Suppression of critical temperature and charge localization in underdoped NdBa2Cu3−xZnxO7−y

We report low temperature resistive properties of several underdoped NdBa2Cu3−xZnxO7−y (NBCZO). Both the normal and superconducting states are strongly affected with x, the concentration of Zn impurity. The exponential nature of the suppression in superconducting critical temperature is observed with x. The residual resistivity decreases with the substitution of Zn. The possibility of scaling of Tc/Tc (x = 0) with ρ0 has been discussed. A nonmetallic upturn in resistivity is found even in the highest doped (x = 0.1) NBCZO. The upturn in T dependence resistivity of the pure sample (x = 0) may be explained by the hopping conduction in the normal state. An increase in x suppresses hopping behavior drastically.