Size dependence of the surface spin disorder and surface anisotropy constant in ferrite nanoparticles.

Autor:	Gerina M; Department of Inorganic Chemistry, Faculty of Science, Charles University Hlavova 2030/8 128 43 Prague 2 Czech Republic zakutnad@natur.cuni.cz., Sanna Angotzi M; Department of Chemical and Geological Sciences, University of Cagliari S.S. 554 bivio per Sestu, 09042 8 Monserrato CA Italy., Mameli V; Department of Chemical and Geological Sciences, University of Cagliari S.S. 554 bivio per Sestu, 09042 8 Monserrato CA Italy., Gajdošová V; Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic 162 06 Prague 6 Czech Republic., Rainer DN; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University Hlavova 2030/8 128 43 Prague 2 Czech Republic., Dopita M; Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5, 121 16 Prague 2 Czech Republic., Steinke NJ; Institut Laue-Langevin 71 Avenue des Martyrs F-38042 Grenoble France., Aurélio D; Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5, 121 16 Prague 2 Czech Republic., Vejpravová J; Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5, 121 16 Prague 2 Czech Republic., Zákutná D; Department of Inorganic Chemistry, Faculty of Science, Charles University Hlavova 2030/8 128 43 Prague 2 Czech Republic zakutnad@natur.cuni.cz.
Jazyk:	angličtina
Zdroj:	Nanoscale advances [Nanoscale Adv] 2023 Aug 03; Vol. 5 (17), pp. 4563-4570. Date of Electronic Publication: 2023 Aug 03 (Print Publication: 2023).
DOI:	10.1039/d3na00266g
Abstrakt:	The magnetic properties of nanoscale magnets are greatly influenced by surface anisotropy. So far, its quantification is based on the examination of the blocking temperature shift within a series of nanoparticles of varying sizes. In this scenario, the surface anisotropy is assumed to be a particle size-independent quantity. However, there is no solid experimental proof to support this simplified picture. On the contrary, our work unravels the size-dependent magnetic morphology and surface anisotropy in highly uniform magnetic nanoparticles using small-angle polarized neutron scattering. We observed that the surface anisotropy constant does not depend on the nanoparticle's size in the range of 3-9 nm. Furthermore, our results demonstrate that the surface spins are less prone to polarization with increasing nanoparticle size. Our study thus proves the size dependence of the surface spin disorder and the surface anisotropy constant in fine nanomagnets. These findings open new routes in materials based on a controlled surface spin disorder, which is essential for future applications of nanomagnets in biomedicine and magnonics. Competing Interests: There are no conflicts to declare. (This journal is © The Royal Society of Chemistry.)
Databáze:	MEDLINE
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