JPS62291785A - Magnetic storage element - Google Patents

Abstract

PURPOSE:To obtain a stripe domain magnetic wall applied with a VBL-pair stabilized holding method by directly attaching another kind of ferromagnetic material to the surface of a stripe domain holding layer, and varying locally the thicknesses of two layers along the stripe domain magnetic wall. CONSTITUTION:Two pieces of Bloch of lines (VBL) 11 and 11' forming a VBL pair 6 are stabilized respectively in domains where a coat layer is thick and thin. In order to transfer this VBL pair, a pulse bias magnetic field is applied in the direction perpendicular to the layer surface, and thus generated gyroscopic force is utilized. Since the coat layer is of so called a high-g material, a large difference is generated between the gyroscopic forces in the stripe domain holding layer and that in the coat layer of a VBL part due to the dynamic transfer of a designated magnetic wall, and the exchange force dynamically increases, accordingly the VBL tends to leave its position. Thereafter, when the dynamic transfer of the magnetic wall ceases, the potential well comes deepest for the VBL 11' again at the position where the coat layer is thick, and the VBL 11' is stabilized at this position.

Description

DETAILED DESCRIPTION OF THE INVENTION 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) Magnetic bubble elements have been developed for the past as a high-density solid-state magnetic memory element. However, with the currently used garnet materials, the minimum attainable bubble diameter is said to be 0.3 μm. Therefore, a bubble material that retains bubbles with a diameter of 0.3 pm or less must be found other than garnet material. This is not easy and is even considered to be the limit of bubble density.

This ultra-high-density solid-state magnetic memory element has significantly improved the density limit based on the characteristics of the bubble retention layer, and can maintain information readout time at the same level as conventional elements in the direction perpendicular to the film surface. A Bloch line pair consisting of two perpendicular Bloch lines that statically and stably exist within a Bloch domain wall that forms the boundary of a stripe domain formed in a ferromagnetic (including ferrimagnetic) film whose easy magnetization direction is . (hereinafter referred to as a VBL pair) was invented (Japanese Patent Application No. 57-182346).

One of the most important parts of this device is the information VB
The VBL pairs are stabilized within the striped domain wall in the form of L pairs, and the VBL pairs are transferred within the Bloch domain wall as necessary.

Regarding the VBL stability maintenance method, please refer to the patent application No. 57-0658.
26, by locally changing the direction of magnetic anisotropy in the film plane along the Bloch domain wall around the striped domain that constitutes the minor loop, VBL pairs stably exist along the striped domain domain wall. It has been shown that it is possible to create a position where it does and a position where it does not.

(Problems to be Solved by the Invention) The specific method for locally changing the direction of magnetic anisotropy in the film plane described in Japanese Patent Application No. 58-065826 is (
1) Utilizing the inverse magnetostriction effect based on lattice strain caused by selective ion implantation into the film; or (2) patterning/patterning the surface of the striped domain holding film using a material with large internal stress.
The IE series analysis method uses the inverse magnetostriction effect based on the inverse magnetostriction effect that forms stress distribution in the film.
on Magnetics (IEEETransaction
on Magnetics) Vol, MA
G-20, No, 5pp1135-1137 (1984
) etc. In (1), the direction of the film surface magnetic anisotropy is controlled only in the film surface layer. This local change in the magnetic anisotropy in the film hardly changes the moving speed of the domain wall,
This method simply controls the difficulty of the VBL pair. Therefore, there is no problem if the in-plane magnetic anisotropy is controlled uniformly over the film thickness direction, but the in-plane magnetic anisotropy is changed only in a part of the film, and there is no ion-implanted surface layer. If the boundary between the layers is clear, the gyroscopic force generated for a given domain wall movement speed is constant, so the movement of the VBL pair will inevitably change depending on the difficulty of the movement of the VBL pair. The film becomes non-uniform along the thickness direction. As a result, in some cases, VBL may be separated in the middle of the film thickness, and
This may lead to the disappearance of the BL pair. This poses a serious problem in terms of device reliability. To remove this obstacle,
It is desirable to uniformly implant ions in the film thickness direction, but this is quite difficult due to the essential characteristics of the ion implantation method or the performance of the ion implantation device. Compared to method (1), method (2) changes the in-plane magnetic anisotropy in the film thickness direction more slowly, and compared to method (1), the probability of instability when the VBL pair moves is lower. Although it is small, the tendency is the same as that of ion implantation.

