JP2022035581A - Control method of magnetic thin wire device, and magnetic thin wire device - Google Patents

Abstract

To provide a control method of a magnetic thin wire device capable of suppressing leakage current and realizing operations as a device.SOLUTION: A control method of a magnetic thin wire device includes: a magnetic thin wire that is a thin wire shaped magnetic material; and a conductive wire that is arranged on the magnetic thin wire through an interlayer insulating layer and records information in the magnetic thin wire as a magnetic domain by a current magnetic field. The method includes the steps of: applying a recording voltage to the conductive wire during a predetermined recording period required for recording the information corresponding to the magnetic domain by a recording power supply electrically connected to the conductive wire; applying a first bias voltage smaller than the recording voltage to the magnetic thin wire during a first period including at least a part of the recording period by a first drive power supply electrically connected to one end of a longitudinal direction of the magnetic thin wire; and applying a second bias voltage smaller than the recording voltage to the magnetic thin wire during a second period including at least a part of the recording period by a second drive power supply electrically connected to one end of the longitudinal direction of the magnetic thin wire.SELECTED DRAWING: Figure 3

Description

The present invention relates to a magnetic wire device control method and a magnetic wire device, and more particularly to a magnetic wire device control method for recording information as a magnetic domain by a current magnetic field, and a magnetic wire device.

Conventionally, as in the magnetic wire device 101 shown in FIG. 13 (a), a recording element that forms a magnetic domain inside the magnetic wire 110 in a state where the magnetic wire 110 as a recording medium and the magnetic wire 110 are electrically separated from each other. A device having a conductive layer (conductive wire 120) for use has been proposed. The magnetic wire device 101 has a structure in which the conductive wire 120 is arranged so as to be twisted with the magnetic wire 110. Here, the magnetic wire device 101 is provided with one magnetic wire 110. Since the conductive wire 120 and the magnetic thin wire 110 need to be electrically separated from each other, an interlayer insulating layer 130 is inserted between them.

As shown in FIGS. 13 (b) and 13 (c), a current magnetic field (hereinafter referred to as a recording magnetic field H) is applied around the conductive wire 120 by passing a current (hereinafter referred to as a recording current A) through the conductive wire 120. Is generated. When the strength of the recording magnetic field H becomes larger than the strength of the anisotropic magnetic field of the magnetic thin wire 110 having vertical magnetic anisotropy, for example, an upward magnetic domain D can be formed on the magnetic thin wire 110 (magnetic domain recording). ..
In the following, when a large number of magnetic wire devices 101 are made, each magnetic wire device 101 is simply referred to as an element. Among the large number of elements, there are elements with good quality such as insulation, and there are elements with poor quality.

14 and 15 are schematic views when operating the magnetic wire device 101. The magnetic wire device 101 further includes a recording power supply 40, a first drive power supply 51, and a second drive power supply 52. The terminal 40a of the recording power supply 40 is connected to one end 121 of the conductive wire 120. The other end 122 of the conductive wire 120 is grounded. The terminal 51a of the first drive power supply 51 is connected to one end (left end) of the magnetic thin wire 110. The other end (right end) of the magnetic thin wire 110 is connected to the terminal 52a of the second drive power supply 52. Reference numerals 40b, 51b, 52b are ground terminals, and reference numerals 40c, 51c, 52c are operation display units. When the recording power supply 40 applies a voltage to the conductive wire 120, a recording current A flows through the conductive wire 120, and a magnetic domain can be formed on the magnetic wire 110. When the first drive power supply 51 applies a positive voltage to the magnetic wire 110, the magnetic domain can be driven to the right by the current flowing through the magnetic wire 110. When the second drive power supply 52 applies a positive voltage to the magnetic wire 110, the magnetic domain can be driven to the left by the current flowing through the magnetic wire 110.

Conventionally, a method of using a conductive metal wiring provided so as to be orthogonal to a magnetic thin wire as a recording element has been widely practiced (see, for example, Non-Patent Document 1). However, in the magnetic field generated by passing a current through one conductive wire 120 as a recording element, it is difficult to form a minute magnetic domain in the longitudinal direction of the magnetic fine wire 110, and the shape of the magnetic domain also fluctuates. Therefore, in the method disclosed in Non-Patent Document 2, the conductive wire as a recording element has a structure in which the conductive wire straddles the magnetic thin wire twice on the outward path and the return path, and the two recording elements are recorded by the combined magnetic field of the two recording elements. It is improved so as to form a magnetic domain in a minute magnetic wire region sandwiched between the elements.

Takeshi Kondo, 7 outsiders, "Co / Ni Fine Wire Domain Wall Position Control Technology and Application to Magnetic Shift Register", IEICE Technical Report, October 12, 2017, vol. 117, no.24, p. .13-16 Mayumi Kawana, 3 outsiders, "Simulation of magnetic domain formation in magnetic thin wires in various recording element shapes", Summary of Academic Lectures of the Japan Society of Magnetic Sciences, August 28, 2018, Vol. 42, P.109

In the magnetic thin wire device 101, the interlayer insulating layer 130 needs to ensure the insulation between the magnetic thin wire 110 and the conductive wire 120. However, if the interlayer insulating layer 130 is made too thick, the magnetic thin wire 110 and the conductive wire As the distance from 120 increases, the recording magnetic field H applied on the magnetic thin wire 110 becomes weak. As a result, it becomes necessary to increase the current value of the recording current A, which in turn causes the element to be destroyed by passing a large current through the conductive wire 120. Therefore, it is desirable that the film thickness of the interlayer insulating layer 30 is thin. However, by thinning the interlayer insulating layer 130, a part of the recording current A flows out as a leak current to the magnetic wire 110 at the time of magnetic domain recording shown in FIGS. 14 and 15. This leakage current causes the magnetic domain already formed on the magnetic domain 10 to be unintentionally driven at the time of recording the magnetic domain. That is, since the magnetic domain recording and the magnetic domain drive occur at the same time, the magnetic domain formed at the time of magnetic domain recording expands due to the influence of the magnetic domain drive, and there is a possibility that the minimum bit length becomes larger than the preset value.

