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

TL;DR

This study investigates how chemical modulation and electron correlations in barrier planes influence electronic properties when sandwiched between metallic layers, revealing complex phase transitions and proximity effects.

Contribution

It introduces a detailed analysis of the Ionic Hubbard model with metallic interfaces, highlighting the emergence of additional energy gaps and phase transitions due to chemical potential and correlations.

Findings

Metallic interface induces an extra energy gap away from half filling.

Reentrant insulator-metal-insulator transitions occur with varying onsite correlation.

Proximity effect allows metal to penetrate the barrier, altering its insulating nature.

Abstract

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.