The purpose of the present invention is to provide a VB that eliminates such conventional problems.
An object of the present invention is to provide an ultrahigh-density recording element having a striped domain domain wall subjected to the L-pair stabilization method.

(Means for Solving the Problem) That is, the present invention resides in a 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. A perpendicular Bloch line pair consisting of two adjacent perpendicular Bloch lines formed in a Bloch domain wall at the boundary of a stripe domain is used as a storage information unit, and means is provided for transferring the perpendicular Bloch line pair within the Bloch domain wall. Motoko's smell *-7L-'; no 7°p no no!
It is characterized in that the ferrimagnetic material of the following types is directly attached, and the two film thicknesses are locally changed along the striped domain domain wall.

(Function) The present invention has shown that by employing the above-described configuration, VBL pairs, which are information units, can be stably held and transferred along the stripe domain magnetic wall. The principle of the present invention will be explained in detail below.

One of the reasons why sufficiently stable transfer of VBL pairs cannot be obtained is that VBL pairs disappear during transfer. VBL
The mechanism by which the pairs disappear is due to the fact that the structure of VBL changes along the thickness direction of the stripe domain retention layer. The reason why the VBL structure changes along the thickness direction of the striped domain retention layer is that the striped domain retention layer is a thin film and has an easy magnetization direction in the normal direction to the retention layer surface. This is because the magnetic pole is induced, and there is an in-plane magnetic field Hs induced from the magnetic pole to the domain wall in the direction normal to the domain wall.

Figure 4 shows the situation. Both sides of the striped domain 3 are surrounded by Bloch domain walls 4 and 4'. XΔ0 is the width of the domain wall. The outside of the domain wall 4 has magnetization 5 in the opposite direction (downward) to the direction (upward) 5' of magnetization M in the stripe domain.
have. Therefore, an e-magnetic pole is induced on the upper side and an e-magnetic pole on the lower side on the film surface of the stripe domain portion 3 of the stripe domain holding layer. On the other hand, in the regions outside 4 and 4', an e magnetic pole is induced on the upper film surface and a Φ magnetic pole is induced on the lower side.

As a result, domain walls 4, 4' with planes parallel to the normal direction of the film surface
An in-plane magnetic field Hs is generated near the film surface in the direction normal to the domain wall surface. In the case of FIG. 4, the direction of Hs is 4 to the left on the upper surface of the membrane and the lower side to the right, and 4' to the right on the upper surface of the membrane and to the lower side to the left. Due to the influence of Hs, the direction of magnetization on the center line of the domain wall gradually rotates from the bottom to the top of the film surface, starting from the right in 4, to the left in the film thickness direction. Inside 4′, the lower side faces left;
The top side is facing right. This change in the domain wall structure in the film thickness direction also has a large effect on the VBL characteristics. FIG. 5 shows the state of magnetization rotation of the VBL portion 11 in the bubble domain domain wall with respect to both surfaces of the striped domain retention layer and the center of the film thickness. The magnetization at the center of this VBL is oriented toward the central axis of the bubble domain along the normal to the surface of the bubble domain domain wall. In this case, the in-plane magnetic field Hs is directed toward the central axis of the bubble domain on the top surface of the bubble domain,
The lower side faces outward. The magnetization on the center line of the domain wall is aligned in the direction of Hs near the film surface. However, near the center of the film thickness, the contributions from the upper and lower surfaces cancel each other out and become zero, and the magnetization at the center of the domain wall becomes the original Bloch domain wall magnetization direction (parallel to the domain wall surface). When the VBL exists in a domain wall having such properties, the magnetization on its center line is oriented in the same direction as the surrounding magnetization on the upper surface of the film, and no particular energy is stored in the VBL region. On the other hand, on the lower surface, the direction of magnetization of VBL is 180° different from the direction of domain wall electrification around it, so exchange energy is stored in VBL. Therefore, the energy E of VBL changes along the film thickness.

FIG. 6 shows this situation qualitatively.

These are the results of calculating the energy EL per VBL unit length with respect to the film thickness of the stripe domain holding layer.

If the left end of the horizontal axis in FIG. 6 is the bottom surface of the film and the right end is the top surface of the film, then the dependence of E of VBL in FIG. 5 in the film thickness direction is expressed as 12. The EL is very high at the bottom of the membrane. On the other hand, if the magnetization on the VBL center line is directed outward in the normal direction of the bubble domain domain wall in FIG. 5, E, as shown in FIG.
The film thickness direction dependence is obtained.