Further, among the many manufactured magnetic wire devices 101, sufficient insulation is provided due to a defect in the film of the interlayer insulating layer 130 between the magnetic wire 110 and the conductive wire 120 and the yield in manufacturing the element. Since it could not be secured, an element having a relatively large leakage current may be included. In such an element having a large leak current, the magnetic domain to be recorded in the magnetic wire 110 and the magnetic domain already formed are destroyed by the Joule heat accompanying the leak current, so that the magnetic domain recording itself is difficult. Become.

The present invention has been made in view of the above problems, and provides a method for controlling a magnetic wire device capable of suppressing a leak current and realizing operation as a device, and a magnetic wire device. That is the issue.

In order to solve the above-mentioned problems, the control method of the magnetic thin wire device according to the present invention is to use a magnetic thin wire which is a thin magnetic material and the magnetic thin wire which is arranged on the magnetic thin wire via an interlayer insulating layer and by a current magnetic field. A method for controlling a magnetic thin wire device including a conductive wire for recording information as a magnetic zone, wherein the recording power supply electrically connected to the conductive wire is required to record the information corresponding to the magnetic zone. During the recording period, the step of applying a recording voltage to the conductive wire and the first drive power source electrically connected to one end of the magnetic thin wire in the longitudinal direction during the first period including at least a part of the recording period. At least a part of the recording period by a step of applying a first bias voltage smaller than the recording voltage to the magnetic wire and a second drive power source electrically connected to the other end of the magnetic wire in the longitudinal direction. In the second period including, a step of applying a second bias voltage smaller than the recorded voltage to the magnetic wire is included.

Further, the magnetic thin wire device according to the present invention includes a magnetic thin wire which is a thin magnetic material and a conductive wire which is arranged on the magnetic fine wire via an interlayer insulating layer and records information on the magnetic fine wire as a magnetic zone by a current magnetic field. In the first period including at least a part of the recording period and the recording power source that applies a recording voltage to the conductive wire during a predetermined recording period required for recording the information corresponding to the magnetic zone, the magnetic wire is covered with the magnetic wire. A first drive power source that applies a first bias voltage smaller than the recording voltage in the first direction of the length of the magnetic wire, and a second period including at least a part of the recording period, from the recording voltage on the magnetic wire. The configuration includes a second drive power supply that applies a small second bias voltage in a second direction opposite to the first direction of the length of the magnetic wire.

The present invention has the following excellent effects.
According to the control method of the magnetic thin wire device, it is possible to suppress the leakage current from the conductive wire to the magnetic thin wire in the magnetic thin wire device and realize the operation as a device. Further, according to the magnetic wire device, it is possible to suppress the leakage current and realize the operation as a device. Further, even a device that is not used in the prior art as an element having a large leak current can be used by suppressing the leak current. Therefore, the yield can be improved.

It is a schematic diagram of the magnetic wire device which concerns on embodiment of this invention. It is a schematic diagram which looked at the magnetic thin wire device of FIG. 1 from the axial direction of a conductive wire. It is a timing chart of the voltage applied when the magnetic domain is recorded in the magnetic wire device of FIG. ing. It is a graph which shows the time change of the recording current flowing through the conductive wire of the magnetic thin wire device which concerns on a comparative example. It is a graph which shows the time change of the leakage current flowing through the magnetic wire of the magnetic wire device which concerns on a comparative example. It is a graph which shows the time change of the pulse voltage applied to the conductive wire of the magnetic thin wire device which concerns on an Example, and the bias pulse voltage applied to a magnetic thin wire. It is a graph which shows the time change of the recording current which flowed in the conductive wire of the magnetic thin wire device which concerns on Example. It is a graph which shows the time change of the leakage current flowing through the magnetic wire of the magnetic wire device which concerns on Example. It is an observation image by a magneto-optical microscope when the upward magnetic domain and the downward magnetic domain are alternately formed on the magnetic wire of the magnetic wire device which concerns on an Example. As shown in FIG. 9, it is an example of the timing chart of the voltage applied when the upward magnetic domain and the downward magnetic domain are recorded alternately. (A) is a recording power supply, (b) is a first drive power supply, and (c) is. The second drive power supply is shown respectively. Another example of the timing chart of the voltage applied when recording the upward magnetic domain and the downward magnetic domain alternately as shown in FIG. 9, is (a) a recording power supply, (b) a first drive power supply, and (c). ) Indicates the second drive power supply, respectively. It is a schematic diagram of the modification of the magnetic wire device which concerns on embodiment of this invention. It is a schematic diagram of the element of a conventional magnetic wire device, (a) is a state where a conductive wire is arranged at a position twisted with a magnetic wire, (b) is a direction of a current flowing through a conductive wire, and (c) is a conductive wire. The state seen from the axial direction of the line is shown respectively. It is a schematic diagram at the time of operating a conventional magnetic wire device. FIG. 6 is a schematic view of the magnetic thin wire device of FIG. 14 as viewed from the axial direction of the conductive wire. It is an observation image by a magnetic force microscope after the leakage current is generated in the magnetic wire device which concerns on a comparative example.

First, an outline of the magnetic wire device will be described with reference to FIGS. 1 and 2. In the present embodiment, the magnetic wire device 1 will be described as being a memory. The magnetic thin wire device 1 includes a magnetic thin wire 10, a conductive wire 20, an interlayer insulating layer 30, a recording power supply 40, a first drive power supply 51, and a second drive power supply 52. The magnetic thin wire 10 is a thin magnetic material. The conductive wire 20 is arranged on the magnetic thin wire 10 via the interlayer insulating layer 30 and records information on the magnetic thin wire 10 as a magnetic domain D by a current magnetic field. The recording power supply 40 applies a recording voltage to the conductive wire 20 during a predetermined recording period required for recording information corresponding to the magnetic domain D. The first drive power supply 51 applies a first bias voltage smaller than the recording voltage to the magnetic wire 10 in the first direction of the length of the magnetic wire 10 during the first period including at least a part of the recording period. During the second period including at least a part of the recording period, the second drive power supply 52 applies a second bias voltage smaller than the recording voltage to the magnetic thin wire 10 in a second direction opposite to the first direction of the length of the magnetic thin wire 10. It is applied in the direction.

