Electromagnetic Waves in a Tangentially Magnetized One-Side Metallized Bigyrotropic Layer (Example of Calculating the Spin Wave Characteristics)

Abstract

The problem of arbitrary propagation of electromagnetic waves in a tangentially magnetized one-side metallized bigyrotropic layer is solved without using the magnetostatic approximation. It is shown that, in this problem, Maxwell’s equations are reduced to a differential equation corresponding to a biquadratic characteristic equation with four roots k_x21, ‒k_x21, k_x22, and –k_x22 describing the distribution of the wave in the layer cross section. A dispersion equation for describing waves with real k_x21 and k_x22 values is obtained. Using this equation, the characteristics of spin waves in a one-side metallized ferrite plate (a special case of a bigyrotropic layer) are calculated for the frequencies above the ferromagnetic resonance frequency. It is found for these waves that quantity k_x21 can take both real and imaginary values, while quantity k_x22, only real ones. It is found that, at a certain frequency, the spin wave has an isofrequency curve almost identical to a straight line.