On the correlation between order parameter, superconducting volume fraction and critical current density in R: 123 superconductors

Resistivity and low field ac susceptibility measurements are made on R: 123 superconducting samples with different rare earth elements R. The order parameter dimensionality OPD is deduced from resistivity versus temperature plot using the Aslamazov and Larkin expression, while the analysis of the temperature dependence of ac susceptibility is done employing Beans’ critical state model and with the help of the Ravi expression. With increasing R, the critical temperatures TcTc are nearly kept constant (∼90 K), while the crossover temperatures ToTo are shifted to lower values. Moreover, the superconducting order parameter OPD is shifted toward 2D behavior. On the other hand, the values of superconducting volume fraction fgfg decrease with increasing ac field amplitude HmHm for all samples and it is higher in Er: 123 sample than in Nd: 123 sample. Although the values of critical current density JcJc at the peak temperature TmTm are nearly unchanged with increasing R, the values of Jc(T)Jc(T), at TTmT>Tm, are found to be dependent on the chosen R. The correlation between the above calculated parameters against R is also mentioned.