Hexatic and Liquid Antiferromagnets in Two Dimensions

We study melting in two-dimensional antiferromagnetic systems. We focus on the case of a six-state clock model on a triangular lattice, as motivated by structural transitions of ions confined in two dimensions. We map this problem to a Coulomb gas and derive renormalization group equations, which we solve to obtain a rich phase diagram. Most interestingly, we find that in the limit of strong magnetic interactions, antiferromagnetic order survives even when the system is in its hexatic and liquid phases.