Memory function approach to in-plane anisotropic resistivity in the antiferromagnetic phase of iron arsenide superconductors

We theoretically examine anisotropy of in-plane resistivity in the striped antiferromagnetic phase of an iron arsenide superconductor by applying a memory function approach to the ordered phase with isotropic nonmagnetic impurity. We find that the anisotropy of the scattering rate is independent of carrier density when the topology of the Fermi surface is changed after the introduction of holes. On the other hand, the anisotropy of the Drude weight monotonically decreases reflecting the distortion of the Dirac Fermi surface and eventually leads to the reverse of anisotropy of resistivity, being consistent with experiment. The origin of the anisotropy is thus attributed to the interplay of impurity scattering and anisotropic electronic states.