Raman and ARPES combined study on the connection between the existence of the pseudogap and the topology of the Fermi surface in Bi2Sr2CaCu2O8+δ

Here, we study the behavior of the pseudogap in overdoped Bi₂Sr₂CaCu₂O_8+δ by electronic Raman scattering (ERS) and angle-resolved photoemission spectroscopy (ARPES) on the same single crystals. Using both techniques we find that, unlike the superconducting gap, the pseudogap related to the antibonding band vanishes above the critical doping p_c = 0.22 . Concomitantly, we show from ARPES measurements that the Fermi surface of the antibonding band is holelike below p_c and becomes electronlike above p_c. This reveals that the existence of the pseudogap depends on the Fermi surface topology in Bi₂Sr₂CaCu₂O_8+δ, and more generally, puts strong constraint on theories of the pseudogap phase.