Effects of impurities on the metal-insulator transition

The effect of impurities on the critical interaction strength for the Mott transition has been investigated using an extension of the Gutzwiller approach to correlation in the metallic state. It is shown that the band narrowing due to impurities causes a reduction of the effective interaction necessary for the transition to the insulating state. The residual resistivity due to impurity scattering is considered and it is argued that the conductivity can be written as the product of the Fermi-surface area and the mean free path. Since the latter is limited by the average impurity separation the residual resistivity is bounded. This upper bound appears to be violated for Cr-doped V2O3.