Impersonating a Superconductor: High-Pressure BaCoO3, an Insulating Ferromagnet

Haozhe Wang; Xianghan Xu; Danrui Ni; David Walker; Jie Li; Robert J Cava; Weiwei Xie

doi:10.1021/jacs.3c08726

Impersonating a Superconductor: High-Pressure BaCoO₃, an Insulating Ferromagnet

J Am Chem Soc. 2023 Oct 4;145(39):21203-21206. doi: 10.1021/jacs.3c08726. Epub 2023 Sep 20.

Authors

Haozhe Wang¹, Xianghan Xu², Danrui Ni², David Walker³, Jie Li⁴, Robert J Cava², Weiwei Xie¹

Affiliations

¹ Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States.
² Department of Chemistry, Princeton University, Princeton, New Jersey 08540, United States.
³ Lamont Doherty Earth Observatory, Columbia University, Palisades, New York 10964, United States.
⁴ Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States.

PMID: 37728505
DOI: 10.1021/jacs.3c08726

Abstract

We report the high-pressure synthesis (6 GPa, 1200 °C) and ambient-pressure characterization of hexagonal HP-BaCoO₃. The material (with a 2H crystal structure) has a short intrachain Co-Co distance of about 2.07 Å. Our magnetization investigation revealed robust diamagnetic behavior below approximately 130 K when the material was exposed to weak applied magnetic fields (10 Oe) and a distinct "half-levitation" phenomenon below that temperature, as is often observed for superconductors. Its field-dependent magnetization profile, however, unveils the characteristics of ferromagnetism, marked by a substantial magnetic retentivity of 0.22(1) μ_B/Co at a temperature of 2 K. Electrical resistivity measurements indicate that HP-BaCoO₃ is a ferromagnetic insulator, not a superconductor.