Monday, April 1, 2013

1303.7235 (Yejin Huh et al.)

Optical conductivity of visons in Z2 spin liquids close to a VBS
transition on the kagome lattice
   [PDF]

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

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