Phase diagram for large two-dimensional bipolarons in a magnetic field

We perform a path-integral calculation of the ground state energy of a bipolaron confined to two dimensions and which is placed in a perpendicular magnetic field. The present calculation is valid for arbitrary magnetic field strength, arbitrary strength of the repulsion between the electrons, and arbitrary electron-phonon coupling constant. We find that the bipolaron exhibits (1) a discontinuous transition from the polaronic state to the bipolaronic state and (2) a transition from the dressed (bi)polaron state to the (bi)polaron stripped state. These three transitions depend on the magnetic field and the strength of the repulsion between the electrons.