Double-lattice magnetoplasmonic structures based on BIG and perforated gold films

A method for the synthesis of magnetoplasmonic crystals containing two Ag gratings with the structure (Au/BIG)$^2$, in which the plasmon lattices of gold are displaced relative to each other by half the period, is presented. Gold films with a thickness of about 40 nm are formed by the method of ion-beam sputtering – deposition, and the adhesive properties of the film make it possible to carry out dimensional etching with a sharply focused ion beam. It was shown that the synthesis of the second plasmon lattice located above the garnet layer of 100 nm thick, preserves the periodicity of the first Au lattice, however a significant influence of the diffusion processes on the lower Au lattice is observed, which leads to a decrease in its density. The dependence of the transmission magneto-optical effect on the thickness of the upper lattice and the presence of an encapsulating Ta$_{2}$O$_{5}$ layer is investigated.