Bilayer Graphene on hexagonal Boron Nitride and the Family of quantum MetaMaterial

TL;DR

This paper reports on the fabrication and characterization of hBN/Bilayer Graphene superlattices, revealing tunable energy gaps, non-trivial band topology, and van Hove singularities, advancing the understanding of quantum meta-materials.

Contribution

It introduces dual-gated hBN/Bilayer Graphene superlattices with tunable energy gaps and topological features, highlighting new quantum properties and engineering possibilities.

Findings

Energy gap at charge neutral point due to moire effect

Electric field tuning of the energy gap in BLG

Presence of van Hove singularities and non-trivial topology

Abstract

We report on the fabrication and characterization of dual-gated hexagonal boron nitride (hBN)/bilayer-graphene (BLG) superlattices. Due to the moire effect, the hBN/BLG superlattice harbors an energy gap at the charge neutral point (CNP) and the satellites even without a perpendicular electric field. In BLG, moreover, the application of a perpendicular electric field tunes the energy gap, which contrasts with the single-layer graphene (SLG) and is linked to the family of rhombohedral multilayer graphene. Therefore, the hBN/BLG superlattice is accompanied with non-trivial energy-band topology and a narrow energy band with van Hove singularities. By the dual gating, systematic engineering of the energy-band structure can be performed and the carrier concentration is fine-tunable. This review is an extended version of the talk based on ref. [1], which is also a supplementary to the ref. T. Iwasaki, Y. Morita, K. Watanabe, T. Taniguchi, Phys. Rev. B106, 165134 (2022) and Phys. Rev. B109, 075409 (2024). The data show the universality and diversity in the physics of the hBN/BLG superlattices.