Next, the detailed configuration of each part of the magnetic wire device 1 will be further described.
In the present embodiment, the magnetic wire device 1 has, as an example, one magnetic wire 10 and two recording elements. In the magnetic thin wire device 1, a conductive wire 20 is formed on the magnetic thin wire 10 at a twisted position with respect to the magnetic thin wire 10 via an interlayer insulating layer 30.

The magnetic thin wire 10 is a thin film, and is formed in a thin wire shape having a thickness and a width smaller than the length. The thickness of the magnetic thin wire 10 can be, for example, 10 nm to 2 μm, the width can be, for example, 20 nm to 100 μm, and the length can be, for example, 100 nm to 500 μm. In the examples described later, the film thickness of the magnetic thin wire 10 is assumed to be on the order of several nm, for example. The magnetic thin wire 10 is formed into the shape by electron beam drawing or photolithography step and etching or lift-off. In order to use the magnetic thin wire 10 as a recording medium and record information at high density, it is preferable to use a magnetic material having vertical magnetic anisotropy as the material of the magnetic fine wire 10. Examples of such materials include alloys such as Co-Tb, Co-Pd, Co-Cr, Co-Pt, and Co-Cr-Pt, and rare earth metals and transition metals such as Tb-Fe-Co and Gd-Fe. An alloy with (RE-TM alloy) can be mentioned.

The conductive wire 20 is a conductive layer for a recording element that forms a magnetic domain inside the magnetic wire in a state of being electrically isolated from the magnetic wire 10. The conductive wire 20 is formed as a pattern so as to straddle the magnetic thin wire 10 twice, for example, at a position twisted with the magnetic thin wire 10. The range of the thickness, width, length, etc. of the conductive wire 20 can be substantially the same as the range of the thickness, width, length, etc. of the magnetic thin wire 10. In the examples described later, the film thickness of the conductive wire 20 is, for example, on the order of 100 nm.

As the material of the conductive wire 20, a general electrode material can be applied. Specific examples thereof include metals such as Cu, Al, Au, Ag, Ta, Cr, and Co having good conductivity and alloys thereof. As an example, it is preferable to use Au as the material of the conductive wire 20. As a method for forming the conductive wire 20, for example, an electrode material is formed by a known method such as a sputtering method, and an electron beam drawing or photolithography step and a step such as etching or lift-off method are used, for example, as shown in FIG. The conductive wire 20 having the indicated shape can be formed.

In the examples shown in FIGS. 1 and 2, the cross-sectional shape of the conductive wire 20 is circular, but it may be rectangular. Further, the cross-sectional shape of the conductive wire 20 and the magnetic thin wire 10 may be a square, a rectangle, a polygon, a circle, an ellipse, or the like.

The insulator forming the interlayer insulating layer 30 is made of a general insulating material. Examples of such a material include an oxide film such as SiO ₂ and Al ₂ O ₃ , silicon nitride (Si ₃ N ₄ ), Mg F ₂ and the like. The shape of the interlayer insulating layer 30 is not limited to the flat plate shape shown as long as it is stably supported on a substrate (not shown), and for example, an insulating material may be filled between the conductive wires 20. Alternatively, the interlayer insulating layer 30 may be an insulating film in which an insulating material is spread around the conductive wire 20.

In the recording power supply 40, the first drive power supply 51, and the second drive power supply 52, the reference numerals 40a, 51a, 52a are terminals, the reference numerals 40b, 51b, 52b are ground terminals, and the reference numerals 40c, 51c, 52c are operation display units.
The recording power supply 40 applies a voltage to the conductive wire 20. Hereinafter, the recording power supply 40 will be described as applying a pulse voltage to the conductive wire 20. The terminal 40a of the recording power supply 40 is connected to one end 21 of the conductive wire 20. The other end 22 of the conductive wire 20 is grounded. When the recording power supply 40 applies a voltage to the conductive wire 20, a recording current A flows through the conductive wire 20, and a magnetic domain can be formed on the magnetic wire 10. When the direction of the recording current A is the direction shown in FIG. 1, an upward magnetic domain can be formed on the magnetic thin wire 10. Here, by changing the direction of the recording current A, that is, the positive or negative of the current, a downward magnetic domain can be formed on the magnetic thin wire 10.

The first drive power supply 51 applies a bias voltage (first bias voltage) to the magnetic wire 10 at the time of magnetic domain recording. The second drive power supply 52 applies a bias voltage (second bias voltage) to the magnetic wire 10 at the time of magnetic domain recording. The terminal 51a of the first drive power supply 51 is connected to one end (left end) of the magnetic thin wire 10. The other end (right end) of the magnetic thin wire 10 is connected to the terminal 52a of the second drive power supply 52. Here, the bias voltage is a magnetic thin wire 10 for increasing the potential of the magnetic fine wire 10 in order to reduce the difference between the potential of the conductive wire 20 at the time of magnetic domain recording and the potential of the magnetic fine wire 10 at the time of magnetic domain recording. It is the voltage applied to.
The inventors of the present application have conducted various studies on a device in which the conductive wire 20 and the magnetic thin wire 10 are insulated by the interlayer insulating film 30. In a device such as the magnetic wire device 1, when a current (recording current) is passed through the conductive wire 20 during magnetic domain recording, a leak current flows through the interlayer insulating film 30 through the interlayer insulating film 30 because the conductive wire 20 flows during recording. This is because there is a potential difference between the magnetic wire 10 and the magnetic wire 10. Therefore, in order to suppress the leakage current at the time of recording, it is not originally necessary to apply a voltage to the magnetic thin wire 10 at the time of recording, but the inventors of the present application apply the bias voltage described above to the magnetic thin wire 10 at the time of recording. And said.

