2014/03/09 by Patrick Maher, Lei Wang, Yuanda Gao +9
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1126/science.1252875
arxiv created 2014/03/09 · arxiv updated 2014/09/11
Symmetry breaking in a quantum system often leads to complex emergent behavior. In bilayer graphene (BLG), an electric field applied perpendicular to the basal plane breaks the inversion symmetry of the lattice, opening a band gap at the charge neutrality point. In a quantizing magnetic field electron interactions can cause spontaneous symmetry breaking within the spin and valley degrees of freedom, resulting in quantum Hall states (QHS) with complex order. Here we report fractional quantum Hall states (FQHS) in bilayer graphene which show phase transitions that can be tuned by a transverse electric field. This result provides a model platform to study the role of symmetry breaking in emergent states with distinct topological order.