用横场伊辛模型研究应力对铁电薄膜的热力学性质的影响

用横场伊辛模型研究了铁电薄膜的热力学性质.在体系的哈密顿量中引入一个两维的在平面内的应力，并假设应力从基底材料和薄膜材料之间的界面层到薄膜的表面层是呈指数形式衰减的.结果显示：压应力有利于极化，使居里温度向高温区移动，而张应力对极化和居里温度的影响正好相反.扩散长度对铁电薄膜的热力学性质有很大的影响.关键词：铁电薄膜应力横场伊辛模型

Impact of stress on the thermodynamic properties of ferroelectric films within the transverse Ising model

The thermodynamic properties of ferroelectric thin films are investigated within the framework of the transverse Ising model. A two-dimensional in-plane stress is introduced into the Hamiltonian of the system, and is supposed exponentially decreasing from the interface between the substrate and the film to the surface of the film. It is demonstrated that the compressive stress is benefitial to the polarization and shifts the Curie temperature to higher temperatures, but the tensile stress has the inverse influence on the Curie temperature and polarization. Besides, it is also shown that the diffusive length greatly affects the thermodynamic properties of the film.