Abstract
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 (with a electronic configuration) and ( configuration), exhibiting the -type oxygen-deficient perovskite structure, with hydrostatic pressure. The -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 -orbital filling: E-type antiferromagnetic (AFM-E) for () and G-type antiferromagnetic (AFM-G) for (). We show that hydrostatic pressure enhances the crystal-field splitting and affects the magnetic stability. We find that the AFM-E order exhibited by is robust over the surveyed ranges of applied pressures, whereas shows a magnetic transition from AFM-G to ferromagnetic spin order at GPa. We also discuss the effect of correlation strength, treated using the Hubbard correction, which we find suppresses a spin crossover transition in and shifts it to higher pressures.
7 More- Received 16 June 2020
- Accepted 7 September 2020
DOI:https://doi.org/10.1103/PhysRevB.102.104426
©2020 American Physical Society