The presence of ordered oxygen vacancies in perovskites governs magnetic phase stability owing to changes in crystal-field splitting with different anion geometries, polyhedral arrangements, and electronic configurations of the transition-metal cations. Here we use density functional theory calculations to assess the magnetic phase stability of Sr2Fe2O5 (with a d5 electronic configuration) and Sr2Mn2O5 (d4 configuration), exhibiting the Ca2Mn2O5-type oxygen-deficient perovskite structure, with hydrostatic pressure. The Ca2Mn2O5-type structure is composed of square pyramidal units, the crystal-field splitting and polyhedral connectivities of which support different ground-state magnetic orders depending on d-orbital filling: E-type antiferromagnetic (AFM-E) for Sr2Mn2O5 (d4) and G-type antiferromagnetic (AFM-G) for Sr2Fe2O5 (d5). We show that hydrostatic pressure enhances the crystal-field splitting and affects the magnetic stability. We find that the AFM-E order exhibited by Sr2Mn2O5 is robust over the surveyed ranges of applied pressures, whereas Sr2Fe2O5 shows a magnetic transition from AFM-G to ferromagnetic spin order at ≈24.5 GPa. We also discuss the effect of correlation strength, treated using the Hubbard U correction, which we find suppresses a spin crossover transition in Sr2Fe2O5 and shifts it to higher pressures.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics