Approaching the Dirac point in high mobility multi-layer epitaxial graphene

TL;DR

This study explores multi-layer epitaxial graphene's electronic properties near the Dirac point using infrared transmission, revealing high mobility, Landau level quantization at room temperature, and minimal scattering effects.

Contribution

It provides new insights into high mobility and Landau level behavior of epitaxial graphene at room temperature and low magnetic fields.

Findings

Carrier mobility exceeds 250,000 cm²/(V·s)

Landau level quantization observed up to room temperature

Cyclotron resonance lines show negligible broadening with temperature

Abstract

Multi-layer epitaxial graphene (MEG) is investigated using far infrared (FIR) transmission experiments in the different limits of low magnetic fields and high temperatures. The cyclotron-resonance like absorption is observed at low temperature in magnetic fields below 50 mT, allowing thus to probe the nearest vicinity of the Dirac point and to estimate the conductivity in nearly undoped graphene. The carrier mobility is found to exceed 250,000 cm$^2$/(V.s). In the limit of high temperatures, the well-defined Landau level (LL) quantization is observed up to room temperature at magnetic fields below 1 T, a phenomenon unique in solid state systems. A negligible increase in the width of the cyclotron resonance lines with increasing temperature indicates that no important scattering mechanism is thermally activated, supporting recent expectations of high room-temperature mobilities in graphene.