JP2020027802A - Domain wall displacement type device, data recording method thereof, and recording apparatus - Google Patents

Abstract

To provide a technique capable of being easily manufactured and writing desired data on a plurality of magnetic thin wires with one recording element.SOLUTION: A data recording method of a domain wall displacement type device repeats a first magnetic domain forming step of forming a magnetic domain in a first magnetization direction in an introduction region 11 of a magnetic thin wire 10 by a magnetic field generated by flowing a current A to conductor wiring 20, a first domain wall driving step of driving a domain wall formed in the introduction region 11 of the magnetic thin wire by flowing a current S to the magnetic thin wire to be recorded with data of the first magnetization direction, a second magnetic domain forming step of forming a magnetic domain in the second magnetization direction in the introduction region 11 of the magnetic thin wire 10 by a magnetic field generated by flowing a current B through the conductor wiring 20, and a second domain wall driving step of driving the domain wall formed in the introduction region 11 of the magnetic thin wire by flowing the current S to the target magnetic thin wire to which data of the second magnetization direction is recorded, according to a predetermined order until a termination condition is satisfied.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a domain wall displacement type device, a data recording method thereof, and a recording apparatus.

  In recent years, a current driving phenomenon of a domain wall due to a spin transfer effect has attracted attention (for example, see Non-Patent Document 1). The race track memory described in Non-Patent Document 1 is a memory having a U-shaped three-dimensional structure in which magnetic thin wires are extended also in a direction perpendicular to a substrate. In a race track memory, magnetic domains are formed in a magnetic thin wire by a write head (recording element) arranged orthogonally to the magnetic thin wire, and a pulse current is applied to the magnetic thin wire to move the position to record data. This write head writes data in a predetermined magnetization direction on a magnetic thin wire by a leakage magnetic field from a wiring to which a write current is applied. In the race track memory, at the time of reproduction, a pulse current is applied to the magnetic thin line until the data to be read (magnetic domain) is immediately below a read head (reproducing element) arranged orthogonally to the magnetic thin line, thereby forming the magnetic domain. It is moving.

  As described above, in the related art of writing data in a predetermined magnetization direction to a magnetic thin wire by a leakage magnetic field from a wiring through which a write current is applied, one recording element and one reproducing element are used for each magnetic thin wire. It is the current situation. Patent Document 1 discloses a technique for writing data to a plurality of magnetic thin wires with one write magnetic line, although the principle of writing data in a predetermined magnetization direction to a magnetic thin wire is different.

JP-A-2015-60971

Parkin Stuart S. P. et al., “Magnetic Domain-Wall Racetrack Memory”, Science, 11 Apr 2008, Vol. 320, Issue 5873, pp. 190-194.

  In the related art in which data in a predetermined magnetization direction is written on a magnetic wire by a leakage magnetic field, a recording element is required for each magnetic wire. For this reason, there has been a problem that the structure becomes more complicated as the number of the magnetic thin wires increases, the processing cost increases, and the manufacturing is difficult. In addition, when the number of recording elements is reduced to facilitate manufacturing, it has not been clear how a single recording element can write desired data on a plurality of magnetic wires. Furthermore, the technology disclosed in Patent Document 1 has a problem that the structure is complicated and it is difficult to manufacture. Therefore, there is room for improvement in the conventional domain wall motion type device.

  The present invention has been made in view of the above-described problems, and is a domain wall displacement type device that is easy to manufacture and can write desired data on a plurality of magnetic wires with one recording element, and a data recording method thereof, and It is an object to provide a recording device.

  In order to solve the above-mentioned problem, a data recording method according to the present invention includes a plurality of magnetic thin wires arranged in parallel with an introduction area for introducing data and a data area adjacent to the introduction area in a length direction. And a linear conductor wiring disposed so as to be orthogonal to the introduction region of each of the plurality of magnetic fine wires, wherein a domain wall formed in each of the plurality of magnetic fine wires is determined by a predetermined method. A data recording method for a domain wall motion type device, wherein data in a predetermined magnetization direction written in the introduction region of the domain wall motion type device is recorded in the data region by driving according to the order of: A first magnetic domain forming step of forming a magnetic domain in a first magnetization direction in each of the introduction regions of the magnetic wire by a magnetic field generated by flowing a current in a first direction; Driving a domain wall formed in the introduction region of the magnetic thin wire by passing a current for driving the domain wall to the magnetic thin wire on which data of the first magnetization direction is to be recorded in accordance with the order of A magnetic domain generated by flowing a current in a second direction opposite to the first direction through the conductor wiring in the one domain wall driving step to form a magnetic domain in a second magnetization direction in each of the introduction regions of the magnetic thin wire. Forming a second magnetic domain, and applying a current for driving a domain wall to the magnetic thin wire on which data in the second magnetization direction is to be recorded in accordance with the predetermined order, thereby introducing the magnetic thin wire. The second domain wall driving step of driving the domain wall formed in the region is repeatedly performed according to the predetermined order until the end condition is satisfied.

  Further, the domain wall motion type device according to the present invention, a plurality of magnetic thin wires arranged in parallel having an introduction region for introducing data and a data region adjacent to the introduction region in the length direction, Linear conductor wiring that is arranged so as to be orthogonal to each of the introduction regions of the magnetic thin wires and forms magnetic domains in each of the introduction regions of the plurality of magnetic thin wires by a magnetic field generated by energization; Has, at both ends in the length direction, electrodes connected to a conductor through which a current for driving a domain wall formed in the magnetic wire is passed, and a plurality of the magnetic wires are arranged in the length direction of the conductor wiring. And arranged in parallel while being separated in the thickness direction of the conductor wiring.

