The electronic and magnetic properties of epitaxial Fe(3)O(4) (001) films on MgO(100) substrates were studied throughout the 2.5- to 30-nm thickness range using conversion electron Mossbauer spectroscopy. Despite the superparamagnetism that was observed for film thickness below 5 nm, the Verwey transition persisted even for the thinnest film. Temperature-dependent Mossbauer measurements between 80 K and 400 K revealed that the activation energy for the magnetic moment fluctuations in the 3-nm magnetite film is higher than the magnetic anisotropy energy by an order of magnitude. (C) 2011 Elsevier B.V. All rights reserved.