Thermodynamics and kinetics of spiral magnetic structures and the method of quasiaverages

Spiral magnetic systems are investigated on the basis of the method of reduced description and the concept of quasiaverages; the equilibrium states and relaxation processes are studied. The spectrum of spin waves is found in the “hydrodynamic” region. It is shown that the system is characterized by ten transport coefficients, which are represented in terms of the two-time correlation functions of the flux operators and satisfy the Onsager principle.