Tetragonal BaCoO <sub> <b>3</b> </sub> : A Co <sup> <b>4+</b> </sup> Ferromagnetic Mott Insulator
We report the stabilization of the metastable body-centered tetragonal (BCT) phase of BaCoO<sub>3</sub> (BCT-BaCoO<sub>3</sub>) under high-pressure (15 GPa) and high-temperature (1200 °C) conditions using a mixture precursor. This double perovskite adopts the EuTiO<sub>3</sub>-type structure (space group <i>I</i>4/<i>mcm</i>), as confirmed by powder X-ray diffraction and high-resolution STEM. X-ray photoelectron spectroscopy indicates a predominant Co<sup>4+</sup> oxidation state without detectable oxygen vacancies. Magnetization and heat capacity measurements reveal ferromagnetic ordering at <i>T</i> <sub>C</sub> ∼ 107 K, attributable to the BCT-BaCoO<sub>3</sub> phase. Above this temperature, the mixed-phase sample exhibits Curie-Weiss paramagnetism, a low-spin to high-spin crossover upon cooling, and a possible intermediate-spin state at elevated temperatures. Resistivity data indicates insulating behavior with weak magnetoresistance. DFT and DFT + DMFT calculations suggest that the insulating state originates from an orbitally selective transition sensitive to the nominal valence of the Co-d shell. The metastable BCT-BaCoO<sub>3</sub> phase cannot be retained in pure form at ambient pressure but can be stabilized by embedding it in a disordered mixture, offering a potential route to discover and preserve other high-pressure phases under ambient conditions.
Authors
- Gabriel Kotliar (ORCID: https://orcid.org/0000-0001-6366-7687)
- Yingge Du (ORCID: https://orcid.org/0000-0001-9680-1950)
- Haozhe Wang (ORCID: https://orcid.org/0000-0003-4820-833X)
- Weiwei Xie (ORCID: https://orcid.org/0000-0002-5500-8195)
- Mario U. González-Rivas (ORCID: https://orcid.org/0000-0003-3667-4149)
- Krishna Prasad Koirala (ORCID: https://orcid.org/0000-0002-9137-917X)
- Mingyu Xu (ORCID: https://orcid.org/0000-0001-7138-6009)
- Robert J. Green (ORCID: https://orcid.org/0000-0003-1849-1576)
- Alannah M. Hallas (ORCID: https://orcid.org/0000-0002-0892-0982)
- Xianglin Ke (ORCID: https://orcid.org/0000-0003-1882-9039)
- Jiaqi Lu (ORCID: https://orcid.org/0000-0002-8967-7178)
- Corey Melnick (ORCID: https://orcid.org/0000-0003-1105-6336)
- Le Wang (ORCID: https://orcid.org/0000-0002-7730-9482)
- Jie Li (ORCID: https://orcid.org/0000-0002-6175-3167)
- Mark Engelhard (ORCID: https://orcid.org/0000-0002-5543-0812)
- Jessica Freese
- Cheng Peng (ORCID: https://orcid.org/0000-0002-8977-2749)
Institutions
- Rutgers, The State University of New Jersey (US)
- University of British Columbia (CA)
- Pacific Northwest National Laboratory (US)
- Brookhaven National Laboratory (US)
- University of Michigan (US)
- University of Saskatchewan (CA)
- Rutgers Sexual and Reproductive Health and Rights (NL)
- Yukhnovskii Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine (UA)
- Rütgers (Germany) (DE)
- Michigan State University (US)
Publication Details
- Journal
- The Journal of Physical Chemistry C
- Published
- 2025-10-23
- DOI
- https://doi.org/10.1021/acs.jpcc.5c03983
- Citations
- 1
- Primary Topic
- Magnetic and transport properties of perovskites and related materials
- Type
- article
- Field-Weighted Citation Impact
- 0.43