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Observing the Quantization of Zero Mass Carriers in Graphene



Joseph A. Stroscio, Gregory M. Rutter, D. L. Miller, K. Kubista, W. A. de Heer, Phillip N. First


Application of a magnetic field to conductors causes the charge carriers to circulate in cyclotron orbits with quantized energies called Landau levels (LLs). These are equally spaced in normal metals and two-dimensional electron gases. In graphene, however, the charge carrier velocity is independent of their energy (like massless photons). Consequently, the LL energies are not equally spaced and include a characteristic zero-energy state (the n = 0 LL). With the use of scanning tunneling spectroscopy of graphene grown on silicon carbide, we directly observed the discrete, non-equally spaced energy-level spectrum of LLs, including the hallmark zero-energy state of graphene. We also detected characteristic magneto-oscillations in the tunneling conductance and mapped the electrostatic potential of graphene by measuring spatial variations in the energy of the n = 0 LL.


graphene, SiC, scanning tunneling microscopy, Landau quantization


Stroscio, J. , Rutter, G. , Miller, D. , Kubista, K. , de, W. and First, P. (2009), Observing the Quantization of Zero Mass Carriers in Graphene, Science, [online], (Accessed July 24, 2024)


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Created May 15, 2009, Updated February 19, 2017