Magnetism in a TiO2/LaAlO3 heterostructure: an ab initio study about the role of oxygen vacancies

TL;DR

This study uses ab initio methods to explore how oxygen vacancies influence magnetism at TiO2/LaAlO3 interfaces, revealing that oxygen vacancies induce stable magnetic solutions particularly at AlO2/TiO2 interfaces.

Contribution

It provides new insights into the role of oxygen vacancies in inducing magnetism at TiO2/LaAlO3 heterostructures using density functional theory.

Findings

Oxygen vacancies promote magnetism at the interface.

LaO/TiO2 interface is energetically favored without vacancies.

Stable magnetic solutions are found only at AlO2/TiO2 interface with vacancies.

Abstract

In this work we study the electronic structure and magnetism of a TiO2 film grown on another non-magnetic oxide such as a LaAlO3 (001) substrate, concentrating on the role played by structural relaxation and oxygen vacancies. Using Density Functional Theory ab-initio methods, we study the free-standing anatase film as well as the interfaces with either the LaO or AlO2 planes of LaAlO3, focusing on the possibility of magnetic solutions. Our results show that the interface LaO/TiO2 is favored against the AlO2/TiO2 one if no oxygen vacancies are present in the interface whereas the contrary happens when there are oxygen vacancies. In both cases, the cohesive energy is of the same order of magnitude but only the AlO2/TiO2 interface presents an stable magnetic solution.