Configurations of a simple cubic lattice of pseudo-spins S=12 with anisotropic exchange

Abstract Nearest neighbour anisotropic exchange in a spin 1 2 cubic lattice is given by H ij = J | S ix S jx + J ⊥ (S iy S jy + S iz S jz ) for a bond along the x axis. Depending on the signs of J | and J ⊥ , a ferromagnetic and three antiferromagnetic configurations are found at low temperature. The phase diagram and the critical temperatures are calculated in the molecular field approximation.