KR20100039794A - Information storage device using magnetic domain wall moving - Google Patents

Abstract

PURPOSE: An information storage device using the movement of a magnetic domain wall is provided to obtain the information storage device with a large storage capacity without a rotating mechanical device using the movement principles of a magnetic domain and a magnetic domain wall. CONSTITUTION: A magnetic track(100) includes a plurality of magnetic domains(D1, D2) and a magnetic domain wall(DW1). A pinning material(200) is spaced apart from the magnetic track and pins the magnetic domain wall. The pining material applies magnetic field to the magnetic track in order to pin the magnetic domain wall. The direction of the magnetic field is identical to the magnetization direction of the magnetic domain wall. The pinning material is magnetic layer pattern.

Description

Information storage device using magnetic domain wall moving}

The present disclosure relates to an information storage device using magnetic domain wall movement.

The disclosed invention is derived from a study conducted as part of the Seoul-Academic-Industry Cooperation Project-Technology Foundation Project in Seoul. [Task unique number: 10543, Assignment name: Nanobio system and application material]

Non-volatile information storage devices that maintain recorded information even when power is cut off include a hard disk drive (HDD) and a nonvolatile RAM (non-volatile RAM).

In general, HDDs tend to wear into storage devices that have rotating parts, and are less reliable because of the greater likelihood of failing during operation. On the other hand, a representative example of a nonvolatile RAM is a flash memory, which does not use a rotating mechanical device, but has a disadvantage in that the read / write operation speed is slow, the life is short, and the storage capacity is smaller than that of an HDD. In addition, flash memory production costs are relatively high.

Therefore, in recent years, as a way to overcome the problems of the conventional nonvolatile information storage device, research and development of a new information storage device using the principle of moving the magnetic domain wall (magnetic domain wall) of the magnetic material has been made. The magnetic domain is a magnetic microregion in which the magnetic moments are arranged in a certain direction in the ferromagnetic material, and the magnetic domain wall is a boundary of magnetic domains having different magnetization directions. The magnetic domain and the magnetic domain wall can be moved by a current applied to the magnetic track. Using the principle of movement of magnetic domains and magnetic domain walls, it is expected that an information storage device having a large storage capacity can be realized without using a rotating mechanical device.

One of the key technologies of data storage devices using magnetic domain wall movement is the pinning technique of magnetic domain walls. The magnetic domain walls that start to move by the current applied to the magnetic tracks must be able to move by a predetermined length and then stop, i.e., pinning, at a specific position of the magnetic tracks. This allows bitwise movement of the magnetic domain walls.

Notches are mainly used for pinning the magnetic domain walls. That is, a notch is formed in the magnetic track and used as a pinning site of the magnetic domain wall. However, in using a notch, various problems may arise. For example, current may be concentrated in the notch portion of the magnetic track, and heat may be generated. As a result, various problems may be caused, such as the reliability of information recorded in the magnetic track, and the magnetic track itself being damaged. In addition, it is not easy to form a notch of minute size in a magnetic track having a thickness and a width of several tens of nanometers (nm). It is more difficult to form fine notches with uniform spacing, size and shape. Non-uniform spacing, size and shape of the notch can result in non-uniform device characteristics because the strength of the magnetic field stopping the magnetic domain wall, i.e., the strength of the pinning magnetic field, varies.

The present invention provides a method of fixing, that is, pinning, a magnetic domain wall without a notch, and an information storage device using the same.

One embodiment of the present invention is a magnetic track having a plurality of magnetic domains and the magnetic domain wall therebetween; And a pinning member spaced apart from the magnetic track, the pinning member for pinning the magnetic domain wall.

The pinning member may be configured to apply a magnetic field for pinning the magnetic domain wall to the magnetic track, and the direction of the magnetic field may be the same as the magnetization direction of the magnetic domain wall.

The pinning member may be a magnetic layer pattern, and at least a portion of the magnetic layer pattern may be magnetized in the same direction as the magnetization direction of the magnetic domain wall.

The magnetic layer pattern may extend in a direction perpendicular to the magnetic track.

One end of both ends of the magnetic layer pattern toward the magnetic track may be sharp.

The magnetic layer pattern may have a symmetrical or asymmetrical structure.

The magnetic layer pattern may have a nanoscale.

An interval between the magnetic layer pattern and the magnetic track may be about several tens of nm.

