Nano granular magnetic phase by interfacial intermixing in Fe50Ni50/Si bilayer structure

The bilayer structures of Fe50Ni50 films on silicon substrate have been studied before and after the swift (∼100 MeV) Fe7+ ion irradiation. The AFM (atomic force microscopy) study of the structures shows the formation of clear ellipsoidal grains of nano dimensions. XRD (X-ray diffraction) data of the structures show the formation of magnetic silicide phases of Fe5Si3, Ni3Si2 and Ni2Si. Electronic flow across the interface has been found to significantly increase by two orders of magnitude on the irradiation. Moreover the electronic flow shows a low magnetic field (of ∼500 G) sensitivity for the irradiated structures and not for the unirradiated ones. The M-H (magnetization versus magnetic field) characteristics show the typical behaviour of nano magnetic grains which are antiferromagnetically coupled in a paramagnetic phase. The observed results have been understood in the realm of interfacial intermixing (which has been further tailored by the irradiation) to result the nano granular phases of magnetic silicides (of ∼50 nm). The intermixing seems to make the interface intimate enough to result in a significant increase of current across interface of the bilayer and its sensitivity for an in plane low magnetic field.