High-field and low-field magnetoresistances of CoFe nanoparticles elaborated by organometallic chemistry

We report on magnetotransport measurements on CoFe nanoparticles surrounded by an insulating organic layer. Samples were obtained by evaporating a solution of nanoparticles on a patterned substrate. Typical behavior of Coulomb blockade in array of nanoparticles is observed. High- and low-field magnetoresistances have been evidenced. Below 10 K, a large high-field magnetoresistance is measured, reaching up to 500%. Its amplitude decreases strongly with increasing voltage. At 1.6 K, this high-field magnetoresistance vanishes and an inverse low-field tunneling magnetoresistance is observed. (C) 2008 American Institute of Physics.