The magnetic layer pattern may include at least one of Co, Ni, and Fe.

The magnetic layer pattern and the magnetic track may be formed of the same material.

The magnetic layer pattern and the magnetic track may be formed of different materials.

The magnetic track may have in-plane magnetic anisotropy or perpendicular magnetic anisotropy.

The magnetic layer pattern may have horizontal magnetic anisotropy or vertical magnetic anisotropy.

The magnetic track and the pinning member may be provided on the same plane. In this case, the pinning member may be provided on one side or both sides of the magnetic track.

The magnetic track and the pinning member may be stacked vertically. In this case, the pinning member may be provided at at least one of the bottom and the top of the magnetic track.

A plurality of pinning members may be provided at at least one side of the magnetic track at equal intervals.

According to an embodiment of the present invention, an information storage device capable of pinning a magnetic domain wall without a notch may be implemented.

Hereinafter, an information storage device using magnetic domain wall movement according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of the layers or regions illustrated in the drawings are somewhat exaggerated for clarity. Like numbers refer to like elements throughout.

1 (A) is a plan view showing an information storage device using the magnetic domain wall movement according to an embodiment of the present invention.

Referring to FIG. 1A, a magnetic track 100 extending in a predetermined direction, for example, the X-axis direction, may be provided. The magnetic track 100 may include a plurality of magnetic domains D1 and D2 and a magnetic domain wall DW1 therebetween. The first and second magnetic domains D1 and D2 may be regions magnetized in opposite directions, and the magnetic domain wall DW1 may be a boundary between the first and second magnetic domains D1 and D2. Although the magnetic track 100 has two magnetic domains (hereinafter, first and second magnetic domains) D1 and D2, the magnetic track 100 may include three or more magnetic domains. A magnetic domain wall may be provided between two adjacent magnetic domains.

The magnetic track 100 may be formed of a material and a structure having in-plane magnetic anisotropy. In this case, the magnetic domains D1 and D2 of the magnetic track 100 may have a magnetization direction parallel to the longitudinal direction of the magnetic track 100. In the present embodiment, the first magnetic domain D1 is magnetized in the X-axis direction, the second magnetic domain D2 is in the reverse direction of the X-axis, and the magnetic domain wall DW1 is magnetized in the Y-axis direction. The first and second magnetic domains D1 and D2 may correspond to information '0' and '1', respectively. The magnetization directions of the first and second magnetic domains D1 and D2 may be changed, and the magnetization directions of the magnetic domain walls DW1 may also be changed. It is also possible for the magnetic track 100 to have perpendicular magnetic anisotropy.

Pinning means 200 for pinning the magnetic domain wall DW1 may be provided. The pinning means 200 may be provided on at least one side, for example, both sides of the magnetic track 100. At this time, the magnetic track 100, one side and the other pinning means 200 may be provided on the same axis. The pinning means 200 may be a means for applying a magnetic field for pinning the magnetic domain wall DW1 to the magnetic track 100. The direction of the magnetic field may be the same as the magnetization direction of the magnetic domain wall DW1. For example, the pinning means 200 may be a "magnetic layer pattern" for generating the magnetic field. In this case, the pinning means 200 may have a structure extending in a direction perpendicular to the magnetic track 200, and may be magnetized in the same direction as the magnetization direction of the magnetic domain wall DW1. At this time, the pinning means 200 may have a horizontal magnetic anisotropy, the length of the Y-axis direction of the pinning means 200 may be longer than the length (hereinafter, the width) in the X-axis direction. For example, the pinning means 200 may have a width on the order of tens to hundreds of nm and a length corresponding to several times thereof. The thickness of the pinning means 200 may be several tens of nm or less. Pinning means 200 having such a dimension can be said to have a nanoscale (nanoscale). When the pinning means 200 has horizontal magnetic anisotropy, it may have a magnetic easy axis in its major axis direction (ie, Y-axis direction). Therefore, the pinning means 200 may be magnetized in a direction parallel to the Y axis. One end of the pinning means 200 toward the magnetic track 100 may be pointed. As such, when one end of the pinning means 200 is pointed, it may be advantageous to have one end magnetized in a direction parallel to the Y axis. In this case, the width of the magnetic field applied from the pinning means 200 to the magnetic track 100 may be narrowed. The other end disposed far from the magnetic track 100 among the both ends of the pinning means 200 may also have a pointed shape. But in some cases, it may not. Therefore, the pinning means 200 may have a symmetrical or asymmetrical structure on the magnetic track 100. The shape of the pinning means 200 is not limited to the illustrated and may be variously modified. On the other hand, the interval between the pinning means 200 and the magnetic track 100 may be several to several tens of nm.

