低维拓扑绝缘体磁特性研究

Study on the Magnetic Property of Low Dimension Topological Insulator

摘要: 量子自旋霍尔效应是拓扑绝缘体(HgTe)中固有的现象，我们研究了不同结构的低维HgTe拓扑绝缘体材料在磁场下的能谱，经研究发现无论是方形量子点还是盘状量子点都有边缘态的存在，并且这些无需磁场存在的边缘态是一个很稳定的结构性质。但是在其施加外磁场时出现的是量子霍尔效应，即在磁场下HgTe量子点的边缘态都将受到影响，尤其是盘状的HgTe量子点在磁场下其边沿处电子都往同一方向运动。所有这些物理现象主要是由于磁场破坏了时间反演对称性而导致。

Abstract: Quantum spin hall effect (QSHE) is intrinsic phenomena in the topological insulator (HgTe). We investigate the energy spectrum of low dimension HgTe topological insulator with different structure under the magnetic field. Then we find that the square topological insulator quantum dot (TIQD) and disk-like TIQD both have edge states without magnetic field, and these edge states is very stable structure property. But there is quantum hall effect in the presence of external magnetic field; namely the edge states of HgTe QD all will be affected under magnetic field; espe-cially the electrons will move toward the same direction along the edge of disk-like HgTe QD under magnetic field. The main reason of all these physical phenomena is that the magnetic field breaks the time reversal symmetry.