JPH0319187A - Bloch line memory device - Google Patents

Abstract

PURPOSE:To attain the stabilized transfer of a pair of Bloch lines by providing areas which are arranged in parallel at prescribed intervals and which show magnetic anisotropy except for a vertical one or para-magnetism for a magnetic film showing vertical magnetic anisotropy. CONSTITUTION:Amorphous areas 2b showing para-magnetism are provided in parallel at the prescribed intervals in the mono-crystal magnetic garnet film 2 showing vertical magnetic anisotropy. Thus, a stripe domain 4 can be stabilized at the periphery (the periphery exists in vertical magnetic anisotropy area 2a) of the para-magnetism areas 2b. Thus, the accurate and highly reliable stabilization of the stripe domain 4 is attained, and accordingly a pair of the Bloch lines can stably be transferred.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a Bloch line device that uses vertical Bloch line pairs as storage information units and is useful for external memory for computers, memory for file devices, etc. Regarding stabilization of line pairs. [Prior art] With the development of high-density memory elements, IEEE Trans
．． Magn. Bloch line memory devices announced in MAG 19, 1838 (1983), Japanese Patent Laid-Open No. 59-101092, etc. have attracted attention in recent years because of their enormous storage capacity and non-volatility.

A Bloch line memory device consists of an information storage section consisting of a domain wall around a striped domain, which is an elongated bubble domain, and stores information in the form of vertical Bloch line pairs in the domain wall. Bloch line pairs exist regularly as storage information units, and for example, if there is a Bloch line pair, it corresponds to "1", and if there is no Bloch line pair, it corresponds to "O". Furthermore, during writing or reading, this Bloch line pair is sequentially transferred to adjacent potential wells by applying a vertical pulsed magnetic field. The main components of such a Bloch line memory device are generally formed by epitaxial growth (YSmLuCa) on a substrate 1 made of a rare earth garnet single crystal such as GGG, as shown in FIG. (FaGe) so. =．
A magnetic garnet film 2 made of (YSmTm), (FeGa), O, etc. is provided, and on top of that, GdCo, TbFe, GdFe is added to stabilize the stripe domain.
, GdFeCo, TbFeCo, etc., or a polycrystalline film such as CoPt, CoCr, etc., is provided. Further, an insulating film of Si3N, , Sin, SiO, etc. is provided between the magnetic film 2 and the perpendicularly magnetized film 3 as necessary. Although not shown, the perpendicular magnetization film 3 is regularly patterned in parallel so that the striped domains are regularly arranged in parallel. A conductor is also provided. A bias magnetic field H8 is applied to the entire device, and the stripe domain 4 is stabilized around the perpendicular magnetization film saturated in the direction opposite to the bias magnetic field H8. A soft magnetic film pattern such as permalloy may be used instead of the perpendicular magnetization film pattern. Strive domains are stabilized by the leakage magnetic field from both perpendicular magnetization film patterns and soft magnetic film patterns. Other methods for stabilizing striped domains include providing a groove in the bubble magnetic film and stabilizing it by the demagnetizing field generated near the stepped portion of the groove, and placing a loop-shaped conductor on the bubble magnetic film. There are methods to stabilize the magnetic field by passing current through the conductor and generating a vertical magnetic field within the loop area. Figure 2 shows an example in which a groove is provided in the magnetic film.
It is provided at a predetermined position (to the extent that the stripe domain is stabilized!) with a width of about 1/2 of the groove, and the stripe domain 4 is stabilized around the groove by applying a bias magnetic field H8. However, in the above-mentioned method of stabilizing a stripe domain, a pattern is provided on the magnetic film for bubbles or the magnetic film itself is processed, so if a conductor or the like is further provided on top of the pattern, a step may occur in the film thickness direction. Due to the influence of the shape, a flattening process is required, and when a patterned film is placed on the magnetic film for bubbles, stress is generated between the magnetic film and the domain wall, causing the domain wall to become stuck. The stability of the stripe domain differs depending on the method, and this causes problems such as the inability to transfer stable vertical Bloch lines. [Problems 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 eliminate potential wells in the domain wall due to the stress of the magnetic film, the shape of the groove, etc., without the need for a planarization process. It is an object of the present invention to provide a Bloch line memory device capable of accurate and reliable stabilization of stripe domains while avoiding non-uniformity of Bloch lines, and thus capable of stable transfer of Bloch line pairs. [Structure/Operation