Wu Fengcheng, Lovorn Timothy, MacDonald A H
Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA.
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Phys Rev Lett. 2017 Apr 7;118(14):147401. doi: 10.1103/PhysRevLett.118.147401. Epub 2017 Apr 5.
Moiré patterns are common in van der Waals heterostructures and can be used to apply periodic potentials to elementary excitations. We show that the optical absorption spectrum of transition metal dichalcogenide bilayers is profoundly altered by long period moiré patterns that introduce twist-angle dependent satellite excitonic peaks. Topological exciton bands with nonzero Chern numbers that support chiral excitonic edge states can be engineered by combining three ingredients: (i) the valley Berry phase induced by electron-hole exchange interactions, (ii) the moiré potential, and (iii) the valley Zeeman field.
莫尔条纹在范德华异质结构中很常见，可用于对元激发施加周期性势场。我们表明，长周期莫尔条纹会深刻改变过渡金属二卤化物双层的光吸收光谱，这些条纹会引入与扭曲角相关的卫星激子峰。通过结合三种因素可以设计出具有非零陈数且支持手性激子边缘态的拓扑激子带：（i）电子 - 空穴交换相互作用诱导的能谷贝里相位，（ii）莫尔势，以及（iii）能谷塞曼场。
