Morphology and magnetic behaviour of an Fe3O4 nanotube array

An Fe3O4 nanotube array was successfully prepared in pores of an anodic aluminium oxide (AAO) template. Fe3O4 nanotubes and the nanotube array were characterized by transmission and scanning electron microscopy. The average diameter of the nanotubes was about 200 nm, and the length was more than 10 mu m. The static distribution of the magnetic moments was investigated by means of magnetostatic energy analysis and Mossbauer spectrum measurement. The resulting Mossbauer spectrum shows that the distribution of the magnetic moments in the Fe3O4 nanotube array is spatially isotropic. However, macroscopic magnetic measurement shows the Fe3O4 nanotube array to have obvious anisotropy, and the easy axis is parallel to the nanotube axis. These magnetic behaviours are discussed on the basis of analysis of the magnetostatic energy.