JP2019033121A - Domain wall movable magnetic recording device, magnetic recording array and control method therefor - Google Patents

Abstract

To improve gradation accuracy of multi-value recording by precisely controlling a movement distance of a domain wall and further, to increase gradations of the multi-value recording by controlling a movement speed of the domain wall.SOLUTION: A domain wall movable magnetic recording device 1 comprises: a magnetic recording layer 2 consisting of a ferromagnetic substance and including a domain wall 3; a pin layer 5 connected to the magnetic recording layer 2 via a non-magnetic layer 4 and consisting of a ferromagnetic substance; at least two electrodes 61 and 62 which are connected to the magnetic recording layer 2 and disposed so as to be separated while holding the pin layer 5 therebetween in a planar view, and apply a current pulse of a first value to the magnetic recording layer 2 for moving the domain wall 3; a magnetic field application mechanism 7 which applies a magnetic field 10 to the magnetic recording layer 2; and a magnetic field control mechanism 9 which controls the magnetic field application mechanism 7 in response to the current pulse and changes the magnetic field 10 to be applied to the magnetic recording layer 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a domain wall motion type magnetic recording apparatus, a magnetic recording array, and a control method thereof.

  As a next-generation non-volatile memory that replaces flash memories and the like that have seen limitations in miniaturization, a resistance change type magnetic recording device that stores data using a resistance change type element, for example, MRAM (Magnetic Resistive Random Access Memory) , ReRAM (Resistance Random Access Memory), PCRAM (Phase Change Random Access Memory), and the like.

  As a method of increasing the density (capacity) of the memory, there is a method of multi-value recording bits per element constituting the memory, in addition to a method of reducing the element itself constituting the memory.

  One type of MRAM is called a domain wall drive type magnetic recording device or a domain wall motion type magnetic recording device. The domain wall motion type magnetic recording device causes a current to flow in the in-plane direction of the magnetic recording layer (or domain wall motion layer), moves the domain wall by the spin transfer effect by spin-polarized electrons, and changes the magnetization of the ferromagnetic film to the direction of the write current. Data is written by reversing the direction according to the above.

  10 and 11 are a schematic perspective view and a schematic plan view of a conventional multi-value domain wall motion type magnetic recording apparatus 100, respectively. The multi-value domain wall motion type magnetic recording apparatus 100 includes a magnetic recording layer 102, a pinned layer 105 connected to the magnetic recording layer 102 via a nonmagnetic layer 104, and both ends of the magnetic recording layer 102. A first magnetic pinned layer 161 having a magnetization of 2 and a second magnetic pinned layer 162. The magnetization direction of the pinned layer 105 is fixed in the same direction as the magnetization direction of either the first magnetic pinned layer 161 or the second magnetic pinned layer 162. The magnetic recording layer 102 includes a first magnetic domain 111 having a magnetization in the same direction as the magnetization of the first magnetic fixed layer 161, and a second magnetic domain 112 having a magnetization in the same direction as the magnetization of the second magnetic fixed layer 162. A domain wall 103 is formed at the boundary between the first magnetic domain 111 and the second magnetic domain 112. The domain wall 103 is disposed at a predetermined position directly below the pinned layer 105.

  When a current pulse is applied in the direction from the second magnetic pinned layer 162 to the first magnetic pinned layer 161 to the multi-value domain wall motion type magnetic recording apparatus 100 configured as described above, the spin of the first magnetic pinned layer 161 is applied. Flows into the magnetic recording layer 102. Therefore, the first magnetic domain 111 spreads in the direction of the second magnetic pinned layer 162, and the domain wall 103 moves in the direction of the second magnetic pinned layer 162. Therefore, the area where the first magnetic domain 111 overlaps the pinned layer 105 is increased, and the area where the second magnetic domain 112 overlaps the pinned layer 105 is decreased.

  If the magnetization of the pinned layer 105 and the magnetization of the magnetic recording layer 102 immediately below it are in the same direction (parallel), the electrical conductivity between the pinned layer 105 and the magnetic recording layer 102 increases, and the opposite direction (anti-counter) If it is (parallel), the electrical conductivity becomes small. When the domain wall 103 stops at a predetermined position immediately below the pinned layer 105, the electrical conductivity between the pinned layer 105 and the magnetic recording layer 102 increases in proportion to the area of the portion where the magnetization is parallel. FIG. 12 shows the area of the portion where the magnetization of the pinned layer 105 and the magnetization of the magnetic recording layer 102 are parallel to each other, and the pinned layer 105 and the magnetic recording layer 102. The graph showing the relationship of electrical conductivity between is shown.

  As described above, since the electrical conductivity between the pinned layer and the magnetic recording layer linearly changes depending on the position of the domain wall, one domain wall motion type magnetic recording can be performed by accurately stopping the domain wall at a predetermined position. The apparatus can be configured as a multi-value recording type domain wall motion magnetic recording apparatus that performs an analog multi-value operation that can take a plurality of values other than 0/1.

  In such a multi-value recording type domain wall motion type magnetic recording apparatus, in order to perform precise multi-value recording, it is necessary to increase the accuracy of the domain wall travel distance by applying a pulse current. Furthermore, in order to increase the gradation of multilevel recording, it is necessary to suppress the domain wall moving speed and reduce the error of the domain wall stop position. Further, in order to perform arbitrary recording, it is necessary to apply a pulse current a plurality of times, which causes an operation delay.

Applied Physics Express 7, 033005 (2014) Nature Materials DOI: 10.1038 / NMAT3675

  An object of the present invention is to precisely control the moving distance of a domain wall and improve the gradation accuracy of multilevel recording. It is another object of the present invention to suppress the moving speed of the domain wall and increase the gradation of multi-value recording, or improve the moving speed of the domain wall and improve the operating speed of multi-value recording.

  A domain wall motion type magnetic recording apparatus according to the present invention is made of a ferromagnetic material, and includes a magnetic recording layer including a domain wall, a ferromagnetic layer connected to the magnetic recording layer via a nonmagnetic layer, and a magnetic recording layer. And at least two electrodes for applying a voltage for moving the domain wall to the magnetic recording layer, and a magnetic field application for applying a magnetic field to the magnetic recording layer. And a magnetic field control mechanism that operates the magnetic field application mechanism in response to a current pulse generated by the applied voltage to change the magnetic field applied to the magnetic recording layer.

  The domain wall motion type magnetic recording apparatus configured as described above can precisely control the moving distance of the domain wall by changing the magnetic field applied to the magnetic recording layer. The gradation of multi-value recording can be increased.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the magnetic field control mechanism operates the magnetic field application mechanism to apply a magnetic field to the magnetic recording layer to control the moving speed of the domain wall.

