Super-resolution phenomenon induced by surface spin-wave diffraction through a hole in in-plane magnetized YIG film

Diffraction of a surface spin wave by a through hole formed inside the in-plane magnetized yttrium iron garnet (YIG) film is investigated both experimentally and theoretically for the case where the hole diameter is significantly smaller than the wavelength. The study reveals a super-resolution and super-directional propagation phenomenon characterized by the formation of a distinct shadow trace from the hole in the spin-wave profile. This shadow is elongated at a long distance from the hole. This occurs along the directions of super-directional wave propagation, corresponding to the inflection points of the isofrequency curve. Theoretical predictions show excellent agreement with experimental observations of super-directional magnon beams engineered by anisotropic dispersion in YIG and are further validated by micromagnetic simulations. The observed formation and splitting of spin-wave beams, along with the extended non-diffracted beam propagation distance, highlight the potential application of these effects in spin-wave multiplexers for magnonic logic devices.