Quantum Hall Effect in Bernal Stacked and Twisted Bilayer Graphene Grown on Cu by Chemical Vapor Deposition

TL;DR

This study investigates the quantum Hall effect in bilayer graphene grown on copper substrates via chemical vapor deposition, revealing different stacking configurations and their influence on quantum Hall states through magnetotransport measurements.

Contribution

It provides the first detailed analysis of quantum Hall states in CVD-grown bilayer graphene with mixed Bernal and twisted stacking domains.

Findings

Bernal-stacked bilayer shows quantum Hall states at ν=4, 8, 12

Twisted bilayer exhibits superposition of monolayer quantum Hall states

Carrier density varies with gate bias and inter-layer capacitance

Abstract

We examine the quantum Hall effect in bilayer graphene grown on Cu substrates by chemical vapor deposition. Spatially resolved Raman spectroscopy suggests a mixture of Bernal (A-B) stacked and rotationally faulted (twisted) domains. Magnetotransport measurements performed on bilayer domains with a wide 2D band reveal quantum Hall states (QHSs) at filling factors $\nu=4, 8, 12$ consistent with a Bernal stacked bilayer, while magnetotransport measurements in bilayer domains defined by a narrow 2D band show a superposition of QHSs of two independent monolayers. The analysis of the Shubnikov-de Haas oscillations measured in twisted graphene bilayers provides the carrier density in each layer as a function of the gate bias and the inter-layer capacitance.