A logic gate and control method based on synthetic antiferromagnetic skyrmions

Abstract

This invention provides a logic gate and control method based on synthetic antiferromagnetic skyrmions. The logic gate track is made of synthetic antiferromagnetic material. From bottom to top, the track is arranged in the order of a heavy metal layer, a ferromagnetic layer, a spacer, and a ferromagnetic layer. The two magnetic tunnel junctions on the left side of the track serve as input terminals A and B of the synthetic antiferromagnetic skyrmions, while the two magnetic tunnel junctions on the right side of the track serve as detection terminals C and D of the synthetic antiferromagnetic skyrmions. This invention can effectively improve the stability of information storage.

Description

Technical Field

[0001] The present invention belongs to the field of information technology, and in particular relates to a logic gate based on synthetic antiferromagnetic skyrmions and a control method thereof. Background Art

[0002] With the rapid development of information technology, traditional information storage technologies are no longer able to meet people's growing needs. High-density, low-energy storage has become an inevitable development trend. Magnetic skyrmions are stable vortex magnetic structures with topologically protected nanoscale properties. Due to their small size, high stability, and easy controllability, skyrmions are expected to be used in future high-density, low-energy information storage and logic operations. Considering the skyrmion Hall effect when ferromagnetic skyrmions are driven by spin-polarized current, their motion can deviate from their initial direction or even annihilate at the edge of the track, ultimately leading to signal loss. Research has found that using spin-polarized current to drive skyrmions in synthetic antiferromagnetic materials effectively suppresses the skyrmion Hall effect during their motion, causing them to move in a straight line along the driving force. Their speed is also greater than that of ferromagnetic skyrmions. Therefore, using the presence or absence of synthetic antiferromagnetic skyrmions to represent binary data "1" and "0" and applying them to logic calculations can effectively increase logic speed, reduce device energy consumption, reduce logic gate size, and enhance device stability.

[0003] Technical solution of prior art 1

[0004] Chinese utility model patent specification CN201710434552.7 discloses a magnetic skyrmion-based OR gate and its control and application methods. The design is based on the reversible conversion of ferromagnetic skyrmions or domain wall pairs between the input and output ends, and uses current drive to realize the logical function of the OR gate.

[0005] Disadvantages of the prior art 1

[0006] Although this logic gate can realize the function of a logical OR gate, the threshold current that drives the conversion between ferromagnetic skyrmions and domain walls is relatively large. During operation, the large current may cause the device to burn out and be damaged. In addition, the operation speed of skyrmions and domain walls in this logic gate is relatively slow, which will prolong the operation time of the logic device.

[0007] Technical solution of existing technology 2

[0008] A reconfigurable logic device based on ferromagnetic skyrmions is proposed in Chinese utility model patent specification CN201711049783.2. The design is based on the movement of single and multiple skyrmions between the input and output ends of the logic track, using voltage to control the operation of different logic functions.

[0009] Disadvantages of the second prior art

[0010] Although this logic gate can realize multiple logical operations, the ferromagnetic skyrmions will drift in the direction of movement due to the skyrmion Hall effect during their movement. There is uncertainty in controlling the skyrmion's movement trajectory using the skyrmion Hall effect, so the human controllability of this logic gate needs to be improved. Summary of the Invention

[0011] The purpose of the present invention is to address the defects of the above-mentioned prior art and provide a logic gate and control method based on synthetic antiferromagnetic skyrmions, which can effectively improve the stability of information storage.

[0012] The present invention adopts the following technical solutions:

[0013] A logic gate based on synthetic antiferromagnetic skyrmions. The material of the logic gate track is synthetic antiferromagnetic material. The track is arranged with heavy metal layer, ferromagnetic layer, gasket, and ferromagnetic layer from bottom to top. The two magnetic tunnel junctions on the left side of the track serve as the input terminals A and B of the synthetic antiferromagnetic skyrmions, and the two magnetic tunnel junctions on the right side of the track serve as the detection terminals C and D of the synthetic antiferromagnetic skyrmions.

[0014] The entire track is like a rectangle with a length × width of 150nm × 100nm. There is an isosceles right triangle gap with a right-angled side of 50nm in the upper right corner of the track. There is a rectangular gap with a length × width of 70nm × 5nm between the tracks where input terminals A and B are located. The detection terminal C corresponding to input terminal B is a logic "OR" gate, and the detection terminal D in the lower right corner is a logic "AND" gate.

