Quantum Antiferromagnets with Easy-Plane Anisotropy

By means of a recently developed formalism for the description of the phase diagram of quantum systems, we have investigated the effects of easy-plane anisotropy in three dimensional quantum antiferromagnets. We show that the cross-over between Heisenberg and XY universality classes can be located at reduced temperatures proportional to the easy-plane anisotropy parameter, which usually falls in the experimentally accessible range.