【摘要】 利用Xα方法研究了氧化物La_2-yBa_yCuO₄的电子结构.研究结果显示,Ba掺杂对氧化物La_2-yBa_yCuO₄的电子态密度分布和能带结构有重要影响:（1）掺杂使由原来导电类型相反的两个基元组成的反铁磁绝缘体La₂CuO₄,变成了由导电类型相同的两个基元组成的超导体La_2-yBa_yCuO₄.（2）掺杂使能带显著展宽,使电子态密度在Fermi面附近显著增大,并且d电子的贡献成为主要成分,而s电子的贡献却很小.说明高温超导主要是d波配对机制,s波配对是次要的,自旋涨落交换耦合可能是产生d波配对的主要原因.（3）Ba掺杂使Ba的电负性增强,O的电负性减弱,使La-O层、Cu-O层中的离子键、共价键特征演变成金属键特征,且使原团簇La₈CuO₆中Cu-O层由原来的接受电子特征变成提供电子的特征.更多还原

【Abstract】 The electronic structures of oxides La_2-yBa_yCuO₄ are studied by using Xαmethod.The results show that doping Ba instead of La in La₂CuO₄ have important effect on the distribution of the electronic density of states and energy band structure of oxide La_2-yBa_yCuO₄.First,by doping the two elements with opposite conductivity in the anti-ferromagnetic insulator La₂CuO₄ change into two elements with same conductivity in the superconductors La_2-yBa_yCuO₄.Second,doping obviously expands the energy bands,and significantly increases the density of electronic states near the Fermi surface,and the contributions of d electrons play a major role,while the contributions of s electrons can be ignored.High-temperature superconductivity is mainly from d-wave pairs and secondarily from s-wave pairs.The spin fluctuation exchange coupling is to produce d-wave pairs.Third,doping Ba enhances the electronegativity of Ba,and weakens that of O,and then the ionic or covalent bonding characteristics of La-O layer or Cu-O layer turns into metal characteristics,and for the Cu-O layer in the cluster La₈CuO₆ the acceptance of electronic features turns into a provision of electronic features.更多还原