  An effect of metallization of the magnonic crystal surface on the band gaps
formation in the spectra of the surface spin wave (SSW) is studied both
theoretically and experimentally. The structures under consideration are
one-dimensional magnonic crystals based on yttrium iron garnet with an array of
etched grooves with metal screen on the top of the corrugated surface and
without it. Due to nonreciprocity of propagation of the SSW the shift of band
gap to higher frequency and from the border of the Brillouin zone in presence
of conducting overlayer was measured in transmission line experiment. Results
of numerical calculations and model analysis are in agreement with experimental
data and give further insight into origin of the band gap and properties of the
nonreciprocal SSW in metallized magnonic crystals. This gives positive answer
to the outstanding question about possibility of detection of magnonic band
gaps in the spectra of the spin waves with nonreciprocal dispersion in magnonic
crystals and creates potential for new applications and improvements of already
existing prototype magnonic devices.
