Observation of resonant spin excitation with in-plane spin wave propagation in hybrid antiskyrmion strings

Topological magnetic textures provide a rich variety of collective excitations. We report microwave resonant dynamics of hybrid antiskyrmion strings in a microfabricated thin plate of ${(\mathrm{F}{\mathrm{e}}_{0.60}\mathrm{N}{\mathrm{i}}_{0.32}\mathrm{P}{\mathrm{d}}_{0.08})}_{3}\mathrm{P}$ at 300 K. With the aid of a micromagnetic simulation, the observed resonant peaks are identified as gyrotropic motions of hybrid antiskyrmions. The simulation reveals that the magnetization dynamics at the singularity points (Bloch points) in the hybrid antiskyrmions induces in-plane propagation of a spin wave, highlighting the internal structure as an important difference from skyrmions.