  Since the domain wall motion type magnetic recording apparatus configured in this way controls and suppresses the domain wall moving speed, the position where the domain wall is stopped can be precisely controlled, and the gradation accuracy of multilevel recording is improved. The gradation of multi-value recording can be increased. Further, the domain wall motion type magnetic recording apparatus configured as described above can improve the operation speed of multilevel recording because the domain wall motion speed is controlled and improved.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the magnetic field control mechanism has a first magnitude of the magnetic field applied to the magnetic recording layer when the current pulse has a predetermined amplitude or when the current pulse falls. Then, the magnetic field application mechanism is operated so as to change to a second size larger than the first size.

  The domain wall motion type magnetic recording apparatus configured in this way can precisely control the position where the domain wall is stopped to stop the current pulse and suppress the domain wall movement speed when stopping the domain wall movement. Therefore, the gradation accuracy of multi-value recording can be improved and the gradation of multi-value recording can be increased.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the first size is non-zero.

  The domain wall motion type magnetic recording apparatus configured in this way suppresses the domain wall motion speed by applying a non-zero magnetic field while applying a current pulse and performing domain wall motion. It is possible to precisely control, improve the gradation accuracy of multi-value recording, and increase the gradation of multi-value recording.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the first size is zero.

  Since the magnetic domain wall motion type magnetic recording apparatus configured as described above applies a magnetic field only when the domain wall is stopped, the power consumption of the magnetic domain wall motion type magnetic recording apparatus can be reduced.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the magnetic field control mechanism applies the magnetic field applied to the magnetic recording layer from the third magnitude when the current pulse has a predetermined amplitude or when the current pulse rises. The magnetic field applying mechanism is operated so as to change the fourth size to be smaller than the third size.

  The domain wall motion type magnetic recording apparatus configured as described above can suppress the variation of individual spins and start the domain wall movement with high accuracy when applying the current pulse and starting the domain wall movement. In addition, the moving distance of the domain wall can be precisely controlled, the gradation accuracy of multilevel recording can be improved, and the gradation of multilevel recording can be increased.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the fourth size is non-zero.

  The domain wall motion type magnetic recording apparatus configured in this way suppresses the domain wall motion speed by applying a non-zero magnetic field while applying a current pulse and performing domain wall motion. It is possible to precisely control, improve the gradation accuracy of multi-value recording, and increase the gradation of multi-value recording.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the fourth size is zero.

  Since the magnetic domain wall motion type magnetic recording apparatus configured as described above applies a magnetic field only when the domain wall motion starts, the power consumption of the magnetic domain wall motion type magnetic recording apparatus can be reduced.

  The domain wall motion type magnetic recording apparatus according to the present invention is a multi-value recording type recording apparatus that holds a value based on the position of the domain wall with respect to the ferromagnetic layer.

  The domain wall motion type magnetic recording apparatus configured as described above can hold a value based on the stop position of the domain wall, and can realize multi-value recording.

  The domain wall motion type magnetic recording apparatus according to the present invention applies a magnetic field in the in-plane direction of the magnetic recording layer.

  The domain wall motion type magnetic recording apparatus configured in this way suppresses the domain wall motion speed by applying a magnetic field to the magnetic recording layer. The gradation accuracy can be improved and the gradation of multi-level recording can be increased.

  The domain wall motion type magnetic recording apparatus according to the present invention applies a magnetic field in the direction perpendicular to the magnetic recording layer.

  The domain wall motion type magnetic recording apparatus configured in this way suppresses the domain wall motion speed by applying a magnetic field to the magnetic recording layer. The gradation accuracy can be improved and the gradation of multi-level recording can be increased.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the magnetic field applying mechanism is a line made of a nonmagnetic metal.

  The domain wall motion type magnetic recording apparatus configured in this way suppresses the domain wall motion speed by applying a magnetic field to the magnetic recording layer. The gradation accuracy can be improved and the gradation of multi-level recording can be increased.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the magnetic field application mechanism is an element in which a nonmagnetic metal coil and a magnetic yoke are combined.

  The domain wall motion type magnetic recording apparatus configured in this way suppresses the domain wall motion speed by applying a magnetic field to the magnetic recording layer. The gradation accuracy can be improved and the gradation of multi-level recording can be increased.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the magnetic field application mechanism is an element in which a permanent magnet and a line made of a nonmagnetic metal are combined.

  The domain wall motion type magnetic recording apparatus configured in this way suppresses the domain wall motion speed by applying a magnetic field to the magnetic recording layer. The gradation accuracy can be improved and the gradation of multi-level recording can be increased.

  In the domain wall motion type magnetic recording apparatus according to the present invention, the magnetic field application mechanism is an element in which a permanent magnet, a nonmagnetic metal coil, and a magnetic yoke are combined.

  The domain wall motion type magnetic recording apparatus configured in this way suppresses the domain wall motion speed by applying a magnetic field to the magnetic recording layer. The gradation accuracy can be improved and the gradation of multi-level recording can be increased.

  In the magnetic recording array according to the present invention, a plurality of the domain wall motion type magnetic recording devices described above are arranged two-dimensionally or three-dimensionally.

  The magnetic recording array configured as described above can realize a large capacity recording device by integrating the multi-value domain wall motion type magnetic recording device.

  Further, the magnetic recording array according to the present invention applies a current pulse to the magnetic recording layer of a part or all of the domain wall motion type magnetic recording device, and according to the application of the current pulse, The magnetic field control mechanism individually operates each of the magnetic field application mechanisms of the domain wall motion type magnetic recording apparatus to change the magnetic field applied to the magnetic recording layer.

  The magnetic recording array configured as described above controls the external magnetic field strength of each domain wall motion type magnetic recording apparatus to individually adjust the domain wall motion speed, and collectively controls a plurality of current domains with a single current pulse. Arbitrary recording can be performed on the domain wall motion type magnetic recording apparatus.

  In the magnetic recording array according to the present invention, the magnetic field application mechanism is shared by a part or all of the domain wall motion type magnetic recording apparatus.

  The magnetic recording array thus configured can simplify the configuration of the external magnetic field control mechanism and the external magnetic field application mechanism, and can collectively control the external magnetic field strength of a plurality of domain wall motion type magnetic recording devices. it can.

  In addition, according to the control method of the domain wall motion type magnetic recording device according to the present invention, the domain wall motion type magnetic recording device is made of a ferromagnetic material and is connected to the magnetic recording layer through the magnetic recording layer including the domain wall and the nonmagnetic layer. And at least two magnetic layers that are connected to the magnetic recording layer and arranged to be separated from each other with the ferromagnetic layer interposed therebetween when viewed in plan. An electrode, a magnetic field application mechanism that applies a magnetic field to the magnetic recording layer, and a magnetic field control mechanism that operates the magnetic field application mechanism to change the magnetic field applied to the magnetic recording layer, and the magnetic field control mechanism is applied Changing a magnetic field applied to the magnetic recording layer in response to a current pulse due to the voltage.

