  We present a tunnel spectroscopy study of the electronic spectrum of single
magnetite \chemform{Fe_3O_4} nanoparticles trapped between nanometer-spaced
electrodes. The Verwey transition is clearly identified in the current
voltage-characteristics where we find that the transition temperature is
electric field dependent. The data show the presence of localized states at
high energy, $\varepsilon \sim 0.6eV$, which can be attributed to polaron
states. At low energy, the density of states (DOS) is suppressed at the
approach of the Verwey transition. Below the Verwey transition, a gap, $\Delta
\sim 300meV$, is observed in the spectrum. In contrast, no gap is observed in
the high temperature phase, implying that electronic transport in this phase is
possibly due to polaron hopping with activated mobility.
