JPS61239488A - Magnetic memory element - Google Patents

Abstract

PURPOSE:To improve stability in transmitting the set of Broch lines and the reliability of Broch line memory by removing the unevenness of the potential well of a magnetic wall on stabilizing a stripe do main without implanting a vertical magnetizing material. CONSTITUTION:A striped main holding layer 1 is provided on a substrate 2 and the surface thereof is selectively grooved by a section desired to hold the stripe do main in a ring shape and a groove 3 is disposed. The width thereof is made larger than the natural width W0 of the stripe do main and below about 2W. In the boundary of the groove, since the boundary 4 has its inner protruding section having the boundary 4, it plays a role for attracting the inner magnetic wall of the stripe do main 6 to 4 and a boundary 5 plays the role of a guide for preventing the inner magnetic wall from separating from 4 when initializing the striped main 6. Further the width of the protruding section having the boundary 4 requires to be above W0. When providing the groove so as to satisfy the above-mentioned conditions, the stripe do main is fixed in a ring shape having the inner diameter of the groove boundary 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) ``Kz Ki BBI+Song η Hair U Surname σ) Diary a Yinara Subaba F Circle Diameter Swallowed Kidney A28 Hand 4-.

(Prior art and its problems) Magnetic bubble devices are being actively developed in various places with the aim of creating high-density solid-state magnetic memory devices.However, with the currently used garnet materials, the minimum bubble diameter that can be achieved is is said to be 0.3 μm.

Therefore, it is necessary to find a bubble material other than garnet material that can hold bubbles with a diameter of 0.3 mm or less. This is not easy and is even considered to be the limit of bubble density.

We have developed an ultra-high-density magnetic memory element that significantly improves the high-density limit based on the characteristics of the bubble retention layer and can maintain the information readout time at the same level as conventional elements. A Bloch line pair (hereinafter referred to as a Bloch line pair) consists of two perpendicular Bloch lines that exist statically and stably within a Bloch domain wall, which is the boundary of a stripe domain formed in a ferromagnetic (including ferrimagnetic) film with an easy magnetization direction. ,VBL
It is called a pair. ) was invented as a storage unit (%GanSho s7-:'tsza46) This magnetic storage element is provided with an information reading means, an information writing means, and an information storage means, and the VBL pair is used as a Bloch It has means for transferring within the domain wall.

One of the most important parts of this device is the information storage section (hereinafter referred to as the minor loop).

In such a magnetic memory element, it is essential to stably hold the VBL pair on the stripe domain wall written as information and to be able to selectively transfer one bit at a time. The patent application was filed in 1982.
065826, the direction of magnetic anisotropy within the film plane is locally changed along the Bloch domain wall around the striped domain that constitutes the minor loop. , it is possible to create a position where the VBL pair stably exists and a position where it does not. Regarding the other condition, selective transfer of each bit of the VBL pair, in principle, it is possible to create a position where the VBL pair exists stably and a position where it does not exist. A means of providing driving force is required. In reality, VB
A method of applying a local in-plane magnetic field in the form of a traveling wave along the domain wall surface to the L pair existing region, and a pulse bias magnetic field is applied to the striped domain domain wall to dynamically move the domain wall, and the reaction that occurs in the position of the VBL pair accordingly It has been considered to utilize gyroscopic force, which is one of the methods, but the former is currently only achieved by using conductor patterns, which poses a problem when aiming to increase the density of elements. On the other hand, in the latter case, the domain wall driving force provided by the externally applied pulsed bias magnetic field is very important. In order to make this domain wall driving force constant at each part on the chip, it is important to determine how to stabilize the stripe domain and to optimize the potential well shape of the domain wall portion of the stripe domain.

As shown in Fig. 3, the conventional method for this method is to remove the region in the stripe domain holding layer l in which the stripe domain 6 is to be stabilized, and add a region with high saturation magnetization and high coercive force thereto. By embedding a perpendicularly magnetized material 19 and utilizing the magnetic field that leaks from that part to the outside, create a region around the periphery of the removed part with magnetization 8 in the opposite direction to the bias magnetic field 10. However, in this method, embedding the perpendicular magnetization material 19 in the cut-out portion was technically problematic in terms of the manufacturing process. 20 in FIG. 3 indicates the direction of magnetization (objective of the invention) The object of the present invention is to eliminate such conventional drawbacks, stably hold VBL pairs in the striped domain domain wall soil with minor loops, The object of the present invention is to provide an ultrahigh-density storage element that uses a VBL pair as an information unit, which enables selective transfer of one bit at a time. Magnetic memory using a VBL pair consisting of two adjacent VBLs formed in a Bloch domain wall at a striped domain boundary existing in a magnetic film as a storage unit; A magnetic memory element is formed by selectively digging a trench over a region where the stripe domain is to be stabilized, and stabilizing the stripe domain in the trench in the form of a ring-shaped stripe domain. Explanation) The present invention eliminates the perpendicular magnetic material embedding process of the prior art and solves the problems by adopting the above-mentioned configuration. FIG. 3 is a configuration diagram of the main part of the striped domain holding layer in the loop portion.

