So what's happening is they are demonstrating diamagnetism. Basically when exposed to an external magnetic field, that field induces a response in the material that repels it.
When people think of magnetism, they think of polar charges that either attract or repel other polar charges. Diamagnetism is neat in that regardless of the orientation and polarity of the external field, a diamagnetic material is always repelled.
Now why this matters. All superconductors exhibit diamagnetism, but not all diamagnetic materials are superconductors. So this lends credibility to lk-99 being a potential super conductor because they have been able to show it has one of properties of a superconductor.
But we're still far off from showing it is a superconductor. That will be harder because impurities and other factors can confound the results, so right now the focus is on synthesis and confirming some of the easier properties we expect to see
So why is everyone getting so excited about superconductors when all we actually know is this (probably) exhibits diamagnetism? Is diamagnetism super rare outside of superconductors?
It's rare for it to be strong, from what i've seen. Based on the videos that have been shown, it appears that it would be the most strongly diamagnetic substance (other than superconductors) known by a wide margin.
In comparison, levitating things like pyrolytic graphite seems to require truly massive magnets to achieve even millimeters of levitation: https://www.youtube.com/watch?v=VC3r9-OaWes
And part of the reason that succeeds is because graphite is very light. A chunk of LK-99 is three times as dense, so getting it to levitate is extremely impressive even if it's just conventional diamagnetism.
Like the other commentor said. It's usually a very weak effect, strong diamagnetism is uncommon. It's exciting to see replication of the material and it exhibiting properties we'd expect to see, as it lends credibility to the original claim.
Right now the original claim is on shakey ground because one of the authors rushed the publication, so there's problems with the original paper that needed addressing (I havent looked at the new paper yet). So there's a bit of parallel construction going on, the authors are fixing the publication while other researchers are working to replicate the material/claims.
So basically, people are super excited because so far, the material has been replicated to some degree of success a few times, and exhibiting properties that support the original claim.
The claim of room temperature super conductors is exciting by itself, but that the science is replicating to any degree in such a short window is awesome
When people think of magnetism, they think of polar charges that either attract or repel other polar charges. Diamagnetism is neat in that regardless of the orientation and polarity of the external field, a diamagnetic material is always repelled.
Now why this matters. All superconductors exhibit diamagnetism, but not all diamagnetic materials are superconductors. So this lends credibility to lk-99 being a potential super conductor because they have been able to show it has one of properties of a superconductor.
But we're still far off from showing it is a superconductor. That will be harder because impurities and other factors can confound the results, so right now the focus is on synthesis and confirming some of the easier properties we expect to see