Abstract
It is well established that the ground-state electron configuration of the octahedral ion is , which corresponds to a low-spin (LS) state. However, we theoretically demonstrate that the octahedral ion in prefers a high-spin (HS) state with the configuration, resulting in unusual magnetism. The density-functional theory plus calculation and ligand-field theory show that weak crystal-field splitting associated with induces a spin crossover from the LS to HS state of the octahedral ion along with a weak Jahn-Teller-like elongation, and as a result, a ferromagnetic (FM) metal phase is energetically stabilized. Nevertheless, this phase is significantly more stable than the antiferromagnetic (AFM) phase experimentally reported at low temperature. Furthermore, phonon calculations suggest that the FM metal phase is possibly one of the polymorphs, appearing in the certain experimental growth environment, but it is not expected to appear due to a temperature-dependent transition from the AFM phase. In addition, the Lyons, Kaplan, Dwight, and Menyuk theory shows that this phase is further expected to undergo a phase transition to the frustrated magnetic state. We believe that our work provides insight into magnetism of cobalt compounds and also paves the way to achieve the HS by design.
- Received 25 March 2022
- Revised 7 July 2022
- Accepted 17 August 2022
DOI:https://doi.org/10.1103/PhysRevResearch.4.033171
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society