Temperature dependence of resistivity and Hall coefficient in strongly disordered NbN thin films

We report the temperature dependence of resistivity (rho) and Hall coefficient (R(H)) in the normal state of homogeneously disordered epitaxial NbN thin films with k(F)l similar to 1.68-10.12. The superconducting transition temperature (T(c)) of these films varies from 2.7 to 16.8 K. While our least disordered film displays usual metallic behavior, for all the films with k(F)l <= 8.13, both d rho/dT and dR(H)/dT are negative up to 285 K. We observe that R(H)(T) varies linearly with rho(T) for all the films and [R(H)(T)-R(H)(285 K)/R(H)(285 K)] = gamma[rho(T)-rho(285 K)/rho(285 K)], where gamma=0.68 +/- 0.11. Measurements performed on a 2-nm-thick Be film show similar behavior with gamma=0.69. This behavior is inconsistent with existing theories of localization and e-e interactions in a disordered metal.