<i>c</i>-axis hopping conductivity in heavily Pr-doped YBCO single crystals

Abstract

We investigated the temperature dependence of the longitudinal and transverse conductivity of Y1−zPrzBa2Cu3O7−δ single crystals with different praseodymium contents. The correlation between the experimental results and the predictions of various theoretical models was analyzed. It is observed that the increase of the praseodymium concentration in Y1−zPrzBa2Cu3O7−δ single crystals leads to increased localization effects and suppression of the superconducting state. Interestingly, for single crystals with large praseodymium content the anisotropy of the normal electrical resistivity ρc/ρab(T) is described by the universal ‘law of 1/2’ for thermally activated hopping conductivity. This is in contrast to the case for comparable crystals of YBa2Cu3O7−δ.