We report on fabrication of a two-dimensional topological insulator-Bi(111) bilayer on Sb nanofilms via a sequential molecular beam epitaxy (MBE) growth technique. Our angle-resolved photoemission measurements demonstrate the evolution of the electronic band structure of the heterostructure as a function of the film thickness and reveal the existence of a two-dimensional spinful massless electron gas within the top Bi bilayer. Interestingly, Our first-principles calculation extrapolating the observed band structure shows that, by tuning down the thickness of the supporting Sb films into the quantum dimension regime, a pair of isolated topological edge states emerges in a partial energy gap at 0.32 eV above the Fermi level as a consequence of quantum confinement effect. Our results and methodology of fabricating nanoscale heterostructures establish the Bi bilayer/Sb heterostructure as a platform of great potential for both ultralow-energy-cost electronics and surface-based spintronics.
@article{arxiv.1511.02417,
title = {Engineering electronic structure of a 2D topological insulator Bi(111) bilayer on Sb nanofilms by quantum confinement effect},
author = {Guang Bian and Z. F. Wang and Xiaoxiong Wang and Caizhi Xu and Su-Yang Xu and T. Miller and M. Zahid Hasan and Feng Liu and T. -C. Chiang},
journal= {arXiv preprint arXiv:1511.02417},
year = {2017}
}