  Further, the recording apparatus according to the present invention is configured such that the domain wall motion type device, a pulse current source for applying a pulse current to the magnetic thin wire, an input information signal is divided, and the pulse current is supplied to the conductor wiring A recording system control unit that controls the supply timing of the pulse current from the pulse current source to the magnetic fine wire, wherein the recording system control unit causes a current in a first direction to flow through the conductor wiring. A first magnetic domain forming process of forming a magnetic domain of a first magnetization direction in each of the introduction regions of the magnetic wire by a generated magnetic field; and a magnetic recording target for recording data of the first magnetization direction in the predetermined order. A first domain wall driving process for driving a domain wall formed in the introduction region of the magnetic thin wire by passing an electric current for driving the domain wall to the thin wire; A second magnetic domain forming process of forming a magnetic domain in a second magnetization direction in each of the introduction regions of the magnetic thin wire by a magnetic field generated by flowing a current in a second direction opposite to the predetermined direction; Therefore, a second domain wall drive that drives a domain wall formed in the introduction region of the magnetic wire by passing a current for driving the domain wall to the magnetic wire on which data of the second magnetization direction is to be recorded. And processing are repeatedly executed in accordance with the predetermined order until the end condition is satisfied.

  ADVANTAGE OF THE INVENTION According to this invention, desired data can be written to several magnetic thin wires by one recording element easily and manufacturing.

(A) is a schematic diagram of a domain wall motion type device according to the first embodiment of the present invention, and (b) is a schematic diagram of a magnetic fine wire in which a magnetic domain whose magnetization direction is downward is formed. It is a schematic diagram of the magnetic fine wire in which the magnetic domain whose magnetization direction was upward was formed. (A)-(c) is a typical explanatory view (the 1) of a data recording method of a domain wall motion type device, respectively. (A)-(d) is a typical explanatory view (the 2) of a data recording method of a domain wall motion type device, respectively. (A) is a schematic diagram of a domain wall motion type device according to a second embodiment of the present invention, and (b) is a schematic diagram of a magnetic thin wire in which a magnetic domain whose magnetization direction is downward is formed. FIG. 13 is a schematic diagram of a magnetic thin wire in which a magnetic domain whose magnetization direction is downward is formed in the domain wall motion device according to the third embodiment of the present invention. It is a schematic diagram which shows the magnetic wire memory which applied the domain wall motion type device. It is a schematic diagram which shows the spatial light modulator which applied the domain wall displacement type device.

(1st Embodiment)
[Structure of domain wall displacement type device]
First, the structure of the domain wall motion device will be described with reference to FIGS. 1, 2 and 3A. The domain wall motion type device 1 includes a plurality of magnetic thin wires 10 and one conductor wiring 20 on a substrate (not shown). Here, the domain wall displacement type device 1 includes three magnetic thin wires 10a, 10b, and 10c as the plurality of magnetic thin wires 10, but the number is not particularly limited. When these are not distinguished, they are simply referred to as magnetic thin wires 10.

In FIG. 1A, the length direction of the magnetic thin wire 10 is the x-axis direction. The length direction of the conductor wiring 20 is the y-axis direction. The thickness direction of the magnetic thin wire 10 and the conductor wiring 20 is the z-axis direction. The width direction of the magnetic thin wire 10 is the y-axis direction, and the width direction of the conductor wiring 20 is the x-axis direction.
The magnetic thin wire 10 is provided on the conductor wiring 20 (positive direction in the z-axis direction). The plurality of magnetic wires 10 are arranged in parallel. The magnetic thin wires 10 adjacent to each other in the y-axis direction are arranged apart from each other by a minute distance. An insulating layer may be provided between the adjacent magnetic wires 10.
The conductor wiring 20 is a linear wiring arranged so as to be orthogonal to each magnetic thin wire 10. The conductor wiring 20 forms a magnetic domain in each magnetic wire 10 by a magnetic field generated by energization.

  In the following description, the current flowing through the conductor wiring 20 in the positive direction (first direction) in the y-axis direction is the current A (FIG. 1B), and the current is negative in the y-axis direction (second direction). It is assumed that the current flowing through the conductor wire 20 is the current B (FIG. 2). The magnetic field generated around the conductor wiring 20 when the current A flows is the magnetic field A (FIG. 1B), and the magnetic field generated around the conductor wiring 20 when the current B flows is the magnetic field B (FIG. 1B). 2).

  The magnetic fine wire 10 is formed by forming a magnetic material into a thin wire shape that is sufficiently long with respect to thickness and width. As the magnetic thin wire 10, a perpendicular magnetization film whose magnetization direction is easily oriented in the film thickness direction (z-axis direction) can be adopted. The perpendicular magnetization film is formed of a magnetic material having perpendicular magnetic anisotropy. A known ferromagnetic material can be used as such a material. Specifically, a multilayer film such as a Co / Pd multilayer film in which a transition metal such as Co and Pd, Pt, and Cu are repeatedly laminated, or a rare earth metal such as Tb-Fe-Co and Gd-Fe and a transition metal are used. (RE-TM alloy), and rare earth multilayer films such as Tb / Co.

  These materials are formed into a film by a known method such as a sputtering method, and are formed into a fine line shape by photolithography and etching or lift-off to form the magnetic thin line 10. In the present embodiment, since the magnetic thin wire 10 is a perpendicular magnetic anisotropic material, the two different magnetization directions indicate either upward or downward. Hereinafter, the downward magnetization direction formed in the magnetic wire 10 is also referred to as, for example, a first magnetization direction, and the upward magnetization direction is also referred to as, for example, a second magnetization direction. Further, a downward magnetization direction may be associated with, for example, data “0”, and an upward magnetization direction may be associated with, for example, data “1”.

  The magnetic thin wire 10 has regions for connecting electrodes (not shown) at both ends in the length direction. These electrodes are made of general metal materials for electrodes such as metals such as Cu, Al, Au, Pt, and Ag and alloys thereof. The pair of electrodes are formed, for example, on the upper surface at one end and the lower surface at the other end of the magnetic thin wire 10, and the conducting wire 15 through which a current for driving a domain wall formed in the magnetic thin wire 10 flows. Connected to each other. In addition, a constriction may be formed in the magnetic thin wire 10 at an appropriate position for controlling the position of a domain wall which is a boundary between magnetic domains.

