[...] the same edge of the sample seemed to stick to the magnet, and it seemed delicately balanced. By contrast, superconductors that levitate over magnets can be spun and even held upside-down.
[...] more likely the result of ferromagnetism. So he constructed a pellet of compressed graphite shavings with iron filings glued to it [...] his disc — made of non-superconducting, ferromagnetic materials — mimicked LK-99’s behaviour.
[...] 104ºC as the temperature at which Cu2S undergoes a phase transition. Below that temperature, the resistivity of air-exposed Cu2S drops dramatically — a signal almost identical to LK-99’s purported superconducting phase transition.
[...] Separated from [Cu2S] impurities, LK-99 is not a superconductor, but an insulator with a resistance in the millions of ohms — too high to run a standard conductivity test. It shows minor ferromagnetism and diamagnetism, but not enough for even partial levitation. “We therefore rule out the presence of superconductivity,” the team concluded.
[...] old, often overlooked data — the crucial measurements that he relied on for the resistivity of Cu2S were published in 1951.