Magnetic impurity engineering for positional control of antiferromagnetic skyrmions in logic devices applications

Abstract

One approach to utilizing antiferromagnetic (AFM) materials as a binary system involves designing traps to control the position of AFM skyrmions in predefined regions of a nanowire, which can then be detected using a magnetic tunnel junction. The binary state is defined by the presence (1) or absence (0) of a skyrmion within the trapped zone (a circular magnetic impurity). These impurities are modeled by modifying specific Hamiltonian parameters, including the exchange stiffness, saturation magnetization, magnetocrystalline anisotropy, and the Dzyaloshinskii–Moriya interaction constant. Depending on the chosen magnetic parameters, the impurity can exhibit either attractive or repulsive behavior, and the positions of the skyrmions, between traps, are then manipulated by spin-polarized current. Our analysis provides key insights into trap efficiency, considering factors such as trap size, Hamiltonian parameters, and spin-polarized current. The simulation results were cross-verified by solving the Thiele equation, showing strong consistency between numerical data and theoretical models. Furthermore, we evaluated the switching time of a skyrmion transitioning between two traps to model memory device functionality. The repositioning time was under 1 ns, highlighting the potential for high-speed operation. We have used our own program to perform the micromagnetic simulations.