Ab-initio study of SrTiO3 surfaces

TL;DR

This study uses first-principles calculations to analyze the surface structures and electronic properties of SrTiO3, comparing different terminations and with BaTiO3, revealing minimal ferroelectric relaxation effects.

Contribution

It provides detailed ab-initio insights into SrTiO3 surface relaxations and electronic structures, contrasting with prior BaTiO3 surface studies, and challenges previous ferroelectric surface relaxation claims.

Findings

No large ferroelectric relaxation in SrTiO3 surface layers

Weak surface ferroelectric instability detected

Surface electronic structures similar to BaTiO3

Abstract

We present first-principles total-energy calculations of (001) surfaces of SrTiO3. Both SrO-terminated and TiO2-terminated surfaces are considered, and the results are compared with previous calculations for BaTiO3 surfaces. The major differences are in the details of the relaxed surface structures. Our calculations argue against the existence of a large ferroelectric relaxation in the surface layer, as had been previously proposed. We do find some indications of a weak surface ferroelectric instability, but so weak as to be easily destroyed by thermal fluctuations except perhaps at quite low temperatures. We also compute surface relaxation energies and surface electronic band structures, obtaining results that are generally similar to those for BaTiO3.