Symmetry-related criteria for the occurrence of defect states in magnonic superlattices

Abstract

We investigate analytically the occurrence of magnonic defect states in the exchange regime for the system geometry with the defect linking two semi-infinite superlattices at the same symmetry points. The frequency ranges forbidden and allowed to defect states are determined in the low-frequency region. Non-overlapping frequency ranges allowed to either even or odd defect states are found to occur within each forbidden gap in higher frequencies. Our semi-analytical calculations of the dispersion relation based on the solutions obtained in the matching procedure are supported by the computed transmission spectra.