Magnetic and semiconducting nanostructures by swift heavy ion irradiation of Fe20Ni80 films on Si substrates

Abstract

Fe20Ni80/Si interface devices have been fabricated and irradiated from swift (100 MeV) heavy (Fe7+) ions with a dose of 1014 cm-2. The current measured across the irradiated devices from room temperature (RT) to liquid nitrogen (LN2) temperature shows a positive temperature coefficient. The results were understood by considering the formation of a semiconducting and magnetic silicide nanophase as a result of ion beam mixing (which was shown from x-ray diffraction (XRD) data). The particle size was estimated to be ∼25 nm from the XRD data. The induced magnetization at the interface was studied from the magnetization versus magnetic field (M-H) variation at room temperature. The magnetization shows superparamagnetic behaviour characterizing the magnetic nanoparticles. © 2005 IOP Publishing Ltd.