  Real magnonic crystals - periodic magnetic media for spin wave (magnon)
propagation - may contain some defects. We report theoretical spin wave spectra
of a one dimensional magnonic crystal with an isolated defect. The latter is
modeled by insertion of an additional layer with thickness and magnetic
anisotropy values different from those of the magnonic crystal constituent
layers. The defect layer leads to appearance of several localized defect modes
within the magnonic band gaps. The frequency and the number of the defect modes
may be controlled by varying parameters of the constituent layers of the
magnonic crystal.
