Interface scattering and spin-dependent transport in granular magnetite

Abstract We have prepared nearly monodisperse Fe 3 O 4 of ∼50 nm by a chemical route and investigated the electrical and magnetic transports of the composite granular system. A Verwey transition is observed in the vicinity of 113 K. Above and below the Verwey transition, the electrical transport is dominated by electron hopping behavior showing a good linear relation between resistance and T −1/2 . The magnetoresistance (MR) increases with the applied field and does not follow the magnetization to reach the saturation at 10 KOe field. This indicates that the MR is mainly arising from the spin-dependent scattering of electrons through the grain boundaries. The temperature dependence of MR shows it has the highest MR value near the Verwey transition.