The structure of FeCo/Ag multilayers

Abstract

Field emission gun transmission electron microscopy and electron spectroscopy imaging have been used to determine the structure of the interface between FeCo and Ag, the local crystallographic texture and the distribution of the Ag in magnetostrictive Fe₅₀Co₅₀/Ag multilayers. These are correlated with the coercivity and magnetostriction of the multilayers, for FeCo layer thickness in the range 3.5—17.5 nm with constant Ag thickness of 2.2 nm. A significant texture exists in the films with preferential {110}_FeCo and {111}_Ag parallel to the growth direction. Where the local orientation of the film coincides with the texture, partial coherency exists between {110}_FeCo and {111}_Ag. Electron spectroscopy imaging indicates that the Ag layer is not continuous and provides a rough interface between the FeCo and Ag. The manner in which the microstructure determines magnetic properties is discussed.