The metal-insulator transition of the half integer quantum-Hall effect in epitaxial graphene

The observation of the half integer quantum-Hall effect (QHE) in Hall resistance along with the pronounced Shubnikov-de Haas (SdH) oscillations confirms that the electrical properties of epitaxial graphene on SiC share the same relativistic physics as those in exfoliated graphene films. The temperature-dependent half-width \textit{$\Delta $B(T) }of the SdH peaks and the maximum of the slope of the Hall resistance \textit{$\partial \rho $}$_{xy}$\textit{/$\partial $B} of gated epitaxial graphene are investigated at temperatures between 0.4 K to 300K. The preliminary data shows \textit{$\Delta $B(T)} for the first Laudau level of electrons in epitaxial graphene on SiC (0001) display a power-law behavior with a scaling exponent \textit{$\kappa $}$\approx $0.43, being consistent with the previously reported results from 2DES formed at AlGaAs/GaAs or InGaAs/InP heterojunctions [1,2] and the exfoliated graphene [3]. More detailed results on \textit{$\kappa $} for high Laudau levels and the study of size-dependence of the quantum-Hall plateau-plateau transition in epitaxial graphene will also be presented. [1] H.P. Wei, D.C. Tsui, M.A. Paalanen, and A.M.M. Pruisken, Phys. Rev. Lett. 61, 1294 (1988). [2] S. Koch, R.J. Haug, K. von Klitzing, and K. Ploog, Phys. Rev. Lett. 67, 883 (1991). [3] A.J.M. Giesbers, U. Zeitler, L.A. Ponomarenko, R. Yang, K.S. Novoselov, A.K. Geim, and J.C. Maan, arXiv:0908.0461v1.