Effect of Extrapolation Length on Electrical Properties for Ba_0.8Sr_0.2TiO₃ Ferroelectric Thin Films

The effect of extrapolation length on the polarization and susceptibility of Ba_0.8Sr_0.2TiO₃ ferroelectric thin films with different thicknesses is investigated using Ginzburg–Landau–Devonshire theory. The polarization profile, the average polarization, and the susceptibility are numerically modeled for films with various thickness and extrapolation length values. Results show that the polarization value near the interface is dramatically suppressed due to the interface effect, and that the average polarization value and the Curie temperature decrease significantly for films with thickness of 60 nm or less. However, the opposite is found for the variation in the susceptibility value. The numerically modeled results indicate that the interface effect plays an important role in the polarization and susceptibility variation in films with different thicknesses.