title: Tunable Dirac cone in the topological insulator Bi(2-x)Sb(x)Te(3-y)Se(y).
abstract: The three-dimensional topological insulator is a quantum state of matter characterized by an insulating bulk state and gapless Dirac cone surface states. Device applications of topological insulators require a highly insulating bulk and tunable Dirac carriers, which has so far been difficult to achieve. Here we demonstrate that Bi(2-x)Sb(x)Te(3-y)Se(y) is a system that simultaneously satisfies both of these requirements. For a series of compositions presenting bulk-insulating transport behaviour, angle-resolved photoemission spectroscopy reveals that the chemical potential is always located in the bulk band gap, whereas the Dirac cone dispersion changes systematically so that the Dirac point moves up in energy with increasing x, leading to a sign change of the Dirac carriers at x~0.9. Such a tunable Dirac cone opens a promising pathway to the development of novel devices based on topological insulators.
authors.affiliation: WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Arakane
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: S
authors.initials: S
authors.lastname: Souma
authors.forename: K
authors.initials: K
authors.lastname: Kosaka
authors.forename: K
authors.initials: K
authors.lastname: Nakayama
authors.forename: M
authors.initials: M
authors.lastname: Komatsu
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: Zhi
authors.initials: Z
authors.lastname: Ren
authors.forename: Kouji
authors.initials: K
authors.lastname: Segawa
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Ando