  According to the control method configured as described above, the moving distance of the domain wall can be precisely controlled by changing the magnetic field applied to the magnetic recording layer, so that the gradation accuracy of multilevel recording is improved. The gradation of multi-value recording can be increased.

  Further, in the method for controlling a domain wall motion type magnetic recording apparatus according to the present invention, the step of changing the magnetic field by the magnetic field control mechanism activates the magnetic field application mechanism by applying the magnetic field to the magnetic recording layer. Controlling the moving speed.

  According to the control method configured as described above, since the moving speed of the domain wall is controlled and suppressed, the position where the domain wall is stopped can be precisely controlled, the gradation accuracy of multilevel recording is improved, The gradation of value recording can be increased. Further, according to the control method configured as described above, the moving speed of the domain wall is controlled and improved, so that the multi-value recording operation speed can be improved.

  The method for controlling a domain wall motion type magnetic recording apparatus according to the present invention includes the step of changing the magnetic field by the magnetic field control mechanism when the current pulse has a predetermined amplitude or when the current pulse falls. Activating the magnetic field applying mechanism so as to change the magnetic field applied to the magnetic recording layer from the first magnitude to the second magnitude greater than the first magnitude.

  According to the control method configured as described above, since the current pulse is stopped and the movement speed of the domain wall is suppressed when stopping the movement of the domain wall, the position where the domain wall is stopped can be precisely controlled. The gradation accuracy of value recording can be improved and the gradation of multi-value recording can be increased.

  In the method for controlling a domain wall motion type magnetic recording apparatus according to the present invention, the first magnitude is non-zero.

  According to the control method configured as described above, the magnetic domain wall moving distance is precisely controlled in order to suppress the domain wall moving speed by applying a non-zero magnetic field while applying the current pulse and moving the magnetic domain wall. It is possible to control, to improve the gradation accuracy of multi-value recording, and to increase the gradation of multi-value recording.

  In the method for controlling a domain wall motion type magnetic recording apparatus according to the present invention, the first magnitude is zero.

  According to the control method configured as described above, since the magnetic field is applied only when the domain wall is stopped, the power consumption of the domain wall motion type magnetic recording apparatus can be reduced.

  Further, in the method for controlling a domain wall motion type magnetic recording apparatus according to the present invention, the step of changing the magnetic field by the magnetic field control mechanism is performed when the current pulse has a predetermined amplitude or when the current pulse rises. Activating the magnetic field application mechanism to change the magnetic field applied to the magnetic recording layer from the third value to a fourth magnitude smaller than the third magnitude.

  According to the control method configured in this way, when applying a current pulse and starting the movement of the domain wall, it is possible to suppress variations in individual spins and start the domain wall movement with high accuracy. Can be precisely controlled, the gradation accuracy of multi-value recording can be improved, and the gradation of multi-value recording can be increased.

  In the control method for a domain wall motion type magnetic recording apparatus according to the present invention, the fourth magnitude is non-zero.

  According to the control method configured as described above, the magnetic domain wall moving distance is precisely controlled in order to suppress the domain wall moving speed by applying a non-zero magnetic field while applying the current pulse and moving the magnetic domain wall. It is possible to control, to improve the gradation accuracy of multi-value recording, and to increase the gradation of multi-value recording.

  In the method for controlling a domain wall motion type magnetic recording apparatus according to the present invention, the fourth size is zero.

  According to the control method configured as described above, since the magnetic field is applied only when the domain wall starts to move, the power consumption of the domain wall motion type magnetic recording apparatus can be reduced.

  The domain wall motion type magnetic recording apparatus according to the present invention can improve the gradation accuracy of multi-level recording because the travel distance of the domain wall can be precisely controlled by changing the magnetic field applied to the magnetic recording layer. The gradation of multi-value recording can be increased.

1 is a schematic cross-sectional view of a domain wall motion type magnetic recording apparatus according to the present invention. 1 is a schematic cross-sectional view of a domain wall motion type magnetic recording apparatus according to the present invention. 3 is a schematic graph showing temporal changes of current pulses and magnetic fields for domain wall driving applied to the domain wall motion type magnetic recording apparatus according to the first embodiment of the present invention. 6 is a schematic graph showing temporal changes of current pulses and magnetic fields for domain wall driving applied to a domain wall motion type magnetic recording apparatus according to a modification of the first embodiment of the present invention. It is a schematic graph which shows the time change of the current pulse for the domain wall drive applied to the domain wall motion type magnetic recording apparatus concerning the 2nd Embodiment of this invention, and a magnetic field. It is a schematic graph which shows the time change of the electric current pulse for the domain wall drive applied to the domain wall motion type magnetic recording apparatus which concerns on the modification of the 2nd Embodiment of this invention, and a magnetic field. It is a schematic graph which shows the time change of the current pulse for the domain wall drive applied to the domain wall motion type magnetic recording apparatus which concerns on the 3rd Embodiment of this invention, and a magnetic field. It is a schematic graph which shows the time change of the electric current pulse for the domain wall drive applied to the domain wall motion type magnetic recording apparatus which concerns on the modification of the 3rd Embodiment of this invention, and a magnetic field. 1 is a perspective view of a magnetic recording array in which domain wall motion type magnetic recording devices according to the present invention are arranged in an array. FIG. It is a perspective schematic diagram of a conventional multi-value domain wall motion type magnetic recording apparatus. It is a schematic plan view of a conventional multi-value domain wall motion type magnetic recording apparatus. It is a graph which shows the electrical conductivity with respect to the area of the part where a magnetization is parallel of a multi-value domain wall motion type magnetic recording apparatus.

  FIG. 1 is a schematic sectional view of a domain wall motion type magnetic recording apparatus 1 according to the present invention. The domain wall motion type magnetic recording apparatus 1 is made of a ferromagnetic material, and includes a magnetic recording layer 2 including a domain wall 3, a pinned layer 5 made of a ferromagnetic material connected to the magnetic recording layer 2 through a nonmagnetic layer 4, and At least two electrodes 61 and 62 connected to the magnetic recording layer 2, which are arranged so as to be separated from each other with the pinned layer 5 in plan view, for moving the domain wall 3 to the magnetic recording layer 2 At least two electrodes 61 and 62 for applying a voltage, a magnetic field applying mechanism 7 for applying a magnetic field 10 to the magnetic recording layer 2, and a magnetic field applying mechanism 7 are operated in response to a current pulse generated by the applied voltage, whereby the magnetic recording layer And a magnetic field control mechanism 9 that changes the magnetic field 10 applied to the magnetic field 2. The magnetic recording layer 2 includes a first magnetic domain 11 and a second magnetic domain 12 having magnetizations in opposite directions, and a boundary between the first magnetic domain 11 and the second magnetic domain 12 forms a domain wall 3. The domain wall 3 is disposed at a predetermined position directly below the pinned layer 5. The pinned layer 5 includes magnetization fixed in the same direction as the magnetization direction of either the first magnetic domain 11 or the second magnetic domain 12. In the embodiment shown in FIG. 1, the magnetization of the pinned layer 5 is in the same direction (parallel) as the magnetization of the first magnetic domain 11, and is in the opposite direction (antiparallel) to the magnetization of the second magnetic domain 11. .

