ARPES studies of c-axis intracell coupling in Bi2Sr2CaCu2O8+δ Original Research Article

Using angle-resolved photoemission spectroscopy we have performed a detailed study of bilayer splitting in Bi2Sr2CaCu2O8+δ as a function of doping level and temperature. In heavily overdoped samples where the splitting is the clearest, we extract an intracell coupling t⊥∼55 meV. As a function of photon energy the intensity ratio of the bonding and antibonding bands varies, allowing us to detect the bilayer splitting effect in the optimal and underdoped regimes. Surprisingly, with reduced doping the intracell coupling is not measurably reduced. Upon cooling to the superconducting state, a gap Δ opens in both bands yet the magnitude of the splitting remains unchanged.