Large magnetoresistive effect in bulk Bi2212 with small additions of USr2CaO6

A large magnetoresistive (MR) effect was observed in Bi2212 in which USr2CaO6 was added in a proportion of 6 wt%. The resistivity of melt-textured (MT) Bi2212 + 6 wt% USr2CaO6 possess a high sensitivity to applied dc fields, as compared to pure Bi2212, in particular at low fields, below 3 T, and in a temperature range between 45 and 85 K. In this temperature range, the MR effects of MT Bi2212 + 6 wt% USr2CaO6 display a maximum that may be tuned to a particular temperature within the above range, by changing the amount of added non-superconducting compound. X-ray results show that during the melt-texturing process of this mixture, the USr2CaO6 phase is stable and the reaction with Bi2212 matrix is minimal, in spite of a small decrease in the superconducting transition temperature. A cryogenic sensor was build and tested at 77 K in low fields. It shows high sensitivity and no hysteresis of resistivity when the applied field was cycled between 0 and 1 T.