Effect of the stoichiometry on the electronic structure of the Ni(111)/\alpha-Al₂O₃(0001) interface: a first-principles investigation

In this paper first-principles calculations of Ni(111)/\alpha -Al_2O_3(0001) interfaces have been performed, and are compared with the preceding results of the Cu (111)/\alpha -Al_2O_3(0001) interface 2004 Phil. Mag. Lett. 84 425. The Al-terminated and O-terminated interfaces have quite different adhesion mechanisms, which are similar to the Cu(111)/\alpha -Al_2O_3(0001) interface. For the O-terminated interface, the adhesion is caused by the strong O-2p/Ni-3d orbital hybridization and ionic interactions. On the other hand, the adhesion nature of the Al-terminated interface is the image-like electrostatic and Ni--Al hybridization interactions, the latter is substantial and cannot be neglected. Charge transfer occurs from Al_2O_3 to Ni, which is opposite to that in the O-terminated interface. The charge transfer direction for the Al-terminated and O-terminated Ni(111)/\alpha-Al_2O_3(0001) interfaces is similar to that in the corresponding Cu(111)/\alpha-Al_2O_3(0001) interface, but there exist the larger charge transfer quantity and consequent stronger adhesion nature, respectively.