  As shown in FIG. 3A, the magnetic thin wire 10 includes at least an introduction region 11 for introducing data and a data region 12 adjacent to the introduction region 11 in the length direction. In the example shown in FIG. 3A, the length direction of the magnetic thin wire 10 is the x-axis direction. In the magnetic thin wire 10, a part of the area on the left side in the figure is used as the introduction area 11, and most of the area on the right side is used as the data area 12. The introduction region 11 and the data region 12 formally divide the magnetic thin wire 10, and the magnetic thin wire 10 is physically formed continuously. The introduction region 11 is a region for writing a desired upward or downward magnetization direction as data. The data area 12 is a recording area for recording data. A magnetic domain having an upward or downward magnetization direction is formed in the introduction region 11 of the magnetic wire 10, and when the magnetic wire 10 is energized, the magnetic domain moves in the length direction of the wire and reaches the data region 12.

The conductor wiring 20 is a linear wiring extending in the y-axis direction. As shown in FIGS. 1A and 3A, the conductor wiring 20 is arranged so as to be orthogonal to the magnetic thin wire 10 in the introduction region 11.
As a material of the conductor wiring 20, a general electrode material can be applied. Specifically, for example, metals such as Cu, Al, Au, Ag, Ta, and Cr having good conductivity and alloys thereof can be used. As an example, it is preferable to use Cu as the material of the conductor wiring 20.
For example, the technique described in Patent Document 1 uses a write wiring made of a magnetic material to form a magnetic domain based on the interaction of a magnetic substance. On the other hand, in the domain wall displacement type device 1 of the present embodiment, the current for driving the domain wall in the magnetic thin wire 10 (current S described later) is reduced by using a non-magnetic material for the conductor wiring 20. be able to.

  As a method for forming the conductor wiring 20, for example, an electrode material is formed by a known method such as a sputtering method, and a photolithography process and a process such as an etching or a lift-off method can be used. The width of the conductor wiring 20 is preferably 40 nm or less, more preferably 10 nm or more and 40 nm or less. By making the material of the conductor wiring 20 a nonmagnetic material, the domain wall motion type device 1 does not necessarily need to be manufactured by a consistent process using a vacuum device or the like. Therefore, for example, the conductor wiring 20 can be formed separately from the step of forming the magnetic thin wire 10 using a vacuum device or the like, and the conductor wiring 20 can be retrofitted on the plurality of magnetic thin wires 10.

  The distance between the conductor wiring 20 and the magnetic thin wire 10 is preferably several tens nm or less, and the shorter the better, the better. Assuming that the current flowing through the conductor wiring 20 is I and the distance from the conductor wiring 20 is r, the magnetic field H generated when the current flows through the conductor wiring 20 is given by H = I / (2πr). As r is closer, a magnetic domain can be formed with a smaller current I.

  Specifically, a micromagnetic simulation of the process of forming magnetic domains in the magnetic wire 10 was performed, and it was confirmed that a magnetic domain having a sufficient length was formed on the magnetic wire 10 when the distance r was 5 nm. . Specifically, in this simulation, for simplicity, calculation was performed on one magnetic thin wire 10 using the LLG (Landau-Lifshitz-Gilbert) equation under the following calculation conditions. The mesh size on the magnetic fine wire 10 was 4 nm. Further, a magnetic domain in the second magnetization direction (upward) was formed in the entire magnetic thin wire 10 in advance. Then, as shown in FIG. 1B, a magnetic domain having a first magnetization direction (downward) was formed in one magnetic thin wire 10 by a magnetic field A generated by passing a current A through the conductor wiring 20. When a magnetization state after 1 [ns] was calculated by applying a current, the magnetic field on the x-axis in the positive direction with respect to the conductor wiring 20 when viewed from the conductor wiring 20 due to the current magnetic field from the conductor wiring 20 separated by 5 nm in the z-axis direction. Downward magnetic domains were formed on the thin wire 10 over 200 nm or more.

[Calculation condition]
(Structure of magnetic fine wire)
Length (x-axis direction): 1.6 [μm]
Width (y-axis direction): 60 [nm]
Film thickness (z-axis direction): 12 [nm]
(Magnetic properties of magnetic fine wire)
Saturation magnetization Ms: 0.25 [T]
Anisotropic magnetic field H _k : 8.5 [kOe]
Exchange coupling coefficient A: 1.2 × 10 ⁻¹¹ [J / m]
(Conductor wiring structure)
Length (y-axis direction): 1.4 [μm]
Width (x-axis direction): 40 [nm]
Film thickness (z-axis direction): 40 [nm]
Distance (z-axis direction) between conductor wiring and magnetic thin wire h: 5 [nm]
Applied current to conductor wiring: 0.5 [A]
Also, 1 [Oe] = 10 ³ / (4π) [A / m].

In the example illustrated in FIG. 1A, the domain wall motion device 1 includes an insulating layer 30 between the magnetic thin wire 10 and the conductor wiring 20. The insulating layer 30 insulates the conductor wiring 20 from the magnetic fine wire 10. The insulating layer 30 is formed on the conductor wiring 20. The magnetic thin wire 10 is formed on the insulating layer 30. The insulator forming the insulating layer 30 is made of a general insulator material. Examples of such a material include an oxide film such as SiO ₂ and Al ₂ O ₃ , and Si ₃ N ₄ and MgF ₂ . The shape of the insulating layer 30 is not limited to the illustrated flat plate as long as it is stably supported on a substrate (not illustrated). It is preferable that an insulating material is filled between the conductive wiring 20 and the conductive wiring 20 or that the insulating material is spread around the conductive wiring 20. It is desirable that an insulating layer 30 having a thickness of several nm or more is disposed between the conductor wiring 20 and the magnetic thin wire 10. However, even when the insulating layer 30 is not provided, it is considered that there is no problem when the electric resistance value of the magnetic thin wire 10 is much larger than the electric resistance value of the conductor wiring 20.

[Data recording method of domain wall displacement type device]
Next, an outline of a data recording method of the domain wall motion type device 1 will be described.
In the data recording method in the domain wall displacement type device 1, a predetermined magnetization written in the introduction region 11 of the domain wall displacement type device 1 is obtained by driving a domain wall formed on each of the plurality of magnetic wires 10 in a predetermined order. The direction data is recorded in the data area 12. In other words, in this method, a magnetic domain is formed by writing any magnetization data into the introduction region 11 of the magnetic wire 10, and a magnetic domain of data already written in the introduction region 11 in the magnetic wire 10 is driven. Moving information to the data area 12.

