uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Size-dependent surface effects in maghemite nanoparticles and its impact on interparticle interactions in dense assemblies
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
The Nanos, Inst Bioengn & Nanotechnol, Singapore 138669, Singapore..
Univ Castilla La Mancha, IRICA, E-13071 Ciudad Real, Spain.;Univ Castilla La Mancha, Dept Fis Aplicada, E-13071 Ciudad Real, Spain..
Show others and affiliations
2015 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, no 47, 475703Article in journal (Refereed) PublishedText
Abstract [en]

The question of the dominant interparticle magnetic interaction type in random closely packed assemblies of different diameter (6.2-11.5 nm) bare maghemite nanoparticles (NPs) is addressed. Single-particle magnetic properties such as particle anisotropy and exchange bias field are first of all studied in dilute (reference) systems of these same NPs, where interparticle interactions are neglible. Substantial surface spin disorder is revealed in all particles except the smallest, viz. for diameters d = 8-11.5 nm but not for d = 6.2-6.3 nm. X-ray diffraction analysis points to a crystallographic origin of this effect. The study of closely packed assemblies of the d >= 8 nm particles observes collective (superspin) freezing that clearly appears to be governed by interparticle dipole interactions. However, the dense assemblies of the smallest particles exhibit freezing temperatures that are higher than expected from a simple (dipole) extrapolation of the corresponding temperatures found in the d >= 8 nm assemblies. It is suggested that the nature of the dominant interparticle interaction in these smaller particle assemblies is superexchange, whereby the lack of significant surface spin disorder allows this mechanism to become important at the level of interacting superspins.

Place, publisher, year, edition, pages
2015. Vol. 26, no 47, 475703
Keyword [en]
nanoparticles, magnetism, dipolar, superexchange
National Category
Nano Technology
URN: urn:nbn:se:uu:diva-272272DOI: 10.1088/0957-4484/26/47/475703ISI: 000366209100010OAI: oai:DiVA.org:uu-272272DiVA: diva2:895186
Swedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of Technology
Available from: 2016-01-18 Created: 2016-01-13 Last updated: 2016-01-18Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Andersson, Mikael SvanteMathieu, RolandNordblad, Per
By organisation
Solid State Physics
In the same journal
Nano Technology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 280 hits
ReferencesLink to record
Permanent link

Direct link