EXCESS FLUCTUATION CONDUCTIVITY AND SUPERCONDUCTING PARAMETERS OF CaLa-DOPED Nd-123

Abstract

Polycrystalline samples of Nd 1-x Ca x Ba 2-x La x Cu 3 O 7-δ (with 0.0 ≤ x ≤ 0.15) were prepared by the standard solid state method. The co-doping effect was studied on the resistivity as a function of temperature and doping concentration x. The fluctuation conductivity was analyzed using the Aslamazov and Larkin model (AL). For all samples, three fluctuation regions; i.e. one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D), were clearly observed with decreasing temperature. A critical region was also observed for high doping concentration (x ≥ 0.1). Superconductivity parameters such as the effective coherence length ξ p , the coherence length along the c-axis ξ c and ab plane ξ ab , the effective interlayer separation d, anisotropy parameter γ a , and the upper critical magnetic field B c2 along the c-axis and ab plane were obtained. It was also found that CuO x chains contribute to conducting.