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In the first part of the talk, the recent advance in the theory of the anomalous Hall effect is reviewed. Remarkably, it was shown that diagrams with crossed impurity lines yield an anomalous Hall conductivity that is independent of impurity concentration, and thus is of the same order as other known extrinsic side jump and skew scattering terms. Based on a semiclassical interpretation, we explain that such diagrams represent diffractive skew scattering contributions originating from rare two-impurity complexes. Next, results for the anomalous Hall conductivity sigma_xy of the surface states in cubic topological Kondo insulators are presented. We consider a generic model for the surface states with three Dirac cones on the (001) surface: The Fermi velocity, the Fermi momentum and the Zeeman energy in different Dirac pockets may be unequal. The microscopic impurity potential mediates mixed intra and interband extrinsic scattering processes. We discuss various special cases of our results and the experimental relevance of our study in the context of the recent hysteretic magnetotransport data in SmB6 samples. The last part of the talk is devoted to our recent study of the temperature dependent anomalous ac Hall conductance sigma_xy(omega, T) for a 2D chiral p-wave superconductor [3]. This quantity determines the polar Kerr effect, as it was observed in Sr2RuO4. We concentrate on a single band model with generic, isotropic dispersion relation subjected to rare, weak impurities treated in the Born approximation. Again, the emphasis is on diffractive skew scattering from quantum impurity complexes. It is explicitly shown, that this effect contributes to leading order in impurity concentration and is thus comparable to earlier results within the same model.

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Elio Koenig, University of Wisconsin, Madison
Seminar Room 0.03, ETP
Contact: Dmitry Bagrets