Skyrmion racetrack memory with an antidot

Abstract

Skyrmion racetrack memory has a lot of potential in future non-volatile solid state devices. By application of current in such devices, both spin-orbit torque and spin-transfer torques are proven to be useful to nucleate and propagate skyrmions. However, the current applied during nucleation of successive skyrmions may have unwanted perturbation viz. Joule heating and the skyrmion Hall effect, on the propagation of previously generated skyrmions. Therefore, new methodology is desired to decouple the generation and propagation of skyrmions. Here, we present a novel route via micromagnetic simulations for generation of skyrmions from triangular antidot structure in a ferromagnetic nanotrack using local Oersted field. Antidots are holes in a magnetic nanoelement. Multiple skyrmions can be simultaneously generated by incorporating a greater number of antidots. Controlled skyrmion injection can be achieved by tuning the separation between the antidots that are placed at either end of the nanotrack. Here, we propose a novel design to realise skyrmionic racetrcak memory, where one can individually generate and manipulate the skyrmions within the nanotrack.

Reconfigurable skyrmion logic gates with auto-annihilating skyrmion function

“…When the horizontal velocity of skyrmion drops to zero, the direction of skyrmion motion changes due to the combined force in the horizontal direction to the left, causing F Magnus to change downward, resulting in the spiral movement of skyrmion to the lower left. When the skyrmion hits the tip of the triangular notch, it is annihilated due to the easy annihilation of skyrmion at the notch structure [16,41], which achieves the function of automatic annihilation of skyrmion, as shown in figure 2(d). In addition, it is noticed that in our model as shown in figure 1, the triangular notch structure at the end of the nanotrack has a similar principle to the triangular notch structure in front of VCMA region to achieve the function of automatically annihilating skyrmion.…”

Skyrmion based universal logic gates and computation operation

“…Magnetic skyrmions [1][2][3][4][5][6][7][8] are swirling particle-like topological spin texture in a magnetic thin films with perpendicular magnetic anisotropy (PMA). Due to their non-collinear spin structure, they cannot be easily deformed into trivial topological states [4].…”

Nucleation of magnetic skyrmions at a notch

“…An efficient generator of Sk should have the following properties: it should not create Sk in waiting mode and create Sk in robust manner under applied control. Nucleation of magnetic Sks on the track with a notch was investigated experimentally [23][24][25][26] and theoretically [27][28][29][30][31][32]. Despite the fact that the works [23][24][25][26][27][28][29][30][31][32] studied systems with different magnetic characteristics, geometries and external conditions, it was shown in all cases that notches may serve as a generator of skyrmions.…”

“…Nucleation of magnetic Sks on the track with a notch was investigated experimentally [23][24][25][26] and theoretically [27][28][29][30][31][32]. Despite the fact that the works [23][24][25][26][27][28][29][30][31][32] studied systems with different magnetic characteristics, geometries and external conditions, it was shown in all cases that notches may serve as a generator of skyrmions. However, these studies considered only one or several notches with fixed geometry, which is not enough for revealing the effect of notch design on Sk nucleation.…”