Magnetoresistance of Carbon Nanotubes Filled by Iron

Paper presents the results of experimental investigations of magnetoresistance of filled with iron multi-walled carbon nanotubes. Multi-walled carbon nanotubes have been prepared by pyrolysis of benzene in a tubular quartz furnace at a temperature of $950 ^{\circ}\text{C}$ with use ferrocene as a source of iron. The obtained by this method carbon nanotubes contain in the inner cavity the particles of the magnetic phase, namely iron, iron carbide and iron oxides in various concentrations. The electrical resistance of bulk specimens of modified carbon nanotubes have been carried out in the temperature interval from 4.2 K to 293 K and in magnetic field up to 2 T. It is shown that magnetoresistance of modified carbon nanotubes is determined by a combination of two effects: the giant magnetoresistance effect and anisotropic magnetoresistance effect, moreover, the relative contribution of each effect depends on the concentration of the magnetic phase.