Angular-selective spin wave modes of magnetic antivortices stabilized by anisotropic Dzyaloshinskii–Moriya interactions

The spin wave modes of antivortices hosted in circular nanodots are investigated using micromagnetic simulations. By stabilizing the antivortex configurations through the inclusion of an anisotropic Dzyaloshinskii–Moriya interaction, we analyze the distinct spin wave modes excited when a magnetic pulse is applied at an angle θ with respect to the nanodot's symmetry axis. We reveal the presence of breathing and gyrotropic modes at θ=0° and θ=90°, respectively. These modes persist over a broad angular range, and their simultaneous excitation is observed at specific angles. For comparison, we perform the same analysis for antivortices hosted in rectangular nanodots and find a greater number of radial modes, along with a similar behavior regarding the coexistence of different spin wave modes across a range of excitation angles. Our results deepen the understanding of antivortex dynamics and may provide valuable insights for identifying specific spin wave modes in ferromagnetic resonance experiments with oblique excitation fields.