Magnetic and magnetotransport properties of a Co-Sn evaporated trilayer

The aim of this work is the magnetic characterization of a Co-Sn-Co trilayer produced by thermal evaporation. Magnetization and magnetotransport measurements performed at low temperatures show that the sample has a complex behaviour related to the different morphologies of the external Co layers. A fitting procedure is introduced to disentangle the magnetization behaviour of different regions of the trilayer; three magnetic phases can be seen. Likewise, the magnetoresistance (MR) curves show the superposition of three different effects: a low-field positive MR, a slowly saturating negative MR similar to the one measured in granular systems, and an ordinary MR which becomes significant at very low temperatures. Combining magnetic and magnetotransport data, the three magnetic phases have been associated with the continuous Co underlayer, to the corrugated Co cap layer and to nanometre-sized Co islands embedded in the Sn layer ( respectively). The three-phase model coherently explains both magnetization and magnetoresistance datasets. A simple MR model based on a resistance network has been created to fit the experimental data; the fit is shown to match the main features of the experimental MR.