Strain effect on the ground-state structure of Sr2SnO4 Ruddlesden-Popper oxides

TL;DR

This study examines how strain influences the structural phases and electronic properties of Sr2SnO4 Ruddlesden-Popper oxides using symmetry analysis and first-principles calculations, revealing strain-induced bandgap widening and effective mass reduction.

Contribution

It provides a detailed phase diagram of Sr2SnO4 under various strains and pressures, highlighting the impact of structural distortions on electronic properties.

Findings

Compressive biaxial strain widens the bandgap.

Strain induces specific symmetry-breaking structural phases.

Structural changes affect electronic effective mass.

Abstract

Ruddlesden-Popper (RP) oxides (A$_{n+1}$B$_n$O$_{3n+1}$) comprised of perovskite (ABO$_3$)$_n$ slabs can host a wider variety of structural distortions than their perovskite counterparts. This makes accurate structural determination of RP oxides more challenging. In this study, we investigate the structural phase diagram of $n=1$ RP Sr$_2$SnO$_4$, one of alkaline earth stannates that are promising for opto-electronic applications by using group theory-based symmetry analysis and first-principles calculations. We explore the symmetry breaking effects of different dynamical instabilities, predict the energies of phases they lead to, and take into account different (biaxial strain and hydrostatic pressure) boundary conditions. We also address the effect of structural changes on the electronic structure and find that compressive biaxial strain drives Sr$_2$SnO$_4$ into a regime with wider bandgap and lower electron effective mass.