Abstract
We report a considerable intrinsic positive magnetoresistance (PMR) effect in Co-doped amorphous carbon films by radio frequency magnetron sputtering. The kind of PMR effect is bias dependence and its ratio reaches a peak at a particular voltage. At room temperature, the maximum PMR ratio is about 10% among these samples. The x-ray absorption spectroscopy and Raman spectra results support the appearance of the bias-dependent PMR effect strongly depends on the sp 2 states and Co dopants. A phenomenological model related to orbital Zeeman splitting has been proposed to describe the resistance, which is controlled by voltage and magnetic field. © 2010 American Institute of Physics.