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arXiv 2210.03381cond-mat.mes-hall
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石墨烯/六方氮化硼莫尔超晶格中的莫尔声子

Moiré phonons in graphene/hexagonal boron nitride moiré superlattice

Lukas P. A. Krisna, Mikito Koshino

摘要:

采用连续介质模型对石墨烯/六方氮化硼莫尔超晶格的面内声学声子进行了理论研究。我们证明了各层的原始声子带被强烈杂化并重构为由色散带和平坦带组成的莫尔声子带。声子能带结构可以有效地描述了一个弹簧-质量网络模型来模拟莫尔畴壁的运动,其中的平带模式被解释为独立的,解耦的字符串的振动。我们还发现,由于hBN的反转对称性破缺,莫尔声子具有角动量,高振幅集中在窄隙区附近。最后,我们将同样的方法应用于扭曲双层石墨烯,我们发现G/hBN和TBG中平带模式的起源之间存在显着差异,反映了不同的几何结构域图案。

英文摘要:

We theoretically study in-plane acoustic phonons of graphene/hexagonal boron nitride moiré superlattice by using a continuum model. We demonstrate that the original phonon bands of individual layers are strongly hybridized and reconstructed into moiré phonon bands consisting of dispersive bands and flat bands. The phonon band structure can be effectively described by a spring-mass network model to simulate the motion of moiré domain walls, where the flat-band modes are interpreted as vibrations of independent, decoupled strings. We also show that the moiré phonon has angular momentum due to the inversion symmetry breaking by hBN, with high amplitudes concentrated near narrow gap region. Finally, we apply the same approach to twisted bilayer graphene, and we find a notable difference between the origins of the flat-band modes in G/hBN and TBG, reflecting distinct geometric structures of domain pattern.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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