This study investigated the compositional optimization of magnetite (Fe3O4) thin films containing a small amount of Ge to enhance magnetization. No substrate bias was applied during deposition. In a pure Ar atmosphere, the film structure changed from the phase mixture of magnetite and wustite (Fe1-xO) to the weak appearance of wustite with increasing Ge content. The antiferromagnetic wustite thus obtained was employed as a starting material to prepare single-phase magnetite, and a gas mixture of Ar and O-2 was then applied. Single-phase magnetite thin films exhibit ferrimagnetic behavior with maximum magnetization of 0.42 Tat 1196 kA m(-1)(15 kOe), which exceeds that of a composite target of ceramic magnetite with Ge chips. Simultaneously adding Ge to the iron-excess wustite target therefore effectively enhanced magnetization. (C) 2011 Elsevier B.V. All rights reserved.