Structural transitions of skyrmion lattices in synthetic antiferromagnets

Abstract

Thin magnetic films with Dzyaloshinskii-Moriya interactions are known to host skyrmion crystals, which typically have a hexagonal lattice structure. We investigate skyrmion-lattice configurations in synthetic antiferromagnets, i.e., a bilayer of thin magnetic films that is coupled antiferromagnetically. By means of Monte-Carlo simulations, we find that by tuning the interlayer coupling the skyrmion lattice structure can be tuned from square to hexagonal. We give a simple interpretation for the existence of this transition based on the fact that for synthetic antiferromagnetic coupling the skyrmions in different layers repel each other and form each others' dual lattice. Our findings may be useful to experimentally switch between two lattice configurations to, for example, modify spin-wave propagation.

Structural transition of skyrmion quasiparticles under compression

“…1(a). The triangular skyrmion lattice can be described by the superposition of three magnetic modulation vectors q i (i = 1, 2, 3) and a uniform out-of-plane spin component [53][54][55][56][57]; see green arrows in Fig. 1(b).…”

“…It may affect the static lattice structure as well as the lattice dynamics of skyrmions. The static lattice structure of a skyrmion solid may be manipulated by an external force or field acting on all skyrmions [52][53][54][55][56][57]. For example, Karube et al have demonstrated that the transition between a triangular skyrmion lattice and a square skyrmion lattice by varying the temperature and magnetic field [53].…”