explained below by way of examples.

Example By LPE method on garnet substrate (YLuBi).

(FeGa) sota was grown to a thickness of 4.0 μm to form a magnetic film. Next, in an 8 μm wide area on this magnetic film,
6V(7) to 00! Energy "?'H" ion 3X
10is/C112 was injected. When this ion-implanted area was examined using an optical microscope, it was confirmed that the ion-implanted region was stabilized in the above-mentioned area.

Next, 10
Sputtering 0.2μ as a spacer in a μm wide area
A SiN film with a thickness of m is formed, and on top of that a Tb2° (FsCo) film with a thickness of 0.2 μm is formed as a high magnetic force perpendicular magnetization film. An amorphous alloy film was formed.

Calculations have revealed that in the Bloch line memory device obtained as described above, the effective magnetic field contributed to the magnetic film by the amorphous alloy film takes a value as shown in FIG. 8 near the center of the magnetic film. However, 0.00 on the horizontal axis
It is assumed that an amorphous alloy film exists within a range of ~10.00 μm. From this figure, the effective magnetic field of pattern A is about 90a larger than that of pattern B, so lHe
It was confirmed that there is a relationship of f5 l < I HeffAl, and the stripe magnetic domain is more easily stabilized in the pattern A region than in the pattern B region.

[Function and effect of the invention]

As described above, in the Bloch line memory device of the present invention, the pattern A@ region is formed by ion implantation and lamination of high magnetic perpendicular magnetization films, and the pattern B region is formed by ion implantation, thereby forming striped magnetic domains. It is possible to maintain the magnetic field stably and to accurately control the position of the striped magnetic domain head section that moves when changing HB.

Further, if the pattern configuration as shown in FIG. 6 is adopted, patterns A and B can be formed only by high magnetic force perpendicularly magnetized films, so that in addition to the above-mentioned effect, the device manufacturing process can be simplified.

Furthermore, in the case of a pattern configuration as shown in Fig. 7, patterns A and B
can be formed simply by changing the amount of ion implantation.
The same effect as in the case of FIG. 6 can be obtained.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the state when the stripe magnetic domain is stabilized by a high magnetic force film in the conventional method, and Figure 2 is a cross-sectional view showing the state when the head portion of the stripe magnetic domain in Figure 1 is stretched. , FIG. 3 is an explanatory diagram of the operating principle and structure of the pattern used in the device of the present invention, and FIGS. 4 and 5 are
The figure shows a manufacturing process diagram of an example of the device of the present invention, FIGS. 6 and 7 show modifications of the device of the present invention, and FIG. 8 shows the effective magnetic field near the center of the magnetic film. 1.6...Pattern or high magnetic force film pattern 1-1...Pattern A 1-2...Pattern B2...Stripe magnetic domain 3...Domain wall 4...Vertical Bloch line pair (VBL) 5 ...Magnetic film HB...Bias magnetic field perpendicular to the film surface 8...High magnetic force perpendicular magnetization film 15...Substrate Fig. 1

Claims (1)

[Claims] 1) In a Bloch line memory device having a magnetic film for storing perpendicular Bloch line pairs on the domain wall of a striped domain surrounded by domain walls, a state in which a bias magnetic field perpendicular to the magnetic film surface is applied within the striped domain. Pattern A for stably holding striped magnetic domains in
and a pattern B for controlling the position of the striped magnetic head part that moves when the bias magnetic field is changed are provided adjacently, the patterns A and B are ion-implanted, and a high magnetic force is further placed on the pattern A. A Bloch line memory device characterized by stacking perpendicularly magnetized films.