Hereinafter, the first bias voltage and the second bias voltage will be described as assuming that they are pulse voltages. The magnitude of the bias pulse voltage is made smaller than the pulse voltage applied to the conductive wire 20 from the recording power supply 40. The reason is that the thickness of the magnetic thin wire 10 and the thickness of the conductive wire 20 are significantly different. Therefore, when a bias pulse voltage similar to the pulse voltage applied to the conductive wire 20 is applied to the magnetic thin wire 10, the magnetic thin wire 10 is formed. This is because there is a risk of destruction. The upper limit of the bias voltage is appropriately set after grasping the withstand voltage of the magnetic thin wire 10 in advance. The upper limit of the bias voltage is a voltage value at which the magnetic domain on the magnetic wire 10 does not move due to the leak current flowing from the conductive wire 20 to the magnetic wire 10 when the recording power supply 40 applies a pulse voltage to the conductive wire 20. Is set as. Further, this upper limit value can be determined by using a device such as a magneto-optical microscope for observing the state of the magnetic domain.

Next, an outline of the control method of the magnetic wire device will be described.
The control method of the magnetic wire device 1 is a method related to magnetic domain control at the time of magnetic domain recording of the magnetic wire device 1, and includes a recording voltage application step, a first bias voltage application step, and a second bias voltage application step. I'm out.
The recording voltage application step is a step of applying a recording voltage to the conductive wire 20 during a predetermined recording period required for recording information corresponding to the magnetic domain D by a recording power supply 40 electrically connected to the conductive wire 20.
The first bias voltage application step is performed by the first drive power supply 51 electrically connected to one end in the longitudinal direction of the magnetic thin wire 10 from the recording voltage on the magnetic thin wire 10 during the first period including at least a part of the recording period. Is also a step of applying a small first bias voltage.
In the second bias voltage applying step, the recording voltage is recorded on the magnetic thin wire 10 during the second period including at least a part of the recording period by the second drive power supply 52 electrically connected to the other end in the longitudinal direction of the magnetic thin wire 10. This is a step of applying a second bias voltage smaller than that of the second bias voltage.

Here, the first period overlapping the recording period and the second period overlapping the recording period may be different within the recording period, or the second period may be started after the first period ends. However, it is more effective and preferable that the first period and the second period have overlapping periods. Further, in order to further enhance the effect, it is desirable that the first period and the second period include the entire recording period. In that case, the first period and the second period may be the same timing as the recording period in which the recording voltage is applied (FIG. 3). Alternatively, the first period and the second period may be longer than the recording period, including the entire recording period.

A specific example of the control method of this magnetic wire device will be described with reference to FIG. 3 (see FIGS. 1 and 2 as appropriate). FIG. 3 shows a timing chart of each power supply when a pulse voltage is simultaneously applied from both ends of the magnetic wire 10 at the time of magnetic domain recording of the magnetic wire device 1.

In the control method of the magnetic wire device according to the present embodiment, as shown in the figure, when the recording voltage is a positive voltage, the first bias voltage and the second bias voltage are also positive voltages, and the recording voltage is a negative voltage. At this time, the first bias voltage and the second bias voltage are also negative voltages.

Specifically, as shown in FIG. 3A, the pulse voltage (recording voltage) applied from the recording power supply 40 to the conductive wire 20 is positive during the period from 0 to t1. Here, when the pulse voltage (recording voltage) applied to the conductive wire 20 is positive, for example, an upward magnetic domain is formed on the magnetic wire 10 as shown in FIG. That is, the period from 0 to t1 is the recording period when an upward magnetic domain is formed on the magnetic thin wire 10.

During the period from 0 to t1, the first bias pulse voltage applied from the first drive power source 51 to the magnetic wire 10 is positive as shown in FIG. 3 (b). The period from 0 to t1 is the first period including at least a part of the recording period, and in this case, the recording period in which the recording voltage is applied and the first period are the same timing.
Further, during the period from 0 to t1, the second bias pulse voltage applied from the second drive power supply 52 to the magnetic wire 10 is also positive as shown in FIG. 3 (c). The period from 0 to t1 is the second period including at least a part of the recording period, and in this case, the recording period in which the recording voltage is applied and the second period are at the same timing.

Further, as shown in FIG. 3A, the pulse voltage (recording voltage) applied from the recording power supply 40 to the conductive wire 20 is negative during the period from t2 to t3. When the pulse voltage (recording voltage) applied to the conductive wire 20 is negative, a downward magnetic domain is formed on the magnetic wire 10. That is, the period from t2 to t3 is the recording period when a downward magnetic domain is formed on the magnetic thin wire 10.

During the period from t2 to t3, the first bias pulse voltage applied from the first drive power source 51 to the magnetic wire 10 is negative as shown in FIG. 3 (b). The period from t2 to t3 is the first period including at least a part of the recording period, and in this case, the recording period in which the recording voltage is applied and the first period are the same timing.
Further, during the period from t2 to t3, the second bias pulse voltage applied from the second drive power supply 52 to the magnetic wire 10 is also negative as shown in FIG. 3C. The period from t2 to t3 is the second period including at least a part of the recording period, and in this case, the recording period in which the recording voltage is applied and the second period are at the same timing.

As shown in FIGS. 3 (b) and 3 (c), the first bias voltage and the second bias voltage can have the same magnitude. Further, the first bias voltage and the second bias voltage can be applied at the same timing.

