Ferromagnetism and Metal-Insulator Transition in the Disordered Hubbard Model

A detailed study of the paramagnetic to ferromagnetic phase transition in the one-band Hubbard model in the presence of binary-alloy disorder is presented. The influence of the disorder (with concentrations x and 1-x of the two alloy ions) on the Curie temperature T_c is found to depend strongly on electron density n. While at high densities, n>x, the disorder always reduces T_c; at low densities, n<x, the disorder can even enhance T_c if the interaction is strong enough. At the particular density n=x (i.e., not necessarily at half-filling) the interplay between disorder-induced band splitting and correlation induced Mott transition gives rise to a new type of metal-insulator transition.