Size and heat treatment effects in the electrical conduction of the [Fe/SiO]n discontinuous multilayers

Abstract

The present work shows the comprehensive investigations of crystal structural and electrical properties of [Fe/SiO]n discontinuous multilayers with various effective thickness of ferromagnetic (dFe) and insulator (dSiO) layers. Results of the study performed by the transmission electron microscopy have demonstrated that the formation of discontinuous magnetic layers occurs at the decrease of dFe from 10 nm to 4 nm. Namely, the discontinuous multilayers at dF = 4 nm are granular nanostructures that consist of an array of Fe particles separated by the SiO insulator channels. It was shown that depending on the heat treatment conditions and an effective thickness of ferromagnetic and insulator layers, three modes of conductivity (metallic, transitional and insulation) were realized. The temperature coefficient of resistance takes a positive, negative, or close to zero value depending on the conductivity mode. The correlation between the crystal structure and electrical properties were discussed.