Screening of disorder by the Hubbard interaction near a metal-insulator transition in two dimensions

We present a determinant quantum Monte Carlo study of the metal-insulator transition in the Hubbard model on a square lattice with random site disorder. We show that beyond a critical value of the Hubbard interaction U, the Anderson insulator can undergo a phase transition to a two-dimensional metal. It is also shown that a further increase of the Hubbard interaction can lead to a decrease in conductivity, in direct analogy with the superfluid to Bose-glass transition in the bosonic Hubbard model. We point out that screening of disorder by the Hubbard interaction is not enough to explain the metal-insulator transition in the two-dimensional disordered Hubbard model.