Seminars Archive

Dilute magnetic oxides and magnetic nanostructures

Abstract
In the last years, I had the possibility to collaborate with many research groups that gave to me the opportunity to study different systems having properties that can be exploited for the development of new generation of spintronic devices, micro- and nanoactuators as well as biomedical applications. In this talk I will present my most recent results obtained on dilute magnetic oxides and nanoparticles. In dilute magnetic oxides (DMO), magnetic impurities, usually transition metals, are introduced to produce a magnetic ground state. These systems have been extensively investigated and are believed to be fundamental to fabricate spin-based electronic devices. The understanding of DMO physical properties constitutes a challenge as the fundamental mechanism leading to ferromagnetic interaction can be hardly explained. As opposite to standard bulk materials, where usually the most stable configuration can be unequivocally identified, in DMO the inclusion of the dopant can induce stress, disorder, and defects in the system with many possible configurations close in energy. Concerning this topic I will briefly summarized the results obtained for Fe doped ZrO2 that was grown in the form of thin films by means of atomic layers deposition and characterized by XPS, XAS and XMCD. Another interesting scientific subject concern the development of magnetic nanoparticles which can represent an answer to the requirement of miniaturization for next-generation devices. I will show you a few results concerning Ni-Mn-Ga nanodisks and Fe3O4 nanoparticles. Ni-Mn-Ga is a system that belong to the big family of the Heusler alloys, showing both the magnetic shape memory and the magnetocaloric effects. Normally these systems are used in the form of bulk, on the other hand great effort has been done in order to reduce, down to the nanometer scale, their dimensionality while preserving their magneto-structural properties. As for Fe3O4 nanoparticles, they are very interesting in view of their possible biomedical applications, in particular for hyperthermia that represent a non-invasive cure for cancer. In particular, in our work we exploited the Lorentz microscopy for shedding light to the magnetic interactions occurring on the nanoscale length and their effects on the macroscopical properties of the system in view of their application as hyperthermia mediators.