Magnetic and semiconducting nanostructures by swift heavy ion irradiation of Fe₂₀Ni₈₀films on Si substrates

Abstract

Fe 20 Ni 80 /Si interface devices have been fabricated and irradiated from swift (100 MeV) heavy (Fe 7+ ) ions with a dose of 10 14 cm −2 . The current measured across the irradiated devices from room temperature (RT) to liquid nitrogen (LN 2 ) 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.

Ion beam induced surface and interface engineering

“…Fe 20 Ni 80 /Si interface devices have been fabricated and irradiated from 100 MeV Fe 7+ ions by Srivastava et al [560]. It is noticed that the current measured across the irradiated devices from RT to LN 2 temperature showed a positive temperature coefficient as shown in Fig.…”

Substrate dependence in the formation of TiO2nanophases by dense electronic excitation

“…Substantial heat is transferred from the electronic subsystem to the atomic subsystem of the lattice only between 10 −14 and 10 −12 s after the ion impact. During this period, large amount of energy gets deposited in the cylindrical region surrounding the ion path and the local temperature of the target material in this region increases [33][34][35]. If this temperature reaches values greater than the melting temperature of the target material, a liquid phase is formed in this region.…”