层间耦合与高温超导体角分辨光电子能谱和Ba位替代效应

Effects of proximity coupling and substitutions for Ba-sites on the transition temperature and ARPES of high-T_c superconductors

根据高温超导体层状结构特点和层间耦合效应 ,提出了一个唯象的S_N双层高温超导模型 (S表示超导层 ,N表示非超导层 ) ,并在Nambu空间求得高温超导态的格林函数 ,得到了S_N模型下高温超导体临界温度Tc 随S ,N层间耦合强度增加而下降的结果 .在该模型的基础上讨论了YBCO材料中Ba位替代对Tc 的抑制效应 ,说明了高温超导体角分辨光电子能谱具有hump dip peak结构的特点 。

Taking into account the proximity effects of the CuO chain on the high_T c 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 T c from the Green's function obtained in the Nambu space. Based on this model, we investigate the negative effects of the substitution for Ba_site on the transition temperature T c in the Y_Ba_Cu_O system. Experimental observations are qualitatively consistent with our theoretical results. Finally, the hump/dip/peak structure in the line shapes of the angle_resolved photoemission of the high_T c superconductors has also been discussed in the framework of the S-N model.