Self Assembled Iron Nanowires: Morphology, Electrical and Magnetic Properties

Abstract

AbstractWe report on the self-assembled formation of iron nanowires from iron nanoparticles. Nanosized iron particles with a diameter of about 35 nm are synthesized by thermal decomposition of iron pentacarbonyl Fe(CO)5 in a hot wall reactor. This particle size is chosen to produce single domain ferromagnetic particles. As a result, the particles are attracted by magnetic forces, leading to iron nanowires of up to 300 μm in length. HRTEM and EELS investigations give detailed morphological, structural and chemical information. They reveal a big metallic iron core surrounded by an iron oxide shell with a thickness of 3-4 nm, originating from self limiting surface oxidation under ambient conditions. For electrical characterization, single iron wires are thermophoretically sampled on interdigital contacts. Impedance spectroscopy on single nanowires indicates both, capacitive and ohmic contributions to the overall conductivity. Magnetic properties are investigated with SQUID magnetometry. Magnetization measurements reveal a saturation magnetization of 160 emu/g at 5 K, which is more than 70% of the iron bulk value.