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arXiv · 0706.2822

Quantum-Hall activation gaps in graphene

A. J. M. Giesbers·U. Zeitler·M. I. Katsnelson·L. A. Ponomarenko·T. M. G. Mohiuddin·J. C. Maan
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Abstract

We have measured the quantum-Hall activation gaps in graphene at filling factors $ν=2$ and $ν=6$ for magnetic fields up to 32 T and temperatures from 4 K to 300 K. The $ν=6$ gap can be described by thermal excitation to broadened Landau levels with a width of 400 K. In contrast, the gap measured at $ν=2$ is strongly temperature and field dependent and approaches the expected value for sharp Landau levels for fields $B > 20$ T and temperatures $T > 100$ K. We explain this surprising behavior by a narrowing of the lowest Landau level.

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A. J. M. Giesbers, U. Zeitler, M. I. Katsnelson, L. A. Ponomarenko, T. M. G. Mohiuddin, J. C. Maan. 2007-10-12. Quantum-Hall activation gaps in graphene. https://doi.org/10.1103/physrevlett.99.206803

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