  In order to write data to the magnetic thin wire 10, an upward or downward magnetic field of sufficient strength is generated by the conductor wiring 20 in accordance with the binary information (0 or 1) to be recorded. When a current is applied to the conductor wiring 20, a magnetic field is generated, and a domain wall is introduced on the magnetic fine wire 10 at a position slightly separated from the conductor wiring 20. For example, when a downward magnetic field is generated from the conductor wiring 20, the introduction region 11 of the magnetic thin wire 10 is magnetized downward, and information of one bit is written as a magnetic domain. Also, in this method, by passing a current in the opposite direction through the conductor wiring 20 alternately, downward magnetization data and upward magnetization data are continuously written alternately in the introduction region 11 of the magnetic thin wire 10. As a result, the data on the introduction area 11 continues to be overwritten. Therefore, on the magnetic thin wire 10, the domain wall is advanced in the positive direction in the x-axis direction, and information is moved from the introduction region 11 to the data region 12, so that data is recorded on the domain wall displacement type device 1.

Next, details of a data recording method of the domain wall motion type device 1 will be described with reference to FIGS. In the data recording method, a first magnetic domain forming step, a first domain wall driving step, a second magnetic domain forming step, and a second domain wall driving step are performed as a series of steps.
In the first magnetic domain forming step, as shown in FIGS. 1B and 3B, a magnetic field A generated by applying a current (current A) in the first direction to the conductor wiring 20 causes each magnetic thin wire 10 to be formed. This is a step of forming a magnetic domain in the first magnetization direction (downward) in each of the introduction regions 11. Thereby, a magnetic domain in the first magnetization direction (downward) can be formed on the plurality of magnetic wires 10 at a time. Here, in FIGS. 1B and 3B, as an example, the downward magnetization is indicated by a dot. Further, in the initial state before the downward magnetic domains are formed in the magnetic fine wire 10, it is assumed that no magnetic domains are formed in the magnetic fine wire 10, as shown in FIG.

  The first domain wall driving step is a step performed subsequent to the first magnetic domain forming step. In the first domain wall driving step, as shown in FIG. 3 (c), the magnetic thin wire 10 (the magnetic thin wire 10b in FIG. 3 (c)) on which data in the first magnetization direction is to be recorded according to the predetermined order. This is a step of driving a domain wall formed in the introduction region 11 of the magnetic fine wire 10b by flowing a current (hereinafter, referred to as a current S) for driving the domain wall. A current S from a power supply (not shown) flows through the conductive wire 15 and a pair of electrodes at both ends of the magnetic wire 10 to the magnetic wire 10.

Specifically, when a pulse current (current S) is applied in the length direction of the magnetic wire 10b, electrons e ⁻ having negative charges move to the right in FIG. 3, and the domain wall formed on the magnetic wire 10b Drive. Due to the domain wall current driving phenomenon, the downward magnetic domain formed in the introduction region 11 of the magnetic thin wire 10b can be driven (bit-shifted) rightward in FIG. 3 by a length of one bit at a high speed. In FIG. 3, the moving direction of the electron e ⁻ is shown as the direction of the current S so that the direction of the bit shift can be easily understood intuitively. However, the pulse current (current S) is opposite to the moving direction of the electrons. Flow in the direction. The domain wall driving direction is not limited to the electron moving direction. Depending on the material forming the magnetic film of the magnetic thin wire 10, the domain wall driving direction may be opposite to the electron moving direction (current direction). There is.
In the first domain wall drive step, the first magnetization is applied to the introduction region 11 of each magnetic wire 10 by the magnetic field A generated by keeping the current A flowing through the conductor wiring 20 in conjunction with the current S flowing through the magnetic wire 10. It continues to form magnetic domains in the direction (downward magnetization). By this first domain wall driving step, downward magnetic domains are recorded in the data area 12 of the magnetic thin wire 10b. On the other hand, no magnetic domains have yet been recorded in the data area 12 of the magnetic thin wires 10a and 10c.

The second magnetic domain forming step is a step performed following the first domain wall driving step.
In the second magnetic domain forming step, as shown in FIGS. 2 and 4A, a magnetic field B generated by flowing a current (current B) in the second direction opposite to the first direction through the conductor wiring 20 is used. Is a step of forming a magnetic domain in the second magnetization direction (upward) in each of the introduction regions 11 of the magnetic thin wires 10. Thereby, the data on the introduction region 11 of each magnetic wire 10 is overwritten on the magnetic domain in the second magnetization direction (upward). In other words, a magnetic domain in the second magnetization direction (upward) can be formed on a plurality of magnetic wires 10 at a time. Here, in FIGS. 2 and 4A, the upward magnetization is shown by cross-hatching as an example. At this time, there is no change in the data on the data area 12 of each magnetic thin wire 10.

  The second domain wall driving step is a step performed following the second magnetic domain forming step. In the second domain wall driving step, as shown in FIG. 4 (b), the magnetic thin wires 10 for recording data in the second magnetization direction in accordance with the predetermined order (the magnetic thin wires 10a and 10c in FIG. 4 (b)). This is a step of driving a domain wall formed in the introduction region 11 of the magnetic fine wires 10a and 10c by applying a current S to the magnetic thin wires 10a and 10c. Thereby, the upward magnetic domain formed in the introduction region 11 of the magnetic thin wires 10a and 10c can be bit-shifted by the length of one bit. In the second domain wall driving step, the second magnetization is applied to the introduction region 11 of each magnetic wire 10 by the magnetic field B generated by keeping the current B flowing through the conductor wiring 20 in conjunction with the current S flowing to the magnetic wire 10. The magnetic domain in the direction (upward magnetization) continues to be formed. By the second domain wall driving step, upward magnetic domains are recorded in the data areas 12 of the magnetic thin wires 10a and 10c. On the other hand, there is no change in the data on the data area 12 of the magnetic thin wire 10b.

