SrTiO3(001)|LaAlO3(001) multilayers:: A density-functional investigation

angstrom SrTiO3(001)vertical bar LaAlO3(001) (STO vertical bar LAO) multilayers were investigated by density-functional band structure calculations. The lattice constant parallel to the interface equals roughly the average of the two constituents (3.81 angstrom). The system contains two interface terminations: (1) SrO(001)vertical bar AlO2(001) with a spacing of 1.92 angstrom as in STO and (II) TiO2(001)vertical bar LaO(001) with a spacing of 1.89 angstrom as in LAO. Additional displacements of the metal atoms close to the boundaries lead to rumplings of up to 0.06 angstrom. A stoichiometric model is electronically neutral and insulating. Model systems with only termination I exhibit spatially localised holes in the O-based valence band; in systems with termination II the additional electron occupies the Ti-based conduction band. The strongly anisotropic dielectric constants obtained from linear response calculations show that the interface chemistry allows a fine tuning of perovskite multilayers. (c) 2006 Acta Materialia, Inc. Published by Elsevier Ltd. All rights reserved.