Abstract
We experimentally investigate the width of extended states in disorder-broadened Landau levels (LLs) in top-gated epitaxial graphene on silicon carbide using two different methods: gated transport spectroscopy and activation gap measurements on integer quantum Hall states. The transport spectroscopy reveals that the widths of the extended states in the zero-energy () and first excited () LLs are of similar magnitude over the ranges of magnetic field (4–16 T) and temperature studied (1.6–150 K). Under certain assumptions we find that the extended-state width follows a power-law temperature dependence with the exponent in the () LL, with almost no (very weak) magnetic-field dependence. Activation gap measurements at the filling factors of and 6 give results consistent with transport spectroscopy for the LL, but indicate a larger broadening for the LL than deduced from the spectroscopy.
- Received 31 July 2013
- Revised 2 June 2015
DOI:https://doi.org/10.1103/PhysRevB.92.125407
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