  We report, for the first time, on a novel planar structure of
magnonic-crystal waveguides, made of a single magnetic material, in which the
allowed and forbidden bands of propagating dipole-exchange spin-waves can be
manipulated by the periodic modulation of different widths in thin-film
nanostrips. The origin of the presence of several magnonic wide band gaps and
the crucial parameters for controlling those band gaps of the order of ~10 GHz
are found by micromagnetic numerical and analytical calculations. This work can
offer a route to the potential application to broad-band spin-wave filters in
the GHz frequency range.
