Someone with the same name as one of the authors of the 6-author-paper, Hyun-Tak Kim, is at least answering questions about superconductor theory on Quora starting five years ago, whatever that counts for.
> 1b) shows the resistivity at some unknown temperature. They are applying current and measuring no potential drop. Just what? First, state the temperature, next measure it as a function of temperature. At the critical temperature the resistance drops to zero. All they have shown is that the contact inputting the current is probably disconnected…
this does not pass the sniff test for me. I explained on reddit myself why I think it doesn't make sense.
The only way that could work is if they just straight up fabricated everything, and in that case all bets are off.
I can't comment about the others since I don't know enough about it. Considering 1b) makes no sense with a modicum of knowledge, I really doubt the veracity of the rest.
This isn't 1 experiment. This is 20 years of research leaking because of a fight over credit.
> So, to clarify for my nonexpert brain, if this were a superconductor and their measurements were accurate:
> Fig 5 means the sample must be completely pure to be a superconductor
> The rest of the paper indicates the sample must have impurities.
> So it's pretty safe to say that either it's not a superconductor or their measurements are wrong (or most likely both). Since they never got it to the critical temperature and showed the full Meissner effect, if the measurements are wrong it's fair to say they don't have evidence for superconductivity anyway, just diamagnetism, which isn't really that big a deal
https://www.reddit.com/r/worldnews/comments/159g2k4/comment/...
In any case, the need for impurities would not itself surprise. Having controlled amounts of impurities is called "doping", it is well-known from studying semiconductors and other high temperature superconductors that the amount of doping can have a huge impact on a substance's properties.
See https://physicsworld.com/a/the-ups-and-downs-of-doping/ for verification of this point.
His earlier comment that graphite can do the same thing is untrue afaict. Graphite can repel the magnetic field but it would slide off, this is why in diamagnetic experiments multiple magnets are used to keep it in place. In the video it doesnt seem to be sliding anywhere, so imo the video is not showing diamagnetism.
https://sciencecast.org/casts/suc384jly50n
Edit: Actually, now I'm not so sure, it does seem like it's held in place by one corner which is always pointing towards the outside of the magnet, so maybe it is just diamagnetism. If anyone has some pyrolytic carbon and wants to try it out? Haha...
Superconducting levitation is just due to the perfect diamagnetism of the superconductor, right?
Reminder that flux-pinned levitation only occurs when superconductors are cooled from above to below their critical temperature while in a local magnetic field.
The researchers probably didn’t heat up their big sample above the critical temperature in air as that could have mechanically destroyed it. It was already chipped almost in two.
Casual demonstrations of levitating superconductors involve first submerging the superconducting material in a (non-magnetized) tub of LN2, and then moving it onto a magnetic track. For example, https://www.youtube.com/watch?v=X5EoUD-BIss
Welcome to Reddit
> However, only one edge of the flat, coin-like material fully levitates, while the other seems to stay in contact with the magnet. Kim says this is due to the sample being imperfect, which means that only some part of it becomes superconductive and exhibits the Meissner effect.
That's a surprising type of dismissive. The authors themselves think [electron paramagnetic resonance] was key experimental validation of their (non-standard) superconductivity model. Wouldn't you be at least a little curious?
In the first paper, they claim to measure zero resistance (on a scale of microvolts), but are very careful not to show full RvT curves - in the second paper, we can still see significant changes below Tc where they include more complete curves. How can the resistance change significantly in the superconducting (zero resistance) state? We can actually see significant noise in paper 1 fig. 1c in the ohmic state and it even appears to behave as an insulator at 0 field (increasing resistance with decreasing temperature), but a metal with applied field. There's something wrong with the measurement.
400 K is an odd choice for your superconducting temperature, and just so happens to be the top end of what an MPMS system can measure so is not completely random. Surely it makes sense to measure significantly above this with one of the oven attachments, verify these results with collaborators at other labs even.
10 Gauss is an extremely small field to use for a ZFC-FC measurement and again if their superconducting Tc is at or above 400K they need higher temperature data to show anything about the phase transition.
The claim that they have measured the density of states is completely unjustified - not even a citation. I don't know how you can believe that to be the case.
And in general the presentation both of the data and the paper itself is poor - if you just made a groundbreaking discovery like this, wouldn't you care?
Hell no! If I had made a discovery of similar magnitude I would have done exactly what they’ve done: push out a rough preprint ASAP to reserve my Nobel prize, then take a deep breath, relax and take my time dotting ‘i’s and crossing ‘t’s for the real paper in Nature.
That doesn’t mean they’re correct, but there’s nothing inherently suspicious about the way this has unfolded.
Their paper is weak on data / results.
This is exactly what you would do if your team genuinely believed you had discovered something monumental.
In poker terms they are "all in" and they want to get called.
That's why it is so interesting. If they had posted lots of extreme results but it needed $10m to replicate then I would be thinking "fraud". It would look like a bluff.
In realistic terms it seems they're grabbing for the prestige without the foundation of crossing their ts. Bad science like this shouldn't be encouraged. It's likely there's not very many groups growing the same material system so they have the time to spare. A paper like this wouldn't be on the arxiv at all if they were 100% sure because they would go straight for the nature publication and take the time to do more follow-up papers while they can.
Edit: to be clear as well, a lot of people are underestimating the time it takes to reproduce a growth even with a manuscript telling you how to do it. People always leave out steps and oversimplify. There is a lot of extra characterization that takes time to double check you have the right material that lines up with what they have here. Only the direct competitors actually already growing this material can do it in a few days.
What? How do they get funding and lab space if they can't read their own measurements? Something is fishy here.
Funding: This research was mainly supported by Quantum Energy Research Centre, Inc. and was also partially supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education(2019R111A1A01059675) and Young-Wan Kwon is supported by a Korea University Grant.
I don't know, either: what's the difference between receiving funding for research and taking investment money for it? Are you talking about public vs private funding?
There's just way too much going on for this to be a sloppy mistake. It's either real or a fraud, and in both cases the alleged errors aren't particularly important.
I'm glad this site doesn't partake in incorrect contrarianism.
This one's in Korean but there are some plots here that I think several people said were missing.
> I would say they are not faking it, but instead they just don’t understand what they are looking at. Based on what measurements they are doing, as well as how they are doing them, they do not have a good understanding of the standard processes to characterise a superconductor. Also, based on their analysis/discussion, they do not have scientific knowledge of the background theory. In review of these two papers, it’s terrible science, not something malicious (as has been seen before in RT superconductivity work…). Even if these claims turn out to be true, it's still terrible science, and that's my main criticism. Either way, these types of claims are not uncommon, see for example this paper from a few years ago which went nowhere. https://doi.org/10.48550/arXiv.1807.08572
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