title: Can correlations drive a band insulator metallic?
abstract: We analyze the effects of the on-site Coulomb repulsion U on a band insulator using dynamical mean field theory (DMFT). We find the surprising result that the gap is suppressed to zero at a critical Uc1 and remains zero within a metallic phase. At a larger Uc2 there is a second transition from the metal to a Mott insulator, in which the gap increases with increasing U. These results are qualitatively different from Hartree-Fock theory which gives a monotonically decreasing but nonzero insulating gap for all finite U.
authors.affiliation: Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005, India.
authors.forename: Arti
authors.initials: A
authors.lastname: Garg
authors.forename: H R
authors.initials: HR
authors.lastname: Krishnamurthy
authors.forename: Mohit
authors.initials: M
authors.lastname: Randeria