Room-temperature superconductor

[Psi]

Assuming it can be replicated it seems like good progress. 

Still some ways to go through. but very promising.

[AndyC_772]

250mA through what cross-sectional area?

[Dr. Frank]

Here are links for the actual paper(s):
https://arxiv.org/ftp/arxiv/papers/2307/2307.12037.pdf

https://arxiv.org/ftp/arxiv/papers/2307/2307.12008.pdf

They do show super conducting property at room temperature indeed, the critical current is around 250mA though.

The first paper as well is not convincing at all.
Levitation over a (super-) strong magnet does not proof SC properties, that could be some diamagnetic stuff as well.

You need a proper sample with 4W connection, defined geometry, to perform electrical measurements to prove SC properties.
No picture, and no such information given.

For the Meissner effect on a bulk sample, you need its geometry to normalize the signal.

Using 2 phase AC susceptibility, the real phase χ' represents the magnetization of the sample, the imaginary part χ'' represents the losses, which go to zero if the sample is really super conducting. Therefore, the susceptibility is as well a measure for the electrical conductivity.
The resistivity of ordinary metals like Copper and Lead goes down for decreasing temperatures, (arbitrary units used), as can be seen in χ'. χ'' first goes up, but in case of Lead, which becomes superconducting at about 7.2K, the losses vanish at its jump temperature.
For an YBCO film sample, it's equivalent.


As both these methods for proving SC are quite old, and were  intensively used on the then new High T_c SC, about 35 years ago, it is quite mediocre, what those guys have presented here, from an experimental point of view. 

Frank

[nfmax]

What would be *really* interesting is if this isn't superconductivity at all, but some different, so-far unobserved phenomenon...

[jt]

For those more knowledgeable than I - is there fundamental physics that indicates superconductivity can not exist at room temperature, or is there optimism that we will one day discover room temperature superconductive materials? 

[Dr. Frank]

For those more knowledgeable than I - is there fundamental physics that indicates superconductivity can not exist at room temperature, or is there optimism that we will one day discover room temperature superconductive materials?

SC @ RT has been observed and proven already in certain substances, but at very high pressure only.

[Kleinstein]

There are no fundamental things to no allow superconductivity at room temperature. However it can not work in a conventional simple metal. It needs special structures like a layered  (2 D) or similar materials.

As far as I understood the article they claim to have internal stress in the material in this way zones with a kind of local high pressure / distorted latice that can ac a bit like a high pressure.
The claimed measurements cover many aspects of superconductivity:  magnetic suceptibility, heat capacity (not a clear result), electric conductity - so if these are not fake data it very much looks like superconductity. The video part showing the repulsion is however poorly made with too much fast movements - so even a normal metal could act of a moving magnet via eddy currents. The special point with a SC is that it also work with DC and not just AC.

From my feeling the critical current density is rather low and maybe only for a fraction of the material actually gets superconducting. The conductivity suggests enough to get the perfect electrical conductivity and thus no big gaps (the SC current can tunnel over short gaps and thus no need to get true perculation of a superconducting phase.

[Dr. Frank]

I've googled a little bit, and I found several sceptical notes, same arguments as mine:
https://physicsworld.com/a/have-scientists-in-korea-discovered-the-first-room-temperature-ambient-pressure-superconductor/

In Germany, from IWF, Institute for Solid State and Material Research Dresden, they came to a ruinous conclusion, by Nicola Poccia, research group leader @ LIWF:
' On basis of the experimental proofs in those not yet peer reviewed papers, my first quick reaction is, that this is not a super-conductor'
The experiment might be erroneous. 'What can be observed, is probably an experimental artefact, mixed with lack of scientific diligence, in best case.
The presentation of their data is confusing, so that it is difficult to draw a final conclusion in this state.'

I've intensively done research on those YBCO and similar cuprates, 35years ago, by means of one of the first HP3458A, used for harmonic analysis of the AC susceptibility.
And I have seen a lot of samples..
That's the reason why I'm more and more reluctant about their paper.
We'll see.

Frank

[thm_w]

You need a proper sample with 4W connection, defined geometry, to perform electrical measurements to prove SC properties.
No picture, and no such information given.

Thats shown in figure 5 in the first paper...
"Figure 5 shows the temperature dependence of the resistivity of sample 2 (4.8 x 10.1 x 1.2mm) measured at 30 mA by the four-probe method"

Its not uncommon to leave out setup photos or steps if they are thought to be well-known.

