强关联稀土材料薄膜体系的拓扑相研究

Topological insulators is one of the hot spot in the condensed matter physics in recent years. The topological insulators with the topology protected surface states which are not affected by external factors such as defects and impurities.At present,the theoretically predicted topological insulators are mostly semiconductor materials, which are weak-correlated system. Due to the limited of method for strongly correlated materials, the development in strongly correlated topological insulators is at the early stage. Now the predicted strongly correlated topological insulators are SmB6,YbB12,PuTe.Types and Numbers are very limited, However, the emergence of strong correlation effect will bring the development of topological insulators many new theoretical problems, such as topological transition between different topological ordered states, and electronic interactions can change the electronic structure of topological index, etc. So this project will use the latest development of strong correlation material method of DFT + DMFT, and develop a simulation package that can be used to study the correlation of topological insulators; Then use this package to study the topological properties of the strongly correlated topological insulator material under the condition of ultrathin film. Also, through the study of the electronic structure of rare earth materials monopnictides, trying to find out a new topological material.

拓扑绝缘体(TI)由于具有不受缺陷、杂质等外界因素影响的拓扑表面态而受到凝聚态领域的科学家们所青睐，并迅速成为研究热点之一。目前，理论上预言了许多TIs，不过它们大多是半导体材料，电子间的关联效应较小。具有强关联效应的TI研究正处在起步阶段，目前被预言出来的强关联TI有SmB6、YbB12、PuTe等，种类和数目非常有限。然而，强关联效应的出现会给TI的发展带来许多全新的理论问题，如电子－电子相互作用是否能改变电子结构的拓扑指数等等。对于强关联体系，基于LDA的第一性原理软件将失效。因此本项目首先将基于近年来发展的DFT+DMFT方法，发展出一套适用于研究强关联薄膜材料的程序包，并加入计算强关联拓扑指数的功能；其次利用这个程序包集中研究强关联拓扑绝缘体材料在薄膜条件下拓扑性质，旨在研究不同的关联环境对拓扑性质的影响；最后利用软件包研究稀土材料磷化物的电子结构，试图找出一类新的拓扑材料

拓扑绝缘体(TI)由于具有不受缺陷、杂质等外界因素影响的拓扑表面态而受到凝聚态领域的科 学家们所青睐，并迅速成为研究热点之一。然而预言的强关联材料不多，涉及的拓扑态也相对有限，同时相关的工具也非常有限。基于这些出发点，在这个基金的支持下，我们积极参与开发具有自主知识产权的关联电子体系第一性原理模拟软件CESSP。我们负责动力学平均场模块的研发（软件第６完成人），并取得软件著作权。同时独立研发了可以研究晶体材料拓扑性质的软件WannierTools，并将其开源，得到同行的广泛使用和引用。我们积极将软件应用于拓扑材料的研究上，解决了几个重要的问题，如Weyl点个数和arc表面态的关系等。.