Magnetic Properties and Electronic Conductivity of Fe3O4 Magnetite Nanowires

Resumo

We have separately assessed the contributions of isolated Fe³⁺ ions and the ferrimagnetic subsystem to the total magnetization of an aligned magnetite (Fe₃O₄) nanowire array grown in pores of an anodized alumina membrane and evaluated the magnetic anisotropy field of the nanowires, which has been found to be an order of magnitude weaker than the expected shape anisotropy field. The reduction in magnetic anisotropy in the nanowires can be accounted for by dipole–dipole interaction between individual nanowires in the array. In electron spin resonance spectra of the nanowires, we have identified a phase-inverted line, corresponding to their microwave magnetoresistance. The Verwey transition in the magnetite nanowires has been shown to be suppressed due to deviations from stoichiometry and size effects.