Mechanism of polar catastrophe cancelling induced by charge compensation for epitaxy γ-Fe_2O_3 film on MgO(001) substrate: A theoretical investigation

摘要

The interface of gamma-Fe2O3/MgO(001) film have revived considerable attention. Polar catastrophe at the interface of gamma-Fe2O3/MgO(001) film was investigated and an attempt to investigate the interface structure and growth mode of gamma-Fe2O3/MgO(001) was given. The results show that the stoichiometric gamma-Fe2O3 with tetragonal space group of P4(1)2(1)2 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 gamma-Fe2O3/MgO films are larger than the bulk value of gamma-Fe2O3 in experimental studies. This study may widen the application of maghemite especially the gamma-Fe2O3/MgO film.