Strong correlation between the cation ordering and magnetic properties of anodically electrodeposited Mn–Co–O nanocrystals

摘要

The rock salt-to-spinel structural transformation that occurs in anodically electrodeposited Mn–Co–O nanocrystals involves a rearrangement of Mn/Co cations from octahedral interstices to tetrahedral interstices. The cation ordering process leads to distinct magnetic properties. Curie temperature (T _C) and blocking temperature (T _B) increase dramatically with annealing temperature (200–400 °C), while the corresponding change in particle size for the oxide nanocrystals is rather small. A strong correlation between the magnetic properties and the cation ordering degree in annealed Mn–Co–O nanocrystals was established. These unique magnetic properties can be attributed to the magnetic moment changes induced by Mn/Co cation ordering from octahedral interstices to tetrahedral interstices in the annealed Mn–Co oxide nanocrystals.