Such dependence of EL in the film thickness direction leads to the disappearance of VBL pairs through the following process. FIG. 7 shows the VBL in the Bloch domain wall in the striped domain retention layer.

11.11' is a VBL structure used as an information carrier in the present invention. 11 corresponds to 12 in FIG. 6, and 11' corresponds to 12'. The magnetization on the center line of VBL 11 or 11' is aligned in the same direction along the domain wall normal direction over the film thickness direction. On the other hand, the direction of magnetization on the center line of VBL No. 13 is opposite between the lower side and the upper side with the center of the film thickness as the boundary. In any part, the magnetization coincides with the direction of Hs. At this time, the center of the film thickness is blotsu + Seno 17 and n ton! By including this point, the change in EL becomes smaller over the film thickness direction. In other words, E of this VBL changes along 12' in the lower part from the center of the membrane in Figure 7, and 12' in the upper half.
It was possible to avoid a sudden change in EL along the film thickness direction as shown in 11.11'. However, when the Bloch point enters, the polarity of VBL is reversed between the upper and lower halves.

In this Bloch line memory, in order to move VBL, which is an information carrier, along a striped domain domain wall, a gyroscopic force, which is a reaction that occurs when a pulse bias magnetic field is applied to the domain wall and moves it, is used. This gyro force is V
The direction of movement is determined depending on the polarity of BL. therefore,
As shown in Figure 7, 13, VBL shares parts with opposite polarity.
As a result, it cannot be moved by a pulsed bias magnetic field. When VBLs adjacent to this immovable VBL collide, the portions of the two VBLs having mutually different polarities in the film thickness direction recombine, and the Bloch line as a whole eventually disappears. This is a very big problem for general-purpose devices.

Bloch points to VBL? The master occurs when kinetic energy equal to the Bloch point generated magnetic field energy is applied to VBL due to domain wall movement or the like. In order to suppress Bloch point injection, Bloch point injection energy may be increased. In other words, the structure should be such that Bloch points are difficult to enter.

Purpose 1 of the present invention Based on this idea, we have eliminated the conventional drawbacks, stably maintained the VBL pair of the striped domain domain wall, which is a minor loop, and made it possible to selectively transfer one bit at a time. An object of the present invention is to provide an ultra-high density magnetic memory element that uses VBL pairs as information units.

In the present invention, a VBL consisting of two adjacent VBLs is created in a Bloch domain wall around a stripe domain existing in a ferrimagnetic film whose easy magnetization direction is perpendicular to the film surface.
In a magnetic memory element that uses a pair as a storage unit, at least one surface of the ferrimagnetic material has a structure in which the contribution from each constituent atom to the direction of spontaneous magnetization of the ferrimagnetic material is reversed. By directly attaching a ferrimagnetic film, the magnetic field energy generated at the Bloch point is controlled. The configuration will be explained in detail below.

FIG. 8 is a diagram showing the structure of the striped domain holding layer in the minor loop portion in the present invention. A ferrimagnetic film 1 for holding striped domains is attached on a substrate 7. A ferrimagnetic material layer 2 is directly placed on top of the ferrimagnetic material, in which the manner of contribution is reversed compared to the manner of contribution from each constituent atom to the direction of spontaneous magnetization of the ferrimagnetic material. By doing this, V
It is possible to prevent the energy density EL of BL from increasing rapidly at the film surface. The mechanism will be explained using a general ferrimagnetic garnet film as an example of a material for a striped domain retention layer. In FIG. 9, 11.11' is VBL. From the dependence of the energy density of VBLII, 11' on the film thickness direction (FIG. 7), in 11 the EL is high at the bottom end of the film, and in 11', the EL is high near the top surface of the film. A ferrimagnetic material 2 is attached to the upper surface of the striped domain holding layer 1 shown in FIG. 8, in which the contribution from each constituent atom to the direction of spontaneous magnetization of 1 is reversed. In this way, exchange energy is stored at the upper end 15 of VBLII at the boundary between 1 and 2. This is because the magnetic domain structure of the ferrimagnetic layer 2 depends on the domain structure of the striped domain holding layer 1, and the magnetization direction of 2 near the domain wall existing in 1 is the direction of the in-plane magnetic field component Hs generated from the domain structure of 1. directed towards. Now, the magnetization of layer 1 is oriented in the same direction as the atomic magnetic moment at the 24d position, and the magnetization of layer 2 is oriented in the same direction as the atomic magnetic moment at the 24d position.
Assume that the direction of the atomic magnetic moment at the position is the same as the direction of the atomic magnetic moment. The contribution of the atomic magnetic moment of the rare earth ion in the 24c position is 16a if the atomic number is 64 or higher.
This is the same as the direction of the atomic magnetic moment at position 16a, and below for convenience, 1 is added to the atomic magnetic moment at position 16a.
Let us consider the relative magnitude of the atomic magnetic moment at the 6a position and the atomic magnetic moment at the 24d position. The direction of magnetization per unit cell is determined by comparing the sum of the atomic moments at the 16a position and the sum of the atomic magnetic moments at the 24d position, whichever is larger.

