Superlattice-Induced Insulating States and Valley-Protected Orbits in Twisted Bilayer Graphene
Superlattice-Induced Insulating States and Valley-Protected Orbits in Twisted Bilayer Graphene
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DOI：
10.1103/physrevlett.117.116804
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发表时间：
2016-09-07
影响因子：
8.6
通讯作者：
Jarillo-Herrero, P.
中科院分区：
文献类型：
--
作者：
Cao, Y.;Luo, J. Y.;Jarillo-Herrero, P.
扭曲双层石墨烯(TBLG)是最简单的范德华异质结构之一，但它产生了复杂的电子系统，云纹物理和层间杂化效应之间存在错综复杂的相互作用。我们报道了高迁移率小角TBLG器件的电子输运测量，结果表明在超晶格带边存在明显的绝缘态，热激活带隙比理论预测的大几倍。此外，Shubnikov-de Haas振荡和紧束缚计算表明，能带结构由两条相交的费米等高线组成，它们的交叉点实际上是非杂化的。我们将其归因于动量传递大于莫尔波矢量的层间跳跃幅度被指数抑制。
Twisted bilayer graphene (TBLG) is one of the simplest van der Waals heterostructures, yet it yields a complex electronic system with intricate interplay between moire physics and interlayer hybridization effects. We report on electronic transport measurements of high mobility small angle TBLG devices showing clear evidence for insulating states at the superlattice band edges, with thermal activation gaps several times larger than theoretically predicted. Moreover, Shubnikov-de Haas oscillations and tight binding calculations reveal that the band structure consists of two intersecting Fermi contours whose crossing points are effectively unhybridized. We attribute this to exponentially suppressed interlayer hopping amplitudes for momentum transfers larger than the moire wave vector.