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Please use this identifier to cite or link to this item: http://hdl.handle.net/10651/25359

Title: Interplay between microstructure and magnetism in NiO nanoparticles: breakdown of the antiferromagnetic order
Author(s): Rinaldi Montes, Natalia Magdalena
Gorría Korres, Pedro
Martínez Blanco, David
Fuertes Arias, Antonio Benito
Fernández Barquín, Luis
Rodríguez Fernández, Jesús
Pedro del Valle, Imanol de
Fernández Gubieda, M. L.
Alonso, J.
Olivi, Luca
Aquilanti, Giuliana
Blanco Rodríguez, Jesús Ángel
Issue date: 2014
Publisher: The Royal Society of Chemistry
Publisher version: http://dx.doi.org/10.1039/c3nr03961g
Citation: Nanoscale, 6(1), p. 457-465 (2014); doi:10.1039/c3nr03961g
Format extent: p. 457-465
Abstract: The possibility of tuning the magnetic behaviour of nanostructured 3d transition metal oxides has opened up the path for extensive research activity in the nanoscale world. In this work we report on how the antiferromagnetism of a bulk material can be broken when reducing its size under a given threshold. We combined X-ray diffraction, high-resolution transmission electron microscopy, extended X-ray absorption fine structure and magnetic measurements in order to describe the influence of the microstructure and morphology on the magnetic behaviour of NiO nanoparticles (NPs) with sizes ranging from 2.5 to 9 nm. The present findings reveal that size effects induce surface spin frustration which competes with the expected antiferromagnetic (AFM) order, typical of bulk NiO, giving rise to a threshold size for the AFM phase to nucleate. Ni2+ magnetic moments in 2.5 nm NPs seem to be in a spin glass (SG) state, whereas larger NPs are formed by an uncompensated AFM core with a net magnetic moment surrounded by a SG shell. The coupling at the core–shell interface leads to an exchange bias effect manifested at low temperature as horizontal shifts of the hysteresis loop (∼1 kOe) and a coercivity enhancement (∼0.2 kOe).
URI: http://hdl.handle.net/10651/25359
ISSN: 2040-3364
Local identifier: 20141220
Sponsored: Ministerio de Educación, Cultura y Deporte (MECD) doctoral grant FPU12/03381. This work was accomplished with financial support from project MAT2011-27573-C04.
Project id.: MAT2011-27573-C04
Appears in Collections:Física

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