EFFECTS OF THE QUADRUPOLAR INTERACTION IN GAMMA(3)-GAMMA(4) SYSTEMS OBSERVED THROUGH A REDUCED MODEL

We study the magnetism of PrX2 intermetallic compounds (X = Kh, Al, Ru Mg) on the basis of a Hamiltonian which includes the quadrupolar inte raction in addition to the magnetic and crystal field interactions. Th e calculations are carried out through a reduced model in which we neg lect the highest energy levels of the ground state multiplet of the Pr ion. In this simplified picture, we obtain an analytic expression for the magnetic state equation. This equation is used to investigate how the quadrupolar interaction affects the nature of the magnetic phase transition. We also investigate the effects of the quadrupolar interac tion on the behaviour of the gyromagnetic and dipolar exchange paramet ers in the present PrX2 compounds. (C) 1997 Elsevier Science Ltd. All rights reserved.