La interstitial defect-induced insulator-metal transition in oxide heterostructures LaAlO3/SrTiO3

Abstract

Perovskite oxide interfaces have attracted tremendous research interest for their fundamental physics and promising all-oxide electronics applications. Here, based on first-principles calculations, we propose a novel surface La interstitial promoted interface insulator-metal transition in LaAlO3/SrTiO3 (110). Compared with surface oxygen vacancies, which play a determining role on the insulator-metal transition of LaAlO3/SrTiO3 (001) interfaces, we find that surface La interstitials can be more experimentally realistic and accessible for manipulation and more stable in ambient atmospheric environment. Interestingly, these surface La interstitials also induce significant spin-splitting states with Ti dyz/dxz character at conducting LaAlO3/SrTiO3 (110) interface. On the other hand, for insulating LaAlO3/SrTiO3 (110) (<4 unit cells LaAlO3 thickness), a distortion between La (Al) and O atoms is found at the LaAlO3 side, partially compensating the polarization divergence. Our results reveal the origin of metal-insulator transition in LaAlO3/SrTiO3 (110) heterostructures, and also shed light on the manipulation of the superior properties of LaAlO3/SrTiO3 (110) for new possibilities of electronic and magnetic applications.

References in corpus (8)

• Theory of spin-orbit coupling at LaAlO3/SrTiO3 interfaces and SrTiO3 surfaces
• A high-mobility two-dimensional electron gas at the heteroepitaxial spinel/perovskite complex oxide interface of γ-Al2O3/SrTiO3
• Avoiding the polarization catastrophe in LaAlO3 overlayers on SrTiO3(001) through a polar distortion
• High mobility conduction at (110) and (111) LaAlO3/SrTiO3 interfaces
• Surface defects and conduction in polar oxide heterostructures
• Polarity-induced oxygen vacancies at LaAlO3|SrTiO3 interfaces
• Creation of high mobility two-dimensional electron gases via strain induced polarization at an otherwise nonpolar complex oxide interface
• Mechanisms of charge transfer and redistribution in LaAlO3/SrTiO3 revealed by high-energy optical conductivity