Strong Correlations in Disordered Systems

Abstract

The effects of strong correlations in a substitutional binary alloy $A_x{B}_{1-x}$ having a single nondegenerate tight-binding band are examined by use of the coherent-potential approximation and the alloy analogy of Hubbard to treat the effects of disorder and Coulomb interactions, respectively. It is shown that there are no ferromagnetic instabilities in the $B$ band for any band structure, carrier number and the concentration of $B$ atoms, if the potential at $A$ atomic sites are assumed to be positive infinite. This assumption causes the $A$ sites to be inaccessible to electrons. Moreover, the spin susceptibility is found to remain finite even if the density of states is vanishing at the Fermi energy in the limit of the half-filled $B$ band.