Transport and magnetic properties of bulk polycrystalline (YBa2Cu3O7)1−x(Nd0.7Sr0.3MnO3)x nanocomposites

We have prepared a series of bulk polycrystalline samples with the nominal compositions (YBa2Cu3O7)1−x(Nd0.7Sr0.3MnO3)x (x=0–1) by a conventional solid-state reaction method using the larger difference in sintering temperature of the two constituent oxides and a well conceived sintering sequence. XRD patterns show that the samples are composites consisting of YBa2Cu3O7 and Nd0.7Sr0.3MnO3 particles with average grain size of ∼65nm. For x⩽0.55, with increasing x, the zero-resistance superconducting transition temperature, TC0, measured at zero magnetic field decreases and the normal state resistivity increases rapidly. The TC0 for the sample with x∼0.48 is estimated to be 0K. The M–H hysteresis loops indicate the coexistence of ferromagnetism and superconductivity in the samples. The depression of TC0 can be attributed to the proximity effect between ferromagnetism and superconductivity.