Investigations on antiferromagnetic skyrmion crystal generated by a staggered magnetic field

Abstract

Antiferromagnetic skyrmions are promising candidates for future spintronic applications due to their particular robustness and ultrafast dynamics. In this work, we have used a staggered magnetic field to produce an antiferromagnetic (AFM) skyrmion crystal. The creation of such a skyrmion crystal is examined in two different situations: a regular clean system and a system containing impurity-like spin vacancies. We have found that defects decisively affect the AFM skyrmions creation, inducing skyrmions connections, the appearance of bimerons, and even the skyrmion lattice destruction at a critical defect density. In addition, we also explore the skyrmion dynamics in a hybrid racetrack which contains two distinct materials displayed in different areas (regions 1 and 2). A spin-polarized current can expel the skyrmions from region 1 (which sustains the skyrmion crystal) to region 2, initially empty of skyrmions. The organized collection of skyrmions of region 1 loses the traditional hexagonal symmetry when they penetrate the second region, composing a skyrmion gas. Nonetheless, this symmetry might be preserved if the spin-polarized current is high enough and reaches a determined value.