Electron transport in folded bilayer-bilayer graphene/hexagonal boron nitride superlattices under high magnetic fields

TL;DR

This paper investigates electron transport in moiré superlattices formed by stacking bilayer or folded bilayer graphene with hexagonal boron nitride under high magnetic fields, revealing emergent Dirac points and their tunability.

Contribution

It demonstrates the fabrication and characterization of moiré superlattices with high magnetic field measurements, extending previous work and exploring temperature effects on transport properties.

Findings

Emergence of higher-generation Dirac points with narrow bandwidth.

Access to Dirac points via in-situ gate tuning.

Temperature dependence of resistivity and magnetoresistance.

Abstract

Employing graphene as a template, we fabricate moir\'e superlattices by stacking bilayer or folded bilayer-bilayer graphene (BLG or fBBLG) and hexagonal boron nitride (hBN), i.e., hBN/BLG/hBN or hBN/fBBLG/hBN stacks, with a small twist angle between the graphene and one of the two hBN layers. Because of the modulation due to the hBN, higher-generation Dirac points can emerge with a narrow bandwidth and van Hove singularities. In the moir\'e superlattice devices, we can therefore access the higher-generation Dirac points by in-situ gate tuning. This study is based on our previous paper (Appl. Phys. Express 13, 035003 (2020)). Here we show more extended data by applying high magnetic fields up to ~24 T. We also comment on the temperature dependence of the resistivity and magnetoresistance with reference to the 'plain' BLG data for a comparative study.