Nanoscale magnetic materials play a central role in many areas of science and technology, such as high density data storage, development of advanced materials, and biomedical devices for cancer hyperthermia therapy, drug delivery and rapid cell sorting. At reduced size, magnetic properties of individual particles are affected by surface states due to the high surface to volume ratio, and the particle shape becomes important. Therefore, magnetic nanoparticles assemblies have to be investigated by means of techniques capable to record magnetic and topography texture simultaneously at both high magnetic sensitivity and nanometer spatial resolution. Magnetic Force Microscopy (MFM) can match both requirements, since it provides the nanometer resolution typical of dynamic atomic force microscopy (AFM), making single particle studies possible.
A proper modification of AFM tip with magnetic layers allows for a functional recognition of material properties, providing contrast at the nanometer scale ferromagnetic or superparamagnetic materials at nanometer size enter into a paramagnetic state characterized by very high magnetic moment and by zero remanent field at room temperature. Once exposed to an external field, long range interactions can induce externally controlled self-aggregation, structuring and collective orientation. We use Magnetic Force Microscopy and Montecarlo simulations to investigate magnetic properties of particles, aggregates and structured nanocomposites.
Related IIT publications:
- B. Torre, G. Bertoni, D. Fragouli, A. Falqui, M. Salerno, A. Diaspro, R. Cingolani, A. Athanassiou “Magnetic field texture in superparamagnetic nanocomposites: a MFM study at nanometer level”, Nature Sci. Rep. (2011) in press.
- M. Allione, B. Torre, P. Piacenza, R. Di Corato, T. Pellegrino, A. Diaspro, “Rod-shaped nanostructures based on superparamagnetic nanocrystals as viscosity sensors in liquid”, J. Appl. Phys. 110 (6), 064907-13 (2011) DOI:10.1063/1.3638695.
- G. Bertoni, B. Torre, A. Falqui, D. Fragouli, A. Athanassiou, R. Cingolani “Nanochains formation of superparamagnetic nanoparticles”, The Journal of Physical Chemistry C., 115, 7249-7254 (2011) DOI: 10.1021/jp111235n.
- D. Fragouli, B. Torre, G. Bertoni, R. Buonsanti, R. Cingolani, A. Athanassiou “Formation and microscopic investigation of iron oxide aligned nanowires into polymeric nanocomposite films”, Microscopy Research and Technique, 73, 952-958 (2010) DOI: 10.1002/jemt.20848.