Quantum approach for magnetic multilayers at finite temperatures

The Green’s function technique has been employed to examine the finite-temperature properties of a magnetic multilayer both in aligned and in canted spin configurations. A local coordinates system is introduced to describe complicated spin configurations which are determined by minimizing the free energy of the magnetic multilayer. Thermal averages of (Formula presented) in each layer are selected to be independent variables, and the necessarily self-consistent equations are obtained successfully based on the random phase approximation. The temperature dependences of the coercivity, the hysteresis, and the magnetic multivalued recording have been discussed, and an application of the present approach to the canted spin state is given in a double-film system.