[0015] When skyrmions are generated simultaneously at input terminals A and B, the skyrmions generated at input terminal B are affected by both boundary repulsion and inter-skyrmion forces during current driving. Therefore, the track in the lower right corner is designed to be longer, and the track at detection terminal D is a raised rectangle with a length × width of 50nm × 30nm, so that the skyrmions generated at terminal B can successfully move to detection terminal D.

[0016] In logic calculations, the presence or absence of synthetic antiferromagnetic skyrmions represents binary data "1" and "0." If input A produces a skyrmion and input B does not, the input signal "1" at input A and "0" at input B are implemented.

[0017] A control method for a logic gate based on synthetic antiferromagnetic skyrmions, comprising:

[0018] When the input signal at input terminal A is “1” and the input signal at input terminal B is “0”, the skyrmion 12 J / m 2It moves to the right along the track and is repelled by the boundary at the hypotenuse, changing its direction and moving to the detection terminal C of the "OR" gate, thus achieving the logical operation "1+0=1" of the "OR" gate. At this time, the detection terminal D of the "AND" gate does not detect the skyrmion, thus achieving the logical operation "1·0=0" of the "AND" gate.

[0019] Or when the input signal at input A is “0” and the input signal at input B is “1”, the skyrmion 12 J / m 2 It moves to the right along the track under the drive, and is repelled by the boundary at the right end of the track, thus changing its direction of movement and moving to the "OR" gate, thus achieving the logical operation "0+1=1" of the "OR" gate. At this time, the detection end D of the "AND" gate does not detect the skyrmion, thus achieving the logical operation "0·1=0" of the "AND" gate.

[0020] Or when both input terminals A and B input signals “1”, the skyrmions generated at input terminal A and the skyrmions generated at input terminal B are in the current 2×10 12 J / m 2 Driven by the skyrmions, they move rightward along the track. Due to the mutual repulsion between skyrmions and the repulsive effect of the boundary, the skyrmions generated at input terminal B are squeezed to detection terminal D, while the skyrmions generated at input terminal A eventually settle at detection terminal C, thus achieving the logical operation "1+1=1" of the "OR" gate and the logical operation "1·1=1" of the "AND" gate.

[0021] Or when both input terminals A and B input the signal "0", neither the "AND" nor the "OR" gate outputs a signal, that is, the logical operation of the "OR" gate is "0+0=0", and the logical operation of the "AND" gate is "0·0=0".

[0022] The detection of synthetic antiferromagnetic skyrmions at the output end can be achieved by using non-collinear magnetoresistance effect, tunneling magnetoresistance effect and tunneling anisotropic magnetoresistance effect.

[0023] For the "AND" gate and the "OR" gate, a horizontal rightward driving current is applied to the track regardless of whether skyrmions are input to the input terminals A and B.

[0024] After each calculation, the logic gate can use a large pulse current to clear the skyrmions on the track.

[0025] Beneficial effects of the present invention:

[0026] 1. Good stability (as a carrier of binary data, skyrmions have a special topologically stable structure, which makes information less likely to be lost during transmission. Using the presence or absence of skyrmions to represent signals "1" and "0" can effectively improve the stability of information storage).

[0027] 2. High accuracy (the movement speed of synthetic antiferromagnetic skyrmions is faster, which can effectively shorten the detection time of logic devices and thus improve the accuracy of device detection. Compared with the Chinese utility model patent specification CN201710434552.7, this design does not involve the conversion process of magnetic domains and skyrmions during the driving process, which simplifies the logical operation method).

[0028] 3. Low energy consumption (the driving level of the current in this design is 10 11 A / m 2 The current density required to manipulate the synthetic antiferromagnetic skyrmion logic gate proposed in the article [Phys. Rev. Appl, 16.1.014040 (2021]) is about 10 12 A / m 2 Therefore, the present invention can appropriately reduce the driving current density to achieve the purpose of reducing energy consumption.

[0029] 4. Strong subjective controllability (synthetic antiferromagnetic skyrmions do not have the skyrmion Hall effect during movement, and spin-polarized current can be used to drive the synthetic antiferromagnetic skyrmions, and the driving current size is artificially controllable).

[0030] 5. Multiple detection methods (synthetic antiferromagnetic skyrmions have more detection methods than antiferromagnetic skyrmions, including non-collinear magnetoresistance effect, tunneling magnetoresistance effect, and tunneling anisotropic magnetoresistance effect). BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Stereograph of the logical AND gate and logical OR gate designed based on synthetic antiferromagnetic skyrmions;

[0032] Figure 2 A top-down view of the circuitry for the logical AND and OR gates designed based on synthetic antiferromagnetic skyrmions.

[0033] Figure 3(a) shows the initial state of the logic operation when the input signal at input terminal A is "1" and the input signal at input terminal B is "0".

