Enhanced dielectric nonlinearity in epitaxial Pb_0.92 La_0.08 Zr_0.52 Ti_0.48 O_3 thin films
Applied Physics Letters 104, 162902 (2014)
Chunrui Ma*, Beihai Ma, Shao-Bo Mi, Ming Liu, and Judy Wu*
* KU Physics and Astronomy Authors
High quality c-axis oriented epitaxial Pb_0.92 La_0.08 Zr_0.52 Ti_0.48 O_3 films were fabricated using pulsed laser deposition on (001) LaAlO_3 substrates with conductive LaNiO3 buffers. Besides confirmation of the in-plane and out-of-plane orientations using X-ray diffraction, transmission electron microscopy study has revealed columnar structure across the film thickness with column width around 100 nm. Characterization of ferroelectric properties was carried out in comparison with polycrystalline Pb_0.92 La_0.08 Zr_0.52 Ti_0.48 O_3 films to extract the effect of epitaxial growth. It is found that the ratio between the irreversible Rayleigh parameter and reversible parameter increased up to 0.028 cm/kV at 1 kHz on epitaxial samples, which is more than twice of that on their polycrystalline counterparts. While this ratio decreased to 0.022 cm/kV with increasing frequency to100 kHz, a much less frequency dependence was observed as compared to the polycrystalline case. The epitaxial Pb_0.92 La_0.08 Zr_0.52 Ti_0.48 O_3 films exhibited a higher mobility of domain wall and the higher extrinsic contribution to the dielectric properties, as well as reduced density of defects, indicating that it is promising for tunable and low power consumption devices.