A microfibre assembly of an iron-carbon composite with giant magnetisation

Iron carbide is among the oldest known materials. The utility of this ancient advanced material is greatly extended in its nanostructured forms. We demonstrate for the first time that one-dimensional iron carbide microfibres can be assembled in liquid using strong magnetic field-assisted laser ablation. The giant saturation magnetisation of these particles was measured a 261 emu/g at room temperature, which is the best value reported to date for iron nitride and carbide nanostructures, is 5.5 times greater than the 47 emu/g reported for Fe3C nanoparticles, and exceeds the 212 emu/g for bulk Fe. The magnetic field-induced dipolar interactions of the magnetic nanospheres and the nanochains played a key role in determining the shape of the product. These findings lead to a variety of promising applications for this unique nanostructure including its use as a magnetically guided transporter for biomedicine and as a magnetic recording material.