Dynamic Response of Epitaxial Ferroelectric Thin Films Bruce

Dynamic Response of Epitaxial Ferroelectric Thin Films Bruce Wessels, Northwestern University, DMR 0605292 • • We have studied the transformation kinetics of ferroelectric domains in epitaxial thin film of barium titanate. The kinetics are determined from the temporal response of the electro -optic effect. The kinetics are best described by a stretched exponential in time and is attributed to the poling and polarization reversal of nano-domains. The average time for polarization reversal, < τ >, is a function of applied electric field E and is proportional to exponential of the ratio of activation field α over applied electric field E. Orientation of ferroelectric domains. The orientation changes upon application of a bias pulse. A typical cycle of excitation and relaxation of electro-optic response of a barium titanate thin film. A 10 ms mono-polar 34. 8 V (Vp-p) pulse is applied to the sample.

Dynamic Response of Epitaxial Ferroelectric Thin Films Bruce Wessels, Northwestern University, DMR 0605292 • • • We have been developing an apparatus to study fast transformation kinetics in thin film materials. The technique is based on measurement of the time dependence of the optical Pockels effect which is sensitive to material structure. The apparatus will ultimately be capable of measuring transformation kinetics on the picosecond time scale. A general kinetic model for driven systems is under development. Apparatus for measurement of the linear electro-optic effect. Changes in the optical birefringence upon application of a voltage bias is measured as a function of time and temperature.