FERROELECTRIC PROPERTIES IN HETEROEPITAXIAL BA0.6SR0.4TIO3 THIN-FILMSON SRRUO3 SRTIO3 SUBSTRATES/

Heteroepitaxial Ba0.6Sr0.4TiO3 thin films with thicknesses from 26nm t o 97nm were grown on SrRuO3 bottom electrode films on SrTiO3 single cr ystal substrates. Although the films have a paraelectric composition, ferroelectric hysteresis was observed in displacement versus electric field (D-E) loops. The ferroelectricity is considered to be developed as a result of bi-axial stress, caused by lattice mismatch between the dielectric films and the bottom electrodes. The maximum difference in the displacement was over 0.4 C/m(2) even when the thickness of the f ilm was reduced to 26nm. The hysteresis loops showed an asymmetric cha racteristic at a polarity of applied voltage. The asymmetry was discus sed in terms of an asymmetrical deformation of the crystal structure, which is probably introduced during the heteroepitaxial growth.