YBa_2Cu_3O_(7-δ)超导体临界温度与氧含量关系的重正化群和分形理论研究  

RENORMALIZATION GROUP AND FRACTAL STUDY.OF THE RELATIONSHIP BETWEEN OXYGEN CONTENT AND SUPERCONDUCTING TRANSITION TEMPERATURE IN YBa_2Cu_3O_(7_δ)

作　　者：辛厚文[1] 张宏光[1] 

机构地区：[1]中国科技大学近代化学系,合肥230026

出　　处：《低温物理学报》1992年第5期335-340,共6页Low Temperature Physical Letters

基　　金：中科院中国科技大学结构分析开放实验室的资助

摘　　要：本文提出:在 YBa_2Cu_3O_(7-δ)超导体中,当δ增加时,在 Cu-O 链层上氧的分布可以用点渗流模型描述.在渗流阈值时,渗流集团具有标度不变性的分形结构,可以用实空间的重正化群方法研究;Cu-O 链层氧渗流网络的分形结构可以通过电荷转移过程调制 Cu-O 面上载流子的结构,使其具有分形结构.如此,在考虑到用载流子分形结构上的分形子与声子的耦合代替周期结构上的电声耦合,利用超导的强耦合理论,计算出了临界温度 T_c 与δ之间的关系曲线,它与实验结果相符合.It was demonstrated in this paper that, as 6 increases, the oxygen distribution in the CuO chain layer of YBa2CusO7-δ can be described by percolation model. At the percolation threshold, the percolation cluster has the characteristic structure of fractal and can be treated with the real space RG method. It was also shown that the fractal structure of oxygen percolation clusters can modulate the structure of carriers on the CuO2 plane, which results in a topological equivalent fractal structure of local carriers on the plane. Thus, we can use the strong-coupling theory of the superconducting critical temperature to calculate the superconducting transition temperatures by considering the fracton of carriers-phonon coupling instead of electron-phonon coupling. The calculated curve of the relation between oxygen content and superconducting transition temperatures is well coincident with the experiment results.

关 键 词：重正化群 YBa₂Cu₃O 分形结构 标度不变性 电荷转移过程 分形子 强耦合理论 临界性质 周期结构 声耦合 

分 类 号：O4[理学—物理]