Although not shown in FIG. 1A, at least one of both ends of the magnetic track 100 may be connected to a current applying means. The current applying means may apply a current for moving the magnetic domain wall to the magnetic track 100.

FIG. 2 is a graph showing a magnetic field generated by the pinning means 200 of FIG. 1. In more detail, FIG. 2 illustrates a change in the intensity of the magnetic field applied to the magnetic track 100 from the pinning means 200 according to the distance d of the magnetic track 100 and the pinning means 200 of FIG. 1. It is a graph. Here, the magnetic field is a magnetic field of the Y-axis component applied to the magnetic track 100 from the pinning means 200. In the graph of FIG. 2, the X axis represents a position along the X axis direction of the magnetic track 100. The point where X = 0 is the point closest to the pinning means 200 in the magnetic track 100.

2, it can be seen that a magnetic field perpendicular to the magnetic track 100 is applied from the pinning means 200 to the magnetic track 100. At this time, the strength of the magnetic field was about tens to hundreds of Oe (oersted). 2, it can be seen that the closer the magnetic track 100 and the pinning means 200 are, the higher the intensity of the magnetic field applied to the magnetic track 100 is.

In the information storage device having the structure as shown in FIG. 1A, when the magnetic domain wall DW1 is placed under the magnetic field generated by the pinning means 200, the magnetization direction of the magnetic domain wall DW1 and the direction of the magnetic field are the same. Therefore, the magnetic track 100 may be in the most stable state of energy. Therefore, the magnetic domain wall DW1 moving by the current applied to the magnetic track 100 may be stopped, that is, pinned at the point where the pinning means 200 is provided. As described above, in the present embodiment, the magnetic domain wall DW1 can be easily pinned by using the magnetic layer pattern generating the magnetic field (that is, stray field) as the pinning means 200 without forming a notch. Therefore, it is possible to implement an information storage device that prevents various problems caused by notches.

1B is a graph showing a change in energy of the magnetic track 100 according to the position of the magnetic domain wall DW1.

Referring to FIG. 1B, when the magnetic domain wall DW1 is located closest to the pinning means 200, it can be seen that the energy of the magnetic track 100 is the smallest.

3 is a plan view of an information storage device using magnetic domain wall movement according to another embodiment of the present invention. In the present embodiment, the magnetic track 100 'has vertical magnetic anisotropy and the pinning means 200' has horizontal magnetic anisotropy.

및

는 이들(D1', D2')의 자화방향을 나타낸다. 자구벽(DW1')은 Y축과 평행한 자화 방향을 가질 수 있다. 자성트랙(100')의 적어도 일측, 예컨대, 양측에 핀닝 수단(200')이 구비될 수 있다. 핀닝 수단(200')은 자구벽(DW1')의 자화 방향과 동일한 방향으로 자화될 수 있다. 핀닝 수단(200')은 도 1의 핀닝 수단(200)과 유사할 수 있으므로, 이에 대한 반복 설명은 생략한다. Referring to FIG. 3, the magnetic track 100 ′ may have perpendicular magnetic anisotropy. In this case, the first magnetic domain D1 ′ of the magnetic track 100 ′ may be magnetized in the Z-axis direction, and the second magnetic domain D2 ′ may be magnetized in the opposite direction of the Z-axis. Indications shown in the first and second magnetic domains D1 ', D2'

And

Represents the magnetization directions of these (D1 ', D2'). The magnetic domain wall DW1 ′ may have a magnetization direction parallel to the Y axis. Pinning means 200 ′ may be provided on at least one side of the magnetic track 100 ′, for example, on both sides. The pinning means 200 ′ may be magnetized in the same direction as the magnetization direction of the magnetic domain wall DW1 ′. Since the pinning means 200 ′ may be similar to the pinning means 200 of FIG. 1, repeated description thereof will be omitted.

In the structure of FIG. 3, similar to the case of FIG. 1, the magnetic domain wall DW1 ′ may be pinned by a magnetic field generated by the pinning means 200 ′.

