Transport measurements on ultra-clean dual-gated suspended bilayer graphene
1 Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA
2 Department of Physics and Astronomy, Stanford University, Stanford, CA 94305, USA
3 National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
We fabricate ultra clean contactless dual-gated devices comprised of suspended bilayer graphene (BLG) and investigate their low temperature electron transport properties as functions of charge density n, magnetic field B and electric field E⊥ We find that for devices with moderate mobility, conductance remains finite at the charge neutrality point and decreases monotonically with increasing |E⊥|, as expected in the picture of single particle behavior. In contrast, devices with highest mobility display an insulating state at B=E⊥=n=0, and conductance’s dependence on E⊥ is non-monotonic. This surprising behavior arises from electronic interactions. In finite B, we observe quantum Hall plateaus with the 8-fold degeneracy of the lowest Landau level completely broken, as well as a fractional state.
© Owned by the authors, published by EDP Sciences, 2012