CRITICAL FIELDS AND FUNDAMENTAL LENGTHS IN A SUPERCONDUCTING ELECTRON-DOPED PR1.85CE0.15CUO4-Y SINGLE-CRYSTAL

Both critical fields H(c1) and H(c2), together with the intrinsic superconducting parameters-lambda and xi, have been obtained from a set of careful systematic measurements of isothermal magnetization curves in a Pr1.085Ce0.15CuO4-y single crystal with H parallel-to c. The analysis of the low-field regime has been performed, taking into account demagnetizing effects. A zone of complete diamagnetic screening is observed, followed by a transition region in which magnetic-flux penetration starts according to the predictions of Bean's critical-state model. The H(c2)(T) values, as well as a kappa less-than-or-equal-to 10, have been obtained from the reversible part of the magnetization curve, in the high-field region, by using Abrikosov's model. The estimated values at T=0 K for the different intrinsic superconducting parameters are H(c1)(0) almost-equal-to 920 Oe, H(c2)(0) almost-equal-to 70 kOe, lambda(ab)(0) almost-equal-to 700 angstrom, and xi(ab)(0) almost-equal-to 70 angstrom. The significance of these intrinsic superconducting parameters. the rather low kappa-value, and a large Sommerfeld constant are discussed and compared with the corresponding values of other cuprates.