Binary Mn-Si nanostructures prepared by focused electron beam induced deposition from the precursor SiH3Mn(CO)5

Abstract

Mixed-metal carbonyls are a family of compounds which can be used to fabricate bimetallic nanostructures by means of focused electron beam induced deposition. In the present work, we show that silicon-metal alloys can be prepared by using silyl-metal carbonyls. In particular, we employ the SiH3Mn(CO)5 precursor to fabricate Mn-Si alloy nanowires, with composition of about 34 at% Mn, 17 at% Si, 31 at% C and 18 at% O, as revealed by energy dispersive x-ray analysis. Magnetotransport measurements are carried out on as-grown samples and on samples treated after-growth by low-energy electron irradiation. All the samples exhibit a quasi-metallic temperature-dependent behavior. Hall-effect measurements indicate either electron-like transport, for as-grown samples, or hole-like transport, for post-growth treated samples, respectively. Correspondingly, the charge carrier density increases from cm-3 to cm-3. We find a small negative transversal magnetoresistance, which depends on irradiation dose and temperature. Microstructural investigations carried out by transmission electron microscopy indicate that the samples are constituted by an amorphous Mn2Si phase embedded in a carbonaceous matrix. Additionally, in treated samples a novel Mn2SiO4 spinel oxide phase is observed.