Fyzikální ústav Akademie věd ČR

Magnetic nanoparticles are under intensive research due to their promising potential applications, e.g. in magnetic recording, spintronics, catalysis and biomedical applications. We study the fundamental magnetic properties of the nanoparticles with the purpose on the correlation of the intrinsic crystallinity, interparticle interactions and presence of surface spins with the magnetic response of these materials. We participate in several projects:

• We are one of the partners in the Europian 7^th Framework program MULTIFUN that deals with the innovation of the new nanotechnologies with objective to improve the diagnosis, detection and treatment of the tumor diseases (cancer). The aim of the project is to develop nanotechnologies based on multi-functionalized magnetic nanoparticles that can be used as the contrast agent for MRI (magnetic resonance imaging), the drug carriers and that could damage the cancer cells via magnetic fluid hyperthermia treatment (Fig. 1). Within the scope of this project, we study the mechanism of growth of the nanoparticles and correlated it with their intrinsic and magnetic properties. One of the results of our work is the proposed internal structure parameter that correlates the intrinsic properties of particle with the specific absorption rate (SAR).
• In cooperation with the Faculty of Science, Charles University; we are interested in the multifunctional nanomaterials that exhibit multiple functional properties simultaneously, e.g. multiferroics and magnetocaloric materials or to design multicomponent nanostructures comprising two different materials, such as magnetic core with the photocatalytic shell (e.g. CoFe₂O₄/TiO₂). Furthemore; we investigate the properties of the nanomaterials that has not been prepared at the nanoscale yet (e.g. ACr₂O₄, kde A=Fe, Mg, Co) or whose properties (such as magnetic ground state) has not been explained yet sufficiently (ε-Fe₂O₃).

The standard macroscopic magnetic measurements are performed in the Joint Laboratory for Magnetic Studies. In the Joint Low Temperature Laboratory, we use the Mössbauer spectroscopy (applicable only for materials containing iron atoms) for studies of the valence state of compounds, local symmetry, defects of crystal lattice, magnetic ordering and the local orientation of the magnetic moments with respect to the externally applied magnetic field. We are also specialized in the Atomic/Magnetic Force Microscopy (AFM/MFM) that allow mapping of the magnetic domains. Furthermore, we deal with the methods based on utilization of the synchrotron or neutron scattering techniques such as neutron diffraction, X-ray magnetic circular dichroism (XMCD) in the large synchrotron and neutron facilities.

Research team: J.Vejpravová, S.Kubíčková, B.Pacáková, A.Mantlíková

Fig.1: Demonstration of the possible utilization of the multifunctional magnetic nanoparticles as: the contrast agents for MRI detection, source of the heat treatment of the cancer cells induced by alternating magnetic field (hyperthermia) and as the drugs carriers with the selective delivery into the cancer cells by the application of magnetic field.