Effects of proximity coupling and substitutions for Ba-sites on the transition temperature and ARPES of high-T＿c superconductors

Taking into account the proximity effects of the CuO chain on the hig h-Tc superconductivity, we introduce an S-N (superconducting-normal) model with d-wave Cooper pairing in the S layer. The hopping interaction between the S and N layers shows the suppression effect on the transition temperature Tc from the Green's function obtained in the Nambu space. Based on this model, we investigat e the negative effects of the substitution for Ba-site on the transition tempera ture Tc in the Y-Ba-Cu-O system. Experimental observations are qualita tively con sistent with our theoretical results. Finally, the hump/dip/peak structure in th e line shapes of the angle-resolved photoemission of the high-Tc supercond uctors has also been discussed in the framework of the S-N model.