A general theory for including correlation effects in static and dynamic properties is presented in terms of Raccah or Stevens operators. It is explicitly developed for general crystal fields and anisotropic interactions and systems with several sublattices, like the rare earth compounds. The theory gives explicitly a temperature dependent renormalization of both the crystal field and the interactions, and a damping of the excitations and in addition a central park component. The general theory is illustrated by a discussion of the singlet-doublet system. The correlation effects on the susceptibility, the first and second moment frequencies and the line shape are calculated self-consistently.
|Journal||Journal of Magnetism and Magnetic Materials|
|Publication status||Published - 1985|