  In the data recording method, the first magnetic domain forming step, the first domain wall driving step, the second magnetic domain forming step, and the second domain wall driving step are repeatedly performed in accordance with the above-described predetermined order until the end condition is satisfied. Therefore, for example, if the termination condition is not satisfied, the first magnetic domain forming step is performed again after the second domain wall driving step. In this case, as shown in FIG. 4C, the data on the introduction region 11 of each magnetic wire 10 is overwritten on the magnetic domain in the first magnetization direction (downward). At this time, there is no change in the data on the data area 12 of each magnetic thin wire 10.

  Further, FIG. 4D shows a magnetization state when the first domain wall driving step is performed again after the first magnetic domain forming step. In the first domain wall driving step, as shown in FIG. 4D, the magnetic thin wire 10 on which data in the first magnetization direction is recorded according to the predetermined order (the magnetic thin wires 10a and 10b in FIG. 4D). 4), the domain wall formed in the introduction region 11 of the magnetic fine wires 10a and 10b is driven. In the first domain wall drive step, the first magnetization is applied to the introduction region 11 of each magnetic wire 10 by the magnetic field A generated by keeping the current A flowing through the conductor wiring 20 in conjunction with the current S flowing through the magnetic wire 10. It continues to form magnetic domains in the direction (downward magnetization). By the first domain wall driving step, the downward magnetic domain formed in the introduction region 11 of the magnetic fine wires 10a and 10b can be shifted by one bit. At this time, the information of one bit (upward magnetic domain) already recorded in the data area 12 of the magnetic wire 10a is bit-shifted in the magnetic wire 10a by the length of one bit. The information of one bit (downward magnetic domain) already recorded in the data area 12 of the magnetic thin wire 10b is shifted by one bit in the magnetic thin wire 10b. The data on the data area 12 of the magnetic thin wire 10c does not change.

  Thereafter, by repeating the magnetic domain formation and the bit shift in the same manner, it is possible to accumulate data of a sequential magnetic domain row in the length direction of each magnetic thin wire 10. The data area 12 of the magnetic thin wire 10 has a first-in-first-out type memory configuration in which information can be sequentially stored in the data area 12 in the same order. As described above, in the data recording method of the domain wall displacement type device 1, magnetic domains are formed on the plurality of magnetic fine wires 10 by alternately applying the current A and the current B to one recording element (conductor wiring 20). By combining with domain wall drive (bit shift) by applying a current S individually to the thin wires 10, for example, as shown in FIG. 4D, a desired data string is individually recorded on the magnetic thin wires 10a, 10 and 10c. can do. FIG. 4D shows an example of the magnetization state of the data region 12 of each magnetic wire 10. The predetermined order may be determined depending on which magnetic thin wire 10 and in what order it is desired to record the binary data. For example, the write operation can be efficiently performed by determining the order of applying the current S to each magnetic thin wire 10 by calculating backward from the ideal final recording state of all the magnetic thin wires 10. The end condition is satisfied by performing the last writing in the predetermined order.

  Although the description has been made on the assumption that no magnetic domain is formed in the initial state of each magnetic thin wire 10, the present invention is not limited to this. For example, the magnetic wire 10 may be in a state in which upward magnetization and downward magnetization are partially arranged at random (random magnetization). In the above description, the first magnetic domain forming step is performed first. However, if a predetermined order is followed, the second magnetic domain forming step may be performed first, or the first magnetic domain forming step and the second magnetic domain forming step may be performed. The number of times of the magnetic domain forming step may be different.

(2nd Embodiment)
[Structure of domain wall displacement type device]
Next, the structure of the domain wall motion device according to the second embodiment will be described with reference to FIG. As shown in FIG. 5A, in the domain wall motion type device 1B according to the second embodiment, the magnetic thin wire 10 is provided not only above the conductor wiring 20 but also below the conductor wiring 20. This is different from the domain wall displacement type device 1 according to the first embodiment. In the following, the same components as those of the domain wall motion device 1 shown in FIG.

  The domain wall motion type device 1B includes a plurality of magnetic thin wires 10a to 10f and one conductor wiring 20. Here, the domain wall motion type device 1B includes six magnetic wires 10a to 10f as the plurality of magnetic wires 10, but the number is not particularly limited. When these are not distinguished, they are simply referred to as magnetic thin wires 10. Each magnetic wire 10 has, in the length direction, an introduction region 11 for introducing data and a data region 12 adjacent to the introduction region 11 (see FIG. 3A). The conductor wiring 20 has a linear shape, and is arranged so as to be orthogonal to the introduction region 11 of each of the magnetic fine wires 10a to 10f.

  The plurality of magnetic fine wires 10a to 10f are arranged in parallel while being separated in the length direction (y-axis direction) of the conductor wiring 20, and are arranged in parallel while being separated in the thickness direction (z-axis direction) of the conductor wiring 20. Have been. As shown in FIG. 5A, in the domain wall motion type device 1 </ b> B, two magnetic thin wires 10 are arranged to face each other across the conductor wiring 20 in the thickness direction (z-axis direction) of the conductor wiring 20. Specifically, the magnetic thin wires 10a and 10d are arranged to face each other. The magnetic thin wire 10b and the magnetic thin wire 10e are arranged to face each other. Further, the magnetic thin wire 10c and the magnetic thin wire 10f are arranged to face each other.

  In the example shown in FIG. 5A, the domain wall motion type device 1B includes an insulating layer 30a between the magnetic thin wires 10d, 10e, and 10f and the conductor wiring 20. Further, the domain wall motion type device 1B includes an insulating layer 30b between the magnetic thin wires 10a, 10b, 10c and the conductor wiring 20. The insulator forming the insulating layers 30a and 30b is made of the above-mentioned general insulator material.

  The insulating layer 30b is formed on the conductor wiring 20, and magnetic fine wires 10a, 10b, and 10c are formed on the upper surface 31b of the insulating layer 30b. In this example, the upper surface 31b of the insulating layer 30b is a surface on which the magnetic thin wires 10 are arranged. The insulating layer 30a is formed below the conductor wiring 20, and magnetic thin wires 10d, 10e, and 10f are formed on the lower surface 31a of the insulating layer 30a. In this example, the lower surface 31a of the insulating layer 30a is also the surface on which the magnetic fine wires 10 are arranged. That is, the domain wall motion type device 1 </ b> B has an arrangement surface of the magnetic thin wires 10 above and below the conductor wiring 20.