The control method of this magnetic thin wire device is that when a current is passed through the conductive wire 20 (during the recording period), for example, a bias voltage is applied to the magnetic thin wire 10 from both ends of the magnetic thin wire 10 so as to overlap the recording period at the same timing. Is applied. Alternatively, a bias voltage is applied to the magnetic thin wire 10 from both ends of the magnetic thin wire 10 so as to overlap the recording period during a period longer than the recording period. Here, the period longer than the recording period means, for example, that the start time is set before the start time of the recording period, the end time is set after the end time of the recording period, or recording. It means that the period including the start and end times of the period is set.
By doing so, the potential difference between the potential of the magnetic thin wire 10 and the potential of the conductive wire 20 can be reduced during the recording period. As a result, the leakage current leaking from the conductive wire 20 to the magnetic thin wire 10 is suppressed, and the operation as a device is realized.

If a pulse voltage (bias voltage) is applied from only one of the magnetic wires 10 during the recording period, the pulse voltage causes an unintended magnetic domain drive or destruction of the magnetic domain. On the other hand, in this control method of the magnetic domain device, a bias voltage is applied from both ends of the magnetic domain 10 to reduce the potential difference between the potential of the magnetic domain 10 and the potential of the conductive wire 20 during the recording period. Can be prevented. Therefore, it is possible to apply a voltage of such a magnitude to the conductive wire 20 that the interlayer insulating layer 30 is originally destroyed and short-circuited. Therefore, according to the magnetic thin wire device 1, a large recording voltage exceeding the withstand voltage of the conventional element can be applied to the conductive wire 20.

Next, a specific example of the magnetic wire device 1 manufactured under the following conditions will be described.
(Conditions for thin magnetic wire)
A magnetic thin wire 10 was formed on a surface-heated silicon oxide substrate by a sputtering method. As the magnetic thin wire 10, a material having vertical magnetic anisotropy was used, and a multilayer laminated film of cobalt and terbium (thickness: 4.5 nm) and platinum were deposited on the multilayer film (thickness: 4.5 nm) to make the total thickness of 7.5 nm. Further, the width of the magnetic thin wire 10 at this time was set to 3 μm.

(Conditions for conductive wire and interlayer insulating layer)
Silicon nitride was deposited on the magnetic thin wire 10 as an interlayer insulating layer 30 with a film thickness of 18 nm. A conductive wire 20 having a film thickness of 100 nm and a width of 3 μm was formed on the interlayer insulating layer 30. At this time, according to the method disclosed in Non-Patent Document 2, as shown in FIG. 1, the conductive wire 20 as a recording element has a structure in which the conductive wire 20 as a recording element straddles the magnetic thin wire 10 twice, an outward path and a return path. The magnetic domain D is formed in a minute magnetic wire region sandwiched between the two recording elements by the synthetic magnetic field of the recording element of the book. The two recording elements here consist of one conductive wire 20. Then, in FIG. 1 of the conductive wire 20, the region on the left side straddles the magnetic thin wire 10 as an outward path, and the region on the right side in FIG. 1 of the conductive wire 20 straddles the magnetic thin wire 10 as a return path.

The film thickness (18 nm) of the interlayer insulating layer 30 is sufficient to ensure the insulating property between the conductive wire 20 and the magnetic thin wire 10. However, when a large number of such magnetic wire devices 1 are made, some elements have good insulation and some have poor insulation due to non-uniformity caused by yield and position on the substrate. Occurs. In this element having poor insulating property, a leakage current is generated from the conductive wire 20 to the magnetic thin wire 10 at the time of magnetic domain recording. Therefore, we dared to select an element with poor insulation and performed the following experiments 1 and 2.

(Supplementary explanation for elements with poor insulation)
Since the film thickness of the interlayer insulating layer 30 is as thin as 18 nm, when a plurality of magnetic fine wires 10 are formed on one and the same substrate, a leakage current may occur due to the difference in each variation. Further, in the process of manufacturing the magnetic thin wire device 1 in which the conductive wire 20 is integrally formed, when each layer is formed in the order of the magnetic fine wire 10 / the interlayer insulating layer 30 / the conductive wire 20 on the substrate, for example, by drawing an electron beam. It is common to form a laminated structure through many processes such as pattern formation, material deposition by a sputtering device, and resist stripping. Therefore, due to the problem of yield during manufacturing, even if the device is designed under the condition that the leakage current does not originally occur, the leakage current may be unavoidably generated. Examples of the cause of the leakage current include the uniformity of the film thickness of the interlayer insulating layer 30, the edge shape of the magnetic thin wire 10 and the conductive wire 20, and the non-uniformity of the film thickness on the substrate.

(Experiment 1)
The following experiment 1 was performed using this element having poor insulation. Experiment 1 is an experiment according to a comparative example for explaining the effect of the present invention, and only performs a recording voltage application step at the time of magnetic domain recording. In this experiment 1, the following evaluation criteria based on the above-mentioned conditions of the conductive wire and the interlayer insulating layer and the condition of the magnetic thin wire were used.

(Evaluation Criteria 1)
According to the research by the present inventors on the current value that needs to be passed through the conductive wire 20 in order to record the magnetic domain on the magnetic domain thin wire 10, the conductive wire and the interlayer insulating layer are conductive in the case of the above-mentioned conditions of the conductive wire and the interlayer insulating layer. It is known that magnetic domain recording can be performed on the magnetic thin wire 10 when the value of the recording current flowing through the wire 20 is about 100 mA.
(Evaluation Criteria 2)
Further, according to the research by the present inventors on the current value that needs to be passed through the magnetic wire 10 when driving the magnetic domain formed on the magnetic wire 10, the above-mentioned conditions of the magnetic wire 10 have been obtained. Is known to drive the magnetic domain when the value of the current flowing through the magnetic wire 10 exceeds about 3.5 mA.

According to the evaluation criteria 1 and 2, for the purpose of recording the magnetic domain on the magnetic domain 10 but not driving the magnetic domain, when a recording current of about 100 mA is passed through the conductive wire 20, the current flows through the magnetic domain 10. It can be seen that the value of the leak current that ends up must be smaller than about 3.5 mA.

