First-Principles Study of Polarizability Distributions for LaAlO₃/SrTiO₃ Superlattices

Abstract

We have investigated polarizability (up to the third order) distributions for LaAlO 3 (LAO)/SrTiO 3 (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.

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“…The development includes the theoretical study of oxide interfaces with polarity and methods of examining the changes in the spin state involving the phase transition. 14,15) However, many issues requiring future academic research, such as quantitative examination of the electron correlation at the device interface, still remain.…”

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