title: Instantaneous band gap collapse in photoexcited monoclinic VO2 due to photocarrier doping.
abstract: Using femtosecond time-resolved photoelectron spectroscopy we demonstrate that photoexcitation transforms monoclinic VO2 quasi-instantaneously into a metal. Thereby, we exclude an 80 fs structural bottleneck for the photoinduced electronic phase transition of VO2. First-principles many-body perturbation theory calculations reveal a high sensitivity of the VO2 band gap to variations of the dynamically screened Coulomb interaction, supporting a fully electronically driven isostructural insulator-to-metal transition. We thus conclude that the ultrafast band structure renormalization is caused by photoexcitation of carriers from localized V 3d valence states, strongly changing the screening before significant hot-carrier relaxation or ionic motion has occurred.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abteilung Physikalische Chemie, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wegkamp
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abteilung Physikalische Chemie, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Herzog
authors.affiliation: Nano-Bio Spectroscopy group, Universidad del País Vasco CFM CSIC-UPV/EHU-MPC & DIPC, 20018 San Sebastián, Spain and European Theoretical Spectroscopy Facility (ETSF).
authors.forename: Lede
authors.initials: L
authors.lastname: Xian
authors.affiliation: European Theoretical Spectroscopy Facility (ETSF) and Laboratoire des Solides Irradiés, École Polytechnique, CNRS-CEA/DSM, F-91128 Palaiseau, France and Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette, France.
authors.forename: Matteo
authors.initials: M
authors.lastname: Gatti
authors.affiliation: Nano-Bio Spectroscopy group, Universidad del País Vasco CFM CSIC-UPV/EHU-MPC & DIPC, 20018 San Sebastián, Spain and European Theoretical Spectroscopy Facility (ETSF).
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Cudazzo
authors.affiliation: Department of Physics and Astronomy and Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37235-1807, USA.
authors.forename: Christina L
authors.initials: CL
authors.lastname: McGahan
authors.affiliation: Department of Physics and Astronomy and Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37235-1807, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Marvel
authors.affiliation: Department of Physics and Astronomy and Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37235-1807, USA.
authors.forename: Richard F
authors.initials: RF
authors.lastname: Haglund
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abteilung Physikalische Chemie, Faradayweg 4-6, 14195 Berlin, Germany and Nano-Bio Spectroscopy group, Universidad del País Vasco CFM CSIC-UPV/EHU-MPC & DIPC, 20018 San Sebastián, Spain and European Theoretical Spectroscopy Facility (ETSF) and Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: Angel
authors.initials: A
authors.lastname: Rubio
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abteilung Physikalische Chemie, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wolf
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abteilung Physikalische Chemie, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Stähler
mesh_terms: D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D044367:Phase Transition; D055668:Photochemical Processes; D056951:Photoelectron Spectroscopy / Q000379:methods; D017968:Vanadium Compounds / Q000737:chemistry*
chemical_list: D010087:Oxides; D017968:Vanadium Compounds; C581824:vanadium dioxide