TAIPEI (Taiwan News) — Hopes may have been dashed of finding a room temperature, ambient pressure superconductor that a South Korean team claimed to have discovered, following weeks of detective work by scientists.
Three South Korean researchers claimed in preprints in late July that a compound called LK-99 is the answer to the long quest for a superconductor at normal temperatures and pressure. The potential breakthrough triggered replication experiments in many labs around the world but most results indicated the claim could not hold water, including one by the prestigious National Taiwan University.
The two hallmarks of superconductivity－a drop in resistance and levitation above a magnet — shown by LK-99, have not been decisively proven in labs in dozens of experiments, per Nature.
Scientists have pointed out that the levitation phenomenon could be a result of ferromagnetism and diamagnetism, but not superconductivity. The sample in the video presented by the South Korean team appears with an edge sticking to the magnet, not levitating over it, cautioned condensed-matter expert Derrick van Gennep. Meanwhile, a Peking University team said their LK-99 samples were only “half-levitating,” as can be seen in an “iron-filing experiment.”
The drop in resistivity seen in the original LK-99 sample may also turn out to be a result of impurities, involving a phase transition of the copper sulfide it contains. This could influence the level of electricity resistance and levitation properties.
Elsewhere, a team at the Max Planck Institute for Solid State Research in Germany found the pure, single crystals of LK-99 it synthesized showed minor ferromagnetism and diamagnetism, but not enough to be defined as levitation. It suggested the crystals are highly insulating, but concluded that LK-99 is not a superconductor.
These explanations have preliminarily ruled out the claim of LK-99 as a superconductor. Any further confirmation will have to come from tests on the samples used by the Korean team for the claim to be convincing, physicist Michael Fuhrer at Monash University in Melbourne said.
