Dependences of the chemical potential shift and superconducting transition temperature on the hole concentration in La2-xSrxCuO4 and Bi2Sr2Ca1-xYxCu2O8+

Abstract

Dependences of the superconducting transition temperature (Tc) on the hole concentration (nh) in La2-xSrxCuO4 and Bi2Sr2Ca1-xYxCu2O8+ have been calculated using the interband model. The phase space for pair-transfer scattering between the overlapping bands is governed by the position of the chemical potential. Downward shifts (µ) of the electron chemical potential (µ) with nh have been found. The slope is µ/ nh8 eV/hole in under-doped Bi2Sr2Ca1-xYxCu2O8+ and it becomes smaller in optimally-doped and over-doped samples (~1.2 eV/hole). In La2-xSrxCuO4 µ/ nh is equal to 1.25 eV/hole in over-doped samples and ~0.4 eV/hole in under-doped samples at T = 80 K. The pseudogap leads to the suppression of µ(nh) up to nh0.17 holes per CuO2 plane at T = 80 K. The shift of the chemical potential µ leads to the curve Tc(nh) with a maximum. The dependences µ(nh) and Tc(nh) for the systems considered agree with the experimental data.