Conduction mechanisms in carbon matrix containing ferromagnetic nanoparticles

We have investigated the low temperature resistance and magnetoresistance behaviour of the carbon matrix containing ferromagnetic nanoparticles. A range of compositions with different levels of disorder and varying iron content were prepared from the pyrolysis of organic precursor maleic anhydride and ferrocene. The temperature dependence of resistivity shows a negative temperature coefficient in the entire measurement range of 1.3 to 300 K. An increase in conductivity with the external magnetic field and a characteristic upturn at low temperature, is seen in all the compositions. The zero-field conductivity and the magnetoresistance can be explained with in the framework of two-dimensional electron-electron interaction model and the Kondo-like behaviour