Thin polyethyleneterephthalate (PET) layers with Fe nanoparticles (NPs) were synthesized by high-fluence ion
implantation. Temperature dependence of conductance and magnetoresistance, were studied as a function of ion fluence.
It is found that the implantation with fluences of about 1.0×1017 cm-2 causes high enough concentration of metal inclusions
to provide conditions for electrical percolation that leads to an insulator-to-metal transition (IMT) in charge carrier
transport mechanisms. The magnetoresistance measurements indicate that the magnetic percolation takes place at metal
concentrations (fluences) lower than those needed for the electrical percolation. For the samples on insulating side of the
IMT, a non-monotonous dependence of resistance in an increasing external magnetic field is observed due to anisotropic
magnetoresistive effect and charge carrier scattering on magnetic inclusions. For the samples implanted with fluences ≥
1.0×1017 cm-2 , the magnetoresistance becomes a monotonous decreasing function of the external magnetic field which is
typical for ferromagnetic metals that indicates effective magnetic coupling of the iron inclusions.