4 is a cross-sectional view of an information storage device using magnetic domain wall movement according to another embodiment of the present invention. In the present embodiment, the magnetic track 100 "has horizontal magnetic anisotropy and the pinning means 200" has vertical magnetic anisotropy. In the structure of FIGS. 1 and 3, the magnetic tracks 100 and 100 ′ and the pinning means 200 and 200 ′ are provided on the same plane, while in the structure of FIG. 4, the magnetic track 100 ″ and the pinning means 200 are provided. Are stacked in the vertical direction.

Referring to FIG. 4, the first and second magnetic domains D1 and D2 of the magnetic track 100 ″ may be magnetized in the opposite direction of the X and X axes, and the magnetic domain wall DW1 ″ may be magnetized parallel to the Z axis. Direction. The difference between the magnetic track 100 ″ and the magnetic track 100 in FIG. 1 is in the magnetization directions of the magnetic domain walls DW1 ″ and DW1. The magnetic domain wall DW "of Fig. 4 is magnetized in the direction parallel to the Z axis. When the magnetic domain wall DW1" has the magnetization direction parallel to the Z axis as shown in Fig. 4, the pinning means 200 " It may be provided on at least one of the top and bottom of the magnetic track 100. At this time, the pinning means (200 ") may have a magnetizing axis parallel to the Z axis. That is, the pinning means 200 "may have perpendicular magnetic anisotropy. When the pinning means 200" has vertical magnetic anisotropy, the easy axis for magnetization may be determined by its crystal structure. Thus, the shape of the end of the pinning means 200 "may not be important. That is, at least one of both ends of the pinning means 200" may not be pointed.

Even in the structure of FIG. 4, the magnetic domain wall DW1 ″ of the magnetic track 100 may be pinned by the magnetic field generated by the pinning means 200 ″.

In FIGS. 1, 3, and 4, the magnetic tracks 100, 100 ′, 100 ″ and pinning means 200, 200 ′, 200 ″ may be formed of a magnetic material including at least one of Co, Ni, and Fe. The magnetic material may further include other elements in addition to Co, Ni, and Fe. The magnetic tracks 100, 100 ′, 100 ″ and the pinning means 200, 200 ′, 200 ″ may be formed of the same material or different materials. For example, at least one of the magnetic tracks 100, 100 ', 100 "and the pinning means 200, 200', 200" is formed of a soft magnetic material having horizontal magnetic anisotropy or a ferromagnetic material having vertical magnetic anisotropy. Can be.

The shape of the pinning means 200, 200 ′, 200 ″ shown in Figs. 1, 3 and 4 can be varied in various ways. An example is shown in Fig. 5.

Referring to FIG. 5, the pinning means may have various shapes such as a triangle (A), a rhombus (B), one end of a pointed pentagon (C), one end of a pointed and the other end of a round shape (D), and a rectangle (E). have.

1, 3 and 4 show that the magnetic tracks 100, 100 ', 100 "have one magnetic domain wall DW1, DW1', DW1", and a pair of pinning means 200, 200 ', 200 corresponding thereto. Although ") is provided, two or more magnetic domain walls DW1, DW1 ', and DW1" may be provided, thereby increasing the number of pinning means 200, 200', and 200 ". The structure as shown in FIG. 6 is possible.

Referring to FIG. 6, a magnetic track 1000 having a plurality of magnetic domains D and magnetic domain walls DW therebetween may be provided. A plurality of pinning means 2000 may be provided at one side of the magnetic track 1000 at equal intervals. The distance between the pinning means 2000 and the magnetic domain wall DW may be the same. A plurality of pinning means 2000 may be provided on the other side of the magnetic track 1000. The pinning means 2000 on the other side of the magnetic track 1000 may be provided to correspond to the pinning means 2000 on one side of the magnetic track 1000 in one-to-one correspondence. The pinning means 2000 may be formed together with the magnetic track 1000. In this case, a photolithography process may be used, or a fine patterning process such as e-beam lithography may be used. If the pinning means 2000 are small in size and the spacing between them 2000 is small, it may be advantageous to use a fine patterning process, such as e-beam lithography. In addition to the above-mentioned method, the pinning means 2000 may be formed by other methods.

