Dynamics and transport of the Z_2 spin liquid: application to kappa-(ET)2Cu2(CN)3

Abstract

We describe neutron scattering, NMR relaxation, and thermal transport properties of Z_2 spin liquids in two dimensions. Comparison to recent experiments on the spin S=1/2 triangular lattice antiferromagnet in kappa-(ET)2Cu2(CN)3 shows that this compound may realize a Z_2 spin liquid. We argue that the topological `vison' excitations dominate thermal transport, and that recent thermal conductivity experiments by M. Yamashita et al. have observed the vison gap.

4 pages, 2 figures; (v2) added refs and minor changes; (v3) updated ref on experiment; (v4) added supplement with calculational details