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Electric-field-induced structural modulation of epitaxial BiFeO3 multiferroic thin films as studied using x-ray microdiffraction

2007; American Institute of Physics; Volume: 90; Issue: 2 Linguagem: Inglês

10.1063/1.2430678

1520-8842

Chung Wung Bark, Sangwoo Ryu, Yang Mo Koo, Hyun M. Jang, Hwa Shik Youn,

Underwater Acoustics Research

An in situ method, called synchrotron x-ray microdiffraction, was introduced to examine the electric-field-induced structural modulation of the epitaxially grown pseudotetragonal BiFeO3 thin film. To evaluate the d spacing (d001) from the measured intensity contour in the 2θ-χ space, the peak position in each diffraction profile was determined by applying two-dimensional Lorentzian fitting. By tracing the change of d spacing as a function of the applied electric field and by examining the Landau free energy function for P4mm symmetry, the authors were able to estimate the two important parameters that characterize the field-induced structural modulation. The estimated linear piezoelectric coefficient (d33) at zero-field limit is 15pm∕V, and the effective nonlinear electrostrictive coefficient (Qeff) is as low as ∼8.0×10−3m4∕C2.