title: Localized excited charge carriers generate ultrafast inhomogeneous strain in the multiferroic BiFeO3.
abstract: We apply ultrafast x-ray diffraction with femtosecond temporal resolution to monitor the lattice dynamics in a thin film of multiferroic BiFeO3 after above-band-gap photoexcitation. The sound-velocity limited evolution of the observed lattice strains indicates a quasi-instantaneous photoinduced stress which decays on a nanosecond time scale. This stress exhibits an inhomogeneous spatial profile evidenced by the broadening of the Bragg peak. These new data require substantial modification of existing models of photogenerated stresses in BiFeO3: the relevant excited charge carriers must remain localized to be consistent with the data.
authors.affiliation: Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schick
authors.affiliation: Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany and Abteilung Physikalische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Herzog
authors.affiliation: X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Haidan
authors.initials: H
authors.lastname: Wen
authors.affiliation: Department of Materials Science and Engineering and Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Pice
authors.initials: P
authors.lastname: Chen
authors.affiliation: Department of Material Science and Engineering, Cornell University, Ithaca, New York 14853, USA and Department of Applied Physics, Stanford University, Stanford, California 94305-4045, USA.
authors.forename: Carolina
authors.initials: C
authors.lastname: Adamo
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Gaal
authors.affiliation: Department of Material Science and Engineering, Cornell University, Ithaca, New York 14853, USA and Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA.
authors.forename: Darrell G
authors.initials: DG
authors.lastname: Schlom
authors.affiliation: Department of Materials Science and Engineering and Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Evans
authors.affiliation: X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Yuelin
authors.initials: Y
authors.lastname: Li
authors.affiliation: Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany and Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
authors.forename: Matias
authors.initials: M
authors.lastname: Bargheer