Peculiarities of the statics and dynamics of magnetic insulators with single-ion anisotropy

We generalize results of the static and dynamic investigations on ferro- and antiferro-ordered magnetic insulators whose anisotropy is brought about by a strong spin-orbit coupling contribution. An attempt is made to substitute the following assertion: magnetic materials of the above type constitutes a special class, for which the basic restriction of the quasielastics, viz., the conservation of the spin modulus, experiences a substantial violation. We consider qualitatively different cases of strong and weak single-ion anisotropy for different magnetic symmetry types, zero and finite temperatures, longitudinal and transverse magnetic fields. Questions of the nonlinear dynamics of such magnetic materials and some peculiarities of their optical properties are touched upon.