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LK-99: Team of Southeast University observed zero resistance below 110 K

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Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#121

Post by modeless »

To me this is encouraging. 110K is really high! It's higher than YBCO which is what they make commercial "high temperature" superconducting tape out of. IMO if this is legit (I have no way of judging the source) then this is the first good third party evidence that the original researchers are not just doing some kind of fraud. A total fraud wouldn't have actually discovered a novel high-temperature, but not room temperature, superconductor.

At worst it seems to me like they discovered a cool new superconductor that may have commercial applications. At best, they may have a variant of this material that really is a room temperature superconductor. Either way, there is an important scientific discovery here.

I'm surprised the prediction markets don't seem to be reacting. Maybe the source isn't actually credible? Any Chinese speakers here know?

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#122

Post by jacquesm »

uyhgr wrote: post #108
Workaccount2 wrote: post #74

Earlier quoted context omitted.

I have seen it posted that diamagnetic materials require multiple magnets stuck together to create field "pockets" (?) for the material to rest in. The few videos of lk99 show it reacting to a singular magnet. A property of superconductors that apparently diamagnetic materials don't have.

The term is “flux pinning”, and it only applies to the “quantum lock” effect. That is the specifically static hovering effect. The diamagnetism, importantly this means repulsion of both poles simultaneously and equally (this is how you can have these magnets spin, a regular magnet repels same poles and attracts opposites, diamagnets repel both poles), is simply a characteristic of the superconductor, but it alone wou…

NileRed is youtube gold. It's one of very few channels that I follow and learn from.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#123

Post by uj8efdjkfdshf »

The one interesting thing I should note is that synthesis of the copper phosphide intermediate tends to result in a copper deficient product, so I wonder if the presence of lattice defects in this might have an effect on where the copper atoms intercalate in the lattice.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#125

Post by marcosdumay »

bigmattystyles wrote: post #75

Novice question - does a material behaving as a superconductor occur all the sudden like a step function if resistance is plotted against temp and pressure - or does it ease into super conductor behavior? (edit) Also is it resistance (aka if I remember my EE degree correctly), DC only or also impedance where frequency also matters?

It's like freezing water.

It happens at a single temperature. It doesn't happen at once, there is a small amount of heat you must take from the material before it becomes a superconductor. Regions of it become superconductors on the process, and those grow until the entire material change.

After the change, it becomes a stronger (yes, there is such a thing) superconductor the cooler it gets.

(Or, at least that's what happens to the kinds I know about. The thing is complex enough that I wouldn't be too surprised to learn about one that behaves differently.)

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#126

Post by legulere »

hatsunearu wrote: post #103

The Fig 3a)b) graphs are not showing superconductivity. That just looks like the resistance dips below the ~1e-5 mark and goes goes deep into the noise. That just looks like a normal conductor that has a positive temperature coefficient. edit: to add speculation, I think they made something that's not quite LK-99, and it's behaving like a normal conductor with no superconductance.

The noise is probably just an artefact from measurement.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#129

Post by flumpcakes »

Palpatineli wrote: post #119
matsemann wrote: post #113

Earlier quoted context omitted.

It doesn't invalidate the original claim, as they haven't been able to make a pure sample to test with, as I understand it. Or at least that there is some difference between their samples and the others, but still it shows promise.

[flagged]

> Purity does not affect Tc.

Here's a lump of 100% Cu and another lump of 50% Cu and 50% "other".

If purity doesn't matter, they must have the same properties? Why not just use 0.0001% copper in all our applications and save millions on material costs.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#130

Post by dotnet00 »

borkt wrote: post #107
jacquesm wrote: post #93

Earlier quoted context omitted.

Yes, that's true, but that would require a shift in our understanding of physics and everything about this saga so far has not done that. And that in part is a reason why people take this serious: it is believable. New physics would raise the bar considerably. So for now I'm on the measuring error, impurity or process issue side of that without committing to which team I think has the problematic side.

The fact that our existing computational models are in agreement with the experimental behavior leads me to believe there is no new physics involved here. That being said this raises the question as to whether this class of material is known and characterized within our national research labs but has been kept classified, and if it was unknown it raises the question of why experimentation is what discovered it and wh…

I think one factor that's overlooked with these simulations is that there are a ton of parameters to these which really hinder automated searching.

It's easy (relatively) to verify the results from a real world test since you know the physical parameters and can tweak the others based on intuition, where if the result matches the real world you can consider it valid, but if it doesn't you can have to check all sorts of things to be sure that it isn't a glitch due to some parameter not being reasonable.

That makes searching for materials really hard because you either need an absurd amount of computational power to be able to set the simulation parameters so high as to not worry about their effects or you get tons of false positives simply because the computer can't as easily tune those parameters to ensure it produces correct results.

As my PhD advisor has often put it regarding my own simulation work, if the simulations were that capable of modeling reality, there would be no need for billion dollar facilities to perform tests irl, you'd just spend all that on building many supercomputers.

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