Antiferromagnetic spin correlations above the bulk ordering temperature in NiO nanoparticles: Effect of extrinsic factors

NiO has been considered one of the attractive materials for advanced technological applications such as anti-ferromagnetic (AF) spintmnics in recent years. For a working application, an adequate knowledge of AF ordering temperature T-N and spin correlations is vital. This study intends to understand extrinsic factors affecting the T-N and AF spin correlations from similar to 63 nm NiO nanoparticles (NPs). The micro-Raman scattering combined with neutron powder diffraction shows that NiO NPs retain T-N degrees similar to 523 K (similar to bulk NiO T-N). The additional anomalies observed at T-N' similar to 560 K and T-N '' = 669 K indicated the persistence of AF spin correlations above T-N, which are suppressed relative to those observed in bulk NiO. The origin of anomalies above T-N was interpreted simply as extrinsic factors such as wide distribution in the particle size and weak interparticle interaction.

Automated summary

The study found that NiO nanoparticles exhibit similar anti-ferromagnetic spin behavior to bulk NiO, but with additional anomalies above the AF ordering temperature due to factors such as particle size distribution and weak interparticle interaction.