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Probing Interlayer Interactions and Commensurate–Incommensurate Transition in Twisted Bilayer Graphene through Raman Spectroscopy
ACS Nano ( IF 15.8 ) Pub Date : 2024-01-31 , DOI: 10.1021/acsnano.3c08344
Vineet Pandey 1 , Subhendu Mishra 2 , Nikhilesh Maity 2 , Sourav Paul 1 , Abhijith M B 1 , Ajit K Roy 3 , Nicholas R Glavin 3 , Kenji Watanabe 4 , Takashi Taniguchi 5 , Abhishek K Singh 2 , Vidya Kochat 1
ACS Nano ( IF 15.8 ) Pub Date : 2024-01-31 , DOI: 10.1021/acsnano.3c08344
Vineet Pandey 1 , Subhendu Mishra 2 , Nikhilesh Maity 2 , Sourav Paul 1 , Abhijith M B 1 , Ajit K Roy 3 , Nicholas R Glavin 3 , Kenji Watanabe 4 , Takashi Taniguchi 5 , Abhishek K Singh 2 , Vidya Kochat 1
Affiliation
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Twisted 2D layered materials have garnered much attention recently as a class of 2D materials whose interlayer interactions and electronic properties are dictated by the relative rotation/twist angle between the adjacent layers. In this work, we explore a prototype of such a twisted 2D system, artificially stacked twisted bilayer graphene (TBLG), where we probe, using Raman spectroscopy, the changes in the interlayer interactions and electron–phonon scattering pathways as the twist angle is varied from 0° to 30°. The long-range Moiré potential of the superlattice gives rise to additional intravalley and intervalley scattering of the electrons in TBLG, which has been investigated through their Raman signatures. Density functional theory (DFT) calculations of the electronic band structure of the TBLG superlattices were found to be in agreement with the resonant Raman excitations across the van Hove singularities in the valence and conduction bands predicted for TBLG due to hybridization of bands from the two layers. We also observe that the relative rotation between the graphene layers has a marked influence on the second order overtone and combination Raman modes signaling a commensurate–incommensurate transition in TBLG as the twist angle increases. This serves as a convenient and rapid characterization tool to determine the degree of commensurability in TBLG systems.
中文翻译：
通过拉曼光谱探测扭曲双层石墨烯中的层间相互作用和相称-不相称转变
扭曲二维层状材料作为一类二维材料最近引起了广泛关注，其层间相互作用和电子特性由相邻层之间的相对旋转/扭曲角度决定。在这项工作中，我们探索了这种扭曲二维系统的原型，即人工堆叠的扭曲双层石墨烯（TBLG），我们使用拉曼光谱探测了随着扭曲角度变化，层间相互作用和电子-声子散射路径的变化从 0° 到 30°。超晶格的长程莫尔势会引起 TBLG 中电子的额外谷内和谷间散射，这已通过拉曼特征进行了研究。 TBLG 超晶格电子能带结构的密度泛函理论 (DFT) 计算被发现与由于两层能带杂化而预测的 TBLG 价带和导带中跨范霍夫奇点的共振拉曼激发一致。我们还观察到，石墨烯层之间的相对旋转对二阶泛音和组合拉曼模式有显着影响，随着扭转角的增加，表明 TBLG 中的相称-不相称转变。这是一种方便、快速的表征工具，用于确定 TBLG 系统的可通约程度。
更新日期：2024-01-31
中文翻译：
通过拉曼光谱探测扭曲双层石墨烯中的层间相互作用和相称-不相称转变
扭曲二维层状材料作为一类二维材料最近引起了广泛关注，其层间相互作用和电子特性由相邻层之间的相对旋转/扭曲角度决定。在这项工作中，我们探索了这种扭曲二维系统的原型，即人工堆叠的扭曲双层石墨烯（TBLG），我们使用拉曼光谱探测了随着扭曲角度变化，层间相互作用和电子-声子散射路径的变化从 0° 到 30°。超晶格的长程莫尔势会引起 TBLG 中电子的额外谷内和谷间散射，这已通过拉曼特征进行了研究。 TBLG 超晶格电子能带结构的密度泛函理论 (DFT) 计算被发现与由于两层能带杂化而预测的 TBLG 价带和导带中跨范霍夫奇点的共振拉曼激发一致。我们还观察到，石墨烯层之间的相对旋转对二阶泛音和组合拉曼模式有显着影响，随着扭转角的增加，表明 TBLG 中的相称-不相称转变。这是一种方便、快速的表征工具，用于确定 TBLG 系统的可通约程度。
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