2016/02/26 by Lung-I Huang, Huang, Lung-I, Yanfei Yang +9
Physics and Astronomy · #Disordered Systems and Neural Networks (cond-mat.dis-nn) #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #cond-mat.dis-nn #cond-mat.mes-hall
paper · pdf · doi:10.48550/arxiv.1602.08198
4 figures with supplementary Information
arxiv created 2016/02/26 · arxiv updated 2016/02/29
We report on magneto-transport measurements on low-density, large-area monolayer epitaxial graphene devices grown on SiC. We show that the zero-energy Landau level (LL) in monolayer graphene, which is predicted to be magnetic field (B)-independent, can float up above the Fermi energy at low B. This is supported by the temperature (T)-driven flow diagram approximated by the semi-circle law as well as the T-independent point in the Hall conductivity σxy near e2/h. Our experimental data are in sharp contrast to conventional understanding of the zeroth LL and metallic-like behavior in pristine graphene prepared by mechanical exfoliation at low T. This surprising result can be ascribed to substrate-induced sublattice symmetry breaking which splits the degeneracy of the zeroth Landau level. Our finding provides a unified picture regarding the metallic behavior in pristine graphene prepared by mechanical exfoliation, and the insulating behavior and the insulator-quantum Hall transition in monolayer epitaxial graphene.