Ferromagnetic half levitation of LK-99-like synthetic samples

• Published in: Science China. Physics, mechanics & astronomy mechanics & astronomy, 2023-10, Vol.66 (10), p.107411, Article 107411
• Main Authors: Guo, Kaizhen, Li, Yuan, Jia, Shuang
• Format: Article
• Language: English
• Subjects: Anisotropy; Astronomy; Chemical composition; Classical and Continuum Physics; Copper sulfides; Diamagnetism; Diffraction; Ferromagnetism; Fragments; Levitation; Magnetic fields; Magnetization; Observations and Techniques; Permanent magnets; Physics; Physics and Astronomy; Powders; Sintering (powder metallurgy); Spectrum analysis; Superconductivity; Superconductors; X ray powder diffraction; X-ray diffraction; X-rays
• ISSN: 1674-7348; 1869-1927
• DOI: 10.1007/s11433-023-2201-9

We successfully synthesized polycrystalline LK-99-like ceramic samples with a solid-state-sintering method. Powder X-ray diffraction shows that the main contents are Pb 10− x Cu x (PO 4 ) 6 O and Cu 2 S, consistent with recent reports (arXiv: 2307.12037; arXiv: 2308.01192). In some small flaky fragments, we successfully observed “half levitation” atop a Nd 2 Fe 14 B magnet. Using magnetization measurements on such small pieces, as well as on a large piece which does not exhibit the half levitation, we show that the samples ubiquitously contain weak yet definitive soft ferromagnetic components. We argue that, together with the pronounced shape anisotropy of the small fragments, the soft ferromagnetism is sufficient to explain the observed half levitation in strong vertical magnetic fields. Our measurements do not indicate the presence of the Meissner effect, nor zero resistance, in our samples, leading us to believe that our samples do not exhibit superconductivity. The precise chemical composition and the physics behind the ferromagnetic component remain outstanding questions to be addressed in future research.