Tunable van Hove singularities and correlated states in twisted monolayer-bilayer graphene
Tunable van Hove singularities and correlated states in twisted monolayer-bilayer graphene
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DOI：
10.1038/s41567-021-01172-9
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发表时间：
2021-02-18
期刊：
影响因子：
19.6
通讯作者：
Shi, Yanmeng
中科院分区：
文献类型：
--
作者：
Xu, Shuigang;Al Ezzi, Mohammed M.;Shi, Yanmeng
理解和调整相关态对现代凝聚态物理学具有重要的意义。最近在魔角扭曲双层石墨烯中发现的非常规超导性和莫特样绝缘态为研究相关现象提供了一个独特的平台，其中库仑能占主导地位，而不是由于杂化平带而导致的淬火动能。将这种方法扩展到扭曲多层石墨烯的情况下，由于系统的对称性降低，可以对能带结构进行更高的控制。本文研究了扭曲单层-双层石墨烯（单层石墨烯异质结构之上的双层）的电子输运性质。我们观察到van Hove奇点的形成，这些奇点可以通过改变扭曲角或外电场而高度可调，并且在最佳条件下可以产生强的相关效应。我们对观察到的电子结构提供了基本的理论解释。单层和双层石墨烯的结构之间有一个小的扭转，显示出相关的绝缘状态，可以通过改变扭转角度或施加电场来调节。
Understanding and tuning correlated states is of great interest and importance to modern condensed-matter physics. The recent discovery of unconventional superconductivity and Mott-like insulating states in magic-angle twisted bilayer graphene presents a unique platform to study correlation phenomena, in which the Coulomb energy dominates over the quenched kinetic energy as a result of hybridized flat bands. Extending this approach to the case of twisted multilayer graphene would allow even higher control over the band structure because of the reduced symmetry of the system. Here we study electronic transport properties of twisted monolayer-bilayer graphene (a bilayer on top of monolayer graphene heterostructure). We observe the formation of van Hove singularities that are highly tunable by changing either the twist angle or external electric field and can cause strong correlation effects under optimum conditions. We provide basic theoretical interpretations of the observed electronic structure.A structure of monolayer and bilayer graphene with a small twist between them shows correlated insulating states that can be tuned by changing the twist angle or applying an electric field.