Paraconductivity and excess Hall conductivity in YBa2Cu3O7-x/PrBa2Cu3O7-x superlattices

The paraconductivities and excess Hall conductivities of YBa2Cu3O7-x (YBCO) films and YBa2Cu3O7-x /PrBg(2)Cu(3)O(7-x) (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 alpha which is temperature dependent. However, the contributions of fluctuation to the excess Hall effect contain the negative Aslamazov-Larkin (AL) term and the positive Maki-Thompson (MT) 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-two-dimensional (quasi-2D) systems and the anisotropic parameter gamma= m(ab)/m(c) governs the dimensionality. With a smaller value of gamma, 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. [S0163-1829(99)05121-8].