Physics of metal-corrrelated barrier with chemical modulation-metal heterostructure

Barrier planes described by the Ionic Hubbard model sandwiched between metallic planes on both sides are studied using unrestricted Hartree Fock. For zero onsite correlation, the presence of the metallic interface generates an additional gap in the energy spectrum away from half filling, if the chemically modulated potential in the barrier planes exceed a critical value. There is an insulator-metal-insulator transition as we tune onsite correlation for fixed strength of chemical modulation. The metallic behaviour penetrates the barrier planes due to proximity effect. The variation of the gaps for varying numbers of intermediate planes is also determined. (C) 2014 Elsevier B.V. All rights reserved.