We report the experimental observation of Snell's law for magneto-static spin waves in thin ferromagnetic Permalloy films by imaging incident, refracted and reflected waves. We use a thickness step as the interface between two media with different dispersion relation. Since the dispersion relation for magneto-static waves in thin ferromagnetic films is anisotropic, deviations from the isotropic Snell's law known in optics are observed for incidence angles larger than 25\textdegree{} with respect to the interface normal between the two magnetic media. Furthermore, we can show that the thickness step modifies the wavelength and the amplitude of the incident waves. Our findings open up a new way of spin wave steering for magnonic applications.
@article{arxiv.1606.02895,
title = {Snell's Law for Spin Waves},
author = {Johannes Stigloher and Martin Decker and Helmut S. Körner and Kenji Tanabe and Takahiro Moriyama and Takuya Taniguchi and Hiroshi Hata and Marco Madami and Gianluca Gubbiotti and Kensuke Kobayashi and Teruo Ono and Christian H. Back},
journal= {arXiv preprint arXiv:1606.02895},
year = {2016}
}