Garg Arti, Krishnamurthy H R, Randeria Mohit
Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005, India.
Phys Rev Lett. 2006 Jul 28;97(4):046403. doi: 10.1103/PhysRevLett.97.046403. Epub 2006 Jul 26.
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.
