## Abstract

We investigate the ground state of the two-dimensional Heisenberg antiferromagnet on two Archimedean lattices, namely, the maple-leaf and bounce lattices as well as a generalized J-J′ model interpolating between both systems by varying J′/J from J′/J=0 (bounce limit) to J′/J=1 (maple-leaf limit) and beyond. We use the coupled cluster method to high orders of approximation and also exact diagonalization of finite-sized lattices to discuss the ground-state magnetic long-range order based on data for the ground-state energy, the magnetic order parameter, the spin-spin correlation functions as well as the pitch angle between neighboring spins. Our results indicate that the “pure” bounce (J'/J=0) and maple-leaf (J′/J=1) Heisenberg antiferromagnets are magnetically ordered, however, with a sublattice magnetization drastically reduced by frustration and quantum fluctuations. We found that magnetic long-range order is present in a wide parameter range 0⩽J′/J≲J′c/J and that the magnetic order parameter varies only weakly with J′/J. At J′c≈1.45J, a transition to a quantum orthogonal-dimer singlet ground state without magnetic long-range order takes place that is probably of first-order type, although we cannot rule out that this transition is second order. The orthogonal-dimer state is the exact ground state in this large-J′ regime, and so our model has similarities to the Shastry-Sutherland model. Finally, we use the exact diagonalization to investigate the magnetization curve. We find a 1/3 magnetization plateau for

J′/J≳1.07 and another one at 2/3 of saturation emerging only at large J′/J≳3.

J′/J≳1.07 and another one at 2/3 of saturation emerging only at large J′/J≳3.

Original language | English |
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Number of pages | 8 |

Journal | Physical Review B |

Volume | 84 |

Issue number | 10 |

DOIs | |

Publication status | Published - 2 Sep 2011 |

## Keywords

- frustrated quantum magnetism