## Abstract

We study the ground-state phase diagram of the frustrated spin-1/2J _{1}-J _{2} antiferromagnet with J _{2} = xJ _{1} > 0 (J _{1} > 0) on the honeycomb lattice, using the coupled-cluster method. We present results for the ground-state energy, magnetic order parameter and plaquette valence-bond crystal (PVBC) susceptibility. We find a paramagnetic PVBC phase for x _{c1} < x < x _{c2}, where x _{c1} ≈ 0.207 ± 0.003 and x _{c2} ≈ 0.385 ± 0.010. The transition at x _{c1} to the Néel phase seems to be a continuous deconfined transition (although we cannot exclude a very narrow intermediate phase in the range 0.21 ≲ x ≲ 0.24), while that at x _{c2} is of first-order type to another quasiclassical antiferromagnetic phase that occurs in the classical version of the model only at the isolated and highly degenerate critical point x = 1/2 . The spiral phases that are present classically for all values x > 1/6 are absent for all x ≲ 1.

Original language | English (US) |
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Article number | 236002 |

Journal | Journal of Physics Condensed Matter |

Volume | 24 |

Issue number | 23 |

DOIs | |

State | Published - Jun 13 2012 |