Electromagnetic waves in a one-sided metallized tangentially magnetized bigyrotropic layer (with an example of calculating the characteristics of spin waves)

Without using the magnetostatic approximation, the problem of the propagation of electrical magnetic waves in an arbitrary direction in a tangentially magnetized one-sided metal sized bigyrotropic layer. It is shown that in this problem Maxwell’s equations reduce to differential equation to which the biquadratic characteristic equation corresponds equation with four roots k_x21, –k_x21, k_x22 and –k_x22, describing the distribution of the wave in the cross section layer. A dispersion equation is obtained that describes waves with real values k_x21 and k_x22. Based on this equation, the characteristics of spin waves in a one-sided metallized ferrite plate (which is a special case of a bigyrotropic layer) were calculated for frequencies above the ferromagnetic resonance frequency. It was found that for these waves the quantity k_x21 can take both real and imaginary values, and the quantity k_x22 can only take real values. It was discovered that at a certain frequency the spin wave has an isofrequency curve that is practically no different from a straight line.