Spontaneously Gapped Ground State in Suspended Bilayer Graphene

Freitag, F. and Trbovic, J. and Weiss, M. and Schonenberger, C.. (2012) Spontaneously Gapped Ground State in Suspended Bilayer Graphene. Physical review letters, Vol. 108 , 076602.

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Official URL: http://edoc.unibas.ch/dok/A6070302

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Bilayer graphene bears an eightfold degeneracy due to spin, valley, and layer symmetry, allowing for a wealth of broken symmetry states induced by magnetic or electric fields, by strain, or even spontaneously by interaction. We study the electrical transport in clean current annealed suspended bilayer graphene. We find two kinds of devices. In bilayers of type B1 the eightfold zero-energy Landau level is partially lifted above a threshold field revealing an insulating nu = 0 quantum-Hall state at the charge neutrality point. In bilayers of type B2 the Landau level lifting is full and a gap appears in the differential conductance even at zero magnetic field, suggesting an insulating spontaneously broken symmetry state. Unlike B1, the minimum conductance in B2 is not exponentially suppressed, but remains finite with a value G less than or similar to e(2)/h even in a large magnetic field. We suggest that this phase of B2 is insulating in the bulk and bound by compressible edge states.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimentalphysik Nanoelektronik (Schönenberger)
UniBasel Contributors:Schönenberger, Christian and Freitag, Frank and Weiss, Markus
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Physical Society
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:01 Mar 2013 11:14
Deposited On:01 Mar 2013 11:12

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