Enhanced room-temperature positive magnetoresistance of a-C:Fe film

Fe-doped amorphous carbon (a-C:Fe) film and pure amorphous carbon (a-C) film were synthesized on n-Si substrate using pulsed laser deposition. The a-C:Fe film has a positive magnetoresistance (15% at magnetic field B = 1 T) at room temperature, while it has a negative magnetoresistance below 260 K. The electrical conduction in a-C:Fe film is one order of magnitude higher than that in pure a-C film. It is found that a-C:Fe film has very different conduction mechanism from that of pure a-C film. The activation energy of electron conduction in a-C:Fe film could be tuned significantly by magnetic field. The magnetoresistance effect of the a-C:Fe film seems difficult to explain by known magnetoresistance mechanisms.