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Title: Capturing ultrafast photoinduced local structural distortions of BiFeO3

The interaction of light with materials is an intensively studied research forefront, in which the coupling of radiation energy to selective degrees of freedom offers contact-free tuning of functionalities on ultrafast time scales. Capturing the fundamental processes and understanding the mechanism of photoinduced structural rearrangement are essential to applications such as photo-active actuators and efficient photovoltaic devices. Using ultrafast x-ray absorption spectroscopy aided by density functional theory calculations, we reveal the local structural arrangement around the transition metal atom in a unit cell of the photoferroelectric archetype BiFeO3 film. The out-of-plane elongation of the unit cell is accompanied by the in-plane shrinkage with minimal change of interaxial lattice angles upon photoexcitation. This uniaxial elastic deformation of the unit cell is driven by localized electric field as a result of photoinduced charge separation, in contrast to a global lattice constant increase and lattice angle variations as a result of heating. The finding of a photoinduced elastic unit cell deformation elucidates a microscopic picture of photocarrier-mediated nonequilibrium processes in polar materials.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [2] ;  [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Univ. of Science and Technology, Hefei (China)
  4. Cornell Univ., Ithaca, NY (United States)
  5. Cornell Univ., Ithaca, NY (United States). Kavli Inst. for Nanoscale Science, Ithaca, NY (United States)
Publication Date:
OSTI Identifier:
1243282
Report Number(s):
PNNL-SA--110895
Journal ID: ISSN 2045-2322; 48274; KC0302060
Grant/Contract Number:
AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY Environmental Molecular Sciences Laboratory