Interação skyrmion–impureza em sistemas antiferromagnéticos: estratégias de controle para dispositivos spintrônicos

Abstract

Antiferromagnetic skyrmions are strong candidates for the development of spintronic devices due to the absence of the Skyrmion Hall Effect. These devices can operate based on a binary system formed by traps that control the position of the skyrmion in predefined regions of a nanowire, allowing detection via a magnetic tunnel junction. The binary state is defined by the presence (1) or absence (0) of a skyrmion within the trapping zone, which is delimited by a circular magnetic impurity. Such impurities are modeled through the modification of micromagnetic Hamiltonian parameters: exchange stiffness, saturation magnetization, magnetocrystalline anisotropy, and the Dzyaloshinskii–Moriya interaction constant. Depending on the choice of magnetic parameters, the impurity may exhibit either attractive or repulsive behavior. The positions of skyrmions between traps are manipulated by spin-polarized current. This work provides relevant insights into the efficiency of these traps, considering key factors such as trap size, Hamiltonian parameters, and spin-polarized current. The simulation results were validated using the Thiele equation, showing strong consistency between numerical data and theoretical models. We also evaluated the switching time of a skyrmion moving between two traps, aiming to model the functionality of memory devices. The repositioning time was found to be below 1 ns, highlighting the potential for high-speed operation. All simulations were performed using a custom code developed by Grupo de Física da Matéria Condensada (GFMC).