Bimagnetic urchin-like Co₃O₄/CoFe₂O₄ nanocomposites: Synthesis and magnetic properties

A heterostructured Co₃O₄/CoFe₂O₄ nanocomposite material is synthetised via the solid-solid reaction of an iron precursor with urchin-like Co₃O₄ which was prepared via hydrothermal treatment. The coupling of Co₃O₄ to the hard ferrimagnet CoFe₂O₄ leads to reinforcement for the magnetic interaction of the interfaces and the mismatched surface spin in the Co₃O₄/CoFe₂O₄ nanocomposite is greatly reduced. The magnetic performance of the exchange-coupled anti-ferromagnetic/ferrimagnetic (AFM/FM) system is investigated with superconducting quantum interference device magnetometry. In an applied magnetic field, the low-temperature magnetization loops of the nanocomposite heterostructure exchange bias under cooling. The antiferromagnetic ordering temperature of Co₃O₄ is increased owing to the adjacent hard magnetic CoFe₂O₄ phase. The Co₃O₄/CoFe₂O₄ nanocomposite behaves as an exchange coupled system with cooperative magnetic switching.