  Here, in the present specification, the “current pulse having a predetermined amplitude for moving the domain wall” has a rising area and a falling area applied to the magnetic recording layer to move the domain wall, A pulse-shaped waveform current having a predetermined amplitude between these regions. 3 to 8 show typical waveforms of a “current pulse having a predetermined amplitude for moving the domain wall” between the rising region and the falling region in order to easily understand the technical idea of the present invention. This is a waveform showing a steady value (corresponding to “predetermined amplitude”). In this typical waveform, for example, the waveform of the rising region and the falling region is not limited to the waveform shown in FIGS. 3 to 8, and various variations are possible. As an example, the waveform of the rising region and the falling region are as follows. Examples include those in which the waveform of the region is asymmetric. Further, the waveform in the steady value region may have an overshoot or the like in the waveform, or may be an inclined waveform whose value increases or decreases. When it is not a steady value, the time average value is set to “predetermined amplitude”.

  In this specification, in the current pulse, a region between the rising region and the falling region is referred to as a predetermined amplitude region. Here, the “rising region” refers to the region from the start of the current pulse rising to the time when the current monotonously increases and reaches the maximum, and the “falling region” refers to the current pulse starting from the start of the current pulse falling. Is a region from when the current monotonously decreases until the current reaches a minimum. Since the “predetermined amplitude region” is a region between the rising region and the falling region, it is a region from the time when the maximum is reached until the time when the falling starts.

  In this specification, “when the current pulse has a predetermined amplitude” has the same meaning as “when the current pulse is in a predetermined amplitude region”.

  When a current pulse is applied to the electrodes 61 to 62 to the domain wall motion type magnetic recording apparatus 1 configured in this way, the first magnetic domain 11 spreads in the direction of the second magnetic domain 12 and the domain wall 3 becomes the second magnetic domain 12. Move in the direction of. Therefore, the area where the first magnetic domain 11 overlaps the pinned layer 5 increases, and the area where the second magnetic domain 12 overlaps the pinned layer 5 decreases.

  If the magnetization of the pinned layer 5 is parallel to the magnetization of the magnetic recording layer 2 immediately below the pinned layer 5, the electric conductivity between the pinned layer 5 and the magnetic recording layer 2 is large. The degree becomes smaller. When the domain wall 3 stops at a predetermined position immediately below the pinned layer 5, the electrical conductivity between the pinned layer 5 and the magnetic recording layer 2 increases in proportion to the area of the portion where the magnetization is parallel. Since the electrical conductivity between the pinned layer 5 and the magnetic recording layer 2 linearly changes depending on the position of the domain wall 3, one domain wall motion type magnetic recording can be performed by accurately stopping the domain wall 3 at a predetermined position. The apparatus can be configured not only as 0/1 but also as a multi-value recording type domain wall motion magnetic recording apparatus that performs an analog multi-value operation that can take a plurality of values between 0 and 1.

  The domain wall motion type magnetic recording apparatus 1 according to the present invention further includes a magnetic field application mechanism 7 and a magnetic field control mechanism 9 for controlling the magnetic field application mechanism 7. The magnetic field application mechanism 7 applies a magnetic field 10 to the magnetic recording layer 2. The magnetic field control mechanism 9 moves the domain wall 3 by controlling the magnitude and application timing of the magnetic field 10 applied to the magnetic recording layer 2 by the magnetic field application mechanism 7 in accordance with the application of the current pulse to the magnetic recording layer 2. The speed can be controlled.

  According to Non-Patent Document 1, when the domain wall is moved by current driving, the spin in the domain wall moves while vibrating between the Bloch type and Neel type magnetization directions. If the difference in magnetic anisotropy energy between the magnetization direction of the Bloch type and the Neel type is large, the energy for moving the domain wall increases, so that the current density required for the movement increases. In addition, when the domain wall is moved at the same current density, the domain wall moving speed is slowed if the magnetic anisotropy energy difference between Bloch type and Neel type is large. In this case, according to Non-Patent Document 2, the magnetic field applied from the outside may be in any direction as long as it is perpendicular to the spin magnetization direction.

  The first magnetic domain 11 and the second magnetic domain 12 of the magnetic recording layer 2 shown in FIG. 1 have a perpendicular magnetization. In this case, the direction of the magnetic field 10 can be the in-plane direction of the magnetic recording layer 2. When the magnetic field 10 is applied in the in-plane direction of the magnetic recording layer 2, as described above, the difference in magnetic anisotropy energy between the spin Bloch type and the Neel type in the magnetic recording layer 2 increases. Precession is inhibited and the domain wall motion speed can be suppressed. Further, the direction of the magnetic field 10 can be the perpendicular direction of the magnetic recording layer 2. For example, when the first magnetic domain 11 is expanded and the domain wall 3 is moved in the direction of the second magnetic domain 12, the magnetic field 10 is applied in the direction perpendicular to the magnetic recording layer 2 in antiparallel to the magnetization of the first magnetic domain 11. Then, the moving speed of the domain wall 3 is suppressed. Similarly, when the first magnetic domain 11 is expanded and the domain wall 3 is moved in the direction of the second magnetic domain 12, the magnetic field 10 is applied in the direction perpendicular to the magnetic recording 2 in parallel with the magnetization of the first magnetic domain 11. Then, magnetization in a direction parallel to the magnetic field 10 is promoted, so that the moving speed of the domain wall 3 is improved.

  The magnetic recording layer 2 can also be configured such that the first magnetic domain 11 and the second magnetic domain 12 have in-plane magnetization. In this case, the direction of the magnetic field 10 can be the perpendicular direction of the magnetic recording layer 2. When the magnetic field 10 is applied in the direction perpendicular to the surface of the magnetic recording layer 2, as described above, the difference in magnetic anisotropy energy between the Bloch type and Neel type of spin in the magnetic recording layer 2 increases. Precession is inhibited and the domain wall motion speed can be suppressed. Further, the direction of the magnetic field 10 may be an in-plane direction of the magnetic recording layer 2. For example, when the first magnetic domain 11 is expanded and the domain wall 3 is moved in the direction of the second magnetic domain 12, the magnetic field is applied in the in-plane direction of the magnetic recording layer 2 and antiparallel to the magnetization of the first magnetic domain 11. Then, the moving speed of the domain wall 3 is suppressed. Similarly, when the first magnetic domain 11 is expanded and the domain wall 3 is moved in the direction of the second magnetic domain 12, the magnetic field is applied in the in-plane direction of the magnetic recording layer 2 in parallel with the magnetization of the first magnetic domain 11. Then, magnetization in a direction parallel to the magnetic field 10 is promoted, so that the moving speed of the domain wall 3 is improved.

