Hall conductivity in the cosmic defect and dislocation space-time
  Influences of topological defect and dislocation on conductivity behavior of charge carries in external electromagnetic fields are studied. Particularly the quantum Hall effect is investigated in detail. It is found that the nontrivial deformations of spacetime due to topological defect and dislocation produce an electric current at the leading order of perturbation theory. This current then induces a deformation on the Hall conductivity. The corrections on the Hall conductivity depend on the external electric fields, the size of the sample and the momentum of the particle. 
Kai Ma, Jian-Hua Wang, Huan-Xiong Yang, and Hua-Wei Fan
cond-mat.mes-hall hep-th