Mechanism of polar catastrophe cancelling induced by charge compensation for epitaxy γ-Fe2O3 film on MgO(001) substrate: A theoretical investigation

The interface of γ-Fe2O3/MgO(001) film have revived considerable attention. Polar catastrophe at the interface of γ-Fe2O3/MgO(001) film was investigated and an attempt to investigate the interface structure and growth mode of γ-Fe2O3/MgO(001) was given. The results show that the stoichiometric γ-Fe2O3 with tetragonal space group of P41212 should grow on MgO(001) in the [100] or [010] direction. The charge compensation by modifying the stoichiometry in the interface layer can not only stabilize the polar surface, but also give a reasonable interpretation for why the saturation magnetization (Ms) values of the very thin γ-Fe2O3/MgO films are larger than the bulk value of γ-Fe2O3 in experimental studies. This study may widen the application of maghemite especially the γ-Fe2O3/MgO film.