Electron-hole hybridization in bilayer graphene

Siqi Wang; Mervin Zhao; Changjian Zhang; Sui Yang; Yuan Wang; Kenji Watanabe; Takashi Taniguchi; James Hone; Xiang Zhang

doi:10.1093/nsr/nwz212

Electron-hole hybridization in bilayer graphene

Natl Sci Rev. 2020 Feb;7(2):248-253. doi: 10.1093/nsr/nwz212. Epub 2019 Dec 19.

Authors

Siqi Wang^{1

2}, Mervin Zhao^{1

2}, Changjian Zhang³, Sui Yang^{1

2}, Yuan Wang^{1

2}, Kenji Watanabe⁴, Takashi Taniguchi⁴, James Hone³, Xiang Zhang^{1

2

5}

Affiliations

¹ NSF Nanoscale Science and Engineering Center (NSEC), University of California, Berkeley, CA 94720, USA.
² Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
³ Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA.
⁴ National Institute for Materials Science, Tsukuba, Japan.
⁵ Faculties of Sciences and Engineering, University of Hong Kong, Hong Kong, China.

Abstract

Band structure determines the motion of electrons in a solid, giving rise to exotic phenomena when properly engineered. Drawing an analogy between electrons and photons, artificially designed optical lattices indicate the possibility of a similar band modulation effect in graphene systems. Yet due to the fermionic nature of electrons, modulated electronic systems promise far richer categories of behaviors than those found in optical lattices. Here, we uncovered a strong modulation of electronic states in bilayer graphene subject to periodic potentials. We observed for the first time the hybridization of electron and hole sub-bands, resulting in local band gaps at both primary and secondary charge neutrality points. Such hybridization leads to the formation of flat bands, enabling the study of correlated effects in graphene systems. This work may provide a novel way to manipulate electronic states in layered systems, which is important to both fundamental research and application.

Keywords: band modulation; bilayer graphene; periodic potential.