We study a class of infinite-range spin-(1/2 quantum Heisenberg antiferromagnets. We show that, in addition to ground states with macroscopic net spin in one or several sublattices (Néel states), there are valence-bond (VB) states that are local spin singlets. We show that there is a class of perturbations that stabilizes the VB state. We characterize the excitation spectrum and find an order parameter for the VB states. Finally, we extend our method to find perturbations that stabilize microscopic as well as macroscopic chiral states.
ASJC Scopus subject areas
- Condensed Matter Physics