Magnetoresistance, Irreversibility Fields, and Critical Currents of Superconducting 2G Tape

Abstract

The magnetoresistance, irreversibility fields, and critical current density were studied for a commercial 2G tape at the two relative orientations of magnetic field and superconductor plane. The critical temperatures of this tape of Tc50 % = 91.5 K and Tc0 = 90 K and the width of superconducting transition of ΔT = 1.5 K were obtained. The widths of the transition from the normal to the superconducting state do not increase at the applied magnetic field up to 90 kOe and do not depend on the orientation of the magnetic field with respect to the tape plane. The irreversibility field values were obtained and successfully fitted as a function of temperature using the formula: Hirr=Hirr0(1−TTc0)n. The irreversibility fields show an anisotropy, and at the liquid nitrogen temperature, they reach Hirr = 430 kOe and Hirr = 106 kOe for the parallel and perpendicular directions, respectively. The anisotropy ratio amounts to γ = 4 at 77 K and is small in comparison with other high-temperature superconducting materials. The critical current density of this tape was found to be of the order of 106 A cm−2 at 77 K in the self-magnetic field.