Magnetotransport Properties of Quasi-Free Standing Epitaxial Graphene Bilayer on SiC: Evidence for Bernal Stacking

TL;DR

This study explores the magnetotransport behavior of quasi-free standing epitaxial graphene bilayer on SiC, revealing quantum Hall states and confirming Bernal stacking through experimental observations.

Contribution

It provides experimental evidence for Bernal stacking in epitaxial graphene bilayers grown on SiC, highlighting unique quantum Hall phenomena.

Findings

Observation of quantum Hall states at multiple filling factors.

Insulating behavior at charge neutrality point due to variable range hopping.

Confirmation of Bernal stacking in the bilayer structure.

Abstract

We investigate the magnetotransport properties of quasi-free standing epitaxial graphene bilayer on SiC, grown by atmospheric pressure graphitization in Ar, followed by H$_2$ intercalation. At the charge neutrality point the longitudinal resistance shows an insulating behavior, which follows a temperature dependence consistent with variable range hopping transport in a gapped state. In a perpendicular magnetic field, we observe quantum Hall states (QHSs) both at filling factors ($\nu$) multiple of four ($\nu=4, 8, 12$), as well as broken valley symmetry QHSs at $\nu=0$ and $\nu=6$. These results unambiguously show that the quasi-free standing graphene bilayer grown on the Si-face of SiC exhibits Bernal stacking.