▎ 摘　　要

The two-dimensional electron gas in a graphene bilayer in the Bernal stacking supports a variety of uniform broken-symmetry ground states in Landau level N = 0 at integer filling factors nu is an element of [-3,4]. When an electric potential difference (or bias) is applied between the layers at filling factors nu = 1,3, the ground state evolves from an interlayer coherent state at small bias to a state with orbital coherence at higher bias, where electric dipoles associated with the orbital pseudospins order spontaneously in the plane of the layers. In this paper, we show that, by further increasing the bias at these two filling factors, the two-dimensional electron gas goes first through an electron crystal with an orbital pseudospin texture at each site and then into a helical state where the pseudospins rotate in space. The pseudospin textures in the electron crystal and the helical state are due to the presence of a Dzyaloshinskii-Moriya interaction in the effective pseudospin Hamiltonian when orbital coherence is present in the ground state. We study in detail the electronic structure of the helical and electron crystal states as well as their collective excitations and then compute their electromagnetic absorption.