title: Quasiparticle dynamics in reshaped helical Dirac cone of topological insulators.
abstract: Topological insulators and graphene present two unique classes of materials, which are characterized by spin-polarized (helical) and nonpolarized Dirac cone band structures, respectively. The importance of many-body interactions that renormalize the linear bands near Dirac point in graphene has been well recognized and attracted much recent attention. However, renormalization of the helical Dirac point has not been observed in topological insulators. Here, we report the experimental observation of the renormalized quasiparticle spectrum with a skewed Dirac cone in a single Bi bilayer grown on Bi(2)Te(3) substrate from angle-resolved photoemission spectroscopy. First-principles band calculations indicate that the quasiparticle spectra are likely associated with the hybridization between the extrinsic substrate-induced Dirac states of Bi bilayer and the intrinsic surface Dirac states of Bi(2)Te(3) film at close energy proximity. Without such hybridization, only single-particle Dirac spectra are observed in a single Bi bilayer grown on Bi(2)Se(3), where the extrinsic Dirac states Bi bilayer and the intrinsic Dirac states of Bi(2)Se(3) are well separated in energy. The possible origins of many-body interactions are discussed. Our findings provide a means to manipulate topological surface states.
authors: Department of Physics, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education),  Shanghai Jiao Tong University, Shanghai 200240,  China.
authors: Lin
authors: L
authors: Miao
authors: Z F
authors: ZF
authors: Wang
authors: Wenmei
authors: W
authors: Ming
authors: Meng-Yu
authors: MY
authors: Yao
authors: Meixiao
authors: M
authors: Wang
authors: Fang
authors: F
authors: Yang
authors: Y R
authors: YR
authors: Song
authors: Fengfeng
authors: F
authors: Zhu
authors: Alexei V
authors: AV
authors: Fedorov
authors: Z
authors: Z
authors: Sun
authors: C L
authors: CL
authors: Gao
authors: Canhua
authors: C
authors: Liu
authors: Qi-Kun
authors: QK
authors: Xue
authors: Chao-Xing
authors: CX
authors: Liu
authors: Feng
authors: F
authors: Liu
authors: Dong
authors: D
authors: Qian
authors: Jin-Feng
authors: JF
authors: Jia
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