title: Symmetry breaking in the zero-energy Landau level in bilayer graphene.
abstract: The quantum Hall effect near the charge neutrality point in bilayer graphene is investigated in high magnetic fields of up to 35 T using electronic transport measurements. In the high-field regime, the eightfold degeneracy in the zero-energy Landau level is completely lifted, exhibiting new quantum Hall states corresponding to filling factors nu=0, 1, 2, and 3. Measurements of the activation energy gaps for the nu=2 and 3 filling factors in tilted magnetic fields exhibit no appreciable dependence on the in-plane magnetic field, suggesting that these Landau level splittings are independent of spin. In addition, measurements taken at the nu=0 charge neutral point show that, similar to single layer graphene, the bilayer becomes insulating at high fields.
authors.affiliation: Department of Physics, Columbia University, New York, New York 10027, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: P
authors.initials: P
authors.lastname: Cadden-Zimansky
authors.forename: Z
authors.initials: Z
authors.lastname: Jiang
authors.forename: P
authors.initials: P
authors.lastname: Kim