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arXiv 2202.12502cond-mat.mes-hall
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非对称扭转石墨烯多层膜中的重正化魔角

Renormalized Magic Angles in Asymmetric Twisted Graphene Multilayers

Adam Eaton, Yantao Li, Herbert Fertig, Babak Seradjeh

AI总结:

本文研究层间狄拉克点不对称(如费米速度不同)对扭转石墨烯多层膜魔角平带的影响,发现平带现象依然存在,且魔角可通过屏蔽或外层扭转角调控并数值增大。

摘要:

层间具有较小相对扭转角的堆叠石墨烯多层膜已被发现在一系列魔角处具有平带。我们考虑了层间狄拉克点不对称性,特别是每层中不同的费米速度,可能对这一现象产生的影响。这种不对称性可能通过与介电衬底的库仑相互作用导致的不相等费米速度重正化而引入。它也在四层系统中以近似方式出现,其中外层扭转角足够大,以至于由内两层的堆叠产生主导的莫尔周期性。我们在这些模型中发现,尽管存在这种不对称性,平带现象仍然持续存在,并且魔角通过控制双层系统中的屏蔽或四层系统中外层的扭转角而获得一定程度的可调性。值得注意的是,我们在模型中发现魔角的定量值有所增大。

英文摘要:

Stacked graphene multilayers with a small relative twist angle between each of the layers have been found to host flat bands at a series of magic angles. We consider the effect that Dirac point asymmetry between the layers, and in particular different Fermi velocities in each layer, may have on this phenomenon. Such asymmetry may be introduced by unequal Fermi velocity renormalizations through Coulomb interactions with a dielectric substrate. It also arises in an approximate way in tetralayer systems, in which the outer twist angles are large enough that there is a dominant moire periodicity from the stacking of the inner two layers. We find in such models that the flat band phenomenon persists in spite of this asymmetry, and that the magic angles acquire a degree of tunability through either controlling the screening in the bilayer system or the twist angles of the outer layers in the tetralayer system. Notably, we find in our models that the quantitative values of the magic angles are increased.

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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