SPONTANEOUS SYMMETRY-BREAKING IN QUANTUM FRUSTRATED ANTIFERROMAGNETS

We show that the spontaneous symmetry breaking mechanism in quantum antiferromagnets is due to the collapse, in the thermodynamical limit, of an infinite set of excited states onto the ground state. We characterize both the nature and the scaling of the relevant tower of states for the quantum antiferromagnet on the triangular lattice. Comparison with recent numerical results for the S = 1/2 case gives strong support for the existence of long range order in this system.