Quantum Hall effect and Landau level crossing of Dirac fermions in trilayer graphene

TL;DR

This study explores the quantum Hall effect in high-mobility trilayer graphene, revealing Landau level crossings and broken-symmetry states that enhance understanding of its electronic structure.

Contribution

It provides direct determination of SWMcC parameters and uncovers Landau level crossings and symmetry breaking in trilayer graphene.

Findings

Observation of Shubnikov-de Haas oscillations.

Identification of Landau level crossings.

Detection of broken-symmetry quantum Hall states.

Abstract

We investigate electronic transport in high mobility (\textgreater 100,000 cm$^2$/V$\cdot$s) trilayer graphene devices on hexagonal boron nitride, which enables the observation of Shubnikov-de Haas oscillations and an unconventional quantum Hall effect. The massless and massive characters of the TLG subbands lead to a set of Landau level crossings, whose magnetic field and filling factor coordinates enable the direct determination of the Slonczewski-Weiss-McClure (SWMcC) parameters used to describe the peculiar electronic structure of trilayer graphene. Moreover, at high magnetic fields, the degenerate crossing points split into manifolds indicating the existence of broken-symmetry quantum Hall states.