Development of Multi-Physics Instability Criterion for Atomic Structures and Application to Domain Switching in Ferroelectrics under External Electric Field
Development of Multi-Physics Instability Criterion for Atomic Structures and Application to Domain Switching in Ferroelectrics under External Electric Field
复制标题
DOI：
10.2472/jsms.61.155
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
T. Shimada;H. Sakamoto;T. Kitamura
中科院分区：
文献类型：
--
作者：
T. Shimada;H. Sakamoto;T. Kitamura
为了理解有限电场下铁电不稳定性的本质，例如，作为铁电器件临界失效的起源，畴变和极化反转，必须评估铁电状态变得不稳定的临界电学和/或机械条件。然而，对于这样一个力学和电学性质相互作用的多物理场系统的不稳定性判据还没有被提出。本文发展了一种分析方法，严格描述了有限电场和/或机械载荷作用下任意原子结构的多物理场不稳定性判据。根据所提出的方法，不稳定开始时的最小特征值的海森矩阵的势能达到零。相应的本征矢量表示原子在不稳定性下的位移。我们将该方法应用于180°畴壁的铁电PbTiO 3在外部电场下，我们的标准可以成功地描述不稳定的开始，即，畴切换，以及它们的位移模式在切换。这清楚地表明了我们的多物理不稳定性判据的有效性。
To understand the nature of ferroelectric instabilities under finite electric fields, e.g., domain switching and polarization reversal, as an origin of critical failure of ferroelectric devices, it is essential to evaluate critical electrical and/or mechanical conditions where the ferroelectric state becomes unstable. However, the instability criterion for such a multi-physics system where the mechanical and electric properties interact each other has not yet been proposed. In this paper, we developed an analytical method to rigorously describe the multi-physics instability criterion for arbitrary atomic structures under finite electric field and/or mechanical load. According to the proposed method, the instability starts when the minimum eigenvalue of the Hessian matrix of the potential energy reaches zero. The corresponding eigenvector indicates the displacement of atoms at the instability. We applied the method to 180° domain walls in ferroelectric PbTiO3 under external electric fields, and our criterion can successfully describe the onset of instability, namely, the domain switching, as well as their displacement pattern at the switching. This clearly indicates the validity of our multi-physics instability criterion.