Nonreciprocal spin-wave beam transport in a metallized T-shaped magnonic junction

Here we present the nonreciprocal propagation of caustic beams and channeling of the backward volume spin wave in an yttrium-iron-garnet structure with the longitudinal symmetry axis and broken translational symmetry. The experimental method of Brillouin spectroscopy and the numerical micromagnetic methods are used to study the mechanisms of control of the nonreciprocal spin-wave signal propagation in a T-shaped junction with a partially metallized surface. It is shown that the partial metallization of the surface together with the reversal of the magnetic field direction can serve as a way to control the propagation of spin-wave beams. The formation of the spin-wave channel between the metal stripe and the edge of the magnetic film is observed experimentally and demonstrated by numerical solution of the Landau-Lifshitz-Gilbert equation and Maxwell's equations. The proposed theoretical analysis explains the experimental results and provides useful technical information for the fabrication of reconfigurable magnonic devices, which utilize the spin-wave beam formation in the region of the junction of the magnonic waveguides with different widths. The proposed structure can be used as a functional element of signal branching and/or power division in magnonic networks and signal-processing devices based on them.