铁电畴壁电导特性及其力电载荷规律可控性理论和实验研究

In recent years, with the rapid development of theoretical calculations and experimental techniques, some important features such as high conductivity and magnetic coupling effects of the ferroelectric domain wall have been reported and quickly become hot researching spots. This encourages people to regard ferroelectric domain wall as the key element for futrue optoelectronic device. How to control a variety of factors to make the ferroelectric materials form stable domain wall structures or to occur regular phase transitions of domain walls thereby effectively regulate relevant characteristics, is a question that people urgely concern at present. The project intends to combine theoretical and experimental methods, with careful consideration of several factors including the coupling effect of order parameters, the flexoelectric effect, defects, surface, mechanical and electrical loads, etc., to develop a multifield and multiscale coupling method for domain wall stability mechanism and conductance characteristics of nanoscale ferroelectrics, and to establish an experimental platform for preparation, analysis and testing of domain wall of nanoscale ferroelectrics. The project will make an in-depth study on domain wall stability mechanism and conductance characteristics of nanoscale ferroelectrics to obtain effective mechanical and electrical control of domain wall stability and conductance of nanoscale ferroelectrics. The research of our project should provide instructive information on how to explore new physical phenomena and develop novel optoelectronic devices based on the domain walls of nanoscale ferroelectrics.

近年随着理论计算和实验技术的迅速发展，铁电畴壁高导电性、磁电耦合效应等重要特性被相继报道并迅速成为研究热点，并促使人们将铁电畴壁视为未来光电子器件的关键单元。如何通过控制各种因素使铁电材料形成稳定的畴壁结构或发生有规律的畴壁相变，进而对其相关特性进行有效调控，是当前人们迫切关心的问题。本项目拟结合理论计算和实验，细致考虑序参量耦合、挠曲电效应、缺陷、表面和力电载荷等几种因素，发展针对铁电纳米材料畴壁稳定机理及其电导特性的多场多尺度耦合研究方法，搭建铁电纳米材料畴壁制备、分析和测试实验平台，深入研究铁电纳米材料畴壁的稳定机理和导电机制，得到力电载荷下铁电纳米畴壁稳定及电导特性的有效调控规律。本项目的研究成果，对如何基于铁电纳米材料畴壁探索物理新现象和发展新型光电器件具有重要的指导意义。

项目围绕“铁电畴壁电导特性及其力电载荷规律可控性理论和实验研究”展开相关理论及实验工作。理论方面，我们基于自主开发的铁电畴壁相场模拟方法，结合密度泛函理论计算、基于有效哈密顿量的分子动力学模拟等方法，深入研究了传统180度畴壁、铁弹畴壁和新型拓扑畴壁等多个类型畴壁的稳定及相变机理研究，并对其电导特性和力电载荷规律可调控性进行了系统分析、总结。实验方面，我们运用物理激光沉积PLD、Langmuir-Blodgett技术等工艺对纳尺度铁电材料的制备进行了大量的探索，成功制备出铁电超薄膜、铁电纳米点等结构；搭建了针对铁电超薄膜畴壁分析和测试的实验平台，对铁电超薄膜、铁电纳米点的畴结构及其电导特性进行了表征测试。基于大量的理论和实验结果，总结了一系列铁电畴壁及其电导特性的有效调控方案和规律。相关成果在力学、材料和物理领域国际期刊发表论文25篇，包括固体力学权威期刊J. Mech. Phys. Solids、物理顶级期刊Rep. Prog. Phys.、npj Computational Materials、Acta Materialia、ACS Appl. Electron. Mater.、Phys. Rev. B、Phys. Rev. Mater.、Phys. Chem. Chem. Phys.、RSC Advances、JPCM、Comput. Mater. Sci.等，应邀撰写综述2篇。本项目揭示了铁电畴壁电导特性及其力电调控规律，提出了一系列有效的铁电畴壁力电调控方案，为铁电畴壁的应用奠定了基础，对于发展铁电畴壁相关理论、实验方法和器件概念设计具有指导意义。