Influence of size effect on the magnetic properties and magnetic circular dichroism spectra of Ni0.5Zn0.5Fe2O4 nanoparticles
Aleksandr Spivakov1*, Tan-Xuan Wu1, En-Szu Lin1, Ying-Zhen Chen1, Chun-Rong Lin1
1Department of Applied Physics, National Pingtung University, Pingtung, Taiwan
* Presenter:Aleksandr Spivakov,
Ni0.5Zn0.5Fe2O4 nanoparticles were synthesized by thermal pyrolysis method at different synthesis conditions and influence of size effect on the evolution of the structural, magnetic and magneto-optical properties was investigated by various methods. Based on magnetic measurements, it was found that the critical nanoparticle size corresponding to the transition between single-domain and multi-domain states is 16.42 nm. A further decrease in the size of nanoparticles leads to their transition to a superparamagnetic state at d ≈ 7 nm. It was shown that for Ni0.5Zn0.5Fe2O4 the major transitions in the magnetic circular dichroism spectra correspond to two intervalence charge transfer transitions as well as two intersublattice charge-transfer transitions between the tetrahedral and octahedral sites and a crystal–field transition in the Ni2+ ions at the tetrahedral sites.

Keywords: magnetic nanoparticles, superparamagnetic state, MCD, synthesis conditions, multi-domain structure