Phase Transitions and

Superconductivity Group



Tel: 55-11-3091-7091
Fax: 55-11-3091-6984

Instituto de Física

Universidade de São Paulo

Depto de Física dos Materiais e Mecânica

CP 66318, 05315-970

São Paulo, Brazil

Renato F. Jardim

Professor of Physics

Research on  Nanoparticles and Nanomaterials

             We have prepared and characterized nanocomposites comprised of Ni nanoparticles embedded in an insulating matrix of amorphous C/SiO2.  The Ni nanoparticles are found to have diameters ranging from 1.5 to 5 nm.  We have focused our efforts on the understanding of very diluted samples with Ni concentration well below the percolation threshold.  This has enabled us to study the magnetic properties of non-interacting magnetic particles and to probe classical theories of the nanomagnetism.

           In addition to this, several samples in which the Ni concentration is varied systematically are being currently characterized in order to better understand the crossover from the non-interacting to the interacting behavior.

           These nanocomposites have been characterized by several techniques including transmission electron microscopy (TEM), x-ray diffraction (XRD), temperature dependence of both ac and dc magnetic susceptibility, and magnetic hysteresis curves.  Most of these characterizations are performed in our laboratory.