  The data recording method of the domain wall motion type device 1B includes a first magnetic domain forming step, a first magnetic domain wall driving step, a second magnetic domain forming step, and a second magnetic domain wall driving step until a termination condition is satisfied in a predetermined order. Repeat. For example, in the first magnetic domain forming step, as shown in FIG. 5B, each of the magnetic fine wires 10a to 10f is caused by a magnetic field A generated by flowing a current (current A) in the first direction through the conductor wiring 20. A magnetic domain in the first magnetization direction (downward) is formed in the introduction region 11. Other steps are the same as the data recording method of the domain wall motion type device 1 (see FIGS. 3 and 4). Therefore, further description is omitted. According to the present embodiment, the number of magnetic thin wires to which data can be written at one time can be doubled compared to the first embodiment.

(Third embodiment)
[Structure of domain wall displacement type device]
Next, the structure of the domain wall motion device according to the third embodiment will be described with reference to FIG. In the following, the same components as those of the domain wall motion device 1 shown in FIG. The domain wall motion device 1C according to the third embodiment includes a plurality of magnetic thin wires 10a to 10f and one conductor wiring 20C. Here, the domain wall motion device 1C includes six magnetic wires 10a to 10f as the plurality of magnetic wires 10, but the number is not particularly limited. When these are not distinguished, they are simply referred to as magnetic thin wires 10. Each magnetic wire 10 has, in the length direction, an introduction region 11 for introducing data and a data region 12 adjacent to the introduction region 11 (see FIG. 3A).

  The conductor wiring 20C has a linear shape and is arranged so as to be orthogonal to the introduction region 11 of each of the magnetic fine wires 10a to 10f. However, the conductor wiring 20C is not arranged above and below each magnetic thin wire 10 (in the z-axis direction), but is arranged on one end side (left side in FIG. 6) of each magnetic thin wire 10 in the x-axis direction. The conductor wiring 20 </ b> C has a thickness at least several times the thickness of the magnetic fine wire 10. Here, the conductor wiring 20C is formed to have a thickness (length in the z-axis direction) larger than a width (length in the x-axis direction). The length (length in the y-axis direction) of the conductor wiring 20C is formed sufficiently larger than the thickness and width of the conductor wiring 20C.

  The plurality of magnetic fine wires 10a to 10f are arranged in parallel while being separated in the length direction (y-axis direction) of the conductor wiring 20, and are arranged in parallel while being separated in the thickness direction (z-axis direction) of the conductor wiring 20. Have been. As shown in FIG. 6, in the domain wall motion type device 1C, all the magnetic thin wires 10a to 10f are arranged on one side (the right side in FIG. 6) in the width direction (x-axis direction) of the conductor wiring 20C.

  In the example shown in FIG. 6, the domain wall motion device 1C includes an insulating layer 30c between the magnetic thin wires 10a to 10f and the conductor wiring 20C. Further, the domain wall motion device 1C includes insulating layers 40a, 40b, and 40c around the magnetic thin wire 10. The insulator forming the insulating layers 30c, 40a to 40c is made of the above-mentioned general insulator material.

The insulating layer 30c insulates the conductor wiring 20C from the magnetic fine wires 10a to 10f, and is formed, for example, in parallel with the yz plane.
The insulating layer 40a is formed, for example, in parallel with the xy plane, and the magnetic thin wires 10e, 10f are formed on the upper surface 41a of the insulating layer 40a in parallel with each other. In this example, the upper surface 41a of the insulating layer 40a is a surface on which the magnetic fine wires 10e and 10f are arranged.
The insulating layer 40b is formed on the magnetic fine wires 10e and 10f, and the magnetic fine wires 10c and 10d are formed on the upper surface 41b of the insulating layer 40b so as to be parallel to each other. In this example, the upper surface 41b of the insulating layer 40b is a surface on which the magnetic fine wires 10c and 10d are arranged.
The insulating layer 40c is formed on the magnetic thin wires 10c and 10d, and the magnetic thin wires 10a and 10b are formed on the upper surface 41c of the insulating layer 40c so as to be parallel to each other. In this example, the upper surface 41c of the insulating layer 40c is the surface on which the magnetic wires 10a and 10b are arranged.
That is, the domain wall motion type device 1C has a structure in which a plurality of arrangement surfaces of the magnetic thin wires 10 are laminated on the side of the conductor wiring 20C.

The data recording method of the domain wall displacement type device 1C is, similarly to the data recording method of the domain wall displacement type device 1, a first magnetic domain forming step, a first domain wall driving step, a second magnetic domain forming step, and a second domain wall driving step. Are repeated according to a predetermined order until the end condition is satisfied. For example, in the first magnetic domain forming step, as shown in FIG. 6, a magnetic field A generated by applying a current (current A) in the first direction to the conductor wiring 20C causes the introduction region 11 of each of the magnetic fine wires 10a to 10f to be formed. Then, a magnetic domain in the first magnetization direction (downward) is formed. Other steps are the same as the data recording method of the domain wall motion type device 1 (see FIGS. 3 and 4). Therefore, further description is omitted.
According to the present embodiment, it is possible to increase the number of magnetic thin wires to which data can be written at once several times as compared with the first embodiment. Note that the number of layers on which the magnetic fine wires 10 are arranged is not limited to three layers, and may be several tens of layers.

  Although the domain wall motion devices 1, 1B, and 1C according to the embodiment have been described in the form in which the insulating layer 30 (30C) is provided between the plurality of magnetic thin wires 10 and the conductor wiring 20 (20C), the present invention provides: The present invention is not limited to the embodiment described above, and various modifications are possible. For example, instead of having the flat insulating layer 30 (30C), an insulating coating can be provided on the conductor wiring 20 (20C).

