Creator is inactive, has been for some time.

Looked at this for the January 1st resolvathon, talked about it with people on the call. I think If the creator doesn't show up, I want to resolve this to N/A. Criteria is not well defined enough for a yes or no resolution in my view.

@Joshua That seems fairly sensible to me.

@EvanDaniel Yeah I tried really hard to come to some kind of consensus with Chris and NC and everyone else but it's just so ambiguous. "Proven" could mean any number of standards of evidence, and "LK-99" could refer to either the material shown in the original videos partially levitating or the pure crystals.

I think after 5 months of inactivity, the creator is unlikely to show up now. So I'm inclined to just N/A it immediately rather than risk it being forgotten.

If there are no objections, I'm going to do that today.

@Joshua Chris made total sense and said it better than he explained it in the Discord thread about this market. I think he is a better talker than chatter/commenter lol.

I agree with N/A, just worried if it hurts the predictors, but than again, there really is no way to resolve Yes or No.

https://arxiv.org/abs/2310.11051

Our as-grown specimen has excellent XRD matching with the original submission of Lee et al.

...

Magnetization measurements show linear diamagnetic behavior

(My comments here are not intended as moderator comments; I'm speaking only in my capacity as a trader in this market and won't be using any mod privileges on this market in any fashion. I posted it in the please-resolve channel on the discord and won't be advocating for any specific resolution there unless asked to.)

Just going off the Description and pulling what I think is a strong thing to meet:

"dominantly diamagnetic in replication"

• I have not found anything to prove it to be "dominantly diamagnetic"

  • Most proof states "partial" or "none"

  • Some proof state a variant in between none and somewhere below dominant.

If there is proof otherwise, someone please post it, please!

(I do not hold a position and do not plan to in this market)

@AvaHowell If you get this notification, or happen to see this, please feel free to chime in. ❤

@SirCryptomind I believe that in context, "dominantly diamagnetic" means that the diamagnetic properties are the dominant contributor to its magnetic behavior. Many materials have both diamagnetic and paramagnetic effects that contribute to their behavior, in opposite directions; we tend to call them "diamagnetic" when those effects are stronger, and vice versa. The effects are in many ways nearly identical aside from sign (a linear response to an applied magnetic field, either reinforcing or opposing it), so in most contexts it makes sense to just add the numbers together and call it one or the other.

And then some materials also have ferromagnetic responses; they can be much stronger than anything else.

IMO this is a good summary:
https://en.wikipedia.org/wiki/Diamagnetism#Materials

So I think the question is basically asking: is the magnetic response of this material best described as a simple magnetic susceptibility, with value < 0? And I think it is.

I believe the reason "dominant" was included in the description is because at the time it seemed possible that the material had both ferromagnetic and diamagnetic behavior, and that this question was intended to resolve No in the case where the ferromagnetic behavior was stronger under ordinary conditions.

I don't think "dominant" is a synonym for "strongly" or otherwise implies a required threshold on the measured magnetic susceptibility.

Most proof states "partial" or "none"

Could you be specific about which ones you're looking at?

@EvanDaniel I can mostly understand what you are meaning. While unlikely, the creator may come back with the recent ping, never know.
I am also not a fan of non peer reviewed experiments, most of the "partial" and "none" are just the ones posted on the wiki page with cited sources for some (but still not peer reviewed).
Understandably being peer reviewed does not seem to be an issue to the most if not nearly all of the traders.

@SirCryptomind My current take is that the scientific community has decided this thing isn't a superconductor without the necessity of formal peer review; there's been lots of peer review of the form "someone else put up a paper on arXiv that's clearly a response" and that's been adequate.

I think this material is a relatively uninteresting diamagnetic insulator or semiconductor (and not an interesting semiconductor). I expect most of the arXiv papers won't get published because the results aren't interesting, not because they're wrong or badly done.

Perhaps the standard of proof here is "must be published in a reputable peer-reviewed journal by EOY 2023", but I don't think that's supported by the question text. In comparison, the Wikipedia article is very thorough, well written, and cites almost entirely sources that don't meet that bar.

@MarcusAbramovitch Mind sharing what makes you think it hasn't already been proven?

@EvanDaniel I don't think it has yet been proven to be diamagnetic. It probably is, but doesn't look like any papers have come out on it to say either way. This to me suggests that this should resolve No

@MarcusAbramovitch I think this paper demonstrates it:

https://arxiv.org/abs/2309.17445

Every material is weaky diamagnetic though. That's not remarkable, and I don't know if that's enough for a YES

@Shump That's not true! While (weak) diamagnetism is common, it is not universal. Some materials are paramagnetic instead.

@Shump Or perhaps more explicitly, in some materials the paramagnetic effects are stronger than the diamagnetic effects. I would say that if LK-99 was dominant paramagnetic instead of diamagnetic that would be a clear case to resolve No.

@AvaHowell what sort of proof would be needed to show that LK-99 is diamagnetic by the end of the year? It looks like Evan has posted some papers already but is it simply a number of papers? Do we need some sort of authoritative source? Who could be such a source?

@wilsonkime Secondary sources and review / summary articles also seem like a relevant source of info. The Wikipedia page is certainly suggestive, but maybe not as unambiguous as I'd want if that were my sole resolution source:

A number of replication attempts identified non-superconducting ferromagnetic and diamagnetic causes for observations that suggested superconductivity.
...
The first synthesis to produce pure crystals found them to be diamagnetic insulators.
...

confirmed the structure using X-ray crystallography (XRD) but failed to find strong diamagnetism.

