Hole Density Dependence of the Critical Temperature and Coupling Constant in the Cuprate Superconductors
M.-H. Whangbo 1 and
C. C. Torardi 2
1 Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204
2 Central Research and Development Department, E. I. du Pont de Nemours and Company, Experimental Station, Wilmington, DE 19880-0356
A bond valence sum (BVS) analysis was performed for the p-type cuprate superconductors. The superconducting critical temperature Tc versus in-plane Cu-O BVS correlation for copper is grouped into classes and subclasses. Only within a class or subclass for which the nonelectronic effect is constant does the variation of the in-plane Cu-O BVS reflect the corresponding change in the hole density nH of the CuO2 layers. This study strongly suggests that the Tc for every class or subclass of the superconductors is an inverted parabolic function of nH, and so is the coupling constant 
for Cooper pair formation.
