Pt thin films on the polar LaAlO3(100) surface:: A first-principles study

Density functional theory has been used to determine the interface structure and energy of Pt films on both ideal terminations of the polar LaAlO3(100) surface. LaAlO3(100) surfaces on bulk LaAlO3 are compared to strained LaAlO3(100) surfaces that would arise if thin LaAlO3 films were grown on SrTiO3(100). The strength of the resulting metal/metal oxide interfaces was characterized by the adsorption energy of the film and the film's work of separation. In comparison to our earlier study of Pt on the nonpolar SrTiO3(100) surface, we find stronger interface strength on the polar LaAlO3(100) surface. Analysis of the layer charges for these two substrates is used to quantify the polarity of these surfaces and the impact of surface strain on this polarity. Our results suggest that LaAlO3(100) will act as a better substrate than SrTiO3(100) surface for the epitaxial growth of (100)-oriented Pt films.