title: The coexistence of superconductivity and topological order in the Bi₂Se₃ thin films.
abstract: Three-dimensional topological insulators (TIs) are characterized by their nontrivial surface states, in which electrons have their spin locked at a right angle to their momentum under the protection of time-reversal symmetry. The topologically ordered phase in TIs does not break any symmetry. The interplay between topological order and symmetry breaking, such as that observed in superconductivity, can lead to new quantum phenomena and devices. We fabricated a superconducting TI/superconductor heterostructure by growing dibismuth triselenide (Bi(2)Se(3)) thin films on superconductor niobium diselenide substrate. Using scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we observed the superconducting gap at the Bi(2)Se(3) surface in the regime of Bi(2)Se(3) film thickness where topological surface states form. This observation lays the groundwork for experimentally realizing Majorana fermions in condensed matter physics.
authors.affiliation: Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Mei-Xiao
authors.initials: MX
authors.lastname: Wang
authors.forename: Canhua
authors.initials: C
authors.lastname: Liu
authors.forename: Jin-Peng
authors.initials: JP
authors.lastname: Xu
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.forename: Lin
authors.initials: L
authors.lastname: Miao
authors.forename: Meng-Yu
authors.initials: MY
authors.lastname: Yao
authors.forename: C L
authors.initials: CL
authors.lastname: Gao
authors.forename: Chenyi
authors.initials: C
authors.lastname: Shen
authors.forename: Xucun
authors.initials: X
authors.lastname: Ma
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: Zhu-An
authors.initials: ZA
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Shou-Cheng
authors.initials: SC
authors.lastname: Zhang
authors.forename: Dong
authors.initials: D
authors.lastname: Qian
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Jia
authors.forename: Qi-Kun
authors.initials: QK
authors.lastname: Xue