Algebraic vortex liquid theory of a quantum antiferromagnet on the kagome lattice
There is growing evidence from both experiment and numerical studies that low half-odd integer quantum spins on a kagome lattice with predominant antiferromagnetic near-neighbor interactions do not order magnetically or break lattice symmetries even at temperatures much lower than the exchange interaction strength. Moreover, there appears to be a plethora of low-energy excitations, predominantly singlets but also spin carrying, which suggests that the putative underlying quantum spin liquid is a gapless "critical spin liquid" rather than a gapped spin liquid with topological order. Here, we develop an effective field theory approach for the spin-(1/2) Heisenberg model with easy-plane anisotropy on the kagome lattice. By employing a vortex duality transformation, followed by a fermionization and flux smearing, we obtain access to a gapless yet stable critical spin liquid phase, which is described by (2+1)-dimensional quantum electrodynamics (QED3) with an emergent SU(8) flavor symmetry. The specific heat, thermal conductivity, and dynamical structure factor are extracted from the effective field theory, and contrasted with other theoretical approaches to the kagome antiferromagnet.
Additional Information© 2007 The American Physical Society (Received 13 January 2007; published 7 May 2007) The authors would like to thank P. Sindzingre for sharing his exact diagonalization results on the spin-1 2 XY kagome system. This research was supported by the National Science Foundation through Grants No. PHY99-07949 and No. DMR-0529399 [to two of the authors (M.P.A.F. and J.A.)].
Published - RYUprb07.pdf