Interaction of propagating spin waves with extended skyrmions

Active control of propagating short-wavelength spin waves in perpendicularly magnetized materials is promising for designing nanoscale magnonic devices. One method of manipulating spin waves on the nanoscale is through their interaction with magnetic textures, an example of which is the magnetic skyrmion—a particle-like topological object stabilized in thin film heterostructures by the Dzyaloshinskii–Moriya interaction (DMI) and perpendicular magnetic anisotropy. In this paper, the interaction between spin waves and skyrmions is studied using micromagnetic simulations. The magnetic parameters chosen are similar to those found experimentally, leading to a skyrmion with an extended core of reversed magnetization. The effect of a propagating spin wave on the skyrmion is to cause the emission of a secondary spin wave by the skyrmion. At low frequencies, where the incoming spin wave wavelength is much larger than the skyrmion, this leads to a nearly circular re-emitted spin wave. The pattern of emission becomes increasingly complex at higher frequencies as the wavelength becomes similar to the skyrmion size due to the complex excitation of the extended core. The emitted spin wave profile can be controlled by altering the size of the skyrmion through the magnitude of the DMI, providing a method of tuning the system.