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TT: Fachverband Tiefe Temperaturen

TT 20: Correlated Electrons - Poster Session

TT 20.26: Poster

Mittwoch, 28. März 2007, 14:00–17:45, Poster A

Bilayer antiferromagnet with four-spin interaction — •Thomas C. Lang¹ and Anders W. Sandvik² — ¹Institut für Theoretische Physik und Astrophysik, Universität Würzburg — ²Department of Physics, Boston University

We investigate a spin-1/2 Heisenberg antiferromagnet with four-spin interaction on bilayer square and honeycomb lattices. In addition to the standard Neel and quantum disordered phases, these models can be expected to have a valence-bond-solid (VBS) phase. We locate the VBS phase and investigate, in particular, a transition from quantum disorder to VBS. This is potentially a deconfined quantum critical point. We use the recently introduced ground state projection Monte Carlo method in the valence bond basis which allows us to study these models without negative-sign problems.