title: Enhancing the magnetic anisotropy of maghemite nanoparticles via the surface coordination of molecular complexes.
abstract: Superparamagnetic nanoparticles are promising objects for data storage or medical applications. In the smallest--and more attractive--systems, the properties are governed by the magnetic anisotropy. Here we report a molecule-based synthetic strategy to enhance this anisotropy in sub-10-nm nanoparticles. It consists of the fabrication of composite materials where anisotropic molecular complexes are coordinated to the surface of the nanoparticles. Reacting 5 nm γ-Fe2O3 nanoparticles with the [Co(II)(TPMA)Cl2] complex (TPMA: tris(2-pyridylmethyl)amine) leads to the desired composite materials and the characterization of the functionalized nanoparticles evidences the successful coordination--without nanoparticle aggregation and without complex dissociation--of the molecular complexes to the nanoparticles surface. Magnetic measurements indicate the significant enhancement of the anisotropy in the final objects. Indeed, the functionalized nanoparticles show a threefold increase of the blocking temperature and a coercive field increased by one order of magnitude.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8234, PHENIX, CNRS, F-75005 Paris, France.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Prado
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8234, PHENIX, CNRS, F-75005 Paris, France.|Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR 7590, CNRS, UPMC, IRD, MNHN, F-75005 Paris, France.|Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48, 91192 Gif-sur-Yvette, France.
authors.forename: Niéli
authors.initials: N
authors.lastname: Daffé
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8234, PHENIX, CNRS, F-75005 Paris, France.
authors.forename: Aude
authors.initials: A
authors.lastname: Michel
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 7197, LRS, F-94200 Ivry-sur-Seine, France.|CNRS, UMR 7197, Laboratoire de Réactivité de Surface, F-94200 Ivry-sur-Seine, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Georgelin
authors.affiliation: Institut des Molécules et Matériaux du Mans CNRS UMR-6283, Université du Maine, F-72085 Le Mans, France.
authors.forename: Nader
authors.initials: N
authors.lastname: Yaacoub
authors.affiliation: Institut des Molécules et Matériaux du Mans CNRS UMR-6283, Université du Maine, F-72085 Le Mans, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Grenèche
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48, 91192 Gif-sur-Yvette, France.
authors.forename: Fadi
authors.initials: F
authors.lastname: Choueikani
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48, 91192 Gif-sur-Yvette, France.
authors.forename: Edwige
authors.initials: E
authors.lastname: Otero
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48, 91192 Gif-sur-Yvette, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ohresser
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR 7590, CNRS, UPMC, IRD, MNHN, F-75005 Paris, France.
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Arrio
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8232, IPCM, F-75005 Paris, France.|CNRS, UMR 8232, Institut Parisien de Chimie Moléculaire, F-75005 Paris, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Cartier-dit-Moulin
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR 7590, CNRS, UPMC, IRD, MNHN, F-75005 Paris, France.|Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48, 91192 Gif-sur-Yvette, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Sainctavit
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8232, IPCM, F-75005 Paris, France.|CNRS, UMR 8232, Institut Parisien de Chimie Moléculaire, F-75005 Paris, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Fleury
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8234, PHENIX, CNRS, F-75005 Paris, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Dupuis
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8232, IPCM, F-75005 Paris, France.|CNRS, UMR 8232, Institut Parisien de Chimie Moléculaire, F-75005 Paris, France.
authors.forename: Laurent
authors.identifier: http://orcid.org/0000-0001-8649-9022
authors.initials: L
authors.lastname: Lisnard
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8234, PHENIX, CNRS, F-75005 Paris, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Fresnais