CPM Seminar

Charge Carriers in Graphene viewed through STM and magneto-transport

Eva Andrei

Department of Physics and Astronomy
Rutgers University

In graphene, a one-atom thick membrane of crystalline carbon, the low energy charge excitations are massless Dirac fermions described by quantum relativistic dynamics. But, because of their purely two dimensional nature, the intrinsic properties of these charge carriers are easily obscured by environmental disturbances such as potential fluctuations induced by the commonly used insulating substrates. I will describe scanning tunneling microscopy and transport experiments showing that, unlike the case of insulating substrates where interaction effects are not observed or extremely weak, when graphene is decoupled from substrate-induced potential fluctuations the intrinsic properties of the relativistic charge carriers including interactions between them become apparent. Our findings include direct observation of Landau levels, measurement of the Fermi velocity, evidence for electron-phonon interactions, and of strong electron-electron interactions manifest in the observation of a robust fractional quantum Hall effect and a magnetically induced insulating phase.

[1] G. Li, A. Luican and E. Y. Andrei, Phys. Rev. Lett. 102, 176804 (2009)
[2] X. Du, I. Skachko, A. Barker, E. Y. Andrei, Nature Nanotecnology 3, 491 (2008)
[3] X. Du, I. Skachko, F. Duerr, A. Luican, E. Y. Andrei, Nature 462, 192 (2009)
[4] G. Li, A. Luican and E. Y. Andrei, Nature Physics 6, 109 ( 2010)