Correlation between superconducting critical temperature and normal-state resistivity parameters from the codoped ErBa₂Cu_3−x−yZn_xFe_yO_7−δ system

Abstract

The Zn and Fe codoped ErBa₂Cu_3−x−yZnxFe_yO_7−δ system for 0<~x<~0.45, 0<~y<~0.18, and 0.02<~d<~0.21 has been investigated. Superconducting critical temperature T_c, residual resistivity ρ₀, resistivity slope corresponding to the linear ρ-T region (dρ/dT)_cc, and a characteristic temperature where ρ-T goes through a minima T_min are extracted from resistivity measurements. Interestingly, Zn and Fe in general are found to interfere with each other in determining the values of T_c, ρ0, (dρ/dT)_cc, and T_min. In one particular case of cosubstitution, T_c is found to enhance. T_c correlates with T_min, ρ₀, and (dρ/dT)_cc such that an increase in the former two parameters tends to degrade T_c, while an increase in the latter tends to enhance it. These observations suggest that pinning of the dynamically fluctuating striped phase due to Zn and Fe is a reasonable source of T_c suppression in the present system. We further discuss the reasons and possible consequences of the unusual interference effects of Zn and Fe.