Electronic and magnetic properties of the interface LaAlO$_3$/TiO$_2$-anatase from density functional theory

TL;DR

This study uses density functional theory to investigate the electronic and magnetic properties of LaAlO$_3$/TiO$_2$-anatase interfaces, revealing local magnetic moments and valence changes at the interface.

Contribution

It provides a detailed ab initio analysis of different interface configurations, including effects of oxygen vacancies and magnetic moments, which was not previously explored.

Findings

Interfacial Ti atoms acquire local magnetic moments.

Valence of Ti decreases below +4 at the interface.

Oxygen vacancies cause abrupt valence changes.

Abstract

Ab initio calculations using the local spin density approximation and also including the Hubbard $U$ have been performed for three low energy configurations of the interface between LaAlO$_3$ and TiO$_2$-anatase. Two types of interfaces have been considered: LaO/TiO$_2$ and AlO$_2$/TiO, the latter with Ti-termination and therefore a missing oxygen. A slab-geometry calculation was carried out and all the atoms were allowed to relax in the direction normal to the interface. In all the cases considered, the interfacial Ti atom acquires a local magnetic moment and its formal valence is less than +4. When there are oxygen vacancies, this valence decreases abruptly inside the anatase slab while in the LaO/TiO$_2$ interface the changes are more gradual.