First-principles study of polarizability distributions for LaAlO 3/SrTiO3 superlattices

Abstract

We have investigated polarizability (up to the third order) distributions for LaAlO3 (LAO)/SrTiO3 (STO) superlattices by first-principles calculations for two different stackings, i.e., [011] and [001], in order to study the basic difference in the electronic structure between the cases with polar discontinuity ([001]) and without it ([011]). In contrast to the [011] stacking, there is strong asymmetry between the ntype interface and p-type one in the [001] stacking. The dependence of the calculated second order polarizability on the thickness of the supercell unit cell gives useful insight into the recent experimental data on the second harmonic generation. A unified explanation is also given to the striking difference in the electronic structure between isolated thin film and superlattice configurations. © 2010 The Physical Society of Japan.