Anisotropy of the superconducting state parameters and intrinsic pinning in low-level Pr-doped Y Ba2Cu3O7-δ single crystals

The influence of low-level Pr substitution in Y1-xPrxBa2Cu3O7-δ single crystals on the anisotropy of the superconducting state parameters was investigated by torque magnetometry in magnetic fields of up to 9 T. An averaged anisotropy parameter, γ, of 7.4 was found and no influence of the Pr ion concentration on γ was observed up to a Pr content of 2.4%. A pronounced maximum at angles between 0.50 and 10 out of the ab-plane was observed for all crystals in the irreversible angular dependence of the torque. This maximum is attributed to intrinsic pinning associated with kinked vortices. The variation of the irreversible torque with the substitution level indicates the influence of the Pr content on pinning within the CuO2 planes, even though the anisotropy of the superconducting state parameters is not affected.