Band structure of magnonic crystals with defects: Brillouin spectroscopy   and micromagnetic simulations
  Using Brillouin spectroscopy, the first observation has been made of the band structures of nanostructured defect magnonic crystals. The samples are otherwise one-dimensional periodic arrays of equal-width Ni80Fe20 and cobalt nanostripes, where the defects are stripes of a different width. A dispersionless defect branch emerges within the bandgap with a frequency tunable by varying the defect stripe width, while the other branches observed are similar to those of a defect-free crystal. Micromagnetic and finite-element simulations performed unveil additional tiny bandgaps and the frequency-dependent localization of the defect mode in the vicinity of the defects. 
Kai Di, Vanessa Li Zhang, Meng Hau Kuok, Hock Siah Lim, Ser Choon Ng,   Kulothungasagaran Narayanapillai, and Hyunsoo Yang
cond-mat.mes-hall cond-mat.dis-nn