Skyrmion dynamics and skyrmion–bimeron crossover in antiferromagnetic thin nanodisks with a random distribution of magnetic impurities

Abstract

Spin texture interacting with lattice defects is an important topic in condensed matter physics. This work investigates skyrmions in antiferromagnetic nanodisks and how a random distribution of magnetic impurities affects the skyrmion dynamics induced by spin-polarized alternating currents. We consider two kinds of magnetic impurities: planar ones, in which the spin on the impurity atoms has easy-plane anisotropy, and exchange-type impurities, in which the spin of the impurity atoms has local out-of-plane anisotropy. The antiferromagnetic skyrmion (AFM-skyrmion) will be either deformed or even destroyed when it moves around the inhomogeneous region, depending on the impurity strength and concentration. The AFM skyrmion can have also breathe modes while moving in aleatory trajectories. The presence of a random distribution of exchange-type impurities may also induce a transformation of the skyrmion in bimeron and bimeron in skyrmion while the texture travels into the region with defects.