Hole Distribution in Underdoped and Overdoped Y(Ba(2-y)Sr(y)())Cu(3)O(6+delta) Compounds Studied by X-ray Absorption Spectroscopy.
The hole distribution of underdoped and overdoped states in the Y(Ba(2)(-)(y)()Sr(y)())Cu(3)O(6+)(delta) (delta approximately 0.1 and 0.9) compounds has been observed by high-resolution O K-edge X-ray-absorption near-edge-structure spectra. The chemical substitution of Sr for Ba in the fully oxygenated Y(Ba(2)(-)(y)()Sr(y)())Cu(3)O(6+)(delta) (delta approximately 0.9) compounds gives rise to high hole concentrations within both the CuO(2) planes and the out-of-plane sites, leading to the overdoped state and the decrease in the superconducting transition temperature from 92 K for y = 0 to 84 K for y = 0.8. In contrast, an increase in the Sr content in the oxygen-deficient Y(Ba(2)(-)(y)()Sr(y)())Cu(3)O(6+)(delta) (delta approximately 0.1) compounds did not indicate superconductivity. The oxygen-deficient compounds exhibit underdoped state due to the low hole concentration.
Liu
R. S.
RS
Department of Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C., and Synchrotron Radiation Research Center (SRRC), Hsinchu, Taiwan, R.O.C.
Chang
C. Y.
CY
Chen
J. M.
JM