In Experiment 1 using this element with poor insulation, the pulse voltage (recording voltage) applied to the conductive wire 20 from the recording power supply 40 in FIG. 1 was gradually increased, and the recording current and leakage current at that time were increased. Asked for a relationship. As a result of Experiment 1, magnetic domain drive occurred before the value of the recording voltage reached the level required for magnetic domain recording. Specifically, when a recording current having a current value (72.4 mA) lower than the current value (about 100 mA) required for magnetic domain recording is passed through the conductive wire 20, the leak current 2 flowing through the magnetic thin wire 10 The value of was 5.7 mA (> 3.5 mA). That is, it was found that the leak current 2 drives the magnetic domain. In the element with poor insulation used in Experiment 1, since the leak current 2 is larger than the leak current 1, the magnetic domain in the magnetic wire 10 has moved to the right side of the magnetic wire 10 when viewed from the conductive wire 20. FIG. 4 shows the time change of the recording current flowing through the conductive wire 20 at this time, and FIG. 5 shows the time change of the leakage current flowing through the magnetic thin wire 10.

As shown in FIG. 2, the leak current 1 is a leak current that flows from the conductive wire 20 to the first drive power supply 51 side via the magnetic thin wire 10. As shown in FIG. 2, the leak current 2 is a leak current that has flowed from the conductive wire 20 to the second drive power supply 52 side via the magnetic thin wire 10.
Further, in FIG. 5, the sharp peaks at the rising and falling edges of the leak current are due to the high frequency component due to the pulse component.
Further, the current value and the voltage value described with reference to FIGS. 5 to 8 are values at the time of 1.5 μs.

In Experiment 1, the presence of a leak current is ignored after the magnetic domain is driven by passing a recording current of a current value (72.4 mA) lower than the current value (about 100 mA) required for magnetic domain recording to the conductive wire 20. Then, I tried to increase the value of the recording current as it is. Then, it was found that the magnetic domain was destroyed by the leak current, and it was difficult to evaluate whether or not the magnetic domain could be recorded. Furthermore, it was found that the dielectric breakdown of the magnetic thin wire 10 and the conductive wire 20 caused the physical destruction phenomenon of the element itself. rice field. FIG. 16 is an observation image by a magneto-optical microscope showing the state of the magnetic domain after the generation of the leak current. As a result of a part of the recording current flowing out to the magnetic thin wire 10 as a leak current at the time of recording, it is broken apart by Joule heat so that the magnetic domain on the magnetic fine wire 10 cannot be determined at all. Such a magnetic domain destruction phenomenon is called a magnetic domain maize pattern.

(Experiment 2)
The following experiment 2 was performed using an element having poor insulation. Experiment 2 is an example in which a recording voltage application step, a first bias voltage application step, and a second bias voltage application step at the time of magnetic domain recording are performed. In Experiment 2, the above evaluation criteria 1 and 2 were also used.

6 and 7 show the experimental conditions of Experiment 2. FIG. 6 shows a pulse voltage (recording voltage) applied to the conductive wire 20 from the recording power supply 40 of FIG. 1, a bias pulse voltage 1 applied from the first drive power supply 51 to the magnetic thin wire 10, and magnetism from the second drive power supply 52. The bias pulse voltage 2 applied to the thin wire 10 is shown. At this time, the recording current flowing through the conductive wire 20 is 100 mA as shown in FIG. 7.

Further, in Experiment 2, the conductive wire 20 and the magnetic thin wire were obtained by applying a bias voltage with the same bals width to the magnetic thin wire 10 at the same time as applying a pulse voltage (recording voltage) for passing a recording current through the conductive wire 20. The potential difference from 10 was reduced. The pulse voltage (recording voltage) applied to the conductive wire 20 at this time is 24.7V.

In the device with poor insulation used in Experiment 2, the film thickness (7.5 nm) of the magnetic thin wire 10 is much thinner than the film thickness (100 nm) of the conductive wire 20. Therefore, if a voltage having the same magnitude as the pulse voltage (recording voltage) applied to the conductive wire 20 is applied to the magnetic thin wire 10, the magnetic thin wire 10 may be destroyed. Therefore, the voltage value of the bias voltage applied to the magnetic wire 10 is set to such a voltage value that the magnetic domain does not move due to the leak current. Under the conditions of the above-mentioned magnetic thin wire and the above-mentioned conductive wire and interlayer insulating layer, the potential difference between the pulse voltage (recording voltage) applied to the conductive wire 20 and the bias voltage applied to the magnetic thin wire 10 is always about 13V. Adjusted to be. That is, as shown in FIG. 6, when the pulse voltage (recording voltage) applied to the conductive wire 20 is 24.7V, the bias voltage applied to the magnetic thin wire 10 is adjusted to be about 11.7V. This means that the potential difference between the potential of the conductive wire 20 and the potential of the magnetic thin wire 10 is 24.7 V when the bias voltage is not used as in the conventional case, whereas in the embodiment, the potential of the conductive wire 20 and the magnetism This means that the potential difference from the potential of the thin wire 10 has been reduced to about 11.7V.

The experimental results of Experiment 2 are shown in FIG. FIG. 8 shows the leak current 1 flowing to the left end of FIG. 2 of the magnetic thin wire 10 and the leak current 2 flowing to the right end of FIG. 2 of the magnetic thin wire 10 under the experimental conditions shown in FIGS. 6 and 7. ing. As shown in FIG. 8, the leak current 1 was 1.5 mA (<3.5 mA), and the leak current 2 was 0.9 mA (<3.5 mA). Therefore, when the recording current (100 mA) required for magnetic domain recording is passed through the conductive wire 20, the value of the leakage current flowing through the magnetic domain wire 10 is the current value required for driving the magnetic domain (about 3.). It was possible to make it sufficiently lower than 5 mA). Therefore, according to Experiment 2 (Example), it was possible to confirm that the magnetic domain could be recorded without causing the destruction of the magnetic domain. The sharp peaks at the rising and falling edges of the leak current in FIG. 8 are due to the high frequency component due to the pulse component and did not contribute to the driving of the magnetic domain.

