Study of dependence upon the magnetic field and transport current of the magnetoresistive effect in YBCO-based bulk composites

摘要

The magnetoresistive properties of bulk YBCO + CuO and YBCO + BaPb_(0.75)Sn_(0.25)O_3 composites for different orientations of external magnetic field H and macroscopic transport current j have been measured. These composites exhibit large magnetoresistance in weak magnetic fields (< 100 O_e), which makes them promising candidates for practical application in magnetic field sensor devices. The difference between p(T) dependences, magnetoresistance curves R(H) and current-voltage characteristics measured for H || j and H perpendicular j is observed indicating the presence of the Lorentz-force-dependent dissipation in the composites. Angular dependences of magnetoresistance R(theta) (where theta = angle H, j) of the composites in weak magnetic fields are found to be proportional to sin~2 theta. This fact suggests that the flux flow in the intergrain boundaries is responsible for the large magnetoresistive effect observed in the composites.