Theory of semi-conducting moiré materials

将原子薄的2D晶体堆叠成多层膜，为凝聚态引入了一个全新的系统：小角莫尔晶格。这种材料的原型石墨烯以外的云纹系统，在制造技术的发展的推动下，现在开始被研究。石墨烯云纹的非凡物理特性使人们希望，普通云纹材料，尤其是由二维半导体制成的云纹材料，可能会呈现出一种既具有基本的科学价值，又具有潜在的广泛技术应用的系统。然而，由二维半导体(如过渡金属二盐化合物)形成的小角度莫尔的结构复杂性，到目前为止阻碍了对这些系统的探索。因此，我们的目的是提供对小角半导体莫尔基本电子结构的理解：(I)允许探索小角度极限的连续介质理论的发展和应用，(Ii)小角度极限中的带隙边缘的性质和莫尔驱动局域化的作用，以及(Iii)对少数层半导体的带隙边缘进行“莫尔设计”的可能性。在积累了这些专业知识之后，我们计划研究这类系统的关键光学特性。特别是，光吸收光谱将用无参数的“自举”方法计算，并研究了单粒子和激子在云纹上的相互作用。

The stacking of atomically thin 2D crystals into multilayers has introduced to the condensed matter community an essentially new system: the small angle moire lattice. Moire systems beyond graphene, the prototype of such materials, are, spurred by developments in fabrication techniques, now beginning to be investigated. The remarkable physics of the graphene moire leads to hopes that the general moire material, especially when created from 2d semiconductors, may present a system both fundamental scientific interest, as well as being of potentially wide technological application. However, the structural complexity of small angle moires created from 2d semiconductors such as transition metal dichalcogenides, has, to date, prevented exploration these systems.We thus aim to provide an understanding of the basic electronic structure of small angle semi-conducting moire: (i) the development and application of continuum theories that will allow the small angle limit to be explored, (ii) the nature of the gap edge and the role of moire driven localization in the small angle limit, and (iii) the possibility of “moire designing” the gap edge of few layer semiconductors. Subsequent to the accumulation of this expertise we then plan to investigate the key optical properties of such systems. In particular the optical absorption spectrum will be calculated both with a parameter free "bootstrap" approach, and the interplay of single particle and excitonic localization on the moire investigated.