Quantum Hall effect in lightly hydrogenated graphene

TL;DR

This study investigates how light hydrogenation alters the electronic properties of monolayer graphene, notably changing its Landau level structure and band dispersion from linear to quadratic, confirmed by experimental measurements and theoretical calculations.

Contribution

It provides experimental evidence that light hydrogenation transforms graphene's band structure from linear to quadratic, supported by ab-initio calculations.

Findings

Landau level distance decreases with hydrogenation

Landau level dependence shifts from square root to linear

Effective electron mass in hydrogenated graphene is 0.24 times the electron mass

Abstract

We have measured the quantum Hall effect in monolayer graphene samples that were exposed to a cold hydrogen plasma leading to a hydrogenation level of a few percent. Compared to pristine graphene, the Landau level distance significantly decreases in the hydrogenated structures, and its field dependence changes from square root type to linear. From this observation we conclude that the band structure in hydrogenated graphene changes from a linear Dirac-Weyl type dispersion to a quadratic one with an effective electron mass $m_e^* = 0.24~m_e$. This is in good agreement with ab-initio band structure calculations of hydrogen decorated graphene monolayer.