A Fe3O4/L1(0)-FePt bilayer thin-film magnet was fabricated via a simple one-step process by annealing Fe/Pt multilayer thin films in a N-2 gas flow. X-ray diffraction and plane-view selected-area electron diffraction results are identified with magnetite phase (Fe3O4) and L1(0)-FePt. Cross-sectional transmission electron microscopy images show the two phases form a bilayer structure. Magnetic hysteresis loops of the bilayer show single phase behavior which is interpreted as a result of the soft Fe3O4 phase exchange-coupled with the hard L1(0)-FePt phase, consistent with micromagnetic simulation prediction. Such bilayer structure may have potential for coercivity control in high density magnetic recording application. (C) 2008 Elsevier B.V. All rights reserved.