title: Electronic origin of ultrafast photoinduced strain in BiFeO3.
abstract: Above-band-gap optical excitation produces interdependent structural and electronic responses in a multiferroic BiFeO(3) thin film. Time-resolved synchrotron x-ray diffraction shows that photoexcitation can induce a large out-of-plane strain, with magnitudes on the order of half of one percent following pulsed-laser excitation. The strain relaxes with the same nanosecond time dependence as the interband relaxation of excited charge carriers. The magnitude of the strain and its temporal correlation with excited carriers indicate that an electronic mechanism, rather than thermal effects, is responsible for the lattice expansion. The observed strain is consistent with a piezoelectric distortion resulting from partial screening of the depolarization field by charge carriers, an effect linked to the electronic transport of excited carriers. The nonthermal generation of strain via optical pulses promises to extend the manipulation of ferroelectricity in oxide multiferroics to subnanosecond time scales.
authors: X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors: Haidan
authors: H
authors: Wen
authors: Pice
authors: P
authors: Chen
authors: Margaret P
authors: MP
authors: Cosgriff
authors: Donald A
authors: DA
authors: Walko
authors: June Hyuk
authors: JH
authors: Lee
authors: Carolina
authors: C
authors: Adamo
authors: Richard D
authors: RD
authors: Schaller
authors: Jon F
authors: JF
authors: Ihlefeld
authors: Eric M
authors: EM
authors: Dufresne
authors: Darrell G
authors: DG
authors: Schlom
authors: Paul G
authors: PG
authors: Evans
authors: John W
authors: JW
authors: Freeland
authors: Yuelin
authors: Y
authors: Li