Breaking of Inversion Symmetry and Interlayer Electronic Coupling in Bilayer Graphene Heterostructure by Structural Implementation of High Electric Displacement Fields,The Journal of Physical Chemistry Letters

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Breaking of Inversion Symmetry and Interlayer Electronic Coupling in Bilayer Graphene Heterostructure by Structural Implementation of High Electric Displacement Fields
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2022-12-08 , DOI: 10.1021/acs.jpclett.2c02407
Marek Kolmer ₁ , Wonhee Ko ₂ , Joseph Hall _{1,

3} , Shen Chen _{1,

3} , Jianhua Zhang ₄ , Haijun Zhao ₅ , Liqin Ke ₁ , Cai-Zhuang Wang _{1,

3} , An-Ping Li ₂ , Michael C Tringides _{1,

3}

Affiliation

Controlling the interlayer coupling in two-dimensional (2D) materials generates novel electronic and topological phases. Its effective implementation is commonly done with a transverse electric field. However, phases generated by high displacement fields are elusive in this standard approach. Here, we introduce an exceptionally large displacement field by structural modification of a model system: AB-stacked bilayer graphene (BLG) on a SiC(0001) surface. We show that upon intercalation of gadolinium, electronic states in the top graphene layers exhibit a significant difference in the on-site potential energy, which effectively breaks the interlayer coupling between them. As a result, for energies close to the corresponding Dirac points, the BLG system behaves like two electronically isolated single graphene layers. This is proven by local scanning tunneling microscopy (STM)/spectroscopy, corroborated by density functional theory, tight binding, and multiprobe STM transport. The work presents metal intercalation as a promising approach for the synthesis of 2D graphene heterostructures with electronic phases generated by giant displacement fields.

中文翻译：

高电位移场的结构实现双层石墨烯异质结构中反演对称性的破缺和层间电子耦合

控制二维 (2D) 材料中的层间耦合会产生新颖的电子相和拓扑相。其有效实施通常通过横向电场来完成。然而，在这种标准方法中，高位移场产生的相位是难以捉摸的。在这里，我们通过模型系统的结构修改引入了异常大的位移场：SiC（0001）表面上的AB堆叠双层石墨烯（BLG）。我们发现，在插入钆后，顶部石墨烯层中的电子态在现场势能方面表现出显着差异，这有效地打破了它们之间的层间耦合。因此，对于接近相应狄拉克点的能量，BLG 系统的行为就像两个电子隔离的单石墨烯层。这已通过局部扫描隧道显微镜 (STM)/光谱学得到证明，并通过密度泛函理论、紧密结合和多探针 STM 传输得到证实。这项工作表明金属插层是合成二维石墨烯异质结构的一种有前途的方法，该异质结构具有由大位移场产生的电子相。

更新日期：2022-12-08

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