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

• Published in: Applied surface science 2022-03, Vol.578, p.152081, Article 152081
• Main Authors: Li, Tai-Yue, Ho, Ming-Kang, Hsu, Tus-En, Chiu, Hsin-Hao, Wu, Kuan-Ting, Peng, Jen-Chih, Wu, Chun-Ming, Chan, Ting Shan, Vijaya Kumar, B., Muralidhar Reddy, P., Ke, Shyue-Chu, Cheng, Chia-Liang, Gandhi, Ashish Chhaganlal, Wu, Sheng Yun
• Format: Article
• Language: English
• Subjects: Antiferromagnetic; Neel temperature; NiO; Size distribution; Spin correlations
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2021.152081

This study intends to understand extrinsic factors affecting the TN and AF spin correlations from ∼ 63 nm NiO nanoparticles (NPs). The micro-Raman scattering combined with neutron powder diffraction shows that NiO NPs retain T°N ∼ 523 K (similar to bulk NiO TN). The additional anomalies observed at TN' ∼ 560 K and TN'' = 669 K indicated the persistence of AF spin correlations above TN, which are suppressed relative to those observed in bulk NiO. [Display omitted] •The antiferromagnetic spin correlations are reported above TN and discussed in terms of extrinsic factors, such as wide distribution in the particle size and weak interparticle interactions.•The outcome of this study highlights the mechanism and the importance of uses of both micro-Raman and NPD techniques for an in-depth characterization of AF ordering temperature and spin correlations in nanomaterials and understanding the role of extrinsic factors, which otherwise could lead to misleading conclusions. NiO has been considered one of the attractive materials for advanced technological applications such as antiferromagnetic (AF) spintronics in recent years. For a working application, an adequate knowledge of AF ordering temperature TN and spin correlations is vital. This study intends to understand extrinsic factors affecting the TN and AF spin correlations from ∼63 nm NiO nanoparticles (NPs). The micro-Raman scattering combined with neutron powder diffraction shows that NiO NPs retain T°N ∼ 523 K (similar to bulk NiO TN). The additional anomalies observed at TN' ∼ 560 K and TN'' = 669 K indicated the persistence of AF spin correlations above TN, which are suppressed relative to those observed in bulk NiO. The origin of anomalies above TN was interpreted simply as extrinsic factors such as wide distribution in the particle size and weak interparticle interaction.