Ultrafast photoinduced transient strain in BiFeO3 thin film probed by x-ray free electron laser diffraction

ORAL

Abstract

Photoinduced structural effects provide an emerging method for manipulating the crystal structure of polar perovskites and for eventual ultrafast control of phenomena such as ferroelectricity and magnetism. Studies of the dynamics of the strain generation and relaxation after photoexcitation can provide fundamental insight into the origin of these photoinduced phenomena. Experiments probing a 35 nm thick BiFeO3 thin film using an x-ray free electron laser (XFEL) providing 100 fs time resolution show that a transient lattice expansion can be produced by intense ultrafast optical excitation. The diffraction employed an x-ray fluence below the BiFeO3 damage threshold. Optical excitation induced a shift of the BiFeO3 002 reflection to lower wavevector by up to 0.8% within 9 ps. Temporal oscillations of the scattered intensity were observed over a wide range of wavevectors, equivalent to several thickness fringes. The dispersion matched the longitudinal acoustic (LA) sound velocity indicates that an impulse propagated into the film in a manner consistent with kinematical calculations. The predicted intensity at 5 ps is not predicted accurately, which may indicate that there is a more complex distribution of the initial stress than is expected from the optical absorption profile.

–

Presenters

  • Hyeonjun Lee

    Department of Materials Science & Engineering, University of Wisconsin - Madison, Madison, Wisconsin 53706, USA, Department of Materials Science and Engineering, University of Wisconsin-Madison

Authors

  • Hyeonjun Lee

    Department of Materials Science & Engineering, University of Wisconsin - Madison, Madison, Wisconsin 53706, USA, Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Youngjun Ahn

    Department of Materials Science & Engineering, University of Wisconsin - Madison, Madison, Wisconsin 53706, USA, Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Samuel Marks

    Materials Science and Engineering, University of Wisconsin - Madison, Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Eric C Landahl

    Department of Physics, DePaul University

  • Joonyoung Lee

    School of Materials Science and Engineering, Gwangju Institute of Science and Technology

  • tayeon kim

    School of Materials Science and Engineering, Gwangju Institute of Science and Technology

  • Sanjith Unithrattil

    School of Materials Science and Engineering, Gwangju Institute of Science and Technology

  • Ji Young Jo

    School of Materials Science and Engineering, Gwangju Institute of Science and Technology

  • Sehwan Cheon

    Pohang Accelerator Lab (PAL), Pohang Accelerator Laboratory,, Pohang Accelerator Laboratory,

  • Sunam Kim

    Pohang Accelerator Lab (PAL), Pohang Accelerator Laboratory,, Pohang Accelerator Laboratory,

  • Carolina Adamo

    Stanford University, Department of Applied Physics, Stanford University

  • Darrell G. Schlom

    Cornell University, Cornell University, Ithaca, New York 14853, USA, Department of Materials Science and Engineering, Cornell University, Department of Materials Science and Engineering, Kavli Institute at Cornell for Nanoscale Science, Cornell University, Materials Science & Engineering, Cornell University, Department of Materials Science and Engineering,, Cornell University, Materials Science and Engineering, University of Cornell

  • Haidan Wen

    Argonne National Laboratory, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA, X-ray Science Division,, Argonne National Laboratory

  • Paul G Evans

    Materials Science and Engineering, University of Wisconsin - Madison, Department of Materials Science and Engineering, University of Wisconsin-Madison