Although the operation of the magnetic domain wire device 1 at the time of magnetic domain recording has been described, the magnetic domain wire device 1 can also perform magnetic domain drive after the magnetic domain recording. That is, in the magnetic wire device 1 according to the present embodiment, the first drive power supply 51 or the second drive power supply 52 drives the magnetic domain formed in the magnetic wire 10 during a drive period set after the recording period. Apply voltage. That is, in the magnetic domain device 1, the magnetic domain formed on the magnetic domain 10 when the first drive power supply 51 and the second drive power supply 52, which are power supplies for generating the bias pulse voltage applied to the magnetic domain wire 10, is driven. Can be used as it is as a power source for driving. Conversely, as the power source for applying the bias pulse voltage to the conductive wire 20, the magnetic domain drive power source for driving the magnetic domain on the magnetic domain wire 10 can be used as it is, so that a special one needs to be prepared. There is no.

Therefore, for example, when the first drive power supply 51 applies a positive voltage to the magnetic wire 10 during magnetic domain drive, a drive current flows through the magnetic wire 10 from the side of the first drive power supply 51 to the side of the second drive power supply 52. , The magnetic domain can be driven to the right. Further, when the second drive power supply 52 applies a positive voltage to the magnetic wire 10 during magnetic domain drive, a drive current flows through the magnetic wire 10 from the side of the second drive power supply 52 to the side of the first drive power supply 51, and the magnetic domain is driven. Can be driven to the left.

As an example, in the magnetic wire device 1, an upward magnetic domain recording and a magnetic domain drive recorded at that time, a downward magnetic domain recording, and a magnetic domain drive recorded at that time will be described alternately.

FIG. 9 is an observation image by a magneto-optical microscope when the upward magnetic domain and the downward magnetic domain are alternately formed on the magnetic thin wire 10. In FIG. 9, the two recording elements are composed of one conductive wire 20. Then, in the magnetic wire 10, the magnetic domain D is formed over the magnetic domain D from the center position in the width direction of the recording element on the left side in FIG. 9 to the center position in the width direction of the recording element on the right side in FIG. .. Further, in the magnetic domain 10, the magnetic domain D formed in the magnetic domain on the right side of the recording element on the right side in FIG. 9 is the downward magnetic domain formed for the second time, and the magnetic domain formed in the magnetic domain on the right side. D is the upward magnetic domain formed for the first time. Although the image of FIG. 9 is difficult to understand, the magnetic domains have moved to two places indicated by reference numeral D on the magnetic thin wire 10.

An example of a control method for the magnetic wire device 1 when the upward magnetic domain and the downward magnetic domain are alternately formed on the magnetic wire 10 will be described with reference to FIG. 10. First, during the period from 0 to t11, the pulse voltage (recording voltage) applied from the recording power supply 40 to the conductive wire 20 is positive as shown in FIG. 10 (a), and FIG. 10 (b). And as shown in FIG. 10 (c), the first and second bias pulse voltages are also positive. Upward magnetic domains are recorded during this period. The operation during this period is the same as the operation during the period from 0 to t1 in the timing chart of FIG.

Next, the period from t11 to t12 is the period for driving the upward magnetic domain formed in the previous period. As shown in FIG. 10B, when the first drive power supply 51 applies a positive pulse voltage (magnetic domain drive pulse) to the magnetic wire 10, the magnetic wire 10 is subjected to the second drive power supply from the side of the first drive power supply 51. A drive current flows to the side of 52, and the upward magnetic domain can be driven to the right in FIG. The magnitude of the magnetic domain drive pulse applied to the magnetic domain wire 10 by the first drive power supply 51 when driving the magnetic domain is smaller than the magnitude of the first bias pulse voltage applied to the magnetic domain wire 10 by the first drive power supply 51 when recording the magnetic domain. ..

Next, a downward magnetic domain is recorded during the period from t12 to t13. The operation during this period is the same as the operation during the period from t2 to t3 in the timing chart of FIG.

Next, the period from t13 to t14 is the period for driving the downward magnetic domain formed in the previous period. As shown in FIG. 10B, when the first drive power supply 51 applies a positive pulse voltage (magnetic domain drive pulse) to the magnetic wire 10, the magnetic wire 10 is subjected to the second drive power supply from the side of the first drive power supply 51. A drive current flows to the side of 52, and the downward magnetic domain can be driven to the right in FIG.

As shown in FIG. 11, instead of the first drive power supply 51, the second drive power supply 52 applies a pulse voltage (magnetic domain drive pulse) to the magnetic wire 10 to alternately alternate between the upward magnetic domain and the downward magnetic domain. It can also be formed on the magnetic thin wire 10.

In this case, as shown in FIG. 11, an upward magnetic domain is recorded in the period from 0 to t11. Next, the period from t11 to t12 is the period for driving the upward magnetic domain formed in the previous period. As shown in FIG. 11C, when the second drive power supply 52 applies a negative pulse voltage (magnetic domain drive pulse) to the magnetic wire 10, the magnetic wire 10 is subjected to the second drive power supply from the side of the first drive power supply 51. A drive current flows to the side of 52, and the upward magnetic domain can be driven to the right in FIG. The magnitude of the magnetic domain drive pulse applied to the magnetic domain wire 10 by the second drive power supply 52 when driving the magnetic domain is smaller than the magnitude of the second bias pulse voltage applied to the magnetic domain wire 10 by the second drive power supply 52 when recording the magnetic domain. ..

