Synthesis of Hard Magnetic Ordered Mesoporous Co3O4/CoFe2O4 Nanocomposites

The nanocomposite Co3O4/CoFe2O4 heterostructured mesoporous material was produced via a simple solid-solid reaction of an iron precursor with ordered mesoporous Co3O4 that had been prepared via nanocasting from mesoporous silica as hard template. The magnetic behavior of the exchange-coupled antiferromagnetic/ferrimagnetic (AFM/FM) system was investigated via superconducting quantum interference device (SQUID) magnetometry and Fe-57 Mossbauer spectroscopy. The low-temperature magnetization loops of the Co3O4/CoFe2O4 heterostructure present exchange bias under cooling in an applied magnetic field. The antiferromagnetic ordering temperature of Co3O4 is increased due to the proximity of the hard magnetic CoFe2O4 phase. The nanocomposite Co3O4/CoFe2O4 behaves as an exchange coupled system with a cooperative magnetic switching.