Temperature-graded ferroelectric thin films under two boundary conditions

摘要

In the framework of the mean field approximation, a transverse Ising model (TIM) was adopted to analyze the polarization properties of temperature-graded ferroelectric films under two boundary conditions, free boundary condition (FBC) and clamped boundary condition (CBC). Due to the ferroelectric distortion aroused by temperature gradient across the film, the elastic thermal stress increased. A distribution function was introduced to characterize the different boundary conditions. The results show that boundary conditions have very important influence on film properties Polarizations under FBC are larger than that under CBC, polarization variations aroused by changed film thickness and temperature gradient under FBC are not as obvious as that under CBC, and films under different boundary conditions present obviously different physical behavior.