title: Creation of helical Dirac fermions by interfacing two gapped systems of ordinary fermions.
abstract: Topological insulators are a unique class of materials characterized by a Dirac cone state of helical Dirac fermions in the middle of a bulk gap. When the thickness of a three-dimensional topological insulator is reduced, however, the interaction between opposing surface states opens a gap that removes the helical Dirac cone, converting the material back to a normal system of ordinary fermions. Here we demonstrate, using density function theory calculations and experiments, that it is possible to create helical Dirac fermion state by interfacing two gapped films-a single bilayer Bi grown on a single quintuple layer Bi(2)Se(3) or Bi(2)Te(3). These extrinsic helical Dirac fermions emerge in predominantly Bi bilayer states, which are created by a giant Rashba effect with a coupling constant of ~4 eV·Å due to interfacial charge transfer. Our results suggest that this approach is a promising means to engineer topological insulator states on non-metallic surfaces.
authors: Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
authors: Z F
authors: ZF
authors: Wang
authors: Meng-Yu
authors: MY
authors: Yao
authors: Wenmei
authors: W
authors: Ming
authors: Lin
authors: L
authors: Miao
authors: Fengfeng
authors: F
authors: Zhu
authors: Canhua
authors: C
authors: Liu
authors: C L
authors: CL
authors: Gao
authors: Dong
authors: D
authors: Qian
authors: Jin-Feng
authors: JF
authors: Jia
authors: Feng
authors: F
authors: Liu