ON THE CRITICAL-BEHAVIOR OF THE SPHERICAL MODEL WITH COMPETING FERROMAGNETIC AND ANTIFERROMAGNETIC INTERACTIONS .1.

A family of three-dimensional spherical models is considered. These mo dels have a ferromagnetic coupling between nearest neighbours and anis otropic finite range interactions (both ferro- and antiferromagnetic) along one of the axes. It is possible to examine the critical behaviou r of these models in the neighbourhood of the critical point and to ca lculate exactly the critical exponents. They depend on the range of in teractions and values of coupling constants. Thus, a non-universality of critical exponents in this family is observed.