Antiferromagnetic Order in MnO Spherical Nanoparticles
| Autor: | Wang, C. H., Baker, S. N., Lumsden, 1 M. D., Nagler, S. E., Heller, W. T., Baker, G. A., Deen, y P. D., Cranswick, L. M. D., Su, Y., Christianson, A. D. |
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| Rok vydání: | 2011 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 83, 214418 (2011) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.83.214418 |
| Popis: | We have performed unpolarized and polarized neutron diffraction experiments on monodisperse 8 nm and 13 nm antiferromagnetic MnO nanoparticles. For the 8 nm sample, the antiferromagnetic transition temperature $T_N$ (114 K) is suppressed compared to the bulk material (119 K) while for the 13 nm sample $T_N$ (120 K) is comparable to the bulk. The neutron diffraction data of the nanoparticles is well described using the bulk MnO magnetic structure but with a substantially reduced average magnetic moment of 4.2$\pm$0.3 $\mu_B$/Mn for the 8 nm sample and 3.9$\pm$0.2 $\mu_B$/Mn for the 13 nm sample. An analysis of the polarized neutron data on both samples shows that in an individual MnO nanoparticle about 80$%$ of Mn ions order. These results can be explained by a structure in which the monodisperse nanoparticles studied here have a core that behaves similar to the bulk with a surface layer which does not contribute significantly to the magnetic order. Comment: 7 pages, 5 figures |
| Databáze: | arXiv |
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