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Evidence for deconfined quantum criticality in a two-dimensional Heisenberg model with four-spin interactions

Anders W. Sandvik
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Abstract

Using ground-state projector quantum Monte Carlo simulations in the valence bond basis, it is demonstrated that non-frustrating four-spin interactions can destroy the Neel order of the two-dimensional S=1/2 Heisenberg antiferromagnet and drive it into a valence-bond solid (VBS) phase. Results for spin and dimer correlations are consistent with a single continuous transition, and all data exhibit finite-size scaling with a single set of exponents; z=1, nu=0.78 +/- 0.03, and eta=0.26 +/- 0.03. The unusually large eta and an emergent U(1) symmetry, detected using VBS order parameter histograms, provide strong evidence for a deconfined quantum critical point.

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Anders W. Sandvik. 2007-07-28. Evidence for deconfined quantum criticality in a two-dimensional Heisenberg model with four-spin interactions. https://doi.org/10.1103/physrevlett.98.227202

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