  Green function diagrammatic technique is used to investigate a model
ferromagnet in the case, when the effective spin at a site is compounded of two
anisotropically interacting electron spins. The results are: the transverse
magnetic excitations and the longitudinal ones are obtained in the random phase
approximation, magnetization and critical temperature are calculated to the
first order in the reciprocal of the effective number z of ions interacting
with a given ion, and exchange interaction at the same site gives the contrary
effects in changes of the magnitudes mentioned above in dependence on the
exchange-isotropy parameter I and the exchange-anisotropy parameter D.
