Unveiling the Landau Levels Structure of Graphene Nanoribbons

TL;DR

This study investigates the Landau level structure in graphene nanoribbons using magnetotransport measurements, revealing unique spectral features, large oscillations, and valley degeneracy lifting, with disorder affecting quantum Hall effects.

Contribution

It provides new insights into the Landau level spectrum and disorder effects in graphene nanoribbons at high magnetic fields.

Findings

Unusual Landau level features observed in graphene nanoribbons.

Large magneto-oscillations of the Fermi energy detected.

Disorder influences the mixing of edge states and quantum Hall effect disappearance.

Abstract

Magnetotransport measurements are performed in ultraclean (lithographically patterned) graphene nanoribbons down to 70 nm. At high magnetic fields, a fragmentation of the electronic spectrum into a Landau levels pattern with unusual features is unveiled. The singular Landau spectrum reveals large magneto-oscillations of the Fermi energy and valley degeneracy lifting. Quantum simulations suggest some disorder threshold at the origin of mixing between opposite chiral magnetic edge states and disappearance of quantum Hall effect.