Synthesis and Characterization of ${\rm Fe-FeO}_{\rm x}$ Core-Shell Nanowires

We report the synthesis and characterization of Fe-FeO_x core-shell nanowires by thermal conversion of the Fe nanowires from pulse electrodeposition in anodized aluminum oxide (AAO) nanotemplates under various conditions. Well-defined core-shell nanostructure of the Fe-FeO_x nanowires was confirmed by TEM and corresponding elemental line scanning and point scanning. The type of the iron oxide in the shell was identified using nano-Raman spectroscopy, which exposes magnetite to be the major constituent. The magnetic measurements demonstrate that the nanowires are robustly soft magnetic, with the magnetization tunable by heat treatment parameters and a weak magnetic easy direction parallel to the nanowire axis.