Bi-Sr-Ca-Cu-O超导体的能带结构

ENERGY BAND STRUCTURES OF Bi-Sr-Ca-Cu-O SUPERCONDUCTORS

用EHT近似下紧束缚态方法讨论了BI-Sr-Ca-Cu-O体系超导体221相和232相的能带结构。结果表明底部刚好落在费米能级上的Bi6p能带很容易接受Cu-O面提供的载流子,使Cu-O面成为导电通带。232相比221相多一穿过费米能级的半满能带,是Tc(232相)远大于Tc(221相)的原因之一。

The energy band structures of 221 phase and 232 phase in Bi-Sr-Ca-Cu-O system superconductors have been calculated by using the tight-binding method based upon EHT approximation. The results show that Bi6p band, it's bottom is just at the Fermi level, can accept electrons easily provided by Cu-O layer and make the Cu-O layer become conducting band. 232 phase has a half-filled band and 221 phase has not, which is why Tc(232 phase) is higher than Tc (221 phase).