手性畴壁对铁电薄膜电学性能调控的相场研究

Domain walls have more and more important effects on the properties of ferroelectric thin films as the miniaturation of the devices. Chiral domain wall is a new kind of internal structure of domain wall, it can be used for information storage of high density, the lower domain wall energy and barrier of domain-wall switching has an important influence on electrical properties of ferroelectric film. At present, the research of chiral domain wall is in an initial stage, the effect of internal structure of domain wall on macroscopic physical properties of ferroelectric film has not been systematically studied. Based on the above consideration, this project will focus on chiral domain wall of ferroelectric film. A phase field model of chiral domain wall simulation will be established and the effects of electromechanical coupling on the formation of chiral domain wall will be analyzed. The polarization vector in internal of domain wall will be controlled using appropriate stress field, electric field, mismatch strain. The relations between the chiral domain wall and electrical properties of ferroelectric film will be discussed, and the tuning method of chiral domain wall for electrical properties of ferroelectric films will be acquired in theory. It is desirable to provide a theoretical basis in favor of the performance of electrical properties of ferroelectric film.

随着器件微型化的发展，畴壁对铁电薄膜性能的影响越来越明显。手性畴壁是一种新型畴壁内部结构，可用于高密度信息存储，其较低的畴壁能和畴壁翻转势垒对铁电薄膜的电学性能有着重要的影响。目前，对于手性畴壁的研究尚处于起步阶段，畴壁内部结构对铁电薄膜宏观物理性能的影响尚未进行系统研究。基于此，本项目以铁电薄膜手性畴壁为研究对象，建立手性畴壁的模拟的相场模型，分析力电耦合作用对手性畴壁形成的影响；采用适当的应力场、电场、失配应变等，调控畴壁内部的极化矢量；研究手性畴壁与铁电薄膜电学性能的关联，从理论上掌握手性畴壁对铁电薄膜电学性能的调控规律，为铁电薄膜电学性能的优化奠定理论基础。

在电子器件与设备小型化、纳米化的趋势下，铁电体中的畴壁成为了基础研究与应用研究的热点。目前对180°畴壁结构的研究表明，180°畴壁包含Ising畴壁、Bloch畴壁与Néel畴壁三种结构类型，新型畴壁内部结构具有较低的畴壁能和畴壁翻转势垒，对铁电薄膜的电学性能有着重要的影响。目前，铁电薄膜的新型畴壁尚处于初步研究阶段，畴壁内部结构对铁电薄膜宏观物理性能的影响尚未进行系统研究。基于此，首先，建立了铁电薄膜畴壁手性模拟的理论模型，掌握了铁电薄膜手性畴壁及其在外场作用下演变的模拟方法；其次，掌握了温度、梯度系数及电场对铁电薄膜手性畴壁极化矢量的影响规律，建立了畴壁手性与外场之间的关联，掌握了使用外场调控铁电薄膜畴壁手性的机理；最后，掌握了电离辐射对畴壁手性的影响，以及畴壁手性对铁电薄膜电热和弹热性能的影响规律，进而通过手性畴壁调控铁电薄膜的宏观物理性能，实现了铁电薄膜性能的优化。