Nonlinear Optical Response of SrTiO3/LaAlO3 Superlattices

TL;DR

This study investigates the nonlinear optical properties of SrTiO3/LaAlO3 superlattices, revealing how interface effects influence electronic symmetry and optical nonlinearity, with implications for interface engineering in oxide heterostructures.

Contribution

It provides new insights into the evolution of electronic reconstruction and nonlinear optical response in SrTiO3/LaAlO3 superlattices with varying thicknesses.

Findings

Large perpendicular optical nonlinearity observed

Abrupt increase in nonlinearity above 3 unit cells

Active nonlinear area extends up to 8 unit cells from interface

Abstract

The electronic symmetry of the SrTiO3/LaAlO3 interface was investigated by optical second harmonic generation, using superlattices with varying periodicity to study the evolution of the electronic reconstruction while avoiding substrate contributions. The superlattices show large perpendicular optical nonlinearity, which abruptly increases when the sublattice thickness goes above 3 unit cells, revealing substantial effects of the polar-nonpolar interface. The nonlinear 'active' area is primarily in SrTiO3, develops with increasing thickness, and extends up to 8 unit cells from the interface.