Superconducting transition and magnetoresistance in Bi2Sr2CaCu2O8+x singlecrystals

The in-plane resistivity of overdoped Bi2Sr2CaCu2O8+x. single crystals was investigated in various magnetic fields up to 13 T in the temperature range from 4.1 K to T-c + 20 K. The characteristic broadening of the resistive t ransition in a magnetic field oriented perpendicular to the CuO2 planes is compared to recent theories of critical order-parameter fluctuations. The e xperimental results agree well with the theoretical predictions in the uppe r part of the superconducting transition. In the lower part of the transiti on dissipative flux motion prevails. (C) 2000 Elsevier Science B.V. All rig hts reserved.