Keywords: electrical properties, Co nanoparticles, nanocomposites, granular films, laser ablation, size effects, nanotechnology, Spain, thin films, absorption, nanoscale
Electrical properties in granular Co-ZrO2 thin films
Granular films composed of well-defined nanometric Co particles embedded in an insulating ZrZrO2 matrix were prepared by laser ablation in a wide range of Co concentration. The temperature-dependent resistivity depends very critically on the Co-volume fraction with percolation threshold in the range 0.45 < x < 0.52. In the dielectric regime, AC transport arises from the competition between the inter-particle thermally assisted tunnelling (R) and capacitive (C) channels. Consequentially, a complex low-frequency absorption phenomenon is observed that mimics the universal response of disordered dielectric materials. The experimental observation can be successfully modelled by a random R-C network.