边界条件对温度梯度铁电薄膜极化和相变性质的影响

摘要

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.%在平均场理论的框架下,采用横场伊辛模型研究了两种不同的边界条件(自由边界条件和固定边界条件)对温度梯度铁电薄膜极化和相变性质的影响.由于薄膜内部的温度梯度分布导致了铁电畸变,使得薄膜的弹性热应力增加,引入分布函数来描述不同边界条件下赝自旋相互作用强度的变化.通过研究发现自由边界条件下的薄膜的极化强度和相变温度要高于固定边界条件下的薄膜的相应值,同时薄膜厚度和温度梯度的变化对固定边界条件下的铁电薄膜的影响要更加显著.