Soft hubbard gaps in disordered itinerant models with short-range interaction

We study the Anderson-Hubbard model in the Hartree-Fock approximation and the exact diagonalization under the coexistence of short-range interaction and diagonal disorder. We show that there exist unconventional soft gaps, where the single-particle (SP) density of states (DOS) A follows a scaling in energy E as A(E)□exp□[-(-γlog□|E-EF|)d] irrespective of electron filling and long-range order. Here, d is the spatial dimension, EF the Fermi energy and γ a nonuniversal constant. We propose a multivalley energy landscape as their origin. Possible experiments to verify the present theory are proposed.