拓扑晶态绝缘体的薄膜生长及能带调控

项目名称： 拓扑晶态绝缘体的薄膜生长及能带调控

项目编号： No.11474058

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 修发贤

作者单位： 复旦大学

项目金额： 88万元

中文摘要： 拓扑晶态绝缘体是一种由晶格对称性所引起的新型拓扑绝缘体。理论预测，拓扑晶态绝缘体在低对称性的晶面上不存在拓扑态，而在高对称性晶体表面具有导电的拓扑态，这与由时间反演对称性保护的传统拓扑态完全不同：其表面态的存在不依赖于自旋轨道耦合，而取决于晶体的对称性。因此研究如何利用和控制晶体的对称性成为拓扑晶态绝缘体的关键问题，而由此所带来的能带结构以及表面态的调控成为本领域的热点和难点。本课题将首先运用分子束外延技术生长高质量的Pb1-xSnxTe(Se)单晶薄膜,通过连续变化Pb组分、控制薄膜厚度、改变晶向以及测试温度，研究拓扑非平庸态到平庸态的相变过程以及在同一体系中实现三维拓扑态到二维拓扑态的转变。并在此基础上，结合理论，开展一系列表面态和边缘态调控方面的工作，例如运用电场和磁场进行调控。本课题的成果将为实现令人激动的量子化反常霍尔效应和量子自旋霍尔效应提供一定的实验基础和经验。

中文关键词： 拓扑晶态绝缘体；分子束外延；表面态；边缘态；霍尔效应

英文摘要： Topological crystalline insulators are new states of matter in which the topological nature of electronic structures arises from crystal symmetries. Theory predicts that the robust surface states exist with an even number of Dirac cones on high symmetric planes, instead of low symmetric ones. This new state of matter is fundamentally different from the traditional topological insulators: its surface states are not originated from a strong spin-orbit coupling but are from crystal symmetry. Therefore it is critical to understand the relation between the topological states and their crystal symmetry and to explore how to control the band structure/surface/edge states. In this project, we will first grow high-quality single crystalline Pb1-xSnxTe(Se) with molecular beam epitaxy. By systematically controlling Pb composition, film thickness, crystal orientation and measurement temperature, we aims to study the phase transitions of topological non-trivial to trivial states and 3-D to 2-D topological insulators. Combining theory, we will carry out the electrical and magnetic field controlled surface states/edge states. It is anticipated that this project may pave the way towards the discovery of quantized anomalous Hall effect and quantum spin hall effect in this system.

英文关键词： Topological Crystalline Insulator;Molecular Beam Epitaxy;Surface States;Edge States;Hall Effect