Influence of annealing on the structural and magnetic properties of Fe thin film Sandwiched between Au and Si

We report the structural and magnetic properties of as deposited and annealed Au capped Fe (20 nm) thin films on Si substrate. The magnetic measurements carried out on as prepared sample show signature square hysteresis loop of Fe, which transforms into non-magnetic one in 500 °C annealed sample due to the formation of FeSi2 interface alloy at the expense of Fe atoms from the layer and Si atoms from the substrate. No intermixing between Fe and Au is seen. Corresponding X-ray reflectivity (XRR) measurements performed on as deposited sample shows clear Kiessig oscillations and can be fitted without considering intermixed layer between Fe and Si, while annealed sample shows interface mixing leading to an increase in thickness and density. The observed results are explained in terms of annealing induced changes at the Fe/Si interface which result in the formation of ß-FeSi2 phase.