Percolation transitions in d-wave superconductor-half-metallic ferromagnet nanocomposites

摘要

Electrical transport properties of random binary networks composed of high-T-c superconductor Bi2Sr2Ca2Cu3O6+x microparticles and half-metallic ferromagnet La0.67Sr0.33MnO3 (LSMO) nanoparticles have been investigated. Two resistive percolation transitions (superconductor-metal-semiconductor) have been observed for the nanocomposites with a volume fraction of the LSMO no more than 30%. The nanocomposites basic attributes (transition critical temperatures, current-voltage characteristics, percolation threshold, etc.), most probably, cannot be quantitatively interpreted within the framework of a conventional percolation model. We have explained the observed behavior by a two-level scale interaction in the system caused by (i) a significant geometric disparity between the constituent components and (ii) proximity-induced superconducting state of the half-metallic manganite. Published under license by AIP Publishing.