  As the magnetic field applying mechanism 7, a line made of a nonmagnetic metal can be employed. In this case, by applying a current to the line, an Oersted magnetic field can be generated and a magnetic field can be applied to the magnetic recording layer 2.

  The magnetic field applying mechanism 7 can be an element in which a nonmagnetic metal coil and a magnetic yoke are combined. As shown in FIG. 2, both ends of the magnetic yoke 72 are arranged so as to sandwich the magnetic recording layer 2, and the nonmagnetic metal coil 71 is wound around the magnetic yoke 72. In this case, since a magnetic field generated by applying a current to the nonmagnetic metal coil 71 can be applied to the magnetic recording layer 2 by the magnetic yoke 72, the magnetic field applied to the adjacent domain wall motion type magnetic recording apparatus 1 can be reduced. Leakage can be prevented and a magnetic field can be applied only to the desired magnetic recording layer 2.

  Further, the magnetic field applying mechanism 7 can be an element in which a permanent magnet and a line made of a nonmagnetic metal are combined. In this case, the sum of the magnetic field generated by the permanent magnet and the Oersted magnetic field generated by applying a current to the line is applied to the magnetic recording layer 2. Therefore, the magnitude of the magnetic field is determined by the current applied to the line.

  Further, the magnetic field applying mechanism 7 can be an element in which a permanent magnet, a nonmagnetic metal coil, and a magnetic yoke are combined. In this case, the sum of the magnetic field generated by the permanent magnet and the current applied to the coil and guided by the yoke is applied to the magnetic recording layer 2. Therefore, the magnitude of the magnetic field is determined by the current applied to the coil.

  FIG. 3 shows a first embodiment of the time change of the current pulse 20 applied to the magnetic recording layer 2 and the magnetic field 10 applied to the magnetic recording layer 2. When the magnetic field control mechanism 9 controls the magnetic field application mechanism 7, application of the magnetic field 10 to the magnetic recording layer 2 is controlled. Before the current pulse 20 is applied, the magnitude of the magnetic field 10 applied to the magnetic recording layer 2 is set to the first magnitude. The current pulse 20 is applied with a predetermined amplitude, and after a predetermined time has elapsed, the magnitude of the magnetic field 10 is set to a second magnitude larger than the first magnitude, and then the application of the current pulse 20 is finished. .

  When the current pulse 20 is applied, the domain wall 3 starts to move. At this time, since the magnitude of the magnetic field 10 is a relatively small first magnitude, the suppression of the moving speed of the domain wall 3 by the magnetic field 10 is small. Next, when the magnetic field 10 is set to a second magnitude larger than the first magnitude, the moving speed of the domain wall 3 is suppressed and the domain wall 3 is decelerated. Next, the application of the current pulse 20 is completed at a desired timing for stopping the domain wall 3. At this time, since the moving speed of the domain wall 3 is suppressed by the application of the magnetic field 10, the domain wall 3 accurately stops at a predetermined position when the application of the current pulse 20 is completed. Therefore, by applying the current pulse 20 and the magnetic field 10 to the magnetic recording layer 2 at the timing shown in FIG. 2, the moving distance of the domain wall can be precisely controlled, and the multivalue of the domain wall motion type magnetic recording apparatus 1 can be controlled. It becomes possible to improve the gradation accuracy of recording.

  FIG. 4 shows a second embodiment of the time change of the current pulse 20 applied to the magnetic recording layer 2 and the magnetic field 10 applied to the magnetic recording layer 2. When the magnetic field control mechanism 9 controls the magnetic field application mechanism 7, application of the magnetic field 10 to the magnetic recording layer 2 is controlled. Before the current pulse 20 is applied, the magnitude of the magnetic field 10 applied to the magnetic recording layer 2 is set to the first magnitude. The current pulse 20 is applied with a predetermined amplitude, and the application of the current pulse 20 is finished after a predetermined time has elapsed. When the current pulse 20 falls, the magnitude of the magnetic field 10 is set to a second magnitude that is greater than the first magnitude.

  When the current pulse 20 is applied to the magnetic recording layer 2 with a predetermined amplitude, the domain wall 3 starts to move. The application of the current pulse 20 is finished, and the magnitude of the magnetic field 10 is set to a second magnitude larger than the first magnitude when the current pulse 20 falls. When the domain wall 3 tries to stop at a predetermined position due to the end of application of the current pulse 20, the moving speed of the domain wall 3 is suppressed by the magnetic field 10, so that the domain wall 3 can be accurately stopped at the predetermined position. Thus, the moving distance of the domain wall can be precisely controlled. Therefore, the gradation accuracy of multilevel recording of the domain wall motion type magnetic recording apparatus 1 can be improved, and the gradation of multilevel recording can be increased.

  In the first and second embodiments of the time variation of the current pulse 20 and the magnetic field 10 shown in FIGS. 3 and 4, the first magnitude of the magnetic field 10 may be zero or non-zero. Good. If the first magnitude of the magnetic field 10 is zero, the power consumption of the domain wall motion type magnetic recording apparatus 1 can be reduced. Further, since the moving speed of the domain wall 3 is not suppressed by the magnetic field 10, the data writing speed to the domain wall moving magnetic recording apparatus 1 is improved. Further, when the first magnitude of the magnetic field 10 is non-zero, the moving speed of the domain wall 3 is suppressed as compared with the case where the first magnitude of the magnetic field 10 is zero. Therefore, the domain wall 3 can be accurately stopped at a predetermined position, and the moving distance of the domain wall can be precisely controlled. Therefore, the gradation accuracy of multilevel recording of the domain wall motion type magnetic recording apparatus 1 can be improved, and the gradation of multilevel recording can be increased.

  FIG. 5 shows a third embodiment of the time change of the current pulse 20 applied to the magnetic recording layer 2 and the magnetic field 10 applied to the magnetic recording layer 2. When the magnetic field control mechanism 9 controls the magnetic field application mechanism 7, application of the magnetic field 10 to the magnetic recording layer 2 is controlled. Before the current pulse 20 is applied, the magnitude of the magnetic field 10 applied to the magnetic recording layer 2 is set to the third magnitude. The current pulse is applied with a predetermined amplitude, and after a predetermined time has elapsed, the magnitude of the magnetic field 10 is set to a fourth magnitude that is smaller than the third magnitude. Thereafter, application of the current pulse 20 is completed.

