Engineering Electronic Structure of a Two-Dimensional Topological Insulator Bi(111) Bilayer on Sb Nanofilms by Quantum Confinement Effect

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• 作者：Guang Bian ; Zhengfei Wang ; Xiao-Xiong Wang ; Caizhi Xu ; SuYang Xu ; Thomas Miller ; M. Zahid Hasan ; Feng Liu ; Tai-Chang Chiang
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：March 22, 2016
• 年：2016
• 卷：10
• 期：3
• 页码：3859-3864
• 全文大小：411K
• ISSN：1936-086X

文摘

We report on the fabrication of a two-dimensional topological insulator Bi(111) bilayer on Sb nanofilms via a sequential molecular beam epitaxy 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 ultra-low-energy-cost electronics and surface-based spintronics.