of the Invention] The Bloch line memory device of the present invention has a magnetic film exhibiting perpendicular magnetic anisotropy that stores perpendicular Bloch line pairs as storage information units on the domain walls of striped domains. This is characterized by stabilizing the stripe domain within the region exhibiting perpendicular magnetic anisotropy by providing regions exhibiting magnetic anisotropy or paramagnetism other than perpendicular to each other at regular intervals. In this way, the device of the present invention stabilizes the stripe domains within the bubble magnetic film without using the conventional planarization process. To explain the Bloch line memory device of the present invention with reference to the drawings, FIGS. 3 to 5 are cross-sectional views showing the main components of the device of the present invention, and in the case of FIGS. By arranging the amorphous regions 2b exhibiting paramagnetism in parallel at regular intervals within the single crystal magnetic garnet [112], in the case of FIG. In the case of FIG. 4, the stripe domain 4 is stabilized between two paramagnetic regions 2b, and in the case of FIG. A band-shaped polycrystalline region 2b exhibiting magnetic anisotropy other than perpendicular (for example, in-plane) (hereinafter referred to as different magnetic anisotropy) is provided in the rare earth metal to transition metal-based amorphous magnetic film 2 exhibiting perpendicular magnetic anisotropy. This stabilizes the stripe domain 4 between the two different magnetic anisotropy regions 2b. There are generally two methods for making the device of the present invention as described above. One is to coat the surface of a non-magnetic substrate such as rare earth garnet single crystal such as GGG, quartz, glass, plastic, etc. with photoresist except for the areas that exhibit paramagnetism or different magnetic anisotropy, and then After performing ion irradiation from ., the photoresist was removed and (YSmLuCa). (FaGe)sO. t,
(YSmLuLu), (FaGe),01,, (YS
A magnetic garnet material such as mTm), (FeGe), or 01■ is formed into a film with a thickness of 0.1 to 5μ by a film method such as RF magnetron sputtering or LPE (liquid phase epitaxial method).
This is a method to form a magnetic garnet film with a thickness of about 100 ml. In this case, a film (region) with an amorphous structure exhibiting paramagnetism is formed in the ion-irradiated part of the substrate, and a single-crystalline film (region) exhibiting perpendicular magnetic anisotropy with a small coercive force He due to epitaxial growth in the part not irradiated with ions. II (area)
is formed. Another method is to coat GdCo on the untreated substrate. TbFe. GdFe. GdFeCo.
A rare earth metal to transition metal based amorphous alloy such as TbFeCo is formed into a film by a film forming method such as RF magnetron sputtering, and exhibits perpendicular magnetic anisotropy with a thickness of approximately 0.1 to 5 μm. This method involves forming a magnetic film and then annealing it by irradiating laser light in a pattern onto regions exhibiting different magnetic anisotropy. In this case, the part of the magnetic film that is irradiated with the laser beam has a polycrystalline structure and exhibits in-plane magnetic anisotropy, while the part that is not irradiated with the laser beam has an amorphous structure with perpendicular magnetic anisotropy. The film (region) showing N remains intact. It is possible to form a heteromagnetic anisotropic or paramagnetic region in addition to the above two methods. For example, it is possible to create a paramagnetic region or a different magnetically anisotropic region by ion implantation into the substrate surface, or to create a different magnetically anisotropic region by irradiating an amorphous perpendicularly magnetized film with an ion beam or an electron beam. In addition, in the device of the present invention, as shown in FIGS. 6 and 7, 0.1 to 1
Insulating layer (Si, NiSin2, SiO
etc.) (not shown), respectively 0.1 to 1 μ■
A conductor 5 for bubble generation, a conductor 6 for Bloch line control, and a conductor 7 for chopping (made of Au, Ag, Am, Cu, etc.) of approximately the same thickness are arranged by patterning. Note that 2b is a paramagnetic region for guiding. Examples of manufacturing the device of the present invention are shown below. Example 1 This example is an example in which a stripe domain is stabilized around the region 2b exhibiting dispersion magnetism as shown in FIG. A substrate made of Gd2Gab01x was coated with photoresist except for the area corresponding to the region 2b exhibiting paramagnetism as shown in FIG. 6, and ion irradiation was performed under the following conditions. Gas pressure: Ar, 5 X10-'Torr
RF discharge power: 20011, 13.56MHz Irradiation time: lOin Next, 100 MHz was applied as a target on the substrate treated in this way.
■RF (YSmTm), (FeGe)s01, of φ
A film was formed using the magnetron scattering method under the following conditions, and the film was deposited approximately 2 times.
A μ-thick magnetic garnet film was formed.

