Dirac electron-hole pairing gap in the heterostructure of ultra-thin films of topological insulator bilayer
Institute of Applied Physics and Computational Mathematics - P. O. Box 8009, Beijing 100088, China
Received: 24 April 2015
Accepted: 1 June 2015
The electron-hole pairing gap in a system of topological insulator (TI) ultra-thin film bilayer separated by a dielectric barrier is theoretically investigated beyond the mean-field approximation. We show that the pairing gap Δ is dramatically suppressed when accounting for the Coulomb correlation effect as well as the finite-thickness effect of the dielectric barrier. However, Δ can be increased by the coupling between the upper and lower surface states of each TI ultra-thin film. In order to observe much larger Δ in the present structure experimentally, the dielectric surrounding media materials with much lower dielectric constant, such as SiO2-based xerogel films, may be needed.
PACS: 71.35.-y – Excitons and related phenomena / 73.20.-r – Electron states at surfaces and interfaces / 73.22.Gk – Broken symmetry phases
© EPLA, 2015