Phase transitions in a cubic magnet with single-ion and exchange anisotropies

Abstract

The temperature-dependent phase diagrams of a multiaxial cubic magnet model with both exchange and crystal-field anisotropy are discussed in the molecular-field approximation. Only the case spin S=1 is considered. It is shown that tricritical points always exist for strong crystal-field anisotropy, D. There is another line of tricritical points for negative D and for exchange anisotropy K/J<or= square root 2. The examples of possible phase diagrams are presented and compared with the results of Khajehpour and co-workers (1975) for a uniaxial model.