Electric-field-induced lattice distortion in epitaxial BiFeO3 thin films as determined by in situ time-resolved x-ray diffraction

Time-resolved X-ray diffraction (XRD) with synchrotron radiation while applying continuous voltage pulses was employed to investigate the electric-field-induced lattice distortion of an epitaxial BiFeO3 (BFO) thin film in a Pt/BFO (1 μm)/SrRuO3 (50 nm)/vicinal SrTiO3 (001) structure. XRD-reciprocal space maps based on the BFO 003, 114, and 1 1 ¯ 4 diffraction spots with and without the application of +15 V (150 kV/cm) to the capacitor demonstrated simultaneous electric-field-induced lattice distortion and crystallographic rotation in the BFO thin film. In response to the application of +15 V, the BFO lattice elongated by 0.08% along the [001]BFO direction and compressed by 0.05% along the [110]BFO direction. In addition, the BFO crystals were rotated by 0.01° along the [ 1 ¯ 1 ¯ 0]STO direction as a result of electric-field-induced lattice distortion under epitaxial strain along the vertical direction at the step edges of the vicinal substrate.