STUDIES ON ANISOTROPY FOR SINGLE-CRYSTAL GdBa 2 Cu 3 O 7-δ

We report the experimental results on anisotropy of the normal state resistivity, transition temperature and magnetic transition in single crystal GdBa 2 Cu 3 O 7-δ . We find that both ρ ∥ and ρ ⊥ are fitted very well to the Anderson-Zou relationship ρ = A/T + BT, except near Tc where fluctuation enhanced conductance becomes prominent. The striking difference in A, B of two directions suggests that charge transport proceeds by different mechanisms in the two directions, that the system exhibit remarkable two-dimensional character in the normal stete. The superconductivity in the c direction is weaker than that in ab plane: T ce⊥ is 2K lower than T ce∥ . a. c. magnetic shielding effect when H∥ab plane is only 76% of that as H⊥ab plane.