Abstract:
Cu 2p core-level photoemission studies of La2-xSrxCuO4, BiPbSr2Y1-xCa1-xCu2O8, and other cuprates show that the relative intensity of the satellite varies with the composition in a direction opposite to that of the hole concentration, nh. The IS/IM-nh relations in the different cuprate series can be understood in terms of the Δ/tpd ratio, where Δ is the charge-transfer excitation energy and tpd is the hybridization strength between the Cu 3d and O 2p orbitals. Interestingly, the IS/IM ratio increases with the Δ/tpd ratio in the cuprates. At a given value of nh, e.g., around the value corresponding to maximum Tc, IS/IM increases in the same direction as Tc among the different series of cuprates, suggesting thereby that Tc itself may be determined by Δ/tpd.