[0034] Figure 3(b) shows the logical operation results of the OR gate "1+0=1" and the AND gate "1·0=0".

[0035] Figure 4(a) shows the initial state of the logic operation when the input signal at input terminal A is "0" and the input signal at input terminal B is "1".

[0036] Figure 4(b) shows the logical operation results of the OR gate "0+1=1" and the AND gate "0·1=0";

[0037] Figure 5(a) shows the initial state of the logic operation when the input terminals A and B input the signal "1" simultaneously;

[0038] FIG5( b ) is a diagram showing the logical operation results of the OR gate “1+1=1” and the AND gate “1·1=1”. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0040] like Figure 1 As shown, the present invention is a logic gate based on synthetic antiferromagnetic skyrmions. The material of the logic gate track is synthetic antiferromagnetic material, and the track is composed of a heavy metal layer, a ferromagnetic layer, a gasket, and a ferromagnetic layer. The two magnetic tunnel junctions on the left side of the track serve as the input terminals A and B of the synthetic antiferromagnetic skyrmions, and the two magnetic tunnel junctions on the right side of the track serve as the detection terminals C and D of the synthetic antiferromagnetic skyrmions.

[0041] like Figure 2 As shown, the entire track is a rectangle with a length × width of 150nm × 100nm. There is an isosceles right triangle gap with a right angle of 50nm in the upper right corner of the track. Figure 2 There is a rectangular gap with a length × width of 70nm × 5nm between the tracks where the middle input terminals A and B are located. The detection terminal C corresponding to the input terminal B is a logic "OR" gate, and the detection terminal D in the lower right corner is a logic "AND" gate.

[0042] Considering that when skyrmions are generated at both input terminals A and B, the skyrmions generated at input terminal B are subject to both boundary repulsion and inter-skyrmion forces during current driving, the track in the lower right corner is designed to be longer, so that the skyrmions generated at terminal B can successfully move to the detection terminal D. Figure 2 As shown, the track at the detection end D is a raised rectangle with a length × width of 50 nm × 30 nm.

[0043] In logical calculations, the presence or absence of synthetic antiferromagnetic skyrmions represents binary data "1" and "0". For example, if a skyrmion is generated at input terminal A and no skyrmion is generated at input terminal B, the operation of input signal "1" at input terminal A and input signal "0" at input terminal B is realized.

[0044] A control method for a logic gate based on synthetic antiferromagnetic skyrmions, comprising:

[0045] To realize logical operations, it is necessary to consider the generation of skyrmions at the input end, their smooth transmission on the track, and their successful detection at the output end.

[0046] In this model, synthetic antiferromagnetic skyrmions are generated by locally injecting spin-polarized currents perpendicularly at input terminals A and B, and the spin transfer torque is used to drive the synthetic antiferromagnetic skyrmions. In this logic gate, the square defect on the left side divides the model into two input tracks. The hypotenuse of the triangle at the gap on the upper right side has a repulsive effect on the skyrmions, so when the skyrmions approach the hypotenuse of the triangle at the gap, the direction of the skyrmions' motion will be changed. The skyrmions' final stable position depends on the lengths of the two bases of the triangular gap, i.e. Figure 2 The two sides of the mid-side triangle are W and H. In this case, when the base length of the triangle gap exceeds a certain range, the skyrmion's final stable position will be affected. Therefore, only when the base length of the triangle gap is within a reasonable range can the skyrmion stably move to the detection position at the output end.

[0047] As mentioned above, this design applies a spin-polarized current to a horizontal track, leveraging the repulsive effect of the hypotenuse on skyrmions and the interaction between skyrmions to change the skyrmions' direction of motion and their final stable position. Therefore, when implementing the logical calculation functions of "AND" and "OR" gates, the length of the track's hypotenuse must be within a reasonable range. The specific logical operation process is as follows:

[0048] For "OR", "AND" gates

[0049] (1) When the input signal at input terminal A is “1” and the input signal at input terminal B is “0”, the skyrmion is in the current (2×10 12 J / m 2 ) drives it to the right along the track, where it is repelled by the boundary at the hypotenuse, changing its direction and moving it to the detection terminal C of the "OR" gate, thus completing the "OR" gate's logical operation "1+0=1". At this time, the "AND" gate's detection terminal D does not detect the skyrmion, thus completing the "AND" gate's logical operation "1·0=0".

