Spin wave modes of antivortices hosted in square ultrathin nanodots

A comprehensive exploration of spin-wave modes excited in ultrathin square nanodots hosting an antivortex texture was performed by means of micromagnetic simulations. By comparing the emerging spin-wave modes with the well-known results for magnetic vortices, the resulting modes in antivortices are categorized as breathing or azimuthal depending on whether the applied magnetic pulse is in-plane or out-of-plane. Within the studied frequency range, we observe the presence of two azimuthal modes, namely a gyrotropic mode and a higher-energy one. Under out-of-plane excitation-unlike in vortices-we observe two different breathing modes characterized by the periodic expansion and contraction of the antivortex core, which differ in the amplitude of these oscillations. Our results could contribute to the design of spintronic devices that employ vortex or antivortex structures as sources of spin-wave signals or magnonic-based logic circuits.