单个双原子层铋(Bi)薄膜能带结构的界面调控和边缘态研究

在现今拓扑绝缘体研究领域，铋元素起到非常关键的作用。铋自身具有奇特的量子力学特性。近期理论计算表明，单个双原子层铋Bi(111)薄膜可能是一种新的二维拓扑绝缘体系统，迫切需要在实验上对此开展系统性研究。我们计划通过分子束外延的方法，在拓扑绝缘体Bi2Te3和Bi2Se3等薄膜基底上外延生长高质量单个双原子层的Bi(111)薄膜。我们前期计算表明，界面效应会大大增强超薄Bi(111)中Rashba自旋轨道耦合，从而在Bi（111）薄膜中产生自旋极化的螺旋型狄拉克圆锥电子结构。我们将采用高分辨率角分辨和自旋分辨光子能谱确定其精细能带结构，并进一步研究其电子结构和基底条件的关系，寻找调节的方法。同时，也将利用低温扫描隧道显微镜和扫描隧道谱研究Bi(111)中可能存在的一维拓扑边缘态。利用原位四探针测量技术Bi(111)的电学性质。

Bi plays very important role in the field of topological insulator. Bi has unique properties. Recent theoretical work proposed that single bilayer Bi(111) could be a two-dimensional topological insulator, which requires systematical experimental study on this system. We plan to use molecular beam epitaxy technique to grow high quality single bilayer Bi(111) on topological insulator Bi2Te3 and Bi2Se3 thin films。Our preliminary calculation shows that helical Dirac cone can form in the single bilayer Bi(111) resulting from the enhanced Rashba type spin-orbital coupling due to interface effects. By using high resolution angle-resolved and spin-resolved photoemission spectroscopy, we will study the electronic energy band structures of single bilayer Bi(111) and its dependence of the substrates. The one dimensional edge states in Bi(111) will be also explored by low-temperature scanning tunneling microscopy/spectroscopy. Electronic transportation properties will be studied using in situ four probes measurements.