title: Momentum-resolved spin dynamics of bulk and surface excited States in the topological insulator Bi(2)Se(3).
abstract: The prospect of optically inducing and controlling a spin-polarized current in spintronic devices has generated wide interest in the out-of-equilibrium electronic and spin structure of topological insulators. In this Letter we show that only measuring the spin intensity signal over several orders of magnitude by spin-, time-, and angle-resolved photoemission spectroscopy can provide a comprehensive description of the optically excited electronic states in Bi_{2}Se_{3}. Our experiments reveal the existence of a surface resonance state in the second bulk band gap that is benchmarked by fully relativistic ab initio spin-resolved photoemission calculations. We propose that the newly reported state plays a major role in the ultrafast dynamics of the system, acting as a bottleneck for the interaction between the topologically protected surface state and the bulk conduction band. In fact, the spin-polarization dynamics in momentum space show that these states display macroscopically different temperatures and, more importantly, different cooling rates over several picoseconds.
authors: Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell OX11 0QX, United Kingdom.
authors: C
authors: C
authors: Cacho
authors: Elettra-Sincrotrone Trieste S. C. p. A., Strada Statale 14, km 163.5, 34149 Basovizza, Trieste, Italy.
authors: A
authors: A
authors: Crepaldi
authors: Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A 1040 Wien, Austria.
authors: M
authors: M
authors: Battiato
authors: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München, Germany.
authors: J
authors: J
authors: Braun
authors: Elettra-Sincrotrone Trieste S. C. p. A., Strada Statale 14, km 163.5, 34149 Basovizza, Trieste, Italy.
authors: F
authors: F
authors: Cilento
authors: CNR-IOM, Strada Statale 14, km 163.5, Trieste 34149, Italy.
authors: M
authors: M
authors: Zacchigna
authors: Laboratoire de Physique des Matriaux et des Surfaces, Université de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise, France.|DSM, IRAMIS, Service de Physique de l'Etat Condensé, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors: M C
authors: MC
authors: Richter
authors: Laboratoire de Physique des Matriaux et des Surfaces, Université de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise, France.|DSM, IRAMIS, Service de Physique de l'Etat Condensé, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors: O
authors: O
authors: Heckmann
authors: Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell OX11 0QX, United Kingdom.
authors: E
authors: E
authors: Springate
authors: Diamond Light Source, Chilton, Didcot, Oxfordshire OX110DE, United Kingdom.
authors: Y
authors: Y
authors: Liu
authors: Diamond Light Source, Chilton, Didcot, Oxfordshire OX110DE, United Kingdom.
authors: S S
authors: SS
authors: Dhesi
authors: Institute of Condensed Matter Physics (ICMP), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors: H
authors: H
authors: Berger
authors: Institute of Condensed Matter Physics (ICMP), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors: Ph
authors: P
authors: Bugnon
authors: Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A 1040 Wien, Austria.
authors: K
authors: K
authors: Held
authors: Institute of Condensed Matter Physics (ICMP), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors: M
authors: M
authors: Grioni
authors: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München, Germany.
authors: H
authors: H
authors: Ebert
authors: Laboratoire de Physique des Matriaux et des Surfaces, Université de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise, France.|DSM, IRAMIS, Service de Physique de l'Etat Condensé, CEA-Saclay, 91191 Gif-sur-Yvette, France.
authors: K
authors: K
authors: Hricovini
authors: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München, Germany.|New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic.
authors: J
authors: J
authors: Minár
authors: Elettra-Sincrotrone Trieste S. C. p. A., Strada Statale 14, km 163.5, 34149 Basovizza, Trieste, Italy.|Università degli Studi di Trieste, Via A. Valerio 2, Trieste 34127, Italy.|International Faculty, University of Köln, 50937 Köln, Germany.
authors: F
authors: F
authors: Parmigiani