Yejin Huh, Matthias Punk, Subir Sachdev
We consider Z2 spin liquids on the kagome lattice on the verge of a valence bond solid (VBS) transition, where vortex excitations carrying Z2 magnetic flux - so-called visons - condense. We show that these vison excitations can couple directly to the external electromagnetic field, even though they carry neither spin nor charge. This is possible via a magneto-elastic coupling mechanism recently identified by Potter et al. For the case of transitions to a 36-site unit cell VBS state the corresponding finite ac-conductivity has a specific power law frequency dependence, which is related to the crossover exponent of the quantum critical point. The visons' contribution to the optical conductivity at transitions to VBS states with a 12-site unit cell vanishes, however.
View original:
http://arxiv.org/abs/1303.7235
No comments:
Post a Comment