▎ 摘　　要

In a graphene bilayer with Bernal stacking, both n=0 and n=1 orbital Landau levels have zero kinetic energy. An electronic state in the N=0 Landau level consequently has three quantum numbers in addition to its guiding center label: its spin, its valley index K or K', and an orbital quantum number n=0,1. The twodimensional electron gas (2DEG) in the bilayer supports a wide variety of broken-symmetry states in which the pseudospins associated with these three quantum numbers order in a manner that is dependent on both filling factor v and the electric potential difference between the layers. In this paper, we study the case of v =- 1 in an external field strong enough to freeze electronic spins. We show that an electric potential difference between layers drives a series of transitions, starting from an interlayer-coherent state (ICS) at small potential and leading to an orbitally coherent state (OCS) that is polarized in a single layer. Orbital pseudospins carry electric dipoles with orientations that are ordered in the OCS and have Dzyaloshinskii-Moriya interactions that can lead to spiral instabilities. We show that the microwave absorption spectra of ICSs and OCSs are sharply distinct.