Speaker
Description
Asmaa Qdemat1, Emmanuel Kentzinger1, Giuseppe Portale2, Marina Ganeva3, Stefan Mattauch3, Oleg Petracic1, Ulrich Rücker1, Thomas Brückel1
1Jülich Centre for Neutron Science (JCNS) and Peter Grünberg Institute (PGI), JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
2 Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen,
The Netherlands
3 Jülich Centre for Neutron Science, Forschungszentrum Jülich, at Heinz Maier Leibnitz Zentrum MLZ, 85748 Garching, Germany
Magnetic nanoparticles and their assembly in highly ordered structures are fundamentally interesting regarding the understanding of magnetic interactions and for a rational design towards potential applications in information technology as e.g. magnetic data storage media or as material for spintronics. With regard to these applications, the main aspects of fundamental interest include magnetic anisotropy, Van-der-Waals forces and interparticle interactions leading to aggregation or even ordered assemblies of nanoparticles.
This work focuses on the chemical and magnetic characterization of monolayers of CoFe2O4 nanoparticles on silicon substrates. The system was characterized laterally by Scanning Electron Microscopy (SEM) and Grazing Incidence Small Angle X-ray Scattering (GISAXS) at the laboratory high brilliance GALAXI instrument [1] with simulation using the BornAgain software [2]. We deduce both the height profile of the individual nanoparticles, and a hexagonal ordering between the nanoparticles. Macroscopic magnetization measurements and polarized neutron reflectometry on a MARIA reflectometer [3] were used to find that the nanoparticles are weakly magnetized with respect to bulk CoFe2O4 and that a random in plane relative orientation of the nanoparticle magnetizations is obtained at zero applied fields.
References
[1] Jülich Centre for Neutron Science. (2016). GALAXI: Gallium anode low-angle x-ray instrument. Journal of large-scale research facilities, 2, A61. http://dx.doi.org/10.17815/jlsrf-2-109
[2] J. Burle, C. Durniak, J. M. Fisher, M. Ganeva, G. Pospelov, W. Van Herck and J. Wuttke, BornAgain – Software for simulating and fitting X-ray and neutron small-angle scattering at grazing incidence, Version 1.11.0 (2013-2018), http://www.bornagainproject.org (2018)
[3] Jülich Centre for Neutron Science. (2015). MARIA: Magnetic reflectometer with high incident angle. Journal of large-scale research facilities, 1, A8. http://dx.doi.org/10.17815/jlsrf-1-29
