Magnetoresistive properties of Y3/4Lu1/4Ba2Cu3O7 + BaPb1-xSnxO3 (x = 0, 0.25) composites

Magnetoresistive properties of composite materials based on 1-2-3 HTSC-structures and a metallic oxide of BaPb1-xSnxO3 (at x = 0, 0.25) are investigated. The composite materials possess an essential magnetoresistive effect in a wide temperature range including a convenient in service liquid nitrogen temperature. The relationship is established between a measuring current j/critical current jc ratio and a type of characteristic ρ(H) of the composites. At j/jc<1 the electrical resistance occurs at a threshold value of magnetic field Hc. At j/jc≅1 the dependence ρ(H) initiates from the origin of the coordinates. At j/jc>1 the dependences ρ(H) begin to grow from some value of ρ(H=0). By way of varying a nonsuperconducting component content in the composite material and a transport current value j (∼0.05-1 A/cm2) it is possible to control the value of electrical resistance response to field variation. The value of ρ0 = (ρ(H) - ρ(H=0))/ρ(H=0) for composite materials at T=77 K reaches 1000-2000% at H=300 e and ρ(H=0) = 0.2 - 2 m Ohm cm, this is promising for using these materials as active elements of magnetic field sensors operating at 77 K