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Spin eigenexcitations of an antiferromagnetic skyrmion

2019; American Physical Society; Volume: 99; Issue: 18 Linguagem: Inglês

10.1103/physrevb.99.184429

2469-9977

Volodymyr P. Kravchuk, Olena Gomonay, Denis D. Sheka, Davi R. Rodrigues, Karin Everschor‐Sitte, Jairo Sinova, Jeroen van den Brink, Yuri Gaididei,

Theoretical and Computational Physics

We theoretically predict and classify the localized modes of a skyrmion in a collinear uniaxial antiferromagnet and discuss how they can be excited. As a central result, we find two branches of skyrmion eigenmodes with distinct physical properties characterized by being low or high energy excitations. The frequency dependence of the low-energy modes scales as $R_0^{-2}$ for skyrmions with large radius $R_0$. Furthermore, we predict localized high-energy eigenmodes, which have no direct ferromagnetic counterpart. Except for the breathing mode, we find that all localized antiferromagnet skyrmion modes, both in the low and high-energy branch, are doubly degenerated in the absence of a magnetic field and split otherwise. We explain our numerical results for the low-energy modes within a string model representing the skyrmion boundary.