Influence of different boundary conditions on polarization and phase transition properties of temperature-graded ferroelectric thin films.

In the framework of the mean field approximation, a transverse Ising model is adopted to investigate the influence of two boundary conditions (free boundary condition and clamped boundary condition) on the polarization and phase transition properties of temperature-graded ferroelectric films. Due to the ferroelectric distortion aroused by temperature gradient across the film, the elastic thermal stress in the film increases. A distribution function is introduced to characterize the variation of interaction couplings between two pseudo-spins under different boundary conditions. It's shown that polarization and phase transition temperatures of films under free boundary condition are larger than that of films under clamped boundary condition, and the variation of temperature gradient and film thickness have more obvious influence on films under clamped boundary condition. [ABSTRACT FROM AUTHOR]