Intralayer charge-transfer moire excitons in van der Waals superlattices
Intralayer charge-transfer moire excitons in van der Waals superlattices
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DOI：
10.1038/s41586-022-04991-9
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发表时间：
2022-09-01
期刊：
影响因子：
64.8
通讯作者：
Louie, Steven G.
中科院分区：
文献类型：
--
作者：
Naik, Mit H.;Regan, Emma C.;Louie, Steven G.
过渡金属二硫属化合物异质双分子膜的云纹图案已被证明是一个理想的平台，在其上托管不寻常的相关电子相位，新兴的磁性和相关激子物理。虽然通过光学测量建立了新的莫尔激子态的存在（1-4），但这些状态的微观性质仍然知之甚少，通常依赖于经验拟合模型。在这里，结合大规模的第一性原理GW（其中G和W表示的单粒子绿色的功能和屏蔽库仑相互作用，分别）加上Bethe-Salpeter计算和微反射光谱，我们确定的激子共振的性质在WSe 2/WS 2莫尔超晶格，发现一组丰富的莫尔激子，不能被捕获的流行的连续模型。我们的计算显示了具有不同特征的莫尔激子，包括调制的Wannier激子和以前未识别的层内电荷转移激子。这些独特的激子字符的签名实验证实了不同的莫尔激子共振的独特的载流子密度和磁场的依赖性。我们的研究突出了过渡金属二硫属化物莫尔超晶格中可能出现的高度非平凡的激子态，并提出了通过工程激发态具有特定空间特性来调整莫尔系统中多体物理的新方法。
Moire patterns of transition metal dichalcogenide heterobilayers have proved to be an ideal platform on which to host unusual correlated electronic phases, emerging magnetism and correlated exciton physics. Whereas the existence of new moire excitonic states is established(1-4) through optical measurements, the microscopic nature of these states is still poorly understood, often relying on empirically fit models. Here, combining large-scale first-principles GW (where G and W denote the one-particle Green's function and the screened Coulomb interaction, respectively) plus Bethe-Salpeter calculations and micro-reflection spectroscopy, we identify the nature of the exciton resonances in WSe2/WS2 moire superlattices, discovering a rich set of moire excitons that cannot be captured by prevailing continuum models. Our calculations show moire excitons with distinct characters, including modulated Wannier excitons and previously unidentified intralayer charge-transfer excitons. Signatures of these distinct excitonic characters are confirmed experimentally by the unique carrier-density and magnetic-field dependences of different moire exciton resonances. Our study highlights the highly non-trivial exciton states that can emerge in transition metal dichalcogenide moire superlattices, and suggests new ways of tuning many-body physics in moire systems by engineering excited-states with specific spatial characters.