  Before application of the current pulse 20, a relatively large third magnitude magnetic field 10 is applied to the magnetic recording layer 2, so that spin precession in the magnetic recording layer 2 is suppressed. It has become. Next, when the current pulse 20 is applied, the domain wall 3 tries to start moving. However, since the precession of the spin in the magnetic recording layer 2 is suppressed by the magnetic field 10, the domain wall 3 moves. Even if it cannot move, or even if it moves, the moving speed is low. Next, when the magnitude of the magnetic field 10 is set to a fourth magnitude smaller than the third magnitude, suppression of spin precession in the magnetic recording layer 2 is reduced, and the domain wall 3 starts to move. be able to. Next, the application of the current pulse 20 is finished, and the domain wall 3 stops at a predetermined position.

  In the state where the magnetic field 10 is not applied, the spin precession in the magnetic recording layer 2 varies. Therefore, when the current pulse 20 is applied in the state where the magnetic field 10 is not applied, the start of change in the spin direction varies. This leads to variations in the timing of starting the movement of the domain wall 3. Therefore, the accuracy of the moving distance of the domain wall 3 is lowered. On the other hand, as shown in FIG. 5, when the current pulse 20 is applied in a state where the magnetic field 10 is applied and then the magnitude of the magnetic field 10 is reduced, the spin direction starts to change at the same time, and the domain wall motion 3 moves. The accuracy of the start timing is improved. Therefore, the moving distance of the domain wall 3 can be precisely controlled. Therefore, the gradation accuracy of multilevel recording of the domain wall motion type magnetic recording apparatus 1 can be improved, and the gradation of multilevel recording can be increased.

  FIG. 6 shows a fourth embodiment of the time change of the current pulse 20 applied to the magnetic recording layer 2 and the magnetic field 10 applied to the magnetic recording layer 2. When the magnetic field control mechanism 9 controls the magnetic field application mechanism 7, application of the magnetic field 10 to the magnetic recording layer 2 is controlled. Before the current pulse 20 is applied, the magnitude of the magnetic field 10 applied to the magnetic recording layer 2 is set to the third magnitude. The current pulse is applied with a predetermined amplitude, and when the current pulse 20 rises, the magnitude of the magnetic field 10 is set to a fourth magnitude smaller than the third magnitude, and then the application of the current pulse 20 is finished.

  Before application of the current pulse 20, a relatively large third magnitude magnetic field 10 is applied to the magnetic recording layer 2, so that spin precession in the magnetic recording layer 2 is suppressed. It has become. Next, when the current pulse 20 is applied, the domain wall 3 tries to start moving. When the magnitude of the magnetic field 10 is set to a fourth magnitude smaller than the third magnitude at the rising edge of the current pulse 20, the suppression of spin precession in the magnetic recording layer 2 is reduced, and the domain wall 3 You can start moving. Next, the application of the current pulse 20 is finished, and the domain wall 3 stops at a predetermined position.

  In the state where the magnetic field 10 is not applied, the spin precession in the magnetic recording layer 2 varies. Therefore, when the current pulse 20 is applied in the state where the magnetic field 10 is not applied, the start of change in the spin direction varies. This leads to variations in the timing of starting the movement of the domain wall 3. Therefore, the accuracy of the moving distance of the domain wall 3 is lowered. On the other hand, as shown in FIG. 6, when the current pulse 20 is applied with the magnetic field 10 applied, and the magnitude of the magnetic field 10 is reduced at the rising edge of the current pulse 20, the spin direction starts to change simultaneously, The accuracy of the movement start timing of the domain wall motion 3 is improved. Therefore, the moving distance of the domain wall 3 can be precisely controlled. Therefore, the gradation accuracy of multilevel recording of the domain wall motion type magnetic recording apparatus 1 can be improved, and the gradation of multilevel recording can be increased.

  In the third and fourth embodiments of the time variation of the current pulse 20 and the magnetic field 10 shown in FIGS. 5 and 6, the fourth magnitude of the magnetic field 10 may be zero or non-zero. . If the fourth magnitude of the magnetic field 10 is zero, the power consumption of the domain wall motion type magnetic recording apparatus 1 can be reduced. Further, since the moving speed of the domain wall 3 is not suppressed by the magnetic field 10, the data writing speed to the domain wall moving magnetic recording apparatus 1 is improved. Moreover, when the 4th magnitude | size of the magnetic field 10 is non-zero, the moving speed of the domain wall 3 is suppressed compared with the case where the 4th magnitude | size of the magnetic field 10 is zero. Therefore, the domain wall 3 can be accurately stopped at a predetermined position, and the moving distance of the domain wall can be precisely controlled. Therefore, the gradation accuracy of multilevel recording of the domain wall motion type magnetic recording apparatus 1 can be improved, and the gradation of multilevel recording can be increased.

  FIG. 7 shows a fifth embodiment of the time change of the current pulse 20 applied to the magnetic recording layer 2 and the magnetic field 10 applied to the magnetic recording layer 2. When the magnetic field control mechanism 9 controls the magnetic field application mechanism 7, application of the magnetic field 10 to the magnetic recording layer 2 is controlled. Before the current pulse 20 is applied, the magnitude of the magnetic field 10 applied to the magnetic recording layer 2 is set to the fifth magnitude. The current pulse 20 is applied with a predetermined amplitude, and after a predetermined time has elapsed, the magnitude of the magnetic field 10 is set to a sixth magnitude smaller than the fifth magnitude. Next, after a predetermined time has elapsed while the current pulse 20 is maintained at a predetermined amplitude, the magnitude of the magnetic field 10 is set to a seventh magnitude larger than the sixth magnitude. Thereafter, application of the current pulse 20 is completed.

  Before the current pulse 20 is applied, a relatively large magnetic field 10 having a fifth magnitude is applied to the magnetic recording layer 2, so that the spin precession in the magnetic recording layer 2 is suppressed. It has become. Next, when the current pulse 20 is applied, the domain wall 3 tries to start moving. However, since the precession of the spin in the magnetic recording layer 2 is suppressed by the magnetic field 10, the domain wall 3 moves. Even if it cannot move, or even if it moves, the moving speed is low. Next, when the magnitude of the magnetic field 10 is set to a sixth magnitude smaller than the fifth magnitude, the suppression of spin precession in the magnetic recording layer 2 is reduced, and the domain wall 3 starts to move. be able to. Next, when the magnitude of the magnetic field 10 is set to a seventh magnitude larger than the sixth magnitude after a predetermined time has elapsed while the current pulse 20 is maintained at a prescribed amplitude, the domain wall 3 moves. The speed is suppressed and the domain wall 3 is decelerated. Next, the application of the current pulse 20 is completed at a desired timing for stopping the domain wall 3. At this time, since the moving speed of the domain wall 3 is suppressed by the application of the magnetic field 10, the domain wall 3 accurately stops at a predetermined position when the application of the current pulse 20 is completed. Therefore, by applying the current pulse 20 and the magnetic field 10 to the magnetic recording layer 2 at the timing shown in FIG. 7, the moving distance of the domain wall can be precisely controlled, and the multivalue of the domain wall motion type magnetic recording apparatus 1 can be controlled. It becomes possible to improve the gradation accuracy of recording.