A striped domain holding layer 1 is provided on a substrate 2 shown in FIG. 1(a). Grooves 3 are formed by selectively digging grooves on the surface only in areas where it is desired to hold the striped domains in a ring shape. This width is larger than the natural @W0 (width in the absence of magnetic field) of the stripe domain and is about 2W or less.
The reason for this can be seen by considering the role of the film thickness step part at the groove boundary. Among the boundaries of the groove, boundary 4 has a convex part inside it with a boundary of 4.
The boundary 5 serves to attract the I domain wall to 4, and the boundary 5 serves as a guide to prevent the inner domain wall from being too far away from 4 when initializing the stripe domain 6. Furthermore, the width of the convex portion with a boundary of 4 is W. If you do not do this, when the striped domain 6 is held in a ring shape in the groove, the repulsive interaction between the linear domains on both sides of the convex part with the boundary 4 will be strong. However, the inner domain wall of the ring-shaped stripe domain is only fixed directly below the boundary 4. When the grooves 3 are formed so as to satisfy the above conditions, the striped domains are fixed in a ring shape having the groove groove boundary 4 as the inner diameter as shown in FIG. 1(b).

When the striped domain is maintained in this way, the profile in the normal direction of the domain wall surface of the potential well of the domain wall outside the ring-shaped domain (the 0 part of the domain wall that exists away from boundary 4) is mainly due to the demagnetizing field effect determined by the width of the striped domain. It is fixed, and is not affected by unevenness in the finish of the 9-part boundary of the trench excavation.

, When an externally applied pulsed bias magnetic field is applied to such a domain wall, the domain wall drive becomes uniform over the entire 4a wall 7. Therefore, by applying a pulse bypass magnetic field 10, information stored in the form of the presence or absence of a VBL pair in the domain wall of VB
When moving using the gyro force generated in the L pair, the amount of movement can be easily controlled by the shape of the pulse bypass magnetic field.

8 and 9 in the figure are the directions of magnetization inside and outside the domain, respectively 〇 (Example) An example is shown below ◎ Figure 2 shows the process of forming a striped domain in a ring shape and the required conditions for this device. Information stored in VBL pairs within the stripe domain domain wall is converted into a bubble domain when reading, or data expressed in the form of bubbles on the major line 17 is converted into VBL pairs within the stripe domain domain wall during write. The tip 1 of the grooving part 3 shows a concrete operation process for an example of the shape of the grooving pattern including the gate part 18 for performing the function of memorizing the shape.
A bubble generator consisting of a conductor pattern 12 is placed on 1. A magnetic field in the same direction as the bias magnetic field 10 is applied to the entire effective chip surface in advance to saturate the entire surface in the direction of lO. After that, a suitable bias magnetic field H2 is applied. Thereafter, when a pulsed current 13 having the shape shown is applied to this bubble generator, bubbles are generated in 11, and the bubbles form striped domains extending along the groove 3, with their apexes being the introduction guides 14 and 14', respectively. It becomes a U-shape.

Conductor pattern 1 for such a striped domain
A pulse current 16 is applied to 5 in the direction of the arrow to form a 0 junction that joins the part extending into 14 and the part extending into 14' of the stripe domain in the region between the two conductor patterns. The striped domain shrinks due to the action of the bias magnetic field H and the domain wall surface tension that tries to minimize the surface energy of the domain wall, and finally forms a ring whose inner edge is the boundary 4 of the groove as shown in Figure 1. V, which is an information carrier, is placed on the outer domain wall 7 of this domain 6, which becomes a striped domain.
Write the BL pair. Grooves 18 and 18' are ring-shaped striped tones that store information in the form of major lines 17 and 17', which represent information by the presence or absence of bubbles necessary for Bloch line memory, and the presence or absence of VBL pairs.

This is for the gate connecting the inner part. Note that the depth of the groove is 5 to 40% of the total thickness of the striped domain holding layer.
We actually evaluated the purity of the white, and there was no problem with the formation of ring-shaped striped domains.90 (Effects of the Invention) The present invention stabilizes the striped domains without embedding perpendicular magnetization material, which has been a problem in the past. Since the non-uniformity of the potential well in the domain wall can be removed, the stability of the Bloch line pair transfer is increased, and therefore the reliability of the Bloch line memory is improved.

A diagram showing an example of the structure of the retention layer, and FIG. 3 shows a conventional example.

[Brief explanation of the drawing]

In the figure, l varnish drive domain holding layer, 2: substrate, 3: trenching)
part, inner boundary of trench 1 part, 5: outer boundary of trench part, 6: ring-shaped stripe domain, 7: outer peripheral domain wall of stripe domain, 8 direction of magnetization within two domains, direction of magnetization outside two domains, lO: Bias magnetic field direction, 1t: tip of IB excavation part (bubble generation part), 12: bubble generator conductor pattern, 13: bubble generation current, 14.14': stripe domain tip introduction guide, 15 for varnish drive domain fusion Conductor pattern, 16: Stripe domain fusion current $17.17': Major line (puzzle transfer path) % IL 18':) Transfer gate part (groove part), 19: Hard magnetic perpendicular magnetization material, 20: Magnetization direction of hard magnetic perpendicularly magnetized material. Figure 1 C========D Figure 2 Kabuto 3 Figure 1, Strive Domain 2, Kisai Anti-Otsu. strike domain 7

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 that uses a vertical Bloch line pair consisting of two adjacent vertical Bloch lines formed in the ferromagnetic film surface as a storage information unit, and has means for transferring the vertical Bloch line pair within a Bloch domain wall. What is claimed is: 1. A magnetic memory element characterized in that the striped domains are formed into ring-shaped striped domains by selectively trenching the striped domains.