Observation of magnonic band gaps in magnonic crystals with nonreciprocal dispersion relation

摘要

An effect of metallization of a magnonic crystal surface on band-gap formation in the spectra of a surface spin wave (SSW) is studied both theoretically and experimentally. The structures under consideration are one-dimensional magnonic crystals based on yttrium iron garnet with an array of etched grooves, with and without a metal screen on the top of the corrugated surface. Due to nonreciprocity of propagation of the SSW, the shift of the band gap to higher frequency and from the border of the Brillouin zone in the presence of a conducting overlayer was measured in a transmission line experiment. Results of numerical calculations and model analysis are in agreement with experimental data and give further insight into the origin of the band gap and properties of the nonreciprocal SSW in metalized magnonic crystals. This gives a positive answer to the outstanding question about the possibility of detection of magnonic band gaps in the spectra of spin waves with nonreciprocal dispersion in magnonic crystals, and creates the potential for new applications and improvements of already existing prototype magnonic devices.