[0050] (2) When the input signal at input terminal A is “0” and the input signal at input terminal B is “1”, the skyrmion 12 J / m 2It moves to the right along the track under the drive, and is repelled by the boundary at the right end of the track, thus changing its direction of movement and moving to the "OR" gate, thus achieving the logical operation "0+1=1" of the "OR" gate. At this time, the detection end D of the "AND" gate does not detect the skyrmion, thus achieving the logical operation "0·1=0" of the "AND" gate.

[0051] (3) When both input terminals A and B input signals “1”, the skyrmions generated at input terminal A and the skyrmions generated at input terminal B are in the current (2×10 12 J / m 2 ) drive the skyrmions to move rightward along the track. Due to the mutual repulsion between skyrmions and the repulsive effect of the boundary, the skyrmions generated at input terminal B are squeezed to detection terminal D, while the skyrmions generated at input terminal A eventually settle at detection terminal C, thus achieving the logical operation "1+1=1" of the "OR" gate and the logical operation "1·1=1" of the "AND" gate.

[0052] (4) When the input terminal A and the input terminal B both input the signal "0", neither the "AND" nor the "OR" gate outputs a signal, that is, the logical operation of the "OR" gate is "0+0=0", and the logical operation of the "AND" gate is "0·0=0".

[0053] Finally, the detection of synthetic antiferromagnetic skyrmions at the output end can be achieved by using non-collinear magnetoresistance effect, tunneling magnetoresistance effect and tunneling anisotropic magnetoresistance effect.

[0054] Note: For the "AND" and "OR" gates, regardless of whether skyrmions are input to terminals A and B, a horizontal rightward driving current is applied to the track. In addition, after each calculation, the logic gate can use a large pulse current to clear the skyrmions on the track.

[0055] Example

[0056] like Figure 1-2 As shown, current is injected into the heavy metal material at the bottom of the track. When the current passes through the "ferromagnetic layer / non-ferromagnetic layer / ferromagnetic layer" sandwich structure, the ordinary current can be converted into spin-polarized current due to spin scattering. The spin-polarized current is then used to induce the magnetic spin at the input end to flip, thereby generating synthetic antiferromagnetic double-layer skyrmions with topological stability.

[0057] As shown in Figure 3(a) and Figure 3(b), a single synthetic antiferromagnetic skyrmion is generated at input terminal A by a spin-polarized current, while no synthetic antiferromagnetic skyrmion is generated at input terminal B. That is, input terminal A inputs a signal of "1" and input terminal B inputs a signal of "0". Based on this, a horizontal current of 2×10 12 J / m 2If a spin-polarized current is applied, the skyrmions generated at input terminal A will move to the right along the driving direction of the current. When the synthetic antiferromagnetic skyrmions approach the hypotenuse of the triangular notch, the repulsive force of the hypotenuse on the synthetic antiferromagnetic skyrmions causes the synthetic antiferromagnetic skyrmions to move along the hypotenuse to the lower right detection terminal C. Accordingly, the magnetic tunnel junction where the detection terminal C is located presents a high-resistance state due to the detection of the synthetic antiferromagnetic skyrmions, thus realizing the operation of the logic "OR" gate "1+0=1"; the magnetic tunnel junction where the detection terminal D is located presents a low-resistance state due to the failure to detect the synthetic antiferromagnetic skyrmions, thus realizing the operation of the logic "AND" gate "1·0=0". Figure 4(a)-Figure 4(b) As shown in the figure, a single synthetic antiferromagnetic skyrmion is generated at input terminal B by a spin-polarized current, while no synthetic antiferromagnetic skyrmion is generated at input terminal A. That is, the input signal at input terminal A is "0" and the input signal at input terminal B is "1". Based on this, a horizontal current of 2×10 12 J / m 2 If a spin-polarized current is applied, the skyrmions generated at input terminal B will move rightward along the current's driving direction. When the synthetic antiferromagnetic skyrmions approach the convex region in the lower right corner, the boundary repulsion of the synthetic antiferromagnetic skyrmions causes them to move slightly upward and rightward, eventually settling at detection terminal C. Accordingly, the magnetic tunnel junction at detection terminal C, detecting the synthetic antiferromagnetic skyrmions, assumes a high-resistance state, achieving a logical OR operation of "0+1=1." The magnetic tunnel junction at detection terminal D, failing to detect the synthetic antiferromagnetic skyrmions, assumes a low-resistance state, achieving a logical AND operation of "0·1=0."

