Magnonic Band Structure in a Skyrmion Magnonic Crystal

We present a numerical investigation of the magnonic band structure of spin waves (SWs) in a novel magnonic crystal consisting of a waveguide with a linear array of periodically spaced skyrmions created along its center by micromagnetic simulations. The interfacial Dzyaloshinskii-Moriya interaction (DMI) induced the presence of skyrmions causes a periodical magnetization modulation of the waveguide, which can be dynamically controlled by changing either the strength of the external magnetic field or the period of the skyrmion lattice. The diameters of the skyrmions are highly dependent on the strength of the applied magnetic field, and they can exist for a wide magnetic field range depending on the density of the DMI. The calculated dispersion relation of SWs in the proposed skyrmion magnonic crystal, frequency versus wave vector, exhibits a periodical property, which is the characteristic feature of the band structure of conventional magnonic crystals. Similarly, the calculated magnonic spectra exhibits allowed frequency band and forbidden frequency bandgaps. Our findings could stimulate further exploration on multiple functionalities provided by magnonic crystals based on periodic skyrmion lattices.