title: Superconducting topological surface states in the noncentrosymmetric bulk superconductor PbTaSe2.
abstract: The search for topological superconductors (TSCs) is one of the most urgent contemporary problems in condensed matter systems. TSCs are characterized by a full superconducting gap in the bulk and topologically protected gapless surface (or edge) states. Within each vortex core of TSCs, there exists the zero-energy Majorana bound states, which are predicted to exhibit non-Abelian statistics and to form the basis of the fault-tolerant quantum computation. To date, no stoichiometric bulk material exhibits the required topological surface states (TSSs) at the Fermi level (EF) combined with fully gapped bulk superconductivity. We report atomic-scale visualization of the TSSs of the noncentrosymmetric fully gapped superconductor PbTaSe2. Using quasi-particle scattering interference imaging, we find two TSSs with a Dirac point atE≅ 1.0 eV, of which the inner TSS and the partial outer TSS crossEF, on the Pb-terminated surface of this fully gapped superconductor. This discovery reveals PbTaSe2as a promising candidate for TSC.
authors.affiliation: Department of Physics, National Taiwan University, Taipei 10617, Taiwan.; Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors.forename: Syu-You
authors.initials: SY
authors.lastname: Guan
authors.affiliation: Department of Physics, National Taiwan University, Taipei 10617, Taiwan.; Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.; Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Peng-Jen
authors.initials: PJ
authors.lastname: Chen
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Ming-Wen
authors.initials: MW
authors.lastname: Chu
authors.affiliation: Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.; Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Raman
authors.initials: R
authors.lastname: Sankar
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Fangcheng
authors.initials: F
authors.lastname: Chou
authors.affiliation: Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.; Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Horng-Tay
authors.initials: HT
authors.lastname: Jeng
authors.affiliation: Department of Physics, National Taiwan University, Taipei 10617, Taiwan.; Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors.forename: Chia-Seng
authors.initials: CS
authors.lastname: Chang
authors.affiliation: Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors.forename: Tien-Ming
authors.identifier: 0000-0002-4524-1380
authors.initials: TM
authors.lastname: Chuang
keywords: Topological superconductor; non-centrosymmetric superconductor