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Physics of interface: Strongly correlated barrier with chemical modulation sandwiched between two metallic planes

Barrier planes described by the Ionic Hubbard model and 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 reentrant behaviour and an insulator-metal-insulator transition as we tune onsite correlation for fixed site potential. The metal is thus able to penetrate the barrier planes due to proximity effect, in a system that is otherwise an insulator throughout.