Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 35: Focus Session: Topological Insulators on Coupled Quantum Wells (joined session with TT)

HL 35.3: Talk

Tuesday, March 21, 2017, 10:15–10:30, POT 151

Fractional quantum Hall effect in the N=2 Landau level in bilayer graphene — Georgi Diankov¹, •Chi-Te Liang^{1, 2}, François Amet^{3, 4}, Patrick Gallagher¹, Menyoung Lee¹, Andrew Bestwick¹, Kevin Tharratt¹, William Coniglio⁵, Jan Jaroszynski⁵, Kenji Watanabe⁶, Takashi Taniguchi⁶, and David Goldhaber-Gordon¹ — ¹Department of Physics, Stanford University, Stanford, California 94305, USA — ²Department of Physics, National Taiwan University, Taipei 106, Taiwan — ³Department of Physics, Duke University, Durham, North Carolina 27708, USA — ⁴Department of Physics and Astronomy, Appalachian State University, Boone, NC 28608, USA — ⁵National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA — ⁶Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305, Japan

To date, most fractional quantum Hall (FQH) studies have focused on the N=0 lowest Landau level (LL). Here we report transport measurements of FQH states in the N=2 LL (filling factors 4 < |ν| < 8) in bilayer graphene, a system with spin and valley degrees of freedom in all LLs, and an additional orbital degeneracy in the 8-fold degenerate N=0/N=1 LLs. In contrast with recent observations of particle-hole asymmetry in the N=0/N=1 LLs of bilayer graphene. The particle-hole symmetric FQH states in the N=2 LL display energy gaps of a few Kelvin, comparable to and in some cases larger than those of fractional states in the N=0/N=1 LLs.