title: Controllable magnetic doping of the surface state of a topological insulator.
abstract: A combined experimental and theoretical study of doping individual Fe atoms into Bi(2)Se(3) is presented. It is shown through a scanning tunneling microscopy study that single Fe atoms initially located at hollow sites on top of the surface (adatoms) can be incorporated into subsurface layers by thermally activated diffusion. Angle-resolved photoemission spectroscopy in combination with ab initio calculations suggest that the doping behavior changes from electron donation for the Fe adatom to neutral or electron acceptance for Fe incorporated into substitutional Bi sites. According to first principles calculations within density functional theory, these Fe substitutional impurities retain a large magnetic moment, thus presenting an alternative scheme for magnetically doping the topological surface state. For both types of Fe doping, we see no indication of a gap at the Dirac point.
authors.affiliation: Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Schlenk
authors.affiliation: Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Bianchi
authors.affiliation: Bremen Center for Computational Materials Science, University of Bremen, D-28359 Bremen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Koleini
authors.affiliation: Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Eich
authors.affiliation: Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Pietzsch
authors.affiliation: Bremen Center for Computational Materials Science, University of Bremen, D-28359 Bremen, Germany and Institute for Theoretical Physics, University of Bremen, D-28359 Bremen, Germany.
authors.forename: T O
authors.initials: TO
authors.lastname: Wehling
authors.affiliation: Bremen Center for Computational Materials Science, University of Bremen, D-28359 Bremen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Frauenheim
authors.affiliation: Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Nordic Institute for Theoretical Physics (NORDITA), S-106 91 Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Balatsky
authors.affiliation: Center for Materials Crystallography, Department of Chemistry, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark.
authors.forename: J-L
authors.initials: JL
authors.lastname: Mi
authors.affiliation: Center for Materials Crystallography, Department of Chemistry, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark.
authors.forename: B B
authors.initials: BB
authors.lastname: Iversen
authors.affiliation: Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wiebe
authors.affiliation: Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany.
authors.forename: A A
authors.initials: AA
authors.lastname: Khajetoorians
authors.affiliation: Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark.
authors.forename: Ph
authors.initials: P
authors.lastname: Hofmann
authors.affiliation: Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Wiesendanger