[Application example of domain wall displacement type device]
(Magnetic wire memory)
The domain wall motion type device 1 can be applied to, for example, a magnetic wire memory. The recording / reproducing apparatus 100 shown in FIG. 7 includes a magnetic wire memory 110 provided on a substrate (not shown) and a pulse current source 120, and performs a process of recording information on the magnetic wire memory 110 and information from the magnetic wire memory 110. To perform a reproduction process for reading out. The magnetic wire memory 110 includes a plurality of magnetic wires 10 as data recording tracks, a conductor wiring 20, and a magnetic head (reproducing head) 50 for reproduction. Here, the domain wall motion type device 1 is constituted by the plurality of magnetic thin wires 10 and the conductor wiring 20. In FIG. 7, the insulating layer 30 is omitted.

  The magnetic wire memory 110 includes a plurality of magnetic wires 10 on a substrate (not shown). Here, the magnetic thin wire 10 is previously made to have, for example, random magnetization. Adjacent magnetic wires 10 are spaced apart from each other by a very small distance with an insulating layer (not shown) therebetween. Each magnetic thin wire 10 has a reproducing head 50 at a predetermined position on a side opposite to the conductor wiring 20 at a predetermined distance. The reproducing head 50 detects the direction of the leakage magnetic flux generated from the magnetic domain immediately below, and outputs a signal corresponding to the direction of the magnetization.

  Each magnetic wire 10 is connected to a pulse current source 120. A pulse current is applied to each magnetic wire 10 from right to left in FIG. Electrons move in a direction opposite to the direction in which the pulse current flows (from left to right in FIG. 7). The moving direction of the electrons and the moving direction of the magnetic domain D are the same direction (from left to right in FIG. 7). Thus, the magnetic domain D is shifted at a high speed to a position facing the reproducing head 50 to perform reading. Depending on the material of the magnetic film of the magnetic thin wire 10, the domain wall may be driven in the direction opposite to the moving direction of electrons (current direction).

  As shown in FIG. 7, the recording / reproducing apparatus 100 includes a recording system control unit 130 and a reproduction system control unit 140. The recording system control unit 130 supplies an electric current to the conductor wiring 20 and divides the input information signal into each magnetic thin wire 10 to record the divided unit information on each magnetic thin wire 10. 10 controls the supply timing of the pulse current to 10. The reproduction system control section 140 restores the signal by synthesizing the information signal obtained by each reproduction head 50, and outputs the signal to the outside.

The procedure in which the recording / reproducing apparatus 100 records data in the magnetic wire memory 110 is the same as the recording procedure described with reference to FIGS. 3 and 4, and a description thereof will be omitted.
The recording / reproducing apparatus 100 includes the recording apparatus 101 having a configuration excluding the reproducing system control unit 140. That is, the recording device 101 includes the magnetic thin wire memory 110, the pulse current source 120, and the recording system control unit 130, and can perform a process of recording information on the magnetic thin wire memory 110.

  In order for the recording / reproducing apparatus 100 to reproduce information recorded in the magnetic wire memory 110, a pulse current is continuously applied to the magnetic wire 10 to move the recorded magnetic domain sequence to just below the reproducing head 50. . As a result, the reproducing head 50 detects the direction of the leakage magnetic flux generated from the magnetic domain immediately below, and outputs a signal corresponding to the direction of the magnetization. Thereafter, the original binary information is reproduced by repeating the bit shift (domain wall drive) and the detection of the magnetic domain by the reproducing head 50 in the same manner. By preparing a plurality of such magnetic thin wires 10 and driving them in synchronization, the magnetic thin wire memory 110 realizes high-speed recording.

(Spatial light modulator)
The domain wall motion type device 1 can be applied to, for example, a spatial light modulator. FIG. 8 is an explanatory diagram showing a configuration of the spatial light modulator 200 using the domain wall motion type device 1. The spatial light modulator 200 includes a conductor wiring 20, an insulating layer 30, a plurality of magnetic thin wires 10, and polarization filters 201 and 202 on a substrate (not shown). The plurality of magnetic wires 10, the conductor wiring 20, and the insulating layer 30 constitute the domain wall motion device 1.

In the spatial light modulator 200, a recording device having the same configuration as the recording device 101 shown in FIG. 7 can be used to record data on the plurality of magnetic wires 10. The recording device (not shown) includes the domain wall motion device 1, a pulse current source 120, and a recording system control unit 130 (see FIG. 7).
Each magnetic wire 10 is connected to a pulse current source 120. A pulse current is applied to the magnetic wire 10 from right to left in FIG. When the electrons move in the opposite direction (from left to right in FIG. 8) to the direction in which the pulse current flows, the domain wall is driven in the direction in which the electrons move. Depending on the material of the magnetic film of the magnetic thin wire 10, the domain wall may be driven in the direction opposite to the moving direction of electrons (current direction).
The recording system control unit 130 performs a process of recording data for displaying a predetermined bright and dark image on the magnetic thin wire 10 by the spatial light modulator 200. Note that the procedure for recording data on the magnetic thin wire 10 is the same as the recording procedure described with reference to FIGS. 3 and 4, and a description thereof will be omitted.

  As an example, as shown in FIG. 8, it is assumed that data of “downward, downward, downward, upward, upward” is recorded in the magnetic thin wire 10 c in order from the right in the length direction. The operation of the spatial light modulator 200 in this case is as follows. For example, the light emitted from the light source 300 such as a laser light source to the spatial light modulator 200 contains various polarization components, but passes through the polarization filter 201 to become one polarization component light 301 and enters the magnetic thin wire 10c. I do. The specific polarized light 302 of the light reflected by the magnetic thin wire 10 c is shielded by the polarizing filter 202. Further, other light 303 of the light reflected by the magnetic thin wire 10c passes through the polarizing filter 202.

Specifically, when the light 301 incident on the magnetic thin wire 10c is reflected by the magnetic thin wire 10c, the direction of the polarization is rotated (rotated) by the magneto-optical effect. In FIG. 8, the light 303 reflected in the region indicating the upward magnetization direction of the magnetic thin wire 10 c rotates by + θ _K as compared with the incident light 301. Further, the light 302 reflected in the region indicating the downward magnetization direction of the magnetic thin wire 10 c rotates by −θ _K as compared with the incident light 301. Therefore, the spatial light modulator 200 can display a bright and dark image.

