Ab-initio Study of Physical Properties of MgO/FeO x /Fe(001) Interfaces

The effects of partially oxidized interfacial FeO (x) layers on the physical properties of MgO/FeO (x) /Fe(001) (x = 0, 0.25, 0.5, 0.75, 1) were studied using ab-initio calculations. The free energy calculations as a function of the O chemical potential Delta mu O showed that the formation of the interfaces occurred in the order of p(1x1) MgO/Fe(001) (in the Mg-rich limit) -> p(2x2) MgO/FeO0.25/Fe(001) -> c(2x2) MgO/FeO0.5/Fe(001) -> p(2x2) MgO/FeO0.75/Fe(001) -> p(1x1) MgO/FeO/Fe(001) (in the O-rich limit) with increasing Delta mu O. The electronic structures, the work functions, and the electron rearrangements for MgO/FeO (x) /Fe(001) interfaces were also investigated. These results indicate that the O contents x of FeOx at the interfaces between MgO and Fe can significantly affect the physical properties of the MgO/FeO (x) /Fe(001) interfaces.