In other words, the magnetization near the top of VBL is oriented in the direction of the Hs force, which means that the atomic magnetic moment at the 24d position is Hs
The fact that the magnetization in layer 2 is oriented in the Hs force direction means that the atomic magnetic moment at position 16a is aligned in the Hs direction. Considering this, at the boundary 15 between the upper end of VBLII and 2, layer 1
The atomic magnetic moment at position 24d and the atomic magnetic moment at position 16a of layer 2 are in the same direction. This is the atomic magnetic moment at the 24d position and 1 in ferrimagnetic garnet.
This contradicts the property that the atomic magnetic moments at the 6-position are coupled antiparallel to each other and stabilized. Therefore, 1
Exchange energy is stored in part 5.

This exchange energy changes the magnetization direction of the ferrimagnetic layer in H
Either the magnetization is reversed against s or the magnetization near the top of VBLII is reversed, but in either case, the Bloch point implanted at position 15 cannot easily advance to the center of the film thickness of 1. .

In order for the Bloch point to advance to the center of the film thickness of 1, 2
The film thickness of 1 is increased so that the magnetization of 1 is reversed,
In addition, in the film thickness direction dependence of EL shown in FIG. 6, 12
It is necessary that the EL at the upper end of the film thickness of the curve shown in is thicker than the value at the center of the film thickness. The point where the EL at the upper end of the film thickness becomes equal to the EL at the center of the film thickness determines the critical thickness of the film 2 to be placed on the film 1 to prevent the Bloch point from advancing to the center of the film thickness of the film 1. On the other hand, at the boundary between the upper end of VBLII' and 2, the magnetization of the atom at 24d in layer 1 and 16a in layer 3
The positional magnetization is coupled in opposite directions to each other, and the arrangement satisfies the stable bonding properties unique to ferrimagnetic garnet. Therefore, no exchange energy is stored in the 16 portion. Rather, VB reflecting the magnetic domain structure of 1
Since Hs at the LII° upper end directs the magnetization at the 16a position of layer 2 in the same direction as Hs, the magnetization direction near the upper end of VBL 1 is stabilized in the opposite direction to Hs. Therefore, in the absence of the film No. 2, the direction of the Hs force is reversed relatively easily, and the Bloch point injection can now be suppressed at the 16 points where the Bloch point was injected.

FIG. 10 shows another example of the present invention, in which the relationship between the bottom surface of the striped domain holding layer 1 and the substrate is similar to the top surface, and the contribution of each constituent atom to the direction of spontaneous magnetization of 1 is greater than that of the substrate. The ferrimagnetic film with the reversed direction is directly
It is attached so that it is in contact with the By doing this,
Bloch point injection from the Manryo surface layer above the striped domain holding layer is suppressed.

FIG. 11 explains the mechanism. The lower end of VBLII has the same structure as the upper end of "VBLII", and
At the lower end of I'', the same structure as at the upper end of VBLII appears.

From this, the Bloch line 11 where Bloch points tend to enter from the lower end of the striped domain holding layer 1 is suppressed by the layer 2' from being injected with Bloch points from 11'. On the other hand, the layer 2 prevents Bloch points from entering from the Bloch line 11' from the upper end of the striped domain holding layer 1 through the Bloch line 11'. In this way, on the surface of the striped domain holding layer (ferrimagnetic material), at least one surface of the ferrimagnetic material has a different contribution than the contribution from each constituent atom to the direction of the spontaneous magnetization of the ferrimagnetic material. VB when directly coated with reversed ferrimagnetic film
It was found that the energy of L is perturbed. This principle is used to set the stable position of the VBL pair. FIG. 1 shows how the film thickness is varied in the striped domain domain wall portion in the present invention. VBLBeO2VBLII in the domain walls (Bloch domain walls) on both sides of stripe domain 3
' is stabilized in the thick part, and VBLII is stabilized in the thin part. Since the magnetization direction of 11' and the magnetization direction of the coating layer are opposite to each other, an advantage is obtained by the exchange energy between the atomic magnetic moments of both layers. On the other hand, in No. 11, the magnetization direction is the same as that of the coating layer, so the presence of the coating layer increases the energy of VBL by the exchange energy, and is therefore stabilized where the coating layer is thin. . In addition to the interaction between the VBLs, maintaining these two VBLs as a pair is due to the in-plane magnetism that is applied from the outside in the longitudinal direction of the domain.
In the stability maintenance method, the energy density of VBL is locally changed along the domain wall. To make this change,
Specifically, since ion implantation or the like is used, non-uniformity in characteristics in the film thickness direction is unavoidable. VBL
The BeO2 tripe domain is moved in the Bloch domain wall by a gyroscopic force generated by a pulse bias magnetic field applied in a direction perpendicular to the film surface of the ferrimagnetic film. Therefore, the moving speed of the VBL becomes non-uniform along the film thickness direction, and the VBL may become fragmented.

