Epitaxial strain induced magnetic transitions and phonon instabilities of the tetragonal SrRuO3

TL;DR

This study uses density-functional theory to explore how epitaxial strain affects magnetic and phonon properties of tetragonal SrRuO3, revealing strain-induced magnetic transitions and structural instabilities with potential implications for oxide materials.

Contribution

It provides a detailed first-principles analysis of strain-induced magnetic and phonon instabilities in SrRuO3, highlighting phenomena not previously characterized.

Findings

Strain induces abrupt magnetic transitions in SrRuO3.

Structural instabilities similar to ferroelectric oxides are observed.

Magnetic moments decrease gradually under tensile strain.

Abstract

Using density-functional theory calculations, we investigate the magnetic as well as the dynamical properties of tetragonal SrRuO3 (SRO) under the influence of epitaxial strain. It is found that both the tensile and compressive strain in the xy-plane could induce the abrupt change in the magnetic moment of Ru atom. In particular, under the in-plane ~4% compressive strain, a ferromagnetic to nonmagnetic transition is induced. Whereas for the tensile strain larger than 3%, the Ru magnetic moment drops gradually with the increase of the strain, exhibiting a weak ferromagnetic state. We find that such magnetic transitions could be qualitatively explained by the Stoner model. In addition, frozen phonon calculations at {\Gamma} point reveal structural instabilities could occur under both compressive and tensile strains. Such instabilities are very similar to those of the ferroelectric perovskite oxides, even though SRO remains to be metallic in the range we studied. These might have influence on the physical properties of oxide supercells taking SRO as constituent.