A core-shell-surface layer model to explain the size dependence of effective magnetic anisotropy in magnetic nanoparticles
| Autor: | Kelly L. Pisane, Sobhit Singh, Mohindar S. Seehra |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Condensed Matter - Materials Science
Materials science Condensed Matter - Mesoscale and Nanoscale Physics Condensed matter physics Magnetoresistance Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Condensed Matter - Other Condensed Matter Magnetic anisotropy Ferromagnetism Ferrimagnetism 0103 physical sciences Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Antiferromagnetism Magnetic nanoparticles Condensed Matter::Strongly Correlated Electrons Surface layer 010306 general physics 0210 nano-technology Anisotropy Other Condensed Matter (cond-mat.other) |
| DOI: | 10.48550/arxiv.1707.07241 |
| Popis: | The particle size (D) dependence of the effective magnetic anisotropy Keff of magnetic nanoparticles (NPs) usually shows Keff increasing with decreasing D. This dependence is often interpreted using the Eq.: Keff = Kb + (6Ks/D) where Kb and Ks are the anisotropy constants of the spins in the bulk-like core and surface layer, respectively. Here, we show that this model is inadequate to explain the observed size-dependency of Keff for smaller nanoparticles with D < 5 nm. Instead the results in NPs of maghemite ({\gamma}-Fe2O3), NiO and Ni are best described by an extension of the above model leading to the variation given by Keff = Kb + (6Ks/D) +Ksh{[1-(2d/D)]^(-3) -1}, where the last term is due to the spins in a shell of thickness d with anisotropy Ksh. The validation of this core-shell-surface layer (CSSL) model for three different magnetic NPs systems viz. ferrimagnetic {\gamma}-Fe2O3, ferromagnetic Ni and antiferromagnetic NiO suggests its possible applicability for all magnetic nanoparticles. Comment: 5 pages, 6 figures |
| Databáze: | OpenAIRE |
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