Paraconductivity and excess Hall conductivity inYBa2Cu3O7−x/PrBa2Cu3O7−xsuperlattices

L. M. Wang, H. C. Yang, H. E. Horng
1999 Physical Review B (Condensed Matter)  
The paraconductivities and excess Hall conductivities of YBa 2 Cu 3 O 7Ϫx (YBCO) films and YBa 2 Cu 3 O 7Ϫx /PrBa 2 Cu 3 O 7Ϫx (YBCO/PBCO) superlattices at temperatures above T c are measured and analyzed within the framework of fluctuation theories. We observe that the fluctuation contributions to the paraconductivity of YBCO/PBCO superlattices are governed by the Lawrence and Doniach process and the dimensionality is characterized by the coupling parameter ␣, which is temperature dependent.
more » ... rature dependent. However, the contributions of fluctuation to the excess Hall effect contain the negative Aslamazov-Larkin ͑AL͒ term and the positive Maki-Thompson ͑MT͒ term. Especially, the positive MT contributions for YBCO/PBCO superlattices suggest that the pair-breaking interaction is important when T is close T c . The scaling of the paraconductivities in the presence of magnetic fields suggests that the YBCO/PBCO superlattices belong to the quasi-twodimensional ͑quasi-2D͒ systems and the anisotropic parameter ␥ϭm ab /m c governs the dimensionality. With a smaller value of ␥, a 2D-like scaling of the paraconductivities is obtained. On the other hand, in the scaling of the excess Hall conductivities, only the AL terms separated from the total conductivities follow a scaling law, while the MT terms do not. The results are discussed.
doi:10.1103/physrevb.59.14031 fatcat:6ysgzws4vjd2npk7kobor4jfya