Abstract
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.
Highlights
The novel advancement of isolating graphene [1,2] single sheets of carbon, by mechanical exfoliation onto insulating substrates has produced an unabated flurry of scientific investigation that continue unabated to today
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
To conclude this section we have found that using our suspended bilayer graphene samples of high quality we can probe the rich physics offered by the lowest LL of Bilayer graphene (BLG)
Summary
The novel advancement of isolating graphene [1,2] single sheets of carbon, by mechanical exfoliation onto insulating substrates has produced an unabated flurry of scientific investigation that continue unabated to today. Recent advances in sample fabrication have allowed access to many-body physics [13,14,15,16], leading to, within the past year, reports of broken symmetry states [17], fractional quantum Hall effect (FQHE) [18], an intrinsic gap at the Dirac point [19] and spectrum reconstruction [20]. The latter two phenomena are attributed to the competition between symmetries for the ground state BLG. We explore the devices’ quantum Hall effect in magnetic fields
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