Growth conditions, structural and magnetic properties of M/Fe3O4/I (M=Al, Ag and I=Al2O3, MgO) multilayers

Abstract M/Fe3O4/I (M=Al, Ag and I=MgO, Al2O3) multilayers have been grown on α-Al2O3 substrate employing molecular beam epitaxy technique and a study of their structural and magnetic properties has been done. We mainly discuss the growth conditions required to synthesize a good quality magnetite thin film on a metal underlayer. In situ X-ray photoelectron spectroscopy (XPS) and reflection high-energy electron diffraction measurements have been carried out to investigate the properties of each growing layer. Both the results indicate that magnetite grows preferentially in (1 1 1) plane on the Ag/Al underlayer. Either of the thin layers of an insulating oxide, MgO or Al2O3 is deposited over this Fe3O4 layer. XPS results indicate that the magnetite surface looks little affected after the growth of MgO layer, whereas a metal Fe phase at the interface appeared by depositing Al which could not be converted into iron oxide upon prolonged exposures to oxygen. Average roughness values obtained from the atomic force microscopy measurements on the magnetite layer and the thin insulator layer are almost the same. This result suggests that Fe3O4/I interface roughness should be similar in all the cases.