The current study unveils the structural origin of the magnetic transition of the Ïµ-Fe2O3polymorph from an incommensurate magnetic order to a collinear ferrimagnetic state at low temperature. The high crystallinity of the samples and the absence of other iron oxide polymorphs have allowed us to carry out temperature-dependent x-ray absorption fine structure spectroscopy experiments out. The deformation of the structure is followed by the Debye-Waller factor for each selected Fe-O and Fe-Fe sub-shell. For nanoparticle sizes between 7 and 15 nm, the structural distortions between the Feteand Fe-D1ocsites are localized in a temperature range before the magnetic transition starts. On the contrary, the inherent interaction between the other sub-shells (named Fe-O1,2 and Fe-Fe1) provokes cooperative magneto-structural changes in the same temperature range. This means that the Fetewith Fe-D1oc polyhedron interaction seems to be uncoupled with temperature dealing with these nanoparticle sizes wherein the structural distortions are likely moderate due to surface effects.
Origin of the magnetic transition at 100 K in Ïµ-Fe2O3nanoparticles studied by x-ray absorption fine structure spectroscopy / J. López-Sánchez, A. Munoz-Noval, C. Castellano, A. Serrano, A. Del Campo, M. Cabero, M. Varela, M. Abuin, J. De La Figuera, J.F. Marco, G.R. Castro, O. Rodriguez De La Fuente, N. Carmona. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - 29:48(2017 Dec 06).
|Titolo:||Origin of the magnetic transition at 100 K in Ïµ-Fe2O3nanoparticles studied by x-ray absorption fine structure spectroscopy|
|Parole Chiave:||epsilon iron oxide; incommensurate magnetic transition; sol-gel synthesis; x-ray absorption spectroscopy; materials science (all); condensed matter physics|
|Settore Scientifico Disciplinare:||Settore CHIM/03 - Chimica Generale e Inorganica|
Settore FIS/01 - Fisica Sperimentale
Settore CHIM/02 - Chimica Fisica
|Data di pubblicazione:||6-dic-2017|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1088/1361-648X/aa904b|
|Appare nelle tipologie:||01 - Articolo su periodico|