Engineering electronic structure of a 2D topological insulator Bi(111) bilayer on Sb nanofilms by quantum confinement effect

Abstract

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.

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Cited by in corpus (8)

• Controlling the growth of Bi(110) and Bi(111) films on an insulating substrate
• Photo-induced electronic and spin topological phase transitions in monolayer bismuth
• Topological phases in Bi/Sb planar and buckled honeycomb monolayers
• The growth of bismuth on Bi${}_2$Se${}_3$ and the stability of the first bilayer
• Interfacing Quantum Spin Hall and Quantum Anomalous Hall insulators: Bi bilayer on MnBi${}_2$Te${}_4$-family materials
• Entanglement entropy and entanglement spectrum of Bi${}_{1-x}$Sb${}_x$ (111) bilayers
• Kinetics and the crystallographic structure of bismuth during liquefaction and solidification on the insulating substrate
• Halogen adsorption and reaction with Bi${}_2$(Se,Te)${}_3$ and Bi/Bi${}_2$(Se,Te)${}_3$