Study of composites consisting of high-T-c superconductor and fine magnetic particles

The composite systems as a mixture of fine magnetic particles of Ee(3)O(4) and superconducting powder such as Bi1.8Pb0.2Sr2Ca2Cu3O10+x were prepared. The influence of internal magnetic field (generated by magnetic particles) on the superconducting properties of prepared composites were studied as a function of concentration of magnetic particles and their magnetic state. T he observed data both of the shielding and the Meissner effect were compare d with corresponding linear combination of pure signals of magnetite and su perconductor, respectively. The large differences were observed for demagne tized samples. It means that result must be discussed in the frame of the d istribution of internal magnetic field created by the magnetic particles.