| authors: |
Krzysztof Byczuk, Walter Hofstetter and
Dieter Vollhardt Institute of Theoretical Physics, Physics Department, Warsaw University, Poland |
Correlated electrons with binary alloy disorder AxB1-x are investigated within the Hubbard model and dynamical mean-field theory (DMFT). The random energies epsilon_i have a bimodal probability distribution and an energy separation Delta. This type of disorder leads to a splitting of the single-electron spectral density, and to the formation of lower and upper alloy subbands in all dimensions d \geq 1. If the lower or upper alloy subband is half filled, i.e., for filling factors nu=x or 1+x, the system becomes a Mott insulator at strong interactions, with a correlation gap at the Fermi level. We solve the DMFT equations by the numerical renormalization group method at zero temperature, and determine the dependence of the spectral densities on the disorder strength Delta and interaction U at different fillings. We find convincing evidence for a Mott transition in the binary alloy Hubbard model away from half-filling (nu unequal 1). At the metal--insulator transition hysteresis is observed. We also analyze the effective theory in the Delta --> infinite limit and find good agreement between analytical and numerical results for the critical interaction Uc at which the metal-insulator transition occurs.