AC/DC conductance in granular nanocomposite films (Fe45Co45Zr10)x(CaF2)100−x

► Nanocomposites deposited in oxygen-containing atmosphere (Ar+O2). ► ‘Lowering of FeCoZr nanoparticles’ dimensions (down to 〈D〉∼3–5nm) in nanocomposites. ► Strong lowering (on 2–3 orders of magnitude) of real part of admittance. ► Higher activation energies values for the hopping electronic transport. ► Formation of FeCo-based oxide “shells” which separate FeCoZr nanoparticles. The present paper investigates dependencies of DC/AC conductances on metallic-to-dielectric phase ratio x, temperature T and frequency f in granular nanocomposite films containing FeCoZr nanoparticles embedded into oxygen-free CaF2 matrix. The specific admittance/conductance dependences on x/T/f for the studied films around the percolation configuration was found to be in agreement with their phase structure which was strongly dependent on the composition of gas atmosphere at deposition. The character of temperature/frequency dependences of AC/DC conductance indicates the predominance of electron tunneling (hopping) over the barriers between metallic nanoparticles in carrier transport.