Coupled Skyrmion Breathing Modes in Synthetic Ferri- and Antiferromagnets*

Magnetic multilayers can combine strong spin-orbit interaction with lacking inversion symmetry, which may give rise to the presence of topologically nontrivial spin textures, so-called skyrmions. Recent studies have indicated enhanced propagation velocities of skyrmions in antiferromagnets and compensated ferrimagnets [1]. At the same time, it is unclear how magnetic compensation affects the dynamic excitations of magnetic skyrmions, such as breathing modes, which entail an oscillation of the skyrmion size at GHz frequencies [2]. Here, we present micromagnetic simulations of these resonance modes in synthetic ferri- and antiferromagnets. The observed features in the calculated power spectra are related to pure in-phase and anti-phase breathing modes as well as to hybridizations of breathing and spin wave modes that are characteristic for the considered circular-shaped geometry [3]. Based on these simulations, we then discuss the impact of these results for potential skyrmion sensing.
[1] L. Caretta et al., Nat. Nanotechnol. 13, 1154-1160 (2018)
[2] M. Lonsky and A. Hoffmann, APL Mater. 8, 100903 (2020)
[3] M. Lonsky and A. Hoffmann, Phys. Rev. B 102, 104403 (2020)