  The discovery of the ultrafast magnetization dynamics twenty years ago has
led to a broad variety of experimental techniques to explore phenomena in
magnetic materials with high temporal resolution. In the present article we
present a study dealing with broadband excitation of spin-wave packets at
different magnonic crystal continuous magnetic film interfaces. Similar to
protected conducting states on the surfaces of topological band insulators,
these interfaces exhibit surface spin-wave modes that propagate out of the
crystal into the continuous film. The propagation distance depends on the
direction of the applied magnetic field as well as the surface geometry of the
crystal.