  FIG. 8 shows a sixth embodiment of the time change of the current pulse 20 applied to the magnetic recording layer 2 and the magnetic field 10 applied to the magnetic recording layer 2. When the magnetic field control mechanism 9 controls the magnetic field application mechanism 7, application of the magnetic field 10 to the magnetic recording layer 2 is controlled. Before the current pulse 20 is applied, the magnitude of the magnetic field 10 applied to the magnetic recording layer 2 is set to the fifth magnitude. When the current pulse 20 is applied with a predetermined amplitude and the current pulse 20 rises, the magnitude of the magnetic field 10 is set to a sixth magnitude smaller than the fifth magnitude. The application of the current pulse 20 is finished after a predetermined time has elapsed, and the magnitude of the magnetic field 10 is set to a seventh magnitude larger than the sixth magnitude when the current pulse 20 falls.

  Before the current pulse 20 is applied, the magnetic recording layer 2 is applied with the relatively large magnetic field 10 of the fifth magnitude, so that the spin precession in the magnetic recording layer 2 is suppressed. It is in a state. Next, when the current pulse 20 is applied, the domain wall 3 tries to start moving. When the magnitude of the magnetic field 10 is set to a sixth magnitude smaller than the fifth magnitude when the current pulse 20 rises, the suppression of spin precession in the magnetic recording layer 2 is reduced, and the domain wall 3 You can start moving. Next, the application of the current pulse 20 is finished, and the magnitude of the magnetic field 10 is set to a seventh magnitude larger than the sixth magnitude when the current pulse 20 falls. When the domain wall 3 tries to stop at a predetermined position due to the end of application of the current pulse 20, the moving speed of the domain wall 3 is suppressed by the magnetic field 10, so that the domain wall 3 can be accurately stopped at the predetermined position. Thus, the moving distance of the domain wall can be precisely controlled. Therefore, the gradation accuracy of multilevel recording of the domain wall motion type magnetic recording apparatus 1 can be improved, and the gradation of multilevel recording can be improved.

  In the fifth and sixth embodiments of the time variation of the current pulse 20 and the magnetic field 10 shown in FIGS. 7 and 8, the sixth magnitude of the magnetic field 10 may be zero or non-zero. Good. If the sixth magnitude of the magnetic field 10 is zero, the power consumption of the domain wall motion type magnetic recording apparatus 1 can be reduced. Further, since the moving speed of the domain wall 3 is not suppressed by the magnetic field 10, the data writing speed to the domain wall moving magnetic recording apparatus 1 is improved. Further, when the sixth magnitude of the magnetic field 10 is non-zero, the moving speed of the domain wall 3 is suppressed as compared with the case where the sixth magnitude of the magnetic field 10 is zero. Therefore, the domain wall 3 can be accurately stopped at a predetermined position, and the moving distance of the domain wall can be precisely controlled. Therefore, the gradation accuracy of multilevel recording of the domain wall motion type magnetic recording apparatus 1 can be improved, and the gradation of multilevel recording can be increased.

  Further, the fifth magnitude and the seventh magnitude of the magnetic field 10 may be different sizes or the same size. When the fifth size and the seventh size are equal, the configuration of the magnetic field control mechanism 9 can be simplified.

  FIG. 9 shows a magnetic recording array 50 in which a plurality of domain wall motion type magnetic recording apparatuses 1 according to the present invention are arranged. The magnetic recording array 50 shown in FIG. 9 has a configuration of a two-dimensional array in which a plurality of domain wall motion type magnetic recording devices 1 arranged in a row are vertically stacked. However, the magnetic recording array 50 may be a two-dimensional array in which a plurality of domain wall motion type magnetic recording devices 1 are two-dimensionally arranged in a plane, and the plurality of domain wall motion type magnetic recording devices 1 are planar. Alternatively, a two-dimensional array arranged two-dimensionally may be arranged in a three-dimensional array so as to overlap each other.

  The magnetic recording array 50 configured as described above applies a write current pulse to each domain wall motion type magnetic recording device 1 and uses the individual magnetic field application mechanism 7 to provide the domain wall motion type magnetic recording device 1. The external magnetic field applied to the magnetic recording layer 2 can be changed for each.

  Further, a current pulse is applied to the magnetic recording layer 2 of a part or all of the domain wall motion type magnetic recording device 1 of the domain wall motion type magnetic recording device 1, and the magnetic field control mechanism 9 moves the domain wall according to the application of the current pulse. Each of the magnetic field application mechanisms 7 of the magnetic recording apparatus 1 can be individually operated to change the external magnetic field applied to the magnetic recording layer 2. Therefore, by controlling the external magnetic field strength of each domain wall motion type magnetic recording apparatus 1, the domain wall motion speed is individually controlled, and a plurality of domain wall motion type magnetic recording apparatuses can be arbitrarily set together with one current pulse. Therefore, the speed of the recording operation can be improved.

  Further, the magnetic recording array 50 can be configured such that a plurality of domain wall motion type magnetic recording apparatuses 1 share one magnetic field applying mechanism 7. FIG. 9 shows a magnetic recording array 50 in which the domain wall motion type magnetic recording devices 1 arranged in one row share one magnetic field applying mechanism 7. For example, the magnetic recording arrays 50 are arranged in two adjacent rows. The domain wall motion type magnetic recording apparatus 1 may share one magnetic field applying mechanism 7. Further, all the domain wall motion type magnetic recording apparatuses 1 of the magnetic recording array 50 may share one magnetic field applying mechanism 7. The magnetic recording array 50 configured as described above can simplify the configuration of the external magnetic field control mechanism 9 and the external magnetic field application mechanism 7, and collectively collect the external magnetic field strengths of the plurality of domain wall motion type magnetic recording apparatuses 1. Can be controlled.

  As shown in FIG. 9, when the magnetic recording array 50 has a configuration of a two-dimensional array in which the domain wall motion type magnetic recording devices 1 are arranged in one row, the domain walls in the vertically stacked rows are arranged. The mobile magnetic recording apparatus 1 can share one magnetic field applying mechanism 7 and a magnetic field control mechanism 9. Therefore, the configuration of the magnetic recording array 50 can be further simplified.

