Magnetoresistance of nanocomposite copper/carbon thin films

Nanocomposite thin films made of partially oxidized Cu nanoparticles embedded into hydrogenated amorphous carbon, with different thicknesses and Cu/C ratio, were prepared by means of radio frequency plasma enhanced chemical vapor deposition and radio frequency sputtering using acetylene gas and copper target. The surface roughness was investigated using atomic force microscopy, revealing the fractal geometry of the Cu/carbon thin films at the nanoscale with fractal dimensions around 2.7. In addition, the electrical properties of these films and their dependence on the application of low magnetic fields were explored at room temperature. It was found that when the Cu nanoparticles are separated by gaps, the electrical conduction is governed by tunneling effects. In these conditions, the samples exhibit negative magnetoresistance values, displaying steps in the dependences on the magnetic field. These properties suggest the potential use of these films as magnetic sensors in spintronics.