Additionally, although not shown here, the information storage device according to the embodiment of the present invention includes a recording unit for recording information on the magnetic tracks 100, 100 ', 100 ", 1000, a reproducing unit, etc. for reproducing the information. Instead of providing a recording unit and a reproducing unit separately, a recording / reproducing unit having both recording and reproducing functions may be provided. When the recording unit is an element for recording information using spin transfer torque, the recording unit may be, for example, TMR (tunnel magneto resistance) or The reproducing unit may be a sensor for reproducing information by using a TMR or a GMR effect. It may be an integrated element that performs recording using the principle of net, and also performs playback by using the principle of the playback unit.The recording unit, the playback unit, and the recording / reproducing unit may be provided. These structures and principles are not limited to the above, but may be variously modified.

While many details are set forth in the foregoing description, they should be construed as illustrative of specific embodiments rather than to limit the scope of the invention. For example, one of ordinary skill in the art will recognize that the idea of the present application may be applied to any device as long as the device uses magnetic domain wall movement. That is, the idea of the present application may be applied to other devices, for example, logic elements using magnetic domain wall movement, in addition to the apparatus for storing information using magnetic domain wall movement. In addition, it will be appreciated that the structure of the information storage device of FIGS. 1, 3, 4, and 6 may be modified in various ways. As a specific example, in FIGS. 1, 3, 4, and 6, the pinning means 200, 200 ′, 200 ″, 2000 may be replaced with elements other than the “magnetic layer pattern” and the magnetic tracks 100, 100 ′. It may be provided only on one side, not both sides of the, 100 ", 1000. And the shape of the magnetic tracks (100, 100 ', 100", 1000) can also be modified in various ways. It should not be determined by example, but should be determined by the technical spirit described in the claims.

1 (A) is a plan view showing an information storage device using the magnetic domain wall movement according to an embodiment of the present invention.

FIG. 1B is a graph showing the energy change of the magnetic track according to the position of the magnetic domain wall of FIG.

FIG. 2 is a graph showing a change in intensity of a magnetic field applied to a magnetic track from the pinning means according to the distance between the magnetic track and the pinning means of FIG. 1.

3 is a plan view of an information storage device using magnetic domain wall movement according to another embodiment of the present invention.

4 is a cross-sectional view of an information storage device using magnetic domain wall movement according to another embodiment of the present invention.

5 is a view showing various forms of pinning means that can be provided in the information storage device according to an embodiment of the present invention.

6 is a plan view of an information storage device using magnetic domain wall movement according to another embodiment of the present invention.

* Explanation of Signs of Major Parts of Drawings *

100 to 100 ", 1000: Magnetic track 200 to 200", 2000: Pinning means

D, D1 to D2 ": Magnetic domain DW, DW1 to DW1": Magnetic domain wall

Claims (16)

A magnetic track having a plurality of magnetic domains and magnetic domain walls therebetween; And And a pinning member spaced apart from the magnetic track, the pinning member for pinning the magnetic domain wall. The method of claim 1, The pinning member applies a magnetic field for pinning the magnetic domain wall to the magnetic track, and the direction of the magnetic field is the same as the magnetization direction of the magnetic domain wall. The method according to claim 1 or 2, The pinning member is a magnetic layer pattern, At least a portion of the magnetic layer pattern is magnetized in the same direction as the magnetization direction of the magnetic domain wall. The method of claim 3, wherein The magnetic layer pattern extends in a direction perpendicular to the magnetic track. The method of claim 4, wherein Information storage device having a pointed end of the magnetic layer pattern toward the magnetic track of both ends of the magnetic layer pattern. The method of claim 4, wherein The magnetic layer pattern is an information storage device having a symmetrical or asymmetrical structure. The method of claim 3, wherein The magnetic layer pattern has a nanoscale (nanoscale) information storage device. The method of claim 3, wherein And an interval between the magnetic layer pattern and the magnetic track is several to several tens of nm. The method of claim 3, wherein The magnetic layer pattern includes at least one of Co, Ni and Fe. The method of claim 3, wherein And the magnetic layer pattern and the magnetic track are formed of the same material. The method of claim 3, wherein The magnetic layer pattern and the magnetic track is an information storage device formed of different materials. The method of claim 1, And the magnetic track and the pinning member are provided on the same plane. The method of claim 12, The pinning member is an information storage device provided on one side or both sides of the magnetic track. The method of claim 1, And the magnetic track and the pinning member are vertically stacked. The method of claim 14, The pinning member is an information storage device provided in at least one of the above and below the magnetic track. The method of claim 1, And a plurality of pinning members on at least one side of the magnetic track at equal intervals.

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