Hlushchenko A. Quantum states and dynamical processes in magnets with spin s=1 and SU(3) symmetry of the exchange interaction

The dissertation is devoted to the study of equilibrium phase states and nonequilibrium processes in spin s=1 magnets in the presence of unitary SU(3) symmetry of exchange interaction. The problem of classification of equilibrium states of spin s=1 magnets is solved with spontaneously broken magnetic symmetry, as well as states of equilibrium with spontaneously broken phase and magnetic symmetries. On the basis of the Hamiltonian formalism, the mechanics of one-sublattice and multi-sublattice spin s=1 magnets was constructed. Nonlinear equations of dynamics of spin s=1 magnets are obtained in one and multi- sublattice case. The spectra of collective magnetic excitations are found; also the influence of relaxation processes and the structure of dissipative flows of density of additive motion integrals are found. The coefficients of damping of magnetic degrees of freedom for these states are calculated. The problem of the influence of a weak field on the evolution of a quadrupole magnet and a spin nematic is considered.