A study on CoFe/p-Si interfacial structures before and after swift heavy ion irradiation

Abstract

Interfacial structures of CoFe/p-Si have been studied before and after the swift heavy ion (∼100 MeV, Ni7+) irradiation to investigate its electronic and magnetic behavior. X-ray diffraction (XRD), atomic force microscopy, magnetic force microscopy and magnetization characteristics (M–H) from vibrating sample magnetometer (VSM) techniques have been used for the above. XRD data have confirmed the formation of the CoFe alloy phase along with the silicide phases of Fe and Co. It is observed that there is an irradiation-induced growth in crystallite but surface remains smooth with a surface roughness of ∼34 nm. A very significant increase has been observed in the magnetization and that too with irradiation dose as compared with unirradiated ones, maintaining their superparamagnetic behavior. The results could be understood due to the role played by various magnetic phases in the structure. The magnetic field sensitivity on electronic transport across the structures has also increased in a significant manner after the irradiation as compared with unirradiated ones. The magnetic field sensitivity has resulted in an MR of 20%. The results could be understood due to the irradiation induced interfacial intermixing to result in increased magnetic phases of silicide for the observed significant magnetic behavior on the irradiation.