铁砷与铁硒基化合物的磁性与金属-绝缘体转变研究

项目名称： 铁砷与铁硒基化合物的磁性与金属-绝缘体转变研究

项目编号： No.11204311

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： 全亚民

作者单位： 中国科学院合肥物质科学研究院

项目金额： 25万元

中文摘要： 理解铁砷与铁硒基超导材料基态复杂的磁构型和丰富的金属或绝缘相对揭示铁基超导体的配对机制和正常态性质具有重要的理论和实际价值。本项目提出从具有关联作用的真实铁基材料的紧束缚模型出发，通过发展多参数的Kotliar-Ruckenstein Slave-Boson平均场方法，开展对多轨道关联的铁基化合物正常相中的金属-绝缘体转变的研究，分析自旋阻挫和轨道涨落在金属-绝缘体转变中的主要作用，重点讨论不同粒子填充数时次近邻跳跃、Hund耦合以及晶场等因素对铁基体系基态性质以及金属-绝缘体转变的影响，探讨铁砷与铁硒基超导材料中是否存在轨道选择的Mott转变及发生的条件，并由轨道分辨性质揭示其中反常磁性和复杂基态的微观机理。本项目的研究不仅有助于我们理解铁基超导材料中丰富的磁现象和超导的形成机制，为进一步的实验提供理论基础，而且还为理解其它多轨道超导体的正常态性质和超导配对的起源提供理论指导。

中文关键词： 多带关联电子体系；金属-绝缘体转变；电子结构；铁基超导；轨道选择莫特转变

英文摘要： In order to reveal the normal state properties and the mechanism for the formation of Cooper pairs of iron based superconductor materials, it is of important theoretical significance and practical value to study the complex magnetic structure and rich metal or insulating phases of the FeAs and FeSe materials' ground states. This project is to generalize multi-parameter Kotliar-Ruckenstein Slave-Boson mean field method based on tight binding model of the real materials, and to study the metal-insulator transition in normal state of iron based compounds which is a multi-orbital correlated system. The aim is to analyze the effects of spin frustration, orbital fluctuation, next nearest neighbor hopping, Hund's rule coupling and crystal field splitting on the ground state properties and metal-insulator transition of iron-based superconductor, and to uncover whether there is orbital selective Mott transition (OSMT) in FeAs and FeSe based superconductors or not, and then to present the critical parameters for OSMT, which can be used to reveal the microcosmic theory for the unusual magnetic property and complex ground states. It will not only be helpful to the better understanding of the rich magnetic properties and the forming mechanism of Cooper pairing of iron based materials, but also provide a theoretical basis fo

英文关键词： multi-band correlated electron system；metal-insulator transition；electronic structure；iron based superconductor；orbital selective Mott-insulator transition