title: Ultrafast optical excitation of a persistent surface-state population in the topological insulator Bi2Se3.
abstract: Using femtosecond time- and angle-resolved photoemission spectroscopy, we investigated the nonequilibrium dynamics of the topological insulator Bi2Se3. We studied p-type Bi2Se3, in which the metallic Dirac surface state and bulk conduction bands are unoccupied. Optical excitation leads to a metastable population at the bulk conduction band edge, which feeds a nonequilibrium population of the surface state persisting for >10 ps. This unusually long-lived population of a metallic Dirac surface state with spin texture may present a channel in which to drive transient spin-polarized currents.
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Sobota
authors.forename: S
authors.initials: S
authors.lastname: Yang
authors.forename: J G
authors.initials: JG
authors.lastname: Analytis
authors.forename: Y L
authors.initials: YL
authors.lastname: Chen
authors.forename: I R
authors.initials: IR
authors.lastname: Fisher
authors.forename: P S
authors.initials: PS
authors.lastname: Kirchmann
authors.forename: Z-X
authors.initials: ZX
authors.lastname: Shen