Structural study of CoFe2/CoFe2O4 multilayers

The study of the CoFe2/CoFe2O4 system is of great interest due to its potential integration in magneto-resistive devices. CoFe2/CoFe2O4 multilayers were elaborated by plasma oxidation of sputtered CoFe2 layers. Exclusive attention is paid, in this paper, to the study by high resolution transmission electron microscopy of the crystallographic relationships between the metal and the oxide networks. The oxide was observed to grow epitaxially from the metal with the following relationship : oxide (1 0 0)[1 0 0] ∥ metal (1 0 0)[1 1 0]. This epitaxial relationship was observed even though the metal (CoFe2 alloy) did not always present its (1 0 0) face to the surface and was oxidised by the violent process that is plasma oxidation. Our conclusion that the growth of epitaxial metal/oxide multilayers by sputtering only depends on the epitaxial growth of the first deposited metal layer is of major interest.