Giant optical enhancement of strain gradient in ferroelectric BiFeO3 thin films and its physical origin

Yuelin Li; Carolina Adamo; Pice Chen; Paul G Evans; Serge M Nakhmanson; William Parker; Clare E Rowland; Richard D Schaller; Darrell G Schlom; Donald A Walko; Haidan Wen; Qingteng Zhang

doi:10.1038/srep16650

Giant optical enhancement of strain gradient in ferroelectric BiFeO3 thin films and its physical origin

Sci Rep. 2015 Nov 20:5:16650. doi: 10.1038/srep16650.

Authors

Yuelin Li¹, Carolina Adamo², Pice Chen³, Paul G Evans³, Serge M Nakhmanson⁴, William Parker⁵, Clare E Rowland⁶, Richard D Schaller^{6

7}, Darrell G Schlom^{8

9}, Donald A Walko¹, Haidan Wen¹, Qingteng Zhang³

Affiliations

¹ Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
² Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
³ Department of Materials Science and Engineering &Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
⁴ Department of Materials Science &Engineering, and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136, USA.
⁵ Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439, USA.
⁶ Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.
⁷ Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA.
⁸ Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA.
⁹ Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA.

Abstract

Through mapping of the spatiotemporal strain profile in ferroelectric BiFeO3 epitaxial thin films, we report an optically initiated dynamic enhancement of the strain gradient of 10(5)-10(6) m(-1) that lasts up to a few ns depending on the film thickness. Correlating with transient optical absorption measurements, the enhancement of the strain gradient is attributed to a piezoelectric effect driven by a transient screening field mediated by excitons. These findings not only demonstrate a new possible way of controlling the flexoelectric effect, but also reveal the important role of exciton dynamics in photostriction and photovoltaic effects in ferroelectrics.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.