Effect of Oxidation Temperature on Structural and Magnetic Properties of Al-doped Iron Oxide Thin Films

Spinel ferrites have attracted worldwide attraction due to technological applications in spintronic and data storage devices. Among spinel structures of the form XAl2O4 (where X= Fe, Al, Mg etc.) very little attention has been given to FeAl2O4. FeAl2O4 is a normal spinel oxide in which Fe2+ cations occupy 1/8th of the tetrahedral sites and Al3+ occupy ½ of the octahedral sites. The distribution of charges on octahedral and tetrahedral depends on the synthesis conditions as octahedral sites can also be occupied by Fe2+ cations. We here report the preparation of FeAl2O4 thin films using thermal evaporation method. The metallic films are oxidized at 250˚C and 450˚C under oxygen flow rate of 10sccm. XRD results indicate that at 250˚C pure FeAl2O4 phase is formed. With increase in oxidation temperature to 450˚C diffraction peaks corresponding to Fe2O3 phase emerge. The presence of Fe2O3 phase in FeAl2O4 thin films leads to degradation in magnetic properties.