On the other hand, in the VBL pair stabilization method of the present invention, VB
No processing was performed on the layer holding the L pairs. simply,
The presence of the coating layer simply allows the VBL to interact with the coating layer, and the drawbacks of the conventional method can be eliminated.

The principle will be explained using FIG. FIG. 2(a) shows a cross section of a part of FIG. 1 cut along a plane including the striped domain domain walls. VBLBeO2 is stabilized in the VRT of 9 thick, 11 and 11' Kakumo Gen-Fh-coated layers in the 600 and thin regions, respectively. In order to transfer this VBL pair, a pulsed bias magnetic field is applied in a direction perpendicular to the film surface, and the resulting gyroscopic force is utilized. This section describes how to evaluate the magnitude of gyroscopic force. Figure 2(b) shows VBLII
, 11' is shown qualitatively from the viewpoint of the interaction between the coating layer and the VBL, corresponding to FIG. 2(a). Generally, the interaction between the VBL and the coating layer is stabilized at the point where the interaction between the VBL and the coating layer is the lowest.The VBL climbs over the peak where the interaction next to it is the highest and goes to the next valley. Moving.

Therefore, the gyroscopic force acting on the VBL pair needs to be larger than the maximum value of the gradient of the interaction change between the interaction valley and peak. The advantage of the present invention is that the bottom of the potential at which VBL vs. BLII'' is stabilized during driving rises, and the so-called bit barrier between it and the adjacent stable position becomes relatively low. Since the layer belongs to a so-called high-g material, there is a large difference in the gyroscopic force acting on the VBL section for a given dynamic movement of the domain wall, and there is a large difference between the live domain holding layer and the coating layer, which causes dynamic exchange. As the force increases, VBL will avoid that position.Afterwards, when the dynamic movement of the domain wall stops, the position where the coat layer is thick will again become VB.
For LII', the potential well is the deepest, and VBLII' is stabilized there.

Next, we will discuss how to change the thickness of the coating layer. Second
The broken line in figure (a) shows the case where the film thickness change region is made very narrow (
The cross section is rectangular). Correspondingly, the dependence of the interaction between VBL and the coating layer on the X direction changes as shown by the broken line in FIG. 2(b). In this case, the gyroscopic force required to move VBL, which has been stabilized at a low energy level, to the next valley becomes much larger than in the case of the solid line, making it difficult to control in practice. therefore,
The wavy structure shown by the solid line is easy to use in practice.

In this method, the striped domain holding layer is not processed at all, so that the response of the VBL pair to the gyroscopic force does not change discontinuously over the film thickness direction as in the case of the ion implantation method. Therefore, the probability of instability such as VBL being cut off in the middle of the film thickness when crossing the inter-bit barrier during transfer can be suppressed to a very low level, and stable VBL pair transfer can be obtained.

The content of the invention will be specifically illustrated below using Examples.

(Example 1) A method of manufacturing this wave pattern will be explained with reference to FIG.

Positive photoresist MP1300 on bubble material film 2
(Shipley Japan Co., Ltd., product name), rt15pm.

A pattern 8 with a period of 10 μm and a film thickness of 1 pm is formed (third
Diagram a). After pattern formation, post-bake is performed at 135°C for 1 hour. The pattern then becomes shaped like 8'. If biking is performed above this temperature, pattern III
fluctuates, which is not desirable. On the other hand, if the temperature is too low, the cross-sectional shape of the pattern remains rectangular, which is not preferable (FIG. 3b). Next, polystyrene with a molecular weight of 117,500 is applied using xylene as a solvent. 10 times the number 17 so L me 74-1 non or si vs solution 1? - At a spin coating speed of 3000 rpm, a polystyrene coating film 9 of about 3000 layers can be obtained on a flat area. The surface after application had a gentle waveform. The height difference of the waveform shape was approximately 1°3 pm. There was no deformation of the positive photoresist pattern before and after the coating process (FIG. 3C). Next, do Aeon Master. The implantation conditions were determined so that ions would penetrate through an organic film with a thickness of 1.3 pm.

