Numerical Investigation of Polarization Reversal Characteristics in a Ferroelectric Thin Film

摘要

A small-shed symmetric thin ferroelectric (FE) film, assumed second order and in the FE phase, of thickness I is considered. The Landau-Devonshire free energy of the film is expressed using the Tilley-Zeks model. A special case, in which the polarization values at both film surfaces are zero, p_(+ -) = 0, is assumed. The initial spontaneous polarization profile of the film at equilibrium is approximated using a cosine function. The Landau-Khalatnikov equation of motion is then used to obtain numerically the initial stable polarization profile; and to describe the dynamics of polarization reversal in the film under the action of a step driving electric fields. A finite-difference time domain method is utilized to simulate the switching process. Changes in the average polarization and the average polarization current during the switching are calculated and studied. The influence of temperature and thickness on switching is investigated.