Cluster superconductivity in diamond-like carbon-silicon nanocomposites containing tungsten

It is shown that the nonhomogeneous structure of the superconducting phase in the diamond-like carbon-silicon nanocomposites containing tungsten with concentration close to the metal-insulator transition is responsible for the perculiarities in the character of the superconducting resistive response. The observed nontrivial quasireentrant resistive transitions can be explained in terms of the phase coherence destruction between the superconducting grains and by the renewal of superconducting phase generation at lower temperatures defined by the presence of the two scales of inhomogeneity in the investigated films. The resistance-current characteristics in the vicinity to the superconducting transition and magnetic measurements do not contradict the qualitative model proposed.