铁电异质结构动力学奇异行为物理机制的理论研究

Ferroelectric heterostructures is one of the topics at the forefront of international new functional materials in this century owing to their fantastic physical phenomena which cannot be in a single ferroelectric materials. Solving the problem of physical mechanism for fantastic phenomena is essential for the realization of practical ferroelectric heterostructures. Contraposing the applied foreground of the ferroelectric heterostructures internationally and the urgent problems, the project will establish factual theoretical model of ferroelectric-ferroelectric heterostructures, and design the theoretical method for this model. The theoretical investigatation on physical mechanism of dynamic abnormal behaviors of ferroelectric-ferroelectric heterostructures will be implemented in depth. The content of this project includes the study of the dynamic basic characteristic with the reversal of polarization, current and time etc.; finding the effect factors for the dynamic abnormal behaviors of multiloop hysteresis loop and huge dielectric susceptibility, and opening out its physical mechanism; discussing the size effect, exploring the abnormal critical behavior and its physical mechanism etc. The goal of this project is to open out the physical mechanism of dynamic abnormal behaviors of ferroelectric heterostructures, prividing the theoretical gist for the realization of multi-state memory and miniaturization of ferroelectric devices, and theoretical guidance for considerable getting the physical characteristics they anticipative demanded synchronously.

铁电异质结构因具有单一铁电材料所不可能有的奇异物理现象，成为21世纪国际新型功能性材料的前沿课题之一。要实现实用意义上的铁电异质结构，必须要解决其产生奇异现象物理机制的问题。本项目针对当前国际上铁电异质结构的应用前景以及亟待解决的问题，建立充分反映实际的铁电-铁电异质结构理论模型，构建此模型的理论方法，对铁电-铁电异质结构动力学奇异行为物理机制进行深入细致的理论研究。具体内容包括：研究铁电异质结构反转极化、反转电流及反转时间等动力学基本特性；寻找到铁电异质结构多回路电滞回线及巨介电极化率动力学奇异行为的影响因素，揭示其产生的物理机制；讨论尺寸效应，探索奇异临界行为及其产生物理机制等问题。本项目旨在揭示铁电异质结构动力学奇异行为的物理机制，为铁电器件实现多态存储器及小型化提供理论依据，同时也为人们可观的获得预期所需求的物理特性提供理论方向的指导。

铁电异质结构因具有单一铁电材料所不及的奇异物理现象，为铁电材料在器件上的应用创造了新的候选材料和提供了新的机会。因此，对铁电异质结构奇异行为物理机制的研究具有重要的实用意义。本项目按照原定计划进行，在项目研究期间共发表论文6篇，其中已被SCI收录论文4篇。主要研究结果：（1）通过引入描述界面附近结构的实际过渡状态、界面耦合、界面结构过渡层等参量，建立了充分反映实际的铁电-铁电异质结构的理论模型， 并构建了处理此模型的Landau动力学理论方法。（2）利用有限差分法进行数值计算，得到并分析了铁电异质结构的动力学基本特性，如反转极化、反转电流及反转时间等性质。（3）发现铁电异质结构在一定条件下呈现多回路电滞回线及巨介电极化率，确定了多回路电滞回线和巨介电极化率的影响因素，并揭示了产生多回路电滞回线及巨介电极化率的物理机制, 为铁电器件实现多态存储器及小型化提供了理论依据。（4）对铁电异质结构多回路电滞回线与介电极化率尺寸效应进行了分析研究，得到了奇异临界行为的物理图像，并阐明了此奇异临界行为的物理机制。通过奇异临界行为物理图像，人们可以获得预期所需求的物理特性。