Electronic correlations in twisted bilayer graphene near the magic angle
Electronic correlations in twisted bilayer graphene near the magic angle
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DOI：
10.1038/s41567-019-0606-5
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发表时间：
2019-11-01
期刊：
影响因子：
19.6
通讯作者：
Nadj-Perge, Stevan
中科院分区：
文献类型：
--
作者：
Choi, Youngjoon;Kemmer, Jeannette;Nadj-Perge, Stevan
扭曲角约为1.1度的扭曲双层石墨烯具有一对隔离的平坦电子带，并形成了研究强相关电子的平台。在这里，我们使用扫描隧道显微镜来探测高度可调的扭曲双层石墨烯器件的局部特性，并表明当与费米能级对齐时，平坦带会变形。当能带被半填充时，我们观察到起源于相关绝缘态的间隙的发展。在电荷中性附近，我们发现了一个以前未识别的相关制度，具有增强分裂的平带。我们描述了这一点在一个微观模型，预测一个强烈的趋势，对cross-ordering。我们的研究结果提供了深入的见解，打破相关效应，并强调电子相互作用的重要性，所有填充分数在扭曲的双层石墨烯。
Twisted bilayer graphene with a twist angle of around 1.1 degrees features a pair of isolated flat electronic bands and forms a platform for investigating strongly correlated electrons. Here, we use scanning tunnelling microscopy to probe the local properties of highly tunable twisted bilayer graphene devices and show that the flat bands deform when aligned with the Fermi level. When the bands are half-filled, we observe the development of gaps originating from correlated insulating states. Near charge neutrality, we find a previously unidentified correlated regime featuring an enhanced splitting of the flat bands. We describe this within a microscopic model that predicts a strong tendency towards nematic ordering. Our results provide insights into symmetry-breaking correlation effects and highlight the importance of electronic interactions for all filling fractions in twisted bilayer graphene.