Suppression of the repulsion phenomenon of magnetic skyrmions at the end of synthetic antiferromagnetic racetracks

Abstract

The synthetic antiferromagnetic (SAF) racetracks can perfectly suppress the skyrmion Hall effect, but the congestion phenomenon of the skyrmions at the end of the racetracks will seriously hinder the development of the skyrmion-based magnetic storage technology. In this paper, we have designed and investigated three racetrack structures of double-layer triangular notch, single-layer triangular notch (SLTN) and square hole-triangular notch (SHTN) in SAF racetracks by micromagnetic simulations. The critical current density that annihilates skyrmions in a racetrack with triangular notches is closely related to the angle of the triangular notches and decreases with the decrease of the angles. If a skyrmion in the top ferromagnetic (FM) layer of SLTN structure is annihilated, its counterpart in the bottom FM layer will also be annihilated due to the interlayer antiferromagnetic exchange coupling. Compared with the critical current density of 3.0 × 10 12 A m −2 in a normal racetrack, the critical current density of SHTN structure can be dropped to 6.0 × 10 10 A m −2 . The results reveal that all the three structures can significantly reduce the critical current density, which can effectively solve the skyrmion congestion at the end of the racetracks.

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.…”

“…The skrmions undergo lateral displacement during their motion, which is known as skyrmion Hall effect (SkHE) [14,15]. When driving current is greater than a threshold current, the skyrmions, as information carriers, may annihilate at the boundary of the nanotrack due to the SkHE [16], resulting in data loss, which is fatal for the application of spintronic devices. So far, lots of studies have focused on finding methods to eliminate the SkHE.…”