title: Engineering Electronic Structure of a Two-Dimensional Topological Insulator Bi(111) Bilayer on Sb Nanofilms by Quantum Confinement Effect.
abstract: 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.
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University , Princeton, New Jersey 08544, United States.|Department of Physics, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801-3080, United States.
authors.forename: Guang
authors.initials: G
authors.lastname: Bian
authors.affiliation: Department of Materials Science and Engineering, University of Utah , Salt Lake City, Utah 84122, United States.
authors.forename: Zhengfei
authors.initials: Z
authors.lastname: Wang
authors.affiliation: College of Science, Nanjing University of Science and Technology , Nanjing 210094, China.
authors.forename: Xiao-Xiong
authors.initials: XX
authors.lastname: Wang
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801-3080, United States.|Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , 104 South Goodwin Avenue, Urbana, Illinois 61801-2902, United States.
authors.forename: Caizhi
authors.initials: C
authors.lastname: Xu
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: SuYang
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801-3080, United States.|Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , 104 South Goodwin Avenue, Urbana, Illinois 61801-2902, United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Miller
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: M Zahid
authors.initials: MZ
authors.lastname: Hasan
authors.affiliation: Department of Materials Science and Engineering, University of Utah , Salt Lake City, Utah 84122, United States.|Collaborative Innovation Center of Quantum Matter , Beijing 100084, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801-3080, United States.|Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , 104 South Goodwin Avenue, Urbana, Illinois 61801-2902, United States.
authors.forename: Tai-Chang
authors.initials: TC
authors.lastname: Chiang
keywords: Bi(111) bilayer; Kane−Mele model; quantum spin Hall effect; quantum well states