  The main object of investigation in magnonics, spin waves (SWs) are promising
information carriers. Presently the most commonly studied are plane wave-like
SWs and SWs propagating in confined structures, such as waveguides. Here we
consider a Gaussian SW beam obliquely incident on an ultra-narrow interface
between two identical ferromagnetic materials. We use an analytical model and
micromagnetic simulations for an in-depth analysis of the influence of the
interface properties, in particular the magnetic anisotropy, on the
transmission of the SW beam. We derive analytical formulas for the reflectance,
transmittance, phase shift and Goos-Hanchen (GH) shift for beams reflected and
refracted by an interface between two semi-infinite ferromagnetic media; the
results for the refracted beam are the first to be reported to date. The GH
shifts in SW beam reflection and transmission are confirmed by micromagnetic
simulations in the thin-film geometry. We demonstrate the dependence of the
characteristic properties on the magnetic anisotropy at the interface, the
angle of incidence and the frequency of the SWs. We also propose a method for
the excitation of high-quality SW beams in micromagnetic simulations.
