Unusual magnetotransport in twisted bilayer graphene.
Unusual magnetotransport in twisted bilayer graphene.
复制标题
DOI：
10.1073/pnas.2118482119
复制
发表时间：
2022-04-19
影响因子：
11.1
通讯作者：
Goldhaber-Gordon, David
中科院分区：
文献类型：
--
作者：
Finney, Joe;Sharpe, Aaron L.;Fox, Eli J.;Hsueh, Connie L.;Parker, Daniel E.;Yankowitz, Matthew;Chen, Shaowen;Watanabe, Kenji;Taniguchi, Takashi;Dean, Cory R.;Vishwanath, Ashvin;Kastner, M. A.;Goldhaber-Gordon, David
当两层石墨烯被扭曲到1.1°的魔角时，所产生的平坦的莫尔带可以拥有奇异的相关电子态，如超导性和铁磁性。在这里，我们展示了在1.38°下扭曲的双层石墨烯装置的输运性质，这比魔角高得多，我们不认为会出现奇异的相关态。相反，我们在调整载流子密度和垂直磁场时，在器件的电阻率中看到了一些不寻常的行为。我们可以用一个基于霍夫施塔特蝴蝶的简单模型来重现这些行为。这些结果揭示了扭曲双层石墨烯的潜在性质。我们提出了具有1.38°层间扭转的双层石墨烯的输运测量。与其他扭曲角大大大于1.1°的装置一样，我们没有观察到相关的绝缘状态或带重组。然而，我们确实在磁输运中观察到一些非常不寻常的行为。在摩尔流带半填充附近的大密度范围内，磁电阻是大的二次型。在这些相同的密度上，与朗道能级之间的间隙相对应的磁电阻最小值作为密度和场的函数而分裂和弯曲。我们在具有各向异性跳跃项的三角形晶格上的霍夫施塔特蝴蝶的简单紧密结合模型中再现了相同的分裂和弯曲行为。这些特征似乎是霍夫施塔特蝴蝶的一般实验表现，并可能为扭曲双层石墨烯的涌现状态提供见解。
When two sheets of graphene are twisted to the magic angle of 1.1∘, the resulting flat moiré bands can host exotic correlated electronic states such as superconductivity and ferromagnetism. Here, we show transport properties of a twisted bilayer graphene device at 1.38∘, far enough above the magic angle that we do not expect exotic correlated states. Instead, we see several unusual behaviors in the device’s resistivity upon tuning both charge carrier density and perpendicular magnetic field. We can reproduce these behaviors with a surprisingly simple model based on Hofstadter’s butterfly. These results shed light on the underlying properties of twisted bilayer graphene. We present transport measurements of bilayer graphene with a 1.38∘ interlayer twist. As with other devices with twist angles substantially larger than the magic angle of 1.1∘, we do not observe correlated insulating states or band reorganization. However, we do observe several highly unusual behaviors in magnetotransport. For a large range of densities around half filling of the moiré bands, magnetoresistance is large and quadratic. Over these same densities, the magnetoresistance minima corresponding to gaps between Landau levels split and bend as a function of density and field. We reproduce the same splitting and bending behavior in a simple tight-binding model of Hofstadter’s butterfly on a triangular lattice with anisotropic hopping terms. These features appear to be a generic class of experimental manifestations of Hofstadter’s butterfly and may provide insight into the emergent states of twisted bilayer graphene.
登录
查看更多内容
影响因子：
13.6
作者：
Fernandes, Rafael M.;Venderbos, Jorn W. F.
通讯作者：
Venderbos, Jorn W. F.
影响因子：
10.8
作者：
Kim, Youngwook;Herlinger, Patrick;Smet, Jurgen H.
通讯作者：
Smet, Jurgen H.
影响因子：
3.7
作者：
Bistritzer, R.;MacDonald, A. H.
通讯作者：
MacDonald, A. H.
影响因子：
8.6
作者：
Cao, Y.;Luo, J. Y.;Jarillo-Herrero, P.
通讯作者：
Jarillo-Herrero, P.
影响因子：
3.7
作者：
HAN, JH;THOULESS, DJ;KOHMOTO, M
通讯作者：
KOHMOTO, M