The magnetoresistance of YBCO/BZO composite superconductors

We study the effect of addition of BaZrO3 (BZO) on normal and superconducting state of YBa2Cu3O7-δ (YBCO). We find that in general both room temperature and residual resistivity increase with the addition of BZO except at low concentration of BZO. The temperature dependence of resistivity in presence of magnetic field also shows less resistivity broadening in composites containing low concentration of BZO below transition temperature (TC). The zero temperature upper critical field (Hc2(0)), estimated by using Werthamer, Helfand and Hohenberg theory and Ginzburg Landau theory, shows an increase by the finite addition of BZO in YBCO. Further, the activation energy (U0) determined from Arrhenius plots and vortex glass transition temperature (Tg) also increase with the limited addition of BZO. Such an enhancement in Hc2(0), Uo and Tg has been attributed to the increase in grain connectivity of YBCO . We conclude that the limited addition of BZO in YBCO significantly improves its superconducting performance in magnetic environment.