{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,18]],"date-time":"2026-04-18T06:23:44Z","timestamp":1776493424115,"version":"3.51.2"},"reference-count":25,"publisher":"AIP Publishing","issue":"11","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2011,6,1]]},"abstract":"<jats:p>The present study investigates the magnetic properties of spherical monodispersed maghemite (\u03b3-Fe2O3) nanoparticles coated with multiple silica (SiO2) layers of different thicknesses, forming core-shell multifunctional nanomaterials. This study was performed using a combination of local probe techniques (M\u00f6ssbauer spectrometry) and magnetization measurements. At room temperature, both techniques confirm the superparamagnetic state of the samples, even after being coated with the SiO2 shells. The zero-field-cooling\u2013field-cooling magnetization curves of the silica-coated \u03b3-Fe2O3 nanomaterials with different shell thicknesses allow the evaluation of the intensity of the interparticle dipole\u2013dipole interactions. We estimate the interparticle energy within the framework of dipolar interaction models and relate it with the hyperfine parameters. We further observe that this dipole\u2013dipole interaction increases the superparamagnetic energy barrier, which largely depends on the interparticle distance. Finally, we consider the effect of spin canting at the surface (\u201cdead layer\u201d) of uncoated \u03b3-Fe2O3 nanoparticles manifested by a layer of \u223c0.5(1) nm.<\/jats:p>","DOI":"10.1063\/1.3583652","type":"journal-article","created":{"date-parts":[[2011,6,18]],"date-time":"2011-06-18T04:16:08Z","timestamp":1308370568000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":48,"title":["Unravelling the effect of interparticle interactions and surface spin canting in <i>\u03b3<\/i>-Fe2O3@SiO2 superparamagnetic nanoparticles"],"prefix":"10.1063","volume":"109","author":[{"given":"Andr\u00e9 M.","family":"Pereira","sequence":"first","affiliation":[{"name":"Universidade do Porto 1 IFIMUP and IN \u2013 Institute of Nanoscience and Nanotechnology, Departamento de F\u00edsica e Astronomia, Faculdade de Ci\u00eancias, , 4169-007 Porto, Portugal"}]},{"given":"Clara","family":"Pereira","sequence":"additional","affiliation":[{"name":"Universidade do Porto 2 REQUIMTE, Departamento de Qu\u00edmica e Bioqu\u00edmica, Faculdade de Ci\u00eancias, , 4169-007 Porto, Portugal"}]},{"given":"Ana S.","family":"Silva","sequence":"additional","affiliation":[{"name":"Universidade do Porto 1 IFIMUP and IN \u2013 Institute of Nanoscience and Nanotechnology, Departamento de F\u00edsica e Astronomia, Faculdade de Ci\u00eancias, , 4169-007 Porto, Portugal"}]},{"given":"David S.","family":"Schmool","sequence":"additional","affiliation":[{"name":"Universidade do Porto 1 IFIMUP and IN \u2013 Institute of Nanoscience and Nanotechnology, Departamento de F\u00edsica e Astronomia, Faculdade de Ci\u00eancias, , 4169-007 Porto, Portugal"}]},{"given":"Cristina","family":"Freire","sequence":"additional","affiliation":[{"name":"Universidade do Porto 2 REQUIMTE, Departamento de Qu\u00edmica e Bioqu\u00edmica, Faculdade de Ci\u00eancias, , 4169-007 Porto, Portugal"}]},{"given":"Jean-Marc","family":"Gren\u00e8che","sequence":"additional","affiliation":[{"name":"Universit\u00e9 du Maine 3 LPEC, UMR CNRS 6087, , 72085 Le Mans Cedex 9, France"}]},{"given":"Jo\u00e3o P.","family":"Ara\u00fajo","sequence":"additional","affiliation":[{"name":"Universidade do Porto 1 IFIMUP and IN \u2013 Institute of Nanoscience and Nanotechnology, Departamento de F\u00edsica e Astronomia, Faculdade de Ci\u00eancias, , 4169-007 Porto, Portugal"}]}],"member":"317","published-online":{"date-parts":[[2011,6,15]]},"reference":[{"key":"2023072106394273100_c1","doi-asserted-by":"publisher","first-page":"1222","DOI":"10.1002\/anie.v46:8","volume":"46","year":"2007","journal-title":"Angew. 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