(0001) Interfaces between M2O3 corundum oxides (MÂ =Â Al, Ti, V, Cr, Fe).

The structural quality of oxide/oxide interfaces, their chemistry, and the nature of their electronic states are critical properties for new promising applications and require continuous advances in their fundamental understanding. To this goal, we have performed a theoretical study of a series of (0001) M2O3/M'2O3 interfaces (M, M'  =  Al, Ti, V, Cr, Fe) between simple and transition metal oxides crystallizing in the corundum structure. Our DFT+U results reveal two qualitatively different mechanisms of interface charge redistribution: an interfacial oxidation-reduction reaction occurring at Ti2O3/V2O3 and Ti2O3/Fe2O3 contacts, and a much weaker electron transfer along anion-cation bonds which follows the difference of ionicity between the two constituting oxides at all interfaces. At variance with interfaces between sp semiconductors, the band bending does not propagate beyond one or two atomic layers. More generally, our results show that the nature of the interface electronic structure and the energetics of its formation can be tightly linked to the properties of the corresponding bulk oxides, thus providing a precious tool for designing oxide/oxide interfaces of required characteristics.