Phase Transition of the Two-Dimensional Heisenberg Antiferromagnet on the Triangular Lattice

Abstract

Ordering process of the antiferromagnetic Heisenberg model on the triangular lattice is studied. It is strongly suggested that there exists a phase transition both by a topological analysis of defects and by a Monte Carlo simulation. The phase transition is attributed to the pair dissociation of a kind of vortices which correspond to the topological point defect, Π₁(SO(3))=Z₂.