Residual gas pressure: I XIO-'TorrAr gas pressure:
5 The film in the area without it had an epitaxially grown single crystal structure, and became a perpendicular magnetic anisotropic film with a small coercive force Hc. Below is the tip of the striped domain using the usual method? An insulating layer made of Si and N with a thickness of 0.5μ is provided on the adjacent magnetic film.
Furthermore, a Bloch line memory device of the present invention as shown in FIG. 6 was fabricated by providing a bubble generation conductor, a Proch line control conductor, and a chopping conductor each made of AU with a thickness of 0.5 μm. In this example, the guiding paramagnetic region 2b is provided at the end portion between each stripe domain 4 so that the stripe domain extends straightly. Example 2 This example is an example in which a stripe domain is stabilized between two paramagnetic regions, as shown in FIG. A substrate made of Gd, Ga, 0■, is coated with photoresist except for the area corresponding to the region 2b exhibiting paramagnetism as shown in FIG. 7, and ion irradiation is performed under the following conditions. Gas pressure: Xe, 5XIO-”T
orrRF discharge power: 2001, 13.56MHz
Irradiation time: 10 min Next, on the substrate treated in this way, 10 min was applied as a target.
(YSmLu)a (FeGe)sO,, of 0■φ is R
A magnetic garnet film with a thickness of approximately 2 μm was formed using the F magnetron scattering method under the same conditions as in Example 1. Thereafter, as in Example 1, Si, N. The Bloch line memory device of the present invention was fabricated by providing an insulating layer made of Au, and further providing a bubble generation conductor, a Bloch line control conductor, and a chopping conductor made of Au, respectively. In this example, as shown in Figure 7, the stripe domain is surrounded by a paramagnetic region so that it does not extend to one side (to the right in Figure 7). Example 3 This example is an example in which a stripe domain is stabilized between two different magnetic anisotropy regions as shown in Fig. 5. A c (Io
．． Zcoo-s alloy was filmed by RF magnetron sputtering under the following conditions to produce a rare earth metal to transition metal amorphous magnetic film having a thickness of approximately 2 μm.

Residual gas pressure: I XIO-'TorrAr gas pressure:
5 X 10-'TorrRF discharge power: 4001
j Substrate temperature: Water cooling Next, this magnetic film was irradiated with 30W+W Ar laser light (beam diameter: approximately 1.5 μm) in a region pattern exhibiting different magnetic anisotropy as shown in Figure 7, and annealed (approximately 400 μm). ℃)
did. As a result, the part that was irradiated with the laser had a polycrystalline structure and exhibited in-plane magnetic anisotropy, while the part that was not irradiated with the laser remained an amorphous structure and showed perpendicular magnetic anisotropy. Hereinafter, as in Example 1, an insulating layer made of Si and N4 is provided on the magnetic film near the tip of the striped domain, and on top of that, a conductor for bubble generation, a conductor for Bloch line control, and a conductor for chopping are made of Au, respectively. A Bloch line memory device of the present invention was fabricated by providing a conductor. In this example, as shown in Figure 7, the stripe domain is surrounded by a different magnetic anisotropy region so that it does not extend to one side (to the right in Figure 7). [Operations and Effects of the Invention] The Bloch line memory device of the present invention has a region exhibiting heteromagnetic anisotropy or paramagnetism within a conventional magnetic film exhibiting perpendicular magnetic anisotropy, thereby reducing stress in the magnetic film and grooves. By avoiding the non-uniformity of the potential well in the domain wall due to the shape etc., accurate and reliable stabilization of the stripe domain, and therefore stable transfer of Bloch line pairs, is possible. In addition, since the striped domain can be stabilized without the need for a planarization process, accurate patterns such as conductors can be formed on this film, resulting in highly reliable writing and
Can be read and transferred.

[Brief explanation of the drawing]

1-2@ are sectional views of the main components of a conventional Bloch line memory device, FIGS. 3-5 are sectional views of the main components of the Bloch line memory device of the present invention, and FIGS. 6 and 7 are respectively 5 is a top view of a device having the main components shown in FIG. 3 and FIGS. 4 and 5. FIG. 1...Substrate 2...Magnetic film 2a...
Region 2b' showing perpendicular magnetization film...Bara magnetic region for guide 4...Stripe domain 5...Bubble generation conductor 6...Bloch line control conductor 7...Chopping conductor H1...Bias Magnetic field Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In a Bloch line memory device having a magnetic film exhibiting perpendicular magnetic anisotropy that stores perpendicular Bloch line pairs as storage information units on the domain wall of a stripe domain,
A Bloch line characterized in that a stripe domain is stabilized within a region exhibiting perpendicular magnetic anisotropy by providing regions exhibiting magnetic anisotropy other than perpendicular or paramagnetism parallel to each other at regular intervals in a magnetic film. memory device.