...

Cu2S is diamagnetic

...

No diamagnetism observed. High resistivity not consistent with superconductivity.

The Wikipedia page also conflates "diamagnetic" with "strong diamagnetism" in some cases, with the latter being something dramatic and the former just being a tiny ordinary effect that lots of materials, including the common Cu2S impurity, have.

I think the Cu2S removal with ammonia is the strongest of the approaches I've seen, and that paper found diamagnetism.

I'm not a materials scientist and don't feel like I have the expertise to judge this to extremely high levels of rigor. But I certainly think the balance of evidence points to a material that some diamagnetic response, at a level that is entirely ordinary for a ceramic insulator.

Continuing to see results that basically support the material being weakly diamagnetic:

Magnetic measurements for Cu2S-removed LK-99 samples across 10 K to 400 K revealed a consistent negative trend. The observed magnetic magnetization deviates from the expected superconductor, showing a diamagnetic nature at room temperature.

https://arxiv.org/abs/2309.17445

The characteristics of LK-99 by Cu$_2$S removal using ammonia solution: A diamagnetic semiconductor

In this study, we re-evaluated the superconducting properties of LK-99. The LK-99 samples were synthesized using the process proposed by the original Korean team. Additionally, we examined whether the results of the Korean team are related to Cu$_2$S by using ammonia solution (NH$_3$-H$_2$O) to remove Cu$_2$S . Through x-ray diffraction (XRD) analysis, a distinct Cu$_2$S phase was identified in the LK-99 samples. A subsequent treatment using an ammonia solution effectively eliminated this phase. The appearance of blue Cu$^{+2}$ ions in the solution and the elimination of the Cu$_2$S peak in XRD support the conclusion. The magnetic and electrical properties of LK-99 with and without Cu$_2$S postulate that the superconducting-like behavior in LK-99 predominantly arises from a transition in resistivity due to the influence of Cu$_2$S . As such, LK-99 is better classified as a diamagnetic semiconductor than a room-temperature superconductor. The room-temperature superconductors still require further research.

Further measurements, showing diamagnetism among other results:
https://arxiv.org/abs/2308.07800

For simplicity, we will refer to the Pb10-xCux(PO4)6O related phase as the “Pb phase” in the subsequent text. The Pb phase dominates the volume fraction of sample C, while Cu-related phases (i.e., Cu2S, Cu, CuOx) make up the majority of L and W.

the Pb phase exhibits a mixture of diamagnetic and weak ferromagnetic responses.

This paper demonstrates diamagnetism in phase pure single crystals:
https://arxiv.org/abs/2308.06256

Single crystal synthesis, structure, and magnetism of Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O

The recent claim of superconductivity above room temperature in Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O with 0.9 < $x$ < 1 (referred to as LK-99) has sparked considerable interest. To minimize the influence of structural defects and impurity phases on the physical properties, we have synthesized phase-pure single crystals with $x \sim 1$. We find that the crystals are highly insulating and optically transparent. X-ray analysis reveals an uneven distribution of the substituted Cu throughout the sample. Temperature ($T$) dependent magnetization measurements for $ 2 \leq T \leq 800$ K reveal the diamagnetic response characteristic of a non-magnetic insulator, as well as a small ferromagnetic component, possibly originating from frustrated exchange interactions in Cu-rich clusters in the Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O structure. No anomalies indicative of phase transitions are observed. We therefore rule out the presence of superconductivity in Pb$_{9}$Cu(PO$_4$)$_6$O crystals, and provide some considerations on the origin of anomalies previously reported in experiments on polycrystalline specimen.

@EvanDaniel Found via https://twitter.com/MichaelSFuhrer/status/1691221944694452224

The latest paper on LK-99 from Peking University finds dominant ferromagnetism, not diamagnetism. They explain the half levitation seen in the videos as a magnetic torque

https://arxiv.org/abs/2308.03110

Ferromagnetic half levitation of LK-99-like synthetic samples

We successfully synthesized polycrystalline LK-99-like ceramic samples with a solid-state-sintering method. Powder X-ray diffraction shows that the main contents are $\mathrm{Pb_{10-x}Cu_x(PO_4)_6O}$ and $\mathrm{Cu_2S}$, consistent with recent reports [arXiv:2307.12037; arXiv:2308.01192]. In some small flaky fragments, we successfully observed ``half levitation'' atop a $\mathrm{Nd_2Fe_{14}B}$ magnet. Using magnetization measurements on such small pieces, as well as on a large piece which does not exhibit the half levitation, we show that the samples ubiquitously contain weak yet definitive soft ferromagnetic components. We argue that, together with the pronounced shape anisotropy of the small fragments, the soft ferromagnetism is sufficient to explain the observed half levitation in strong vertical magnetic fields. Our measurements do not indicate the presence of the Meissner effect, nor zero resistance, in our samples, leading us to believe that our samples do not exhibit superconductivity.

@AvaHowell hmm, upon a more careful read it appears that they’re saying the sample is diamagnetic but has regions that are ferromagnetic, leading to the stable “half levitation”

https://twitter.com/condensed_the/status/1688747914288312320