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-Hänchen (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.

In this paper, we show that the phase shift of spin waves propagating in the plane of the film can be controlled by a metasurface formed by an ultra-narrow non-magnetic spacer separating edges of the two thin ferromagnetic films. We used this approach to demonstrate numerically the metalens for spin waves.

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In this paper, we show that the phase shift of the spin waves can be controlled by metasurface formed by an ultra-narrow non-magnetic spacer separating two thin ferromagnetic films. For this purpose, we exploit the strength of the exchange coupling of RKKY type between the films which allows to tune the phase of the transmitted spin waves in the wide range of angles [−π/2;π/2]. We combined the phase-shift dependency along the interface with the lens equation to demonstrate numerically the metalens for spin waves.