Anisotropic in-plane resistivity in the nematic phase of the iron pnictides

We show that the interference between scattering by impurities and by critical spin fluctuations gives rise to anisotropic transport in the Ising-nematic state of the iron pnictides. The effect is closely related to the non-Fermi-liquid behavior of the resistivity near an antiferromagnetic quantum critical point. Our theory not only explains the observed sign of the resistivity anisotropy Δρ in electron-doped systems but also predicts a sign change of Δρ upon sufficient hole doping. Furthermore, our model naturally addresses the changes in Δρ upon sample annealing and alkaline-earth substitution.