Analysis of electronic and structural properties of surfaces and interfaces based on LaAlO3 and SrTiO3

TL;DR

This study uses density functional theory to analyze how surface defects and reconstructions in LaAlO3 and SrTiO3 influence their electronic and structural properties, especially at interfaces.

Contribution

It provides a detailed theoretical investigation of surface deformations, density of states, and atomic displacements affecting LaAlO3/SrTiO3 interfaces.

Findings

Surface defects alter the local density of states at the Fermi level.

Surface reconstruction impacts electronic properties of the interface.

Atomic displacements correlate with changes in conductivity.

Abstract

Recently, it was established that a two-dimensional electron system can arise at the interface between two oxide insulators LaAlO3 and SrTiO3. This paradigmatic example exhibits metallic behaviour and magnetic properties between non-magnetic and insulating oxides. Despite a huge amount of theoretical and experimental work a thorough understanding has yet to be achieved. We analyzed the structural deformations of a LaAlO3 (001) slab induced by hydrogen ad-atoms and oxygen vacancies at its surface by means of density functional theory. Moreover, we investigated the influence of surface reconstruction on the density of states and determined the change of the local density of states at the Fermi level with increasing distance from the surface for bare LaAlO3 and for a conducting LaAlO3/SrTiO3 interface. In addition, the Al-atom displacements and distortions of the TiO6-octahedra were estimated.