REBaCuO超导体电子结构及其与超导电性的关系

利用量子化学的ＳＣＦ－Ｘα－ＳＷ方法计算了ＲＥＢａＣｕＯ (ＲＥ＝Ｙ,Ｌａ、Ｎｄ．Ｓｍ,Ｅｕ,Ｇｄ;Ｄｙ,Ｅｒ和 Ｔｍ)等氧化物超导体体系的电子结构,计算结果表明:氧化物超导体中存在一种特殊内层轨道耦合作用,它是由ＲＥ的ＳＰ电子轨道与Ｏ的２ｓ电子轨道的空间交叠引起的,内层轨道耦合的大小由两个饱和轨道的空间交叠程度,以及两个轨道能级的接近程度决定．此外,与实验结果对比可以看出,超导临界温度与两个饱和轨道的交叠程度有相似的变化规律,超导临界电流密度与参与耦合的电子数量随ＲＥ原子序数的变化规律类似,因此,内层轨道耦合对高温超导电性的影响是不可忽略的．

Electronic Structures of REBaCuO Systems and Its Relation withSuperconductivities

The electronic structures of RECu₈O₈(RE=La, Pr, Nd, Sm, Gd, Dy, Ho, Er) were calculated by means of SCF-Xα-SW methods. The result shows that: There is an inner-orbit coupling for these oxide superconductor systems. The inner-orbit coupling is due to interaction of two saturated electronic orbits of RE5p and O2s since they have a nearly similar energy state level and relatively larger orbital electronic clouds. Compared with experiments, the overlaps in space between two orbits has a close relation with T_c and the number of enrolling electrons has a similar relation with J_c, therefore the influence of inner-orbit coupling on superconductivity can not be overlooked.