[0058] like Figure 5(a)-Figure 5(b) As shown in the figure, the spin polarized current is injected into the input terminals A and B at the same time to induce the generation of synthetic antiferromagnetic skyrmions, that is, the input terminals A and B input the signal "1" at the same time. On this basis, a horizontal current of 2×10 12 J / m 2 If a spin-polarized current flows, the skyrmion generated at input terminal A moves downward along the hypotenuse and meets the skyrmion generated at input terminal B at the right end of the track. Due to the interaction between the skyrmions and the repulsive force of the boundary on the skyrmions, the skyrmion generated at input terminal B is squeezed and eventually stabilizes at detection terminal D, while the skyrmion generated at input terminal A eventually moves to detection terminal C. Accordingly, the magnetic tunnel junction between detection terminals C and D exhibits a high-resistance state due to the detection of the synthetic antiferromagnetic skyrmion, thus realizing the logical OR gate "1+1=1" and the logical AND gate "1·1=1".

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A logic gate based on synthetic antiferromagnetic skyrmions, characterized in that The logic gate track is made of synthetic antiferromagnetic material. From bottom to top, the track is arranged in order: heavy metal layer, ferromagnetic layer, gasket, and ferromagnetic layer. The two magnetic tunnel junctions on the left side of the track serve as the input terminals A and B of the synthetic antiferromagnetic skyrmions, and the two magnetic tunnel junctions on the right side of the track serve as the detection terminals C and D of the synthetic antiferromagnetic skyrmions. The entire track resembles a rectangle measuring 150nm by 100nm. There's an isosceles right triangle gap with a 50nm right-angled side in the upper right corner. There's a rectangular gap measuring 70nm by 5nm between the tracks where input terminals A and B are located. Detection terminal C, corresponding to input terminal B, is a logic OR gate, and detection terminal D in the lower right corner is a logic AND gate. When skyrmions are generated simultaneously at input terminals A and B, the skyrmions generated at input terminal B are affected by both boundary repulsion and inter-skyrmion forces during current driving. Therefore, the track in the lower right corner is designed to be longer, and the track at detection terminal D is a raised rectangle with a length × width of 50nm × 30nm, so that the skyrmions generated at terminal B can successfully move to detection terminal D.

2. The logic gate based on synthetic antiferromagnetic skyrmions according to claim 1, characterized in that: In logical calculations, the presence or absence of synthetic antiferromagnetic skyrmions represents binary data "1" and "0". Input terminal A produces a skyrmion, while input terminal B does not produce a skyrmion, thus realizing the operation of input terminal A inputting a signal "1" and input terminal B inputting a signal "0".

3. The method for controlling a logic gate based on synthetic antiferromagnetic skyrmions according to claim 1, characterized in that: include: When the input signal at input terminal A is "1" and the input signal at input terminal B is "0", the skyrmion 12 J / m 2 It moves to the right along the track and is repelled by the boundary at the hypotenuse, changing its direction and moving to the detection terminal C of the "OR" gate, thus completing the "OR" gate's logical operation "1+0=1". At this time, the "AND" gate's detection terminal D does not detect the skyrmion, thus completing the "AND" gate's logical operation "1·0=0". Or when the input signal at input A is "0" and the input signal at input B is "1", the skyrmion 12 J / m 2 It moves to the right along the track under the drive, and is repelled by the boundary at the right end of the track, thus changing its direction of movement and moving to the "OR" gate, thus achieving the "0+1=1" logic operation of the "OR" gate. At this time, the "AND" gate detection terminal D does not detect the skyrmion, thus achieving the "0·1=0" logic operation of the "AND" gate. Or when both input terminals A and B input signals "1", the skyrmions generated at input terminal A and the skyrmions generated at input terminal B are in the current 2×10 12 J / m 2 Driven by the skyrmions, they move rightward along the track. Due to the mutual repulsion between skyrmions and the repulsive effect of the boundary, the skyrmions generated at input terminal B are squeezed to detection terminal D, while the skyrmions generated at input terminal A eventually settle at detection terminal C, thus achieving the logical operation "1+1=1" of the "OR" gate and the logical operation "1·1=1" of the "AND" gate. Or when both input terminals A and B input the signal "0", neither the "AND" nor the "OR" gate outputs any signal, that is, the logical operation "0+0=0" of the "OR" gate and the logical operation "0·0=0" of the "AND" gate are realized.

4. The method according to claim 3, characterized in that For the detection of synthetic antiferromagnetic skyrmions at the output end, non-collinear magnetoresistance effect, tunneling magnetoresistance effect and tunneling anisotropic magnetoresistance effect are used.

5. The method according to claim 3, characterized in that For the "AND" gate and the "OR" gate, a horizontal rightward driving current is applied to the track regardless of whether skyrmions are input to the input terminals A and B.

6. The method according to claim 3, characterized in that After each calculation, the "AND" gate and the "OR" gate use a large pulse current to clear the skyrmions on the track.

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