Unique magnetic properties and magnetization reversal process of CoFe2O4nanotubes fabricated by electrospinning

Abstract

CoFe₂O₄ nanotubes have been directly fabricated by single-capillary spinneret electrospinning. The external diameter of the CoFe₂O₄ nanotubes ranges from 60 nm to 160 nm. The morphology and structure characterizations show that individual CoFe₂O₄ nanotubes are made of CoFe₂O₄ nanocrystals stacking along the nanotubes with no preferred growth directions and these individual nanocrystals are single crystal with a cubic spinel structure. Each nanocrystal was shown to be a single magnetic domain. The magnetic measurements show that the coercivity (H_c) of the CoFe₂O₄ nanotubes decreases from 10 400 Oe at 5 K to 300 Oe at 360 K. The CoFe₂O₄ nanotubes have a spin reorientation (SR) at 5 K, which is different from CoFe₂O₄ nanorods and nanoparticles. Based on the observed morphology and crystal structure, a micromagnetic model, “chain-of-rings”, is developed to interpret the magnetic behavior of the CoFe₂O₄ nanotubes. The theoretical coercivity (534 Oe) is in good agreement with the experimental results (509 Oe). It is believed that our work should open a new route to prepare various magnetic ferrite nanotubes and is significant for expanding the application of CoFe₂O₄ into the new fields.