Hopes of a room-temperature superconductor have faded

Consensus among scientists is rapidly growing that social-media hit LK-99 is, in fact, not a superconductor at room temperature and ambient pressure. An article published by Nature News sums up the failed attempts to replicate the findings and, more importantly, gives a convincing explanation for the observations made by the Korean scientists, who published their preliminary findings – along with LK-99’s recipe – on the Arxiv pre-print server in July.

The Korean team at Quantum Energy Research Center, a small company operating from a basement in Seoul, based its superconductivity claim on the observation that the electrical resistance of LK-99 dropped sharply at a certain temperature and the fact that the material (partially) levitated above a magnet. Both are hallmarks of a superconductor.

By now, however, dozens of attempts to confirm LK-99’s superconductivity have failed. What’s more, the reported transition temperature of about 105 degrees Celsius rang a bell with many scientists: it’s close to the temperature at which pure copper sulfide’s resistance changes drastically (but not to zero). Synthesizing LK-99 requires copper and sulfur compounds to be mixed in such a way that the formation of copper sulfide is likely.