Issue 3, 2013

2D to 3D crossover of the magnetic properties in ordered arrays of iron oxide nanocrystals

Abstract

The magnetic 2D to 3D crossover behavior of well-ordered arrays of monodomain γ-Fe2O3 spherical nanoparticles with different thicknesses has been investigated by magnetometry and Monte Carlo (MC) simulations. Using the structural information of the arrays obtained from grazing incidence small-angle X-ray scattering and scanning electron microscopy together with the experimentally determined values for the saturation magnetization and magnetic anisotropy of the nanoparticles, we show that MC simulations can reproduce the thickness-dependent magnetic behavior. The magnetic dipolar particle interactions induce a ferromagnetic coupling that increases in strength with decreasing thickness of the array. The 2D to 3D transition in the magnetic properties is mainly driven by a change in the orientation of the magnetic vortex states with increasing thickness, becoming more isotropic as the thickness of the array increases. Magnetic anisotropy prevents long-range ferromagnetic order from being established at low temperature and the nanoparticle magnetic moments instead freeze along directions defined by the distribution of easy magnetization directions.

Graphical abstract: 2D to 3D crossover of the magnetic properties in ordered arrays of iron oxide nanocrystals

Supplementary files

Article information

Article type
Paper
Submitted
02 Oct 2012
Accepted
27 Nov 2012
First published
03 Dec 2012
This article is Open Access

Nanoscale, 2013,5, 953-960

2D to 3D crossover of the magnetic properties in ordered arrays of iron oxide nanocrystals

B. Faure, E. Wetterskog, K. Gunnarsson, E. Josten, R. P. Hermann, T. Brückel, J. W. Andreasen, F. Meneau, M. Meyer, A. Lyubartsev, L. Bergström, G. Salazar-Alvarez and P. Svedlindh, Nanoscale, 2013, 5, 953 DOI: 10.1039/C2NR33013J

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