THEORY OF ANDERSON LOCALIZATION IN AN ELECTRIC-FIELD

A microscopic diagrammatic theory of Anderson localization under the i nfluence of a constant electric field has been worked out on the basis of the Keldysh formalism, where the main localizing processes are com prised into a self-consistent effective potential. A direct influence of the electric held on the pole structure of the diffusion function i s detected. This leads to the appearance of a delocalization edge. In the vicinity of the metal-insulator phase transition the Einstein rela tion is extended to a relationship between the spectral drift mobility and the spectral diffusion coefficient, which gives rise to a nonline ar field dependence. For isotropic electronic systems and energy-indep endent renormalized scattering times the presented theory justifies ou r former phenomenological approach concerning the electric-field effec ts on Anderson localization.