title: Robust protection from backscattering in the topological insulator Bi1.5Sb0.5Te1.7Se1.3.
abstract: Electron scattering in the topological surface state (TSS) of the topological insulator Bi1.5Sb0.5Te1.7Se1.3 was studied using quasiparticle interference observed by scanning tunneling microscopy. It was found that not only the 180° backscattering but also a wide range of backscattering angles of 100°-180° are effectively prohibited in the TSS. This conclusion was obtained by comparing the observed scattering vectors with the diameters of the constant-energy contours of the TSS, which were measured for both occupied and unoccupied states using time- and angle-resolved photoemission spectroscopy. The robust protection from backscattering in the TSS is good news for applications, but it poses a challenge to the theoretical understanding of the transport in the TSS.
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Sunghun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Yoshizawa
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Yukiaki
authors.initials: Y
authors.lastname: Ishida
authors.affiliation: Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Eto
authors.affiliation: Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Segawa
authors.affiliation: Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Ando
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Shik
authors.initials: S
authors.lastname: Shin
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Komori