Magnetoresistance and conductivity fluctuations in (Tl0.5Pb0.5)Sr2(Ca1-xYx)Cu2O7 superconductors
Journal
Journal of Alloys and Compounds
Journal Volume
195
Journal Issue
C
Pages
651-654
Date Issued
1993
Author(s)
Abstract
We have studied magnetoresistance R(H) of the (Tl0.5Pb0.5)Sr2(Ca1-xYx)Cu2O7 high-Tc superconductors, with x=0.1, 0.2, 0.3, 0.4 at T < Tc in a magnetic field H up to 12 T. For H > 1T, the magnetoresistance can be successfully fitted by the Larkin two-dimensional superconducting fluctuation expression with only two adjustable parameters ( A(T) and HΦ(T) ) per each R vs H curve. This indicates that a large part of the resistive transition broadening in applied magnetic field is related to the giant conductivity fluctuations in these ceramic samples. The first scaling parameter A(T) is determined by the fluctuation amplitude. For x=0.1, the temperature dependence of A(T) follows the behaviour of the β(T) function introduced by Larkin. For larger x, the deviation of A(T) from β(T) is observed which may be attributed to an additional scattering caused by the Y3+ → Ca2+ substitution. The second parameter HΦ, corresponding to the phase coherence breaking field, shows a good agreement with the the recent theoretical prediction by Reizer. © 1993.
Other Subjects
Calcium compounds; Copper compounds; Copper oxides; Electric conductivity; High temperature superconductors; Lead compounds; Magnetic field effects; Magnetic variables measurement; Strontium compounds; Thallium compounds; Yttrium compounds; Cuprate superconductors; Lead strontium calcium cuprates; Thallium strontium calcium cuprates; Superconducting materials
Type
journal article