We study possible paramagnetic phases of antiferromagnets on the Shastry-Sutherland lattice by a gauge-theoretic analysis of fluctuations in a theory with Sp(2N) symmetry. In addition to the familiar dimer phase, we find a confining phase with plaquette order, and a topologically ordered phase with deconfined S=1/2 spinons and helical spin correlations. The deconfined phase is contiguous to the dimer phase, and in a regime of couplings close to those found in the insulator SrCu2(BO3)2. We suggest that a superconductor obtained by doping this insulator with mobile charge carriers will be an attractive candidate for observing the anomalous magnetic flux properties associated with topological order.
@article{arxiv.cond-mat/0102222,
title = {Quantum Phases of the Shastry-Sutherland Antiferromagnet},
author = {C. H. Chung and J. B. Marston and Subir Sachdev},
journal= {arXiv preprint arXiv:cond-mat/0102222},
year = {2007}
}
Comments
8 pages, 8 figures; (v2) added new appendix and references