Ferromagnetic half levitation of LK-99-like synthetic samples · HackerPapers discussions

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by scythe

Wed, 16 Aug 2023 20:37:11 GMT

Copper sulfide's diamagnetism is not that high. It would be notable if it were. So that isn't a possible explanation. Cu2S was suggested as a culprit for the observed conductivity changes. The preprint reporting the high value of diamagnetism is here: https://arxiv.org/pdf/2308.03110.pdf >The subtracted diamagnetic susceptibility is larger than that of Bismuth and water but smaller than that of Pyrolytic carbon (page 3, bottom left)

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by lamontcg

Thu, 10 Aug 2023 15:50:32 GMT

Ferromagnetic half levitation of LK-99-like synthetic samples https://arxiv.org/abs/2308.03110

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by awwkaw

Wed, 09 Aug 2023 14:03:37 GMT

What really annoys me is that we have not seen a single reproduction of LK-99 yet. A lot of the arxiv papers will measure PXRD. Then they will say stuff like "the position of the peaks is almost identical" (https://arxiv.org/pdf/2308.03110.pdf) (emphasis is mine). Anyone who knows anything about diffraction knows that almost identical means different. The original paper specified that LK-99 requires a 0.48% contraction of the unit cell volume. if you are off by a small fraction (either from over- or under-doping) the sample is not LK-99. it is something different. so far all "reproduction"…

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by Arn_Thor

Wed, 09 Aug 2023 00:04:22 GMT

Vindication https://arxiv.org/abs/2308.03110

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by lamontcg

Tue, 08 Aug 2023 17:49:34 GMT

The preprint from earlier showing that LK99 is not superconductive and the 'half-levitating' samples have regions of soft-ferromagnetism and diamagnetism and shows a semiconductive temperature-resistance curve: https://arxiv.org/abs/2308.03110 Discussion on the preprint from earlier: https://news.ycombinator.com/item?id=37043447

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by lamontcg

Tue, 08 Aug 2023 17:22:21 GMT

Well it looks like I'm right and LK99 is ferromagnetic and not superconductive. And the paper that shows it looks a lot more like I'd expect good science to look: https://arxiv.org/abs/2308.03110 Difference between science and spectacle.

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by lamontcg

Tue, 08 Aug 2023 15:10:39 GMT

They're citing a study from the International Center for Quantum Materials at Peking University in Beijing (which has several Alumni from the Condensed Matter Theory Center at U of Maryland which is the twitter account) which goes into the matter in some depth and finds that chunks of the material are ferromagnetic and some chunks are diamagnetic and the whole thing is a semiconductor. They also replicate the half-levitation effect from the original video and which some people have replicated: https://arxiv.org/pdf/2308.03110.pdf The twitter account may have had a biased tone because they're…

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by lamontcg

Tue, 08 Aug 2023 15:04:17 GMT

> I feel like such strong statements should directly reference strong evidence. They did link the strong evidence upthread: https://arxiv.org/abs/2308.03110 > To conclude, we have observed a semiconductor-like, non-superconducting electric property in our LK-99-like synthetic samples, along with diamagnetic and soft-ferromagnetic properties arising from supposedly different phases of the mixed product. Our results suggest that one needs to be cautious when interpreting half-levitation observations as evidence for net levitating forces (and, further, as evidence for the Meissner effect). The…

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by nisegami

Tue, 08 Aug 2023 11:54:02 GMT

This study https://arxiv.org/abs/2308.03110

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by bigbacaloa

Tue, 08 Aug 2023 11:53:25 GMT

https://arxiv.org/abs/2308.03110

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — mentioned by TillE

Tue, 08 Aug 2023 01:51:13 GMT

This isn't a particularly meaningful paper because they failed to produce any kind of partial levitation. This one which finds substantial ferromagnetism and minimal diamagnetism is a far better reason to doubt that LK-99 is a superconductor: https://arxiv.org/abs/2308.03110 Still very inconclusive because the synthesis is difficult and messy and nobody knows precisely what materials they're analyzing, but I've adjusted from cautious optimism to mostly resigned pessimism.

Paper and discussion history. A mention is not an endorsement.

Ferromagnetic half levitation of LK-99-like synthetic samples — HN submission

Tue, 08 Aug 2023 01:46:55 GMT

Ferromagnetic half levitation of LK-99-like synthetic samples

339 points; 314 discussion replies on HN. Paper and source history. A submission is not an endorsement.