Probing the extended-state width of disorder-broadened Landau levels in epitaxial graphene

K. Takase, H. Hibino, and K. Muraki
Phys. Rev. B 92, 125407 – Published 8 September 2015

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 (N=0) and first excited (N=1) 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 η0.3 in the N=0 (N=1) LL, with almost no (very weak) magnetic-field dependence. Activation gap measurements at the filling factors of ν=2 and 6 give results consistent with transport spectroscopy for the N=1 LL, but indicate a larger broadening for the N=0 LL than deduced from the spectroscopy.

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  • Received 31 July 2013
  • Revised 2 June 2015

DOI:https://doi.org/10.1103/PhysRevB.92.125407

©2015 American Physical Society

Authors & Affiliations

K. Takase*, H. Hibino, and K. Muraki

  • NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan

  • *takase.keiko@lab.ntt.co.jp
  • Present address: Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan.

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Vol. 92, Iss. 12 — 15 September 2015

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