Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe2/MoSe2bilayers
Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe2/MoSe2bilayers
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DOI：
10.1038/s41565-020-0728-z
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发表时间：
2020-07-13
影响因子：
38.3
通讯作者：
Park, Hongkun
中科院分区：
文献类型：
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作者：
Sung, Jiho;Zhou, You;Park, Hongkun
磁区分辨光谱揭示了近0度扭角MoSe2/MoSe2的局域原子注册和晶体对称性对单个磁区激子性质的影响。通过堆积和扭转获得的范德华异质结被用来产生莫尔超晶格(1)，使固体系统具有新的光学和电学性质。过渡金属二卤化物(TMD)扭曲双层膜中的莫尔晶格导致激子陷阱(2-5)、基质Mott绝缘态和超导态(6)，并作为独特的Hubbard系统(7-9)，其关联的电子态可以被光学地检测和操纵。在结构上，这些扭曲的异质结构以原子重建和磁区形成为特征(10-14)。然而，由于云纹区的纳米尺度，原子重构对其电子和激子性质的影响还没有得到系统的研究。在这里，我们使用近0度扭角的MoSe2/MoSe(2)大的菱面体AB/BA域(15)双层膜来直接探测具有远场光学的单个域的激子性质。结果表明，该系统具有破缺的镜像/反转对称性，AB区和BA区以相反方向的离面电偶极矩支持层间激子。基态Gamma-K层间激子的偶极取向可以随电场反转，而高能K-K层间激子与层内K-K激子发生场不对称杂化。我们的研究揭示了晶体对称性对TMD激子的影响，并指出了通过域图案工程实现拓扑非平凡系统(16，17)、奇异亚表面(18)、集体激子相(19)和量子发射体阵列(20，21)的新途径。
Domain-resolved spectroscopy reveals the impact of local atomic registry and crystal symmetry on the exciton properties of individual domains in near-0 degrees-twist-angle MoSe2/MoSe2.Van der Waals heterostructures obtained via stacking and twisting have been used to create moire superlattices(1), enabling new optical and electronic properties in solid-state systems. Moire lattices in twisted bilayers of transition metal dichalcogenides (TMDs) result in exciton trapping(2-5), host Mott insulating and superconducting states(6)and act as unique Hubbard systems(7-9)whose correlated electronic states can be detected and manipulated optically. Structurally, these twisted heterostructures feature atomic reconstruction and domain formation(10-14). However, due to the nanoscale size of moire domains, the effects of atomic reconstruction on the electronic and excitonic properties have not been systematically investigated. Here we use near-0 degrees-twist-angle MoSe2/MoSe(2)bilayers with large rhombohedral AB/BA domains(15)to directly probe the excitonic properties of individual domains with far-field optics. We show that this system features broken mirror/inversion symmetry, with the AB and BA domains supporting interlayer excitons with out-of-plane electric dipole moments in opposite directions. The dipole orientation of ground-state Gamma-K interlayer excitons can be flipped with electric fields, while higher-energy K-K interlayer excitons undergo field-asymmetric hybridization with intralayer K-K excitons. Our study reveals the impact of crystal symmetry on TMD excitons and points to new avenues for realizing topologically non-trivial systems(16,17), exotic metasurfaces(18), collective excitonic phases(19)and quantum emitter arrays(20,21)via domain-pattern engineering.