SYMMETRY AND PROBLEM OF SPIN-WAVE SPECTRA IN MAGNETS

A general method is utilized to study the linear dynamics of one-sublattice and many-sublattice magnets with arbitrary spin. A concept of the order parameter based on the density matrix formalism is determined. Dynamic equations of motion and their solutions for some cases are derived. It has been shown for these magnetics that it is convenient to use symmetry analysis for finding the order parameter and the spin wave spectra. An extension of the symmetry analysis procedure for magnets with S > 1/2 is also presented. As an example, the magnetic properties of KNiF3 compound are considered.