Ionized-oxygen vacancies related dielectric relaxation in heteroepitaxial K0.5Na0.5NbO3/La0.67Sr0.33MnO3 structure at elevated temperature

Ferroelectric K0.5Na0.5NbO3 (KNN) thin film was epitaxially grown on La0.67Sr0.33MnO3 (LSMO) buffered LaAlO3 substrate by pulse laser deposition. The crystallographic structure of KNN/LSMO was confirmed by x-ray diffraction. Interestingly, a dielectric relaxor feature was found in the temperature range 200-350 degrees C. The activation energies for relaxation and conduction of the films were found to be 1.87 and 0.63-0.71 eV, respectively. The mechanism for dielectric relaxation in KNN/LSMO structure was discussed under a thermally activated process. The remnant polarization and coercive field of the films were 21.3 mu C/cm(2) and 91 kV/cm, respectively. (C) 2009 American Institute of Physics. [doi:10.1063/1.3242009]