  We have investigated the magnetic and transport properties of nanoscaled
Fe3O4 films obtained from Chemical Vapor Deposition (CVD) technique using
[FeIIFe2III(OBut)8] and [Fe2III(OBut)6] precursors. Samples were deposited on
different substrates (i.e., MgO (001), MgAl2O4 (001) and Al2O3 (0001)) with
thicknesses varying from 50 to 350 nm. Atomic Force Microscopy analysis
indicated a granular nature of the samples, irrespective of the synthesis
conditions (precursor and deposition temperature, Tpre) and substrate. Despite
the similar morphology of the films, magnetic and transport properties were
found to depend on the precursor used for deposition. Using [FeIIFe2III(OBut)8]
as precursor resulted in lower resistivity, higher MS and a sharper
magnetization decrease at the Verwey transition (TV). The temperature
dependence of resistivity was found to depend on the precursor and Tpre. We
found that the transport is dominated by the density of antiferromagnetic
antiphase boundaries (AF-APB's) when [FeIIFe2III(OBut)8] precursor and Tpre =
363 K are used. On the other hand, grain boundary-scattering seems to be the
main mechanism when [Fe2III(OBut)6] is used. The Magnetoresistance (MR(H))
displayed an approximate linear behavior in the high field regime (H > 796
kA/m), with a maximum value at room-temperature of \sim2-3% for H = 1592 kA/m,
irrespective from the transport mechanism.