Next, a downward magnetic domain is recorded during the period from t12 to t13. Next, the period from t13 to t14 is the period for driving the downward magnetic domain formed in the previous period. As shown in FIG. 11C, when the second drive power supply 52 applies a negative pulse voltage (magnetic domain drive pulse) to the magnetic wire 10, the magnetic wire 10 is subjected to the second drive power supply from the side of the first drive power supply 51. A drive current flows to the side of 52, and the downward magnetic domain can be driven to the right in FIG.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the bias voltage applied to the magnetic wire 10 from the first drive power supply 51 and the second drive power supply 52 is assumed to be a pulse voltage (bias pulse voltage), but may be a DC voltage (bias DC voltage). In this case as well, the effect of reducing the leakage current can be similarly achieved. However, since the DC bias voltage is always applied, it is desirable to use a pulse voltage (bias pulse voltage) from the viewpoint of reducing power consumption.

Further, although a specific example in which the magnetic thin wire 10 contains Co-Tb as a magnetic material has been described, another material having vertical magnetic anisotropy may be used. When the magnetic material constituting the magnetic wire device includes a material such as Tb that is oxidized by oxygen or moisture, the magnetic wire may be oxidized, which may make it difficult to drive the magnetic domain. Further, if the magnetization in the magnetic wire is lost due to the progress of oxidation and it becomes difficult to record the magnetic domain, the function as the magnetic wire device is lost. Therefore, depending on the type of magnetic material, it is preferable to enclose the element of the magnetic wire device in a container that can sufficiently shield from the outside air in order to prevent oxidation of the magnetic wire device. A schematic diagram of this modification is shown in FIG. Reference numeral 2 indicates an element excluding the respective power supplies 40, 51, 52 of the magnetic wire device 1. The element 2 includes a magnetic thin wire 10, a conductive wire 20, and an interlayer insulating layer 30. The container 60 that shuts off the outside air isolates the element 2 of the magnetic wire device 1 from the atmosphere. Reference numerals 60a, 60b, and 60c are connectors, and these connectors can energize the conductive wire 20 and the magnetic thin wire 10 of the element 2 inside the container 60 while isolating the atmosphere outside the container 60. Further, the atmosphere 70 inside the container 60 that shuts off the outside air is filled with a dry nitrogen atmosphere or is in a vacuum. According to this modification, by preventing oxidation of the magnetic domain wire device, more accurate magnetic domain recording and magnetic domain drive control and evaluation become possible.

The magnetic wire device 1 is assumed to be a memory, but may be a spatial light modulator. Further, in the case of a reflective spatial light modulator, the magnetic thin wire 10 is preferably made of a material having a high light reflectance.

1 Magnetic wire device 10 Magnetic wire (magnetic material)
20 Conductive wire 30 Interlayer insulation layer 40 Recording power supply 51 First drive power supply 52 Second drive power supply 60 Container that shuts off outside air D Magnetic domain

Claims (11)

A method for controlling a magnetic wire device including a magnetic wire which is a thin magnetic material and a conductive wire which is arranged on the magnetic wire via an interlayer insulating layer and records information on the magnetic wire as a magnetic domain by a current magnetic field. There,
A step of applying a recording voltage to the conductive wire during a predetermined recording period required for recording the information corresponding to the magnetic domain by a recording power supply electrically connected to the conductive wire.
A first drive power source electrically connected to one end of the magnetic wire in the longitudinal direction applies a first bias voltage to the magnetic wire that is smaller than the recording voltage during the first period including at least a part of the recording period. The process of applying and
A second bias voltage smaller than the recording voltage on the magnetic wire during the second period including at least a part of the recording period by the second drive power supply electrically connected to the other end in the longitudinal direction of the magnetic wire. And the process of applying
A method for controlling a magnetic wire device, which comprises. The first period and the second period have overlapping periods.
The method for controlling a magnetic thin wire device according to claim 1. The first period and the second period are periods including all of the recording periods.
The method for controlling a magnetic wire device according to claim 1 or 2, wherein the magnetic wire device is controlled. The first bias voltage and the second bias voltage are pulse voltage or DC voltage.
The method for controlling a magnetic wire device according to any one of claims 1 to 3, wherein the magnetic wire device is controlled. The conductive wire is formed as a pattern so as to straddle the magnetic thin wire twice at a position twisted with the magnetic fine wire.
The method for controlling a magnetic thin wire device according to any one of claims 1 to 4, wherein the magnetic wire device is controlled. The first drive power supply or the second drive power supply applies a drive voltage for driving a magnetic domain formed in the magnetic thin wire during a drive period set after the recording period.
The control method for a magnetic thin wire device according to claim 5. When the recorded voltage is a positive voltage, the first bias voltage and the second bias voltage are also positive voltages, and when the recorded voltage is a negative voltage, the first bias voltage and the second bias voltage are used. The voltage is also a negative voltage,
The method for controlling a magnetic wire device according to any one of claims 1 to 6, wherein the magnetic wire device is controlled. The first bias voltage and the second bias voltage have the same magnitude.
The method for controlling a magnetic wire device according to any one of claims 1 to 7, wherein the magnetic wire device is controlled. The magnetic wire device is a memory or spatial light modulator.
The method for controlling a magnetic thin wire device according to any one of claims 1 to 8, wherein the magnetic wire device is controlled. The magnetic wire, the interlayer insulating layer, and the conductive wire of the magnetic wire device are all enclosed in a container that can be kept in a dry nitrogen atmosphere or a vacuum in isolation from the outside air.
The control method for a magnetic thin wire device according to claim 9. Magnetic fine wire, which is a thin magnetic material, and
A conductive wire that is arranged on the magnetic thin wire via an interlayer insulating layer and records information on the magnetic thin wire as a magnetic domain by a current magnetic field.
A recording power supply that applies a recording voltage to the conductive wire during a predetermined recording period required for recording the information corresponding to the magnetic domain, and
A first drive power source that applies a first bias voltage smaller than the recording voltage to the magnetic wire in the first direction of the length of the magnetic wire during the first period including at least a part of the recording period.
During the second period including at least a part of the recording period, a second bias voltage smaller than the recording voltage is applied to the magnetic wire in a second direction opposite to the first direction of the length of the magnetic wire. 2nd drive power supply and
A magnetic thin wire device characterized by being equipped with.

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