First-principles study on interfacial properties and the electronic structure of the Al(001)/MgAl₂O₄(001) interface

In this work, the interfacial structure, adhesion properties, and electronic structure of the Al(001)/MgAl₂O₄(001) interface are investigated via density functional theory calculations. Considering different termination atoms and stacking sites, six interfacial models are explored. The results show that the OAlO-terminated O-top stacking configuration has the greatest interfacial adhesion work of 2.51 J m⁻². The nature of bonding between atoms at the Al(001)/MgAl₂O₄(001) interface is determined by analyzing their interfacial electronic structures, such as valence charge density difference, Bader charge, and density of states. The atoms of the Al(001)/MgAl₂O₄(001) OAlO-terminal exhibit not only the Al-Al metal bonding but also ionic bonding. For the O-top and two hollow configurations, Al-O covalent bonding components are also present, which mainly originate from the coupling between the Al-3p and O-2p orbitals. In turn, the OAlO-terminated O-top stacking configuration possesses deeper negative energy bands in the Al-O resonance peaks of the interfacial atoms than the OAlO-terminated hollow stacking configuration, resulting in stronger interfacial bonding. Finally, the OAlO-terminated O-top stacking interface corresponds to the most stable interfacial structure.