Emergence of a potential charge-disproportionated insulating state in SrCrO3

Abstract

We use a combination of density functional theory (DFT) and dynamical mean-field theory (DMFT) to investigate the potential emergence of a charge-disproportionated insulating phase in SrCrO3, whereby the Cr cations disproportionate according to 3Cr4+→2Cr3++Cr6+ and arrange in ordered planes perpendicular to the cubic [111] direction. We show that the charge disproportionation couples to a structural distortion where the oxygen octahedra around the nominal Cr6+ sites contract, while the octahedra surrounding the Cr3+ sites expand and distort. Our results indicate that the charge-disproportionated phase can be stabilized for realistic values of the Hubbard U and Hund's J parameters, but this requires a scaling of the DFT+DMFT double-counting correction by at least 35%. The disproportionated state can also be stabilized in DFT+U calculations for a specific magnetic configuration with antiparallel magnetic moments on adjacent Cr3+ sites and no magnetic moment on the Cr6+ sites. While this phase is higher in energy than other magnetic states that can arise in SrCrO3, the presence of an energy minimum suggests that the charge-disproportionated state represents a metastable state of SrCrO3. Published by the American Physical Society 2024