Micromagnetic Study of Reducing Forbidden Bandgaps and its Width in a Triangular Antidot Array Waveguide With Different Orientations

Dipole-exchange spin waves (SWs) propagating in a 1-D magnonic waveguide embedded with different orientations of triangular antidots are investigated through the micromagnetic simulation. The dipole-exchange SW propagation is affected due to the effect of changing the triangular antidots orientation. This leads to reduction in the number of forbidden bands and their gap width in the magnonic waveguide. The SW characteristics are interpreted by plotting frequency dispersion curves and analyzing the power and phase distribution profile (PPDP) and static demagnetization field profile to substantiate the occurrence of bandgaps. The number of forbidden bands and their gap width get reduced due to the formation of symmetric and antisymmetric modes, and it will be further clarified by the PPDPs. For θ = 0°, four wide bandgaps are recorded; I and II bandgaps are due to symmetric modes, whereas the remaining gaps are due to antisymmetric modes. From θ = 0° to 90°, the number of forbidden bands is reduced from 4 to 2 because of the inhomogeneous distribution of the internal field introduced by the presence of triangular array antidots in the transverse direction, and it is confined via the static demagnetization field. The way to develop magnonic antidot-based waveguide for SW filter applications is paved by opening, closing, and tuning of the gap width. This can be effectively brought about by changing the orientation of triangular antidots.