Here, 130KeV/He/4.8 X 1015 pieces/am", 50KeV/He/1.7X1015 pieces1
cm2. Ions are implanted into the portion of the layer coated on the surface of the striped domain retention layer, indicated by 10" in FIG. 3(d). When ions are implanted into the coating layer material, lattice strain is induced in the implanted layer. Although it is generally known that chemical etching resistance changes, the sample prepared by the above procedure was exposed to oxygen plasma to remove the organic film, and then immersed in phosphoric acid at 90°C for 10 minutes.
As shown in e), the coating layer could be processed into a wavy shape with a height difference of 0.4 pm.

The striped domain holding material is a 5pm bubble material (YSmLuCa)3(FeGe) grown by LPE on a Gd3Ga,,O4,,(111) substrate.
501□ film (film thickness = 3.88 pm, stripe width = 5.
EuC directly on top of 0pm, 4rMs = 202 Gauss
a5iGeYZG was grown by liquid phase epitaxial growth. 1st
Regarding the sample formed to have a wave-like structure shown in the figure with a period of 5 pm (mask pattern width 311 m or 2 pm) and a peak height of 0.4 yen 1 m, stripe domains were arranged in this region to stabilize the VBL pair. It was found that the VBL pair was stabilized at the peaks and valleys of the wave-like structure, respectively.
When a rectangular wave-like pulsed bias magnetic field with a width of Ions was applied to the L pair, the VBL pair climbed over the peak of the wave structure at an amplitude of around 250e.

(Effects of the Invention) The present invention improves the stability of Bloch line pairs to the striped domain domain wall and the stability of transfer along the domain wall, which are one of the most important elements in Bloch line memory, compared to conventional methods. I was able to improve it.

[Brief explanation of the drawing]

FIG. 1 is an overview of the vertical Bloch line stabilizing and holding means according to the present invention, and FIGS. 2(a) and (b) show the ferrimagnetic stripe domain holding layer and the ferrimagnetic properties when cut along the plane including the domain walls, respectively. FIG. 2 is a diagram showing a cross section of a body coat layer and the position dependence of the interaction between Bloch lines and the coat layer. FIG. 3 is a diagram showing an embodiment of the process of forming an element. Figure 4 is an explanatory diagram of the film thickness direction dependence of the magnetization direction on the domain wall center line on both sides of the stripe domain, Figure 5 is a diagram showing the state of magnetization rotation in the VBL section within the bubble domain domain wall, and Figure 6 is the VBL unit length. Figure 7 is an explanatory diagram of various VBLs existing in a striped domain domain wall, and Figures 8 and 9 are examples of the structure of a striped domain retention layer. FIG. 10 and FIG. 11 are diagrams illustrating another example of the structure of a striped domain holding layer and its basic principles. In the figure, 1... Ferrimagnetic striped domain holding layer, 2... Ferrimagnetic coating layer, 3... Striped domain, 4,4''... Striped domain domain wall, 500. Magnetization in the striped domain , 5'...
Magnetization outside the stripe domain, 6... Vertical Bloch line (VBL) pair, 7... Substrate, 8'... Photoresist pattern after post-baking, 9... Polystyrene, 10゛... Ion implantation ferrimagnetic material coating layer, 11.11'... vertical Bloch line (VBL
), 12.12'...VBLII, dependence of energy density of 11' on stripe main retention layer inner film thickness direction, 1301. Figure 2 (7) Figure 3 (e) Figure 4 Circle 5

Claims (1)

[Claims] A pair of perpendicular Bloch lines formed in a Bloch domain wall around a stripe domain existing in a 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 is used to store information. In a magnetic memory element used as a unit, at least one surface of the ferrimagnetic film has ferrimagnetism in which the manner of contribution is reversed compared to the manner of contribution from each constituent atom to the direction of spontaneous magnetization of the ferrimagnetic material. What is claimed is: 1. A magnetic memory element characterized in that a body film is directly coated, and the thickness of the coating layer varies locally along a Bloch domain wall of a striped domain retention layer.