DESCRIPTION OF SYMBOLS 1, 1B, 1C Domain wall displacement type device 10, 10a-10f Magnetic thin wire 11 Introducing area 12 Data area 15 Conducting wire 20, 20C Conducting wiring 30, 30C Insulating layer 31a Lower surface 31b Upper surface 40a, 40b, 40c Insulating layer 41a, 41b, 41c Top surface 50 Magnetic head for reproduction (reproduction head)
REFERENCE SIGNS LIST 100 recording / reproducing device 101 recording device 110 magnetic thin wire memory 120 pulse current source 130 recording system control unit 140 reproduction system control unit 200 spatial light modulator 201 polarization filter 202 polarization filter 300 light source 301 incident light 302 polarization 303 reflected light

Claims (6)

A plurality of magnetic thin wires arranged in parallel with an introduction area for introducing data and a data area adjacent to the introduction area in the length direction, and orthogonal to the introduction area of each of the plurality of magnetic thin wires. And a linear conductor wiring disposed in the magnetic domain wall moving device, wherein the domain wall formed in each of the plurality of magnetic thin wires is driven in a predetermined order to thereby form the introduction region of the domain wall moving device. A data recording method of a domain wall motion type device for recording data in a predetermined magnetization direction written in the data area,
A first magnetic domain forming step of forming a magnetic domain in a first magnetization direction in each of the introduction regions of the magnetic thin wire by a magnetic field generated by flowing a current in a first direction through the conductor wiring;
A current for driving a domain wall is applied to the magnetic thin wire on which data in the first magnetization direction is to be recorded in accordance with the predetermined order, thereby driving the domain wall formed in the introduction region of the magnetic thin wire. A first domain wall driving step to be performed;
A second magnetic domain formation for forming a magnetic domain in a second magnetization direction in each of the introduction regions of the magnetic fine wire by a magnetic field generated by flowing a current in a second direction opposite to the first direction to the conductor wiring. Process and
A current for driving a magnetic domain wall is applied to the magnetic thin wire on which data in the second magnetization direction is to be recorded in accordance with the predetermined order, thereby driving the magnetic domain wall formed in the introduction region of the magnetic thin wire. A second domain wall driving step of
Is repeatedly performed according to the predetermined order until the end condition is satisfied. A plurality of magnetic thin wires arranged in parallel with an introduction area for introducing data and a data area adjacent to the introduction area in the length direction,
Linear conductor wiring that is arranged so as to be orthogonal to each of the introduction regions of the plurality of magnetic thin wires and forms a magnetic domain in each of the introduction regions of the plurality of magnetic thin wires by a magnetic field generated by energization,
The magnetic fine wire has electrodes at both ends in the length direction connected to a conductive wire that flows a current for driving a domain wall formed in the magnetic fine wire,
A domain wall displacement type device in which a plurality of the magnetic thin wires are arranged in parallel while being separated in a length direction of the conductor wiring, and are arranged in parallel while being separated in a thickness direction of the conductor wiring.   The domain wall displacement type device according to claim 2, wherein the two magnetic thin wires are arranged to face each other across the conductor wiring in a thickness direction of the conductor wiring.   3. The domain wall displacement type device according to claim 2, wherein all the magnetic thin wires are arranged on one side in the width direction of the conductor wiring. The domain wall motion device according to any one of claims 2 to 4, wherein the domain walls formed in each of the plurality of magnetic thin wires are driven in a predetermined order, thereby forming the domain wall motion device. A data recording method of a domain wall motion type device for recording data of a magnetization direction written in an introduction region in the data region,
A magnetic domain in a first magnetization direction is formed in each of the introduction regions of the magnetic thin wires arranged in the length direction and the thickness direction of the conductor wiring by a magnetic field generated by flowing a current in the first direction through the conductor wiring. A first magnetic domain forming step;
A current for driving a domain wall is applied to the magnetic thin wire on which data in the first magnetization direction is to be recorded in accordance with the predetermined order, thereby driving the domain wall formed in the introduction region of the magnetic thin wire. A first domain wall driving step to be performed;
Each of the introduction regions of the magnetic thin wires arranged in the length direction and the thickness direction of the conductor wiring by a magnetic field generated by flowing a current in a second direction opposite to the first direction to the conductor wiring. A second magnetic domain forming step of forming a magnetic domain in the second magnetization direction in
A current for driving a magnetic domain wall is applied to the magnetic thin wire on which data in the second magnetization direction is to be recorded in accordance with the predetermined order, thereby driving the magnetic domain wall formed in the introduction region of the magnetic thin wire. A second domain wall driving step of
Is repeatedly performed according to the predetermined order until the end condition is satisfied. A domain wall displacement type device according to any one of claims 1 to 4,
A pulse current source for applying a pulse current to the magnetic wire,
A recording system control unit that divides the input information signal, supplies the pulse current to the conductor wiring, and controls a timing of supplying the pulse current from the pulse current source to the magnetic wire.
The recording system control unit includes:
A first magnetic domain forming process of forming a magnetic domain in a first magnetization direction in each of the introduction regions of the magnetic thin wire by a magnetic field generated by flowing a current in a first direction through the conductor wiring;
A current for driving a domain wall is applied to the magnetic thin wire on which data in the first magnetization direction is to be recorded in accordance with the predetermined order, thereby driving the domain wall formed in the introduction region of the magnetic thin wire. A first domain wall driving process,
A second magnetic domain formation for forming a magnetic domain in a second magnetization direction in each of the introduction regions of the magnetic fine wire by a magnetic field generated by flowing a current in a second direction opposite to the first direction to the conductor wiring. Processing,
A current for driving a magnetic domain wall is applied to the magnetic thin wire on which data in the second magnetization direction is to be recorded in accordance with the predetermined order, thereby driving the magnetic domain wall formed in the introduction region of the magnetic thin wire. A second domain wall driving process,
A recording device that repeatedly executes the following until the end condition is satisfied in the predetermined order.

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