Novel Ba-hexaferrite structural variations stabilized on the nanoscale as building blocks for epitaxial bi-magnetic hard/soft sandwiched maghemite/hexaferrite/maghemite nanoplatelets with out-of-plane easy axis and enhanced magnetization
Belec, B. (Jožef Stefan International Postgraduate School)
Dražić, G. (National Institute of Chemistry. Department for Materials Chemistry)
Gyergyek, Sašo (Jožef Stefan Institute. Department for Materials Synthesis)
Podmiljšak, B. (Jožef Stefan Institute. Department for Nanostructured Materials)
Goršak, T. (Jožef Stefan International Postgraduate School)
Komelj, M. (Jožef Stefan Institute. Department for Nanostructured Materials)
Nogués, Josep (Institut Català de Nanociència i Nanotecnologia)
Makovec, Darko (Jožef Stefan International Postgraduate School)

Date:	2017
Abstract:	Atomic-resolution scanning-transmission electron microscopy showed that barium hexaferrite (BHF) nanoplatelets display a distinct structure, which represents a novel structural variation of hexaferrites stabilized on the nanoscale. The structure can be presented in terms of two alternating structural blocks stacked across the nanoplatelet: a hexagonal (BaFeO) R block and a cubic (FeO) spinel S block. The structure of the BHF nanoplatelets comprises only two, or rarely three, R blocks and always terminates at the basal surfaces with the full S blocks. The structure of a vast majority of the nanoplatelets can be described with a SR∗S∗RS stacking order, corresponding to a BaFeO composition. The nanoplatelets display a large, uniaxial magnetic anisotropy with the easy axis perpendicular to the platelet, which is a crucial property enabling different novel applications based on aligning the nanoplatelets with applied magnetic fields. However, the BHF nanoplatelets exhibit a modest saturation magnetization, M, of just over 30 emu g. Given the cubic S block termination of the platelets, layers of maghemite, γ-FeO, (M), with a cubic spinel structure, can be easily grown epitaxially on the surfaces of the platelets, forming a sandwiched M/BHF/M platelet structure. The exchange-coupled composite nanoplatelets exhibit a remarkably uniform structure, with an enhanced M of more than 50 emu g while essentially maintaining the out-of-plane easy axis. The enhanced M could pave the way for their use in diverse platelet-based magnetic applications.
Grants:	Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-1015 Ministerio de Economía y Competitividad MAT2016-77391-R Ministerio de Economía y Competitividad SEV-2013-0295
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Subject:	Applied magnetic fields ; Atomic resolution ; Barium hexaferrites ; Cubic spinel structure ; Magnetic applications ; Novel applications ; Structural variations ; Uniaxial magnetic anisotropy
Published in:	Nanoscale, Vol. 9, Issue 44 (November 2017) , p. 17551-17560, ISSN 2040-3372

DOI: 10.1039/c7nr05894b

Preprint 30 p, 2.6 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles