Magnetism in nanometer-thick magnetite

PACS number(s): 75.70.−i, 75.47.Lx, 68.37.Nq, 78.20.Ls.-- et al.
The oldest known magnetic material, magnetite, is of current interest for use in spintronics as a thin film. An open question is how thin can magnetite films be and still retain the robust ferrimagnetism required for many applications. We have grown 1-nm-thick magnetite crystals and characterized them in situ by electron and photoelectron microscopies including selected-area x-ray circular dichroism. Well-defined magnetic patterns are observed in individual nanocrystals up to at least 520 K, establishing the retention of ferrimagnetism in magnetite two unit cells thick.
This researchwas supported by the Spanish Ministry of Science and Innovation through Projects No. MAT2009-14578-C03-01, MAT2009-14578-C03-02 and MAT2010-21156-C03-02, by the Office of Basic Energy Sciences, Division of Materials and Engineering Sciences, US Department of Energy under Contract No. DE-AC04-94AL85000, and by the European Union through 226716-ELISA. M. M. and B. S. thank the Spanish Ministry of Science and Innovation for supporting them through FPI fellowships.