The anisotropy of conductive characteristics of Y1−yPryBa2Cu3O7−δ single crystals

Abstract

The anisotropy of the conduction mechanisms of Y1− yPr yBa2Cu3O7−δ single crystals has been studied in a wide range of praseodymium concentrations in the region of the transition from metallic to semiconductor conductivity with account fluctuation conductivity in the 3D Aslamazov–Larkin model. The correspondence of the obtained experimental results with the predictions of various theoretical models is analyzed. The anisotropy of Tc increases with increasing y, and the anisotropy of Tc increases most sharply when approaching the nonsuperconducting composition. As the concentration of praseodymium increases, the anisotropy of the ideal resistance passes through a maximum at y ≈ 0.19. It is shown that the temperature dependence of the anisotropy of the resistance in the semiconductor state exhibits a maximum associated with jumps of variable length along the c axis. At the same time, the temperature dependence of the fluctuating conductivity anisotropy passes through a maximum due to the significant anisotropy of the coherence length.