Size Effects in Antiferromagnetic NiO Nanoparticles

Size-dependent magnetization fluctuations in NiO nanoparticles

The finite size and surface roughness effects on the magnetization of NiO nanoparticles is investigated. A large magnetic moment arises for an antiferromagnetic nanoparticle due to these effects. The magnetic moment without the surface roughness has a non-monotonic and oscillatory dependence on R, the size of the particles, with the amplitude of the fluctuations varying linearly with R. However...

Memory and aging effects in antiferromagnetic nanoparticles

We investigate the slow dynamics of polydisperse antiferromagnetic NiO nanoparticles using Monte Carlo simulations. The zero-field cooled and field cooled magnetizations exhibit the size-dependent fluctuations. We find memory effects and very weak aging effects in a noninteracting polydisperse assembly of nanoparticles. The relaxation measurements of magnetization after a sudden cooling, heatin...

Interplay between microstructure and magnetism in NiO nanoparticles: breakdown of the antiferromagnetic order.

The possibility of tuning the magnetic behaviour of nanostructured 3d transition metal oxides has opened up the path for extensive research activity in the nanoscale world. In this work we report on how the antiferromagnetism of a bulk material can be broken when reducing its size under a given threshold. We combined X-ray diffraction, high-resolution transmission electron microscopy, extended ...

Interparticle interactions in composites of nanoparticles of ferrimagnetic „g-Fe2O3... and antiferromagnetic „CoO,NiO... materials

Size and surface effects on the magnetic properties of NiO nanoparticles.

NiO nanoparticles (NPs) were prepared by a sol-gel process using the citrate route. The sol-gel parameters were tuned to obtain samples with different average particle sizes, ranging from 12 to 70 nm. Magnetic characterization revealed an increase in the blocking temperature with the diameter of the NPs and an increase in the effective magnetic anisotropy (K(eff)) with decreasing particle size....