Spontaneous trimerization in two-dimensional Antiferromagnets
  In this paper, we propose a novel quantum paramagnetic state in two-dimensional antiferromagnets: the spontaneously trimer state, which is constructed by the trimers of spins. Each trimer is a singlet state formed by three neighboring spins with SU(3) symmetry. A frustrated spin-1 Heisenberg model in the kagome lattice is investigated. By analogy to the pseudo-potential approach in the fractional quantum Hall effect (FQHE), we find that the trimer state provides a perfect description for the exact ground state of this model. Other interesting properties, such as the local excitations as well as magnetization plateaus have also been investigated. It is shown that this novel state would deepen our understanding of the nature of the many-body entanglement in the two-dimensional strong correlated systems. 
Zi Cai, Shu Chen, Yupeng Wang