Observation of spectral narrowing and mode conversion in two-dimensional binary magnonic crystal

Abstract We study binary magnonic crystal, where Ni80Fe20 nanodots of two different sizes are diagonally connected forming a unit and those units are arranged in a square lattice. The magnetization dynamics of the sample is measured by using time-resolved magneto-optical Kerr effect microscope with varying magnitude and orientation (ϕ) of the bias magnetic field, which is applied at about 10° angle from the sample plane. Interestingly, at ϕ = 0°, the spin-wave mode profiles show frequency selective spatial localization of spin-wave power within the array. With the variation of ϕ in the range 0°