Magneto-Resistance Investigations on the In-situ Synthesized Stainless Steel Sheathed MgB 2 Tapes

We report the measurement of magnetoresistance in MgB 2 tapes with a varying magnetic field applied perpendicular to the tape surface. Scaling functions for excess conductance suggested by Ullah and Dorsey have been used to analyze the scaling behavior of the resistivity in MgB 2 tapes just above their critical region. The fluctuations in the magnetoresistance, R ( T , H ), behavior is found to follow 3D scaling for the MgB 2 tape. From the slope of the upper critical field, H C2 vs. T curve, it is ∼68 Å. The zero temperature H C2 that was found following the WHH model was ∼5 T, whereas, from linear extrapolation of H C2 versus T yield a value of H C2 (0)∼24.5 T.