title: Anomalous dressing of Dirac fermions in the topological surface state of Bi2Se3, Bi2Te3, and Cu-doped Bi2Se3.
abstract: Quasiparticle dynamics on the topological surface state of Bi(2(3), Bi(2)Te(3), and superconducting Cu(x)Bi(2)Se(3) are studied by 7 eV laser-based angle resolved photoemission spectroscopy. We find strong mode couplings in the Dirac-cone surface states at energies of ~3 and ~15-20 meV associated with an exceptionally large coupling constant λ of ~3, which is one of the strongest ever reported for any material. This result is compatible with the recent observation of a strong Kohn anomaly in the surface phonon dispersion of Bi(2)Se(3), but it appears that the theoretically proposed "spin-plasmon" excitations realized in helical metals are also playing an important role. Intriguingly, the ~3 meV mode coupling is found to be enhanced in the superconducting state of Cu(x)Bi(2)Se(3).
authors.affiliation: ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan. kondo1215@issp.u-tokyo.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kondo
authors.forename: Y
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Y
authors.initials: Y
authors.lastname: Ota
authors.forename: Y
authors.initials: Y
authors.lastname: Ishida
authors.forename: W
authors.initials: W
authors.lastname: Malaeb
authors.forename: K
authors.initials: K
authors.lastname: Okazaki
authors.forename: S
authors.initials: S
authors.lastname: Shin
authors.forename: M
authors.initials: M
authors.lastname: Kriener
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sasaki
authors.forename: Kouji
authors.initials: K
authors.lastname: Segawa
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Ando