钙钛矿LaNiO3 外延薄膜中结构耦合的金属-绝缘体转变的第一性原理研究

项目名称： 钙钛矿LaNiO3 外延薄膜中结构耦合的金属-绝缘体转变的第一性原理研究

项目编号： No.11204230

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 物理学I

项目作者： 缑高阳

作者单位： 西安交通大学

项目金额： 25万元

中文摘要： 钙钛矿LaNiO3 外延薄膜因奇特的金属-绝缘体转变效应近年来备受研究者们的关注。尽管实验上在薄膜样品制备和性能表征上取得了很大的进展，然而对于LaNiO3 外延薄膜的本征物理性质，尤其是其金属-绝缘体转变的物理机制尚存在较大的分歧。因此利用第一性原理计算对LaNiO3 外延薄膜本征物理性质的系统理论研究就显得尤为重要。本项目采用第一性原理方法，并结合Landau 相变理论，系统地研究外延生长的LaNiO3 薄膜和异质结构超晶格的晶体结构和电子态性质，揭示外延应力、薄膜厚度和界面效应对LaNiO3 薄膜物理性质的影响。据此，建立体系的Landau 相变模型，用以表征LaNiO3 薄膜因外延应力而发生的结构相转变，并重点探索体系中晶格、轨道和电荷有序自由度之间的相互耦合， 阐明上述物理量在LaNiO3 外延薄膜中金属-绝缘体转变效应中的贡献。

中文关键词： 第一性原理计算；金属-绝缘体转变；钙钛矿镍氧化物LaNiO3；外延薄膜；Landau 相变模型

英文摘要： Epitaxial strained Perovskite LaNiO3 thin film has recently become an active research topic due to its novel metal-insulator transition phenomenon. Despite the recent experimental progress in the synthesis and characterization of epitaxial strained LaNiO3 film, the underlying mechanism for its metal-insulator transition effect however is still under debate. Therefore,exploring the intrinsic properties of strained LaNiO3 system by means of ab initio computational method will be quite necessary. In this proposed research project, we will use density functional theory calculation, combining with Landau phase-transition formulism to study the crystal structures and electronic properties of the epitaxial strained LaNiO3 thin film and heterostructured super-lattice. We will also investigate the importance of epitaxial strain, film thickness and interface effect on the properties of LaNiO3 thin film. To characterize the strain induced structural phase transition in LaNiO3 film, we will examine the evolution of structural order parameters with respect to the epitaxial strain, using Landau formalism and ab initio-derived phenomenological coefficients. Based on our calculations, we will present a complete understanding of the coupling between crystal lattice, orbital and charge ordering. The impact of each physical quant

英文关键词： Ab-initio calculations；Metal-insulator transitions；Perovksite nickelate LaNiO3；Epitaxial strained thin film；Phenomenological Landau phase-transition formulism