Symmetry-dependent exciton-exciton interaction and intervalley biexciton in monolayer transition metal dichalcogenides
Symmetry-dependent exciton-exciton interaction and intervalley biexciton in monolayer transition metal dichalcogenides
复制标题
单层过渡金属二硫属化物中对称依赖的激子-激子相互作用和间隔双激子
DOI：
10.1038/s41699-022-00290-z
复制
发表时间：
2022
影响因子：
9.7
通讯作者：
Vladimir A. Osipov
中科院分区：
文献类型：
--
作者：
Hoang Ngoc Cam;Nguyen Thanh Phuc;Vladimir A. Osipov
过渡金属二硫属化合物（TMD）的单分子层多带结构产生谷内和谷间激子。人们已经对这些激子有了很多了解，但基本问题仍然存在，例如如何用它们的相关性在一个统一的图像中描述它们，来自不同谷的激子如何耦合形成谷间双激子？为了解决这个问题，我们从两个激子的组成载流子-费米子之间的相互关联导出激子哈密顿量。通过点对称群的不可约表示识别激子，我们发现它们的成对相互作用依赖于相互作用激子的对称性。除了来自不同谷的激子相互吸引形成谷间双激子的情况外，它通常是排斥的。我们建立了双激子结合能与激子质量和材料及周围环境的介电特性之间的半解析关系。总的来说，通过提供洞察到不同的激子和它们的相关性的性质，我们的理论模型捕获的激子相互作用特性允许一个包容性的描述的结构和能量特征的谷间双激子在单层TMD。
The multivalley band structure of monolayer transition metal dichalcogenides (TMDs) gives rise to intravalley and intervalley excitons. Much knowledge of these excitons has been gained, but fundamental questions remain, such as how to describe them all in a unified picture with their correlations, how are those from different valleys coupled to form the intervalley biexciton? To address the issues, we derive an exciton Hamiltonian from interpair correlations between the constituent carriers-fermions of two excitons. Identifying excitons by irreducible representations of their point symmetry group, we find their pairwise interaction depending on interacting excitons’ symmetry. It is generally repulsive, except for the case excitons from different valleys, which attract each other to form the intervalley biexciton. We establish a semianalytical relationship between the biexciton binding energy with exciton mass and dielectric characteristics of the material and surroundings. Overall, by providing insight into the nature of diverse excitons and their correlations, our theoretical model captures the exciton interaction properties permitting an inclusive description of the structure and energy features of the intervalley biexciton in monolayer TMDs.