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| Paper IPM / P / 12120 |
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| Abstract: | |||||||
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We study an S = 1/2 Heisenberg model on the honeycomb lattice with first and second
neighbor antiferromagnetic exchange (J1?J2 model), employing exact diagonalization in both
the Sz = 0 basis and nearest neighbor singlet valence bond (NNVB) basis. We find that for
0.2 < J2/J1 < 0.3, the NNVB basis gives a proper description of the ground state in
comparison with the exact results. By analyzing the dimer?dimer as well as the
plaquette?plaquette correlations and also defining appropriate structure factors, we investigate
possible symmetry breaking states as the candidates for the ground state in the frustrated region.
We provide a body of evidence in favor of plaquette valence bond ordering for
0.2 < J2/J1 < 0.3. By further increasing the ratio J2/J1, this state undergoes a transition to the
staggered dimerized state.
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