Interface phenomena in correlated electron systems

We present theoretical studies of heterostructures comprised of a Mott insulator and a band insulator. A model calculation based on the Hartree-Fock approximation on LaTiO3/SrTiO3-type heterostructure is performed. It is found that spin and orbital ordering patterns in thin heterostructures differ from those in bulk LaTiO3, and that LaTiO3/SrTiO3 interface region, about three unit cell wide, is always metallic. We further discuss strong correlation effects on the physical properties using dynamical-mean-field theory. It is shown that metallic behavior is supported by heavy quasiparticle bands centered at the interfaces.