Kerr Effect from Diffractive Skew Scattering in Chiral px +/- ipy Superconductors

We calculate the temperature dependent anomalous ac Hall conductance sigma(H)(Omega, T) for a two-dimensional chiral p-wave superconductor. This quantity determines the polar Kerr effect, as it was observed in Sr2RuO4 [J. Xia et al., Phys. Rev. Lett. 97, 167002 (2006)]. We concentrate on a single band model with an arbitrary isotropic dispersion relation subjected to rare, weak impurities treated in the Born approximation. As we explicitly show by detailed computation, previously omitted contributions to the extrinsic part of an anomalous Hall response, physically originating from diffractive skew scattering on quantum impurity complexes, appear to the leading order in the impurity concentration. By direct comparison with published results from the literature we demonstrate the relevance of our findings for the interpretation of the Kerr effect measurements in superconductors.