We study the ground-state (gs) phase diagram of the frustrated spin-1/2 J1–J2–J3 antiferromagnet with J2=J3=?J1 on the honeycomb lattice using coupled-cluster theory and exact diagonalization methods. We present results for the gs energy, magnetic order parameter, spin-spin correlation function, and plaquette valence-bond crystal (PVBC) susceptibility. We find a Néel antiferromagnetic (AFM) phase for ??c2˜0.60, and a paramagnetic PVBC phase for ?c1????c2. The transition at ?c2 appears to be of first-order type, while that at ?c1 is continuous. Since the Néel and PVBC phases break different symmetries our results favor the deconfinement scenario for the transition at ?c1.
- frustrated quantum magnetism
- quantum many-body theory
- strongly correlated electrons