Institute for Theoretical Physics and Department of Modern Physics, University of Science and Technology of China, Hefei, 230026, People's Republic of China.
J Phys Condens Matter. 2012 Aug 15;24(32):325502, 1-6. doi: 10.1088/0953-8984/24/32/325502. Epub 2012 Jul 12.
We study a star lattice with Rashba spin-orbit coupling and an exchange field and find that there is a quantum anomalous Hall effect in this system, and that there are five energy gaps at Dirac points and quadratic band crossing points. We calculate the Berry curvature distribution and obtain the Hall conductivity (Chern number ν) quantized as integers, and find that ν =- 1,2,1,1,2 when the Fermi level lies in these five gaps. Our model can be viewed as a general quantum anomalous Hall system and, in limit cases, can give what the honeycomb lattice and kagome lattice give. We also find that there is a nearly flat band with ν = 1 which may provide an opportunity for realizing the fractional quantum anomalous Hall effect. Finally, the chiral edge states on a zigzag star lattice are given numerically, to confirm the topological property of this system.
我们研究了一个具有拉什巴自旋轨道耦合和交换场的星型晶格，发现该系统存在量子反常霍尔效应，在狄拉克点和二次能带交叉点处存在五个能隙。我们计算了Berry 曲率分布，并得到了霍尔电导率（陈数 ν）的量子化整数，发现当费米能级位于这五个能隙中时，ν 分别为-1、2、1、1、2。我们的模型可以看作是一个一般的量子反常霍尔系统，在极限情况下，可以给出蜂窝晶格和 kagome 晶格的结果。我们还发现存在一个ν=1 的近平带，这可能为实现分数量子反常霍尔效应提供了机会。最后，数值给出了锯齿形星型晶格上的手性边缘态，以验证该系统的拓扑性质。
