Transport Properties of La_0.7Sr_0.3MnO₃/MgB₂ Random Nanocomposites

Abstract

We have investigated electrical transport properties of random binary networks composed of superconducting MgB 2 micro-particles and half-metallic ferromagnet La 0.7 Sr 0.3 MnO 3 nano-particles. Unusually large value of the threshold for a percolation transition to a superconducting state of the nanocomposite has been detected for MgB 2. We explain the observed behavior by significant geometric disparity between particles of the constituents and unconventional (triplet) superconducting state induced in the nanocomposite due to the proximity effect. The effect of highfrequency irradiation on a superconducting transition of the nanocomposite was investigated as well. The influence of a highfrequency signal on the critical current magnitude and superconducting transition of a nanocomposite is revealed. A nonthermal effect of an external electromagnetic irradiation on the nanocomposite characteristics has been found.