S.A. Vyatkina, N.P. Nistratov, R.K. Babichev, I.I. Natkhin

The dispersion characteristics of the lowest modes of magnetostatic backward volume waves (MSBVW) excited in two different layered structures which include tangentially magnetized ferrite film of yttrium iron garnet with substrate of gadolinium gallium garnet have been theoretically and experimentally investigated. The first structure includes magnetized ferrite film bordered on air medium with the permittivity equal to 1 from its top-surface. The second structure includes ferrite film with top surface bordered on ceramic substrate with the permittivity equal to 100. Theoretical calculations have been made using the exact dispersion equation of electromagnetic modes propagating in structures that include tangentially magnetized ferrite film with surfaces bordered on media with different permittivity. This equation is based on an electrodynamics approximation. Experimental results have been obtained utilizing experimental device specially developed for these purposes. Experimental data obtained are in a good agreement with theoretical results. It has been found that in the low-wavenumber region the lowest modes of magnetostatic backward volume waves correspond to electromagnetic backward volume waves, the dispersion characteristics of which are calculated using the exact dispersion equation based on an electrodynamics approximation. Particularly, using such dispersion equation the minimum wavenumber value and the upper frequency range value of electromagnetic backward volume waves with high accuracy can be computed. It has been shown that at given values of bias field and saturation magnetization of the ferrite film boundary characteristics of wavenumber and frequency range of electromagnetic backward volume waves in structures investigated depend significantly on the permittivities of media surrounding the ferrite film.