The emergence of kπ skyrmions and their spin wave modes in a ferromagnetic disk

Using micromagnetic simulations, we show that varying the perpendicular anisotropy constant K z and the Dzyaloshinskii–Moriya exchange constant D int one can stabilize k π skyrmions (k =1, 2, … 5) in a ferromagnetic nanodisk. We have studied their spin wave modes, and obtained the spatial profile of the radial and azimuthal modes, for different values of D int . Hysteresis curves and the variation of the skyrmion topological charges were obtained as a function of the value of a planar applied magnetic field. The curves show how the application of the field induces the conversion between different k π skyrmions.