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 ∼65 nm. 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 0 K. 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.