Competing orders, the Wess-Zumino-Witten term, and spin liquids
Yen-Ta Huang (Department of Physics, University of California, Berkeley, USA, Materials Sciences Division, Lawrence Berkeley National Laboratories, Berkeley, USA); Dung-Hai Lee (Department of Physics, University of California, Berkeley, USA, Materials Sciences Division, Lawrence Berkeley National Laboratories, Berkeley, USA)
In this paper, we demonstrate that in frustrated magnets when several conventional (i.e., symmetry-breaking) orders compete, and are “intertwined” by a Wess-Zumino-Witten (WZW) term, the possibility of spin liquid arises. The resulting spin liquid could have excitations which carry fractional spins and obey non-trivial self/mutual statistics. As a concrete example, we consider the case where the competing orders are the Néel and valence-bond solid (VBS) order on square lattice. Examining different scenarios of vortex condensation from the VBS side, we show that the intermediate phases, including spin liquids, between the Néel and VBS order always break certain symmetry. Remarkably, our starting theory, without fractionalized particles (partons) and gauge field, predicts results agreeing with those derived from a parton theory. This suggests that the missing link between the Ginzberg-Landau-Wilson action of competing order and the physics of spin liquid is the WZW term.
