SINGLE AVERAGE MAGNETIZATION, STAGGERED SYMMETRY, AND NEXT NEAREST NEIGHBORS IN DILUTE SYSTEMS

Abstract
The usual mean field treatment of dilute antiferromagnets in a uniform field considers two sublattice magnetizations and yields a continuous transition. On the opposite, starting with one single average magnetization produces a tricritical point. This apparent discrepancy is explained by showing that a single magnetization approach does indeed account for the staggered symmetry but also simultaneously includes the effects of next nearest neighbor interactions which were not present in the initial Hamiltonian. The results are discussed with respect to the random field Ising model.