Broken-Symmetry States in Doubly Gated Suspended Bilayer Graphene

Abstract

Broken Symmetries Bilayer graphene samples are expected exhibit quantum Hall states that are ferromagnetic with different types of spin ordering. Weitz et al. (p. 812 , published online 14 October) studied the conductance of high-quality suspended bilayer graphene samples. They used an applied perpendicular electric field to induce transitions between the different broken-symmetry states that appear at low carrier densities and deduced their order parameters. These states appeared in both the absence of a magnetic field, as well as in the presence of a symmetry-breaking magnetic field. They also showed that, even in absence of both an applied magnetic or electric field, the bilayer exhibits an energy gap, which indicates that electron-electron interactions contribute to the band structure.