PHASE-DIAGRAMS OF ANTIFERROMAGNETIC-Z(Q) MODELS

The phase diagrams of general q-state antiferromagnetic Z(q) models ar e studied for different values of q within a real space renormalizatio n-group scheme for a d-dimensional hypercubic lattice. The model exhib its a rich variety of phase diagrams for even values of q. The odd val ues of q give no phase transition for bidimensional lattices except at temperature T = 0. Nevertheless, an antiferromagnetic order appears a t low temperature for d greater-than-or-equal-to 3. Between phase tran sitions between antiferromagnetic phases and the disordered phase, the model undergoes a phase transition between antiferromagnetic phases a nd ferromagnetic phase for q > 5.