  Further, when one magnetic field application mechanism 7 and magnetic field control mechanism 9 are shared in the magnetic recording array 50, after a magnetic field is applied to the domain wall motion type magnetic recording apparatus 1 arranged in a line and data is written at a time, a predetermined value is applied. After this delay, it can be configured to write data by applying a magnetic field to the domain wall motion type magnetic recording apparatus 1 arranged in another column at a time. Such a writing operation is realized by applying a magnetic field to the domain wall motion type magnetic recording apparatus 1 arranged in a line and then generating a delay time until the next magnetic field application using a delay circuit such as a shift register. be able to.

DESCRIPTION OF SYMBOLS 1 Domain wall movement type magnetic recording apparatus 2 Magnetic recording layer 3 Domain wall 4 Nonmagnetic layer 5 Pin layer 61, 62 Electrode 7 Magnetic field application mechanism 71 Nonmagnetic metal coil 72 Magnetic body yoke 9 Magnetic field control mechanism 10 Magnetic field 11 First magnetic domain 12 First 2 magnetic domain 20 current pulse 50 magnetic recording array 100 conventional multi-value domain wall motion type magnetic recording device 102 magnetic recording layer 103 domain wall 104 nonmagnetic layer 105 pinned layer 161 first magnetic pinned layer 162 second magnetic pinned layer 111 first 1 magnetic domain 112 2nd magnetic domain

Claims (26)

A magnetic recording layer made of a ferromagnetic material and including a domain wall;
A ferromagnetic layer connected to the magnetic recording layer via a nonmagnetic layer;
At least two electrodes connected to the magnetic recording layer and arranged to be separated from each other with the ferromagnetic layer sandwiched in plan view, and applying a voltage for moving the domain wall to the magnetic recording layer;
A magnetic field application mechanism for applying a magnetic field to the magnetic recording layer;
A magnetic domain wall motion type magnetic recording comprising: a magnetic field control mechanism that operates the magnetic field application mechanism in response to a current pulse generated by the applied voltage and changes a magnetic field applied to the magnetic recording layer. apparatus.   2. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field control mechanism activates the magnetic field application mechanism and applies the magnetic field to the magnetic recording layer to control a moving speed of the domain wall. 3. .   When the current pulse has the predetermined amplitude, or when the current pulse falls, the magnetic field control mechanism changes the magnetic field applied to the magnetic recording layer from the first magnitude to the first magnitude. 2. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field applying mechanism is operated so as to be changed to a large second size.   4. The domain wall motion type magnetic recording apparatus according to claim 3, wherein the first size is non-zero.   4. The domain wall motion type magnetic recording apparatus according to claim 3, wherein the first size is zero.   When the current pulse has the predetermined amplitude, or when the current pulse rises, the magnetic field control mechanism reduces the magnetic field applied to the magnetic recording layer from the third magnitude to the third magnitude. 4. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field application mechanism is operated so as to be changed to a fourth size. 5.   The domain wall motion type magnetic recording apparatus according to claim 6, wherein the fourth size is non-zero.   The domain wall motion type magnetic recording apparatus according to claim 6, wherein the fourth size is zero.   9. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic wall moving type magnetic recording apparatus holds a value based on a position of the domain wall with respect to the ferromagnetic layer.   10. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field application mechanism applies the magnetic field in an in-plane direction of the magnetic recording layer. 11.   10. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field applying mechanism applies the magnetic field in a direction perpendicular to a plane of the magnetic recording layer. 11.   12. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field applying mechanism is a line made of a nonmagnetic metal.   12. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field applying mechanism is an element in which a nonmagnetic metal coil and a magnetic yoke are combined.   12. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field applying mechanism is an element in which a permanent magnet and a line made of a nonmagnetic metal are combined.   12. The domain wall motion type magnetic recording apparatus according to claim 1, wherein the magnetic field applying mechanism is an element in which a permanent magnet, a nonmagnetic metal coil, and a magnetic yoke are combined.   16. A magnetic recording array, wherein a plurality of domain wall motion type magnetic recording devices according to claim 1 are arranged two-dimensionally or three-dimensionally.   A current pulse is applied to a magnetic recording layer of a part or all of the plurality of domain wall motion type magnetic recording devices, and the magnetic field control mechanism is configured to apply the current pulse in response to the application of the current pulse. The magnetic recording array according to claim 16, wherein each of the magnetic field application mechanisms of the movable magnetic recording apparatus is individually operated to change a magnetic field applied to the magnetic recording layer.   The magnetic recording array according to claim 16, wherein the magnetic field applying mechanism is shared by some or all of the plurality of domain wall motion type magnetic recording devices. A method for controlling a domain wall motion type magnetic recording apparatus, comprising:
The domain wall motion type magnetic recording apparatus comprises:
A magnetic recording layer made of a ferromagnetic material and including a domain wall;
A ferromagnetic layer connected to the magnetic recording layer via a nonmagnetic layer;
At least two electrodes connected to the magnetic recording layer and arranged to be separated from each other with the ferromagnetic layer sandwiched in plan view, and applying a voltage for moving the domain wall to the magnetic recording layer;
A magnetic field application mechanism for applying a magnetic field to the magnetic recording layer;
A magnetic field control mechanism that operates the magnetic field application mechanism and changes a magnetic field applied to the magnetic recording layer, and
The method according to claim 1, wherein the magnetic field control mechanism includes a step of changing a magnetic field applied to the magnetic recording layer in response to a current pulse generated by the applied voltage.   The step of the magnetic field control mechanism changing the magnetic field includes the step of the magnetic field control mechanism operating the magnetic field application mechanism and applying the magnetic field to the magnetic recording layer to control the moving speed of the domain wall. The control method according to claim 19, wherein the control method is characterized. The magnetic field control mechanism changing the magnetic field;
When the current pulse has the predetermined amplitude, or when the current pulse falls, the magnetic field control mechanism changes the magnetic field applied to the magnetic recording layer from the first magnitude to the first magnitude. The control method according to claim 19, further comprising a step of activating the magnetic field applying mechanism so as to be changed to a large second magnitude.   The control method according to claim 21, wherein the first magnitude is non-zero.   The control method according to claim 21, wherein the first magnitude is zero. The magnetic field control mechanism changing the magnetic field;
When the current pulse has the predetermined amplitude, or when the current pulse rises, the magnetic field control mechanism determines a magnetic field to be applied to the magnetic recording layer from a third value that is smaller than the third magnitude. The control method according to claim 19 or 21, further comprising a step of activating the magnetic field application mechanism so as to change the magnitude to four.   The control method according to claim 24, wherein the fourth magnitude is non-zero.   The control method according to claim 24, wherein the fourth magnitude is zero.

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