Schottky barrier formation at the Fe/SrTiO3 (001) interface: Influence of oxygen vacancies and layer oxidation

International audienceSchottky barrier formation at metal/insulating oxide interfaces relies on complex mechanisms which are difficult to unravel. We propose a detailed numerical study of the atomic, magnetic, and electronic properties of the Fe/SrTiO3 (001) interface, in which we focused our discussion on different parameters which can affect the Schottky barrier height (SBH). The interface termination appears to be the most critical aspect to be controlled for this interface: While an ideal TiO2-terminated interface would guarantee a n-type barrier of about 1.2-1.6 eV, the presence of a SrO termination can drastically decrease its value down to few meV. The oxidation state of the interface is also an important criterium to maintain a high barrier value. Oxygen vacancies are always cited as the source of a deterioration of the SBH. For a TiO2-terminated interface, we found that in their most stable position, i.e., in the interface layer, the oxygen vacancies do not affect the value of the SBH; when moving some atomic layers away from the interface, the SBH on the contrary decreases regularly. We propose that oxidizing the interface would allow us to improve the n-type SBH by healing the oxygen vacancies and forming an interfacial FeO layer, which seems favorable to the formation of a higher SBH