Anyway there is some resistance step at 40C in the measurements which is kinda odd.

[EEVblog]

The paper in question:
https://arxiv.org/ftp/arxiv/papers/2307/2307.12037.pdf

I smell BS

[EEVblog]

Anton Petrov did a video on it:

[benbradley]

So what on Earth could possibly be more BS than this superconductor announcement?

#congressionalhearings

[Brumby]

He is demonstrating Lenz's law, nothing else.  Any copper or aluminum or silver would demonstrate the same motion when exposed to a strong moving magnetic filed.

This is the very first thing I thought as well.  In fact, I dug out some neodymium magnets I have and located an aluminium knob which I hung on a piece of cotton ... and did a quick video.  It took me all of 1 minute to set up with materials I had within reach while sitting at my desk.

How is it possible here at EEVBlog, no one knows about Lenz's law, or recognize that this is what happens when you move a magnet in front a copper coin.

I am quite surprised as well that there has been as much conversation as we have seen that:
 1. Makes no reference to Lenz's law or even eddy currents
 2. Does not question the relevance of the video to the claim.  I see absolutely none, other than a possible attempt to wow the uninformed.

I add my own facepalm: 

[daqq]

I've intensively done research on those YBCO and similar cuprates, 35years ago, by means of one of the first HP3458A, used for harmonic analysis of the AC susceptibility.
And I have seen a lot of samples..
That's the reason why I'm more and more reluctant about their paper.
We'll see.

Frank

Realistically, how long till someone could verify their results? According to the paper, the manufacture should be reasonably doable with common-ish lab tech.

[EEVblog]

Claimed critical temperature is 127C:

https://arxiv.org/abs/2307.12008

Oh, I missed that that video was from the lab and purports to show the superconducting material?
LOL, yeah, tons of things are going to do that! 

[Kleinstein]

I've intensively done research on those YBCO and similar cuprates, 35years ago, by means of one of the first HP3458A, used for harmonic analysis of the AC susceptibility.
And I have seen a lot of samples..
That's the reason why I'm more and more reluctant about their paper.
We'll see.

Frank

Realistically, how long till someone could verify their results? According to the paper, the manufacture should be reasonably doable with common-ish lab tech.

It could be relatively fast to reproduce, but there could still be minute differences that could explain a negative (no SC) result.
The alternative would be sending out a sample to an independent lab.

[bitwelder]

"Is the room temperature superconductor paper legit?"
Poll says NOPE
https://manifold.markets/fortenforge/is-the-room-temperature-superconduc

[gnuarm]

"Is the room temperature superconductor paper legit?"
Poll says NOPE
https://manifold.markets/fortenforge/is-the-room-temperature-superconduc

Yeah, they didn't believe cold fusion was real either!

[switchabl]

How is it possible here at EEVBlog, no one knows about Lenz's law, or recognize that this is what happens when you move a magnet in front a copper coin.

I am quite surprised as well that there has been as much conversation as we have seen that:
 1. Makes no reference to Lenz's law or even eddy currents
 2. Does not question the relevance of the video to the claim.  I see absolutely none, other than a possible attempt to wow the uninformed.

I add my own facepalm: 

I don't think anyone really cares about the video, it just isn't very relevant one way or the other. Ultimately, the important parts are the susceptibility, resistance and specific heat measurements, so that's what people are discussing.

[KedasProbe]

Luckily that person has plastic gloves on because shit will be flying in that room soon

I was checking the conductivity graph yes they have an bump around 41°C but also the values on the scale seem high to me, if i'm not mistaken in that graph lead would also be on that zero line.
2.2×10-7 ohm meter  (unit is a factor 100 but still, 0.000022 ohm cm, 0.0022 10-2 ohm cm)

Graph from PDF but I deleted the 'change graph' inside it

[Psi]

Nothing new is real, until it is.

Just have to wait and hope someone can reproduce it and confirm superconductivity, or some other previously unknown new effect. Either would be great.

[Marco]

If it's not a superconductor maybe it can be useful as an inrush current limiter.

[Brumby]

I don't think anyone really cares about the video, it just isn't very relevant one way or the other. Ultimately, the important parts are the susceptibility, resistance and specific heat measurements, so that's what people are discussing.

The issue I have is why the video was even presented at all.  Anybody even vaguely familiar with the principles involved will know there is no need for superconductivity to explain the behaviour.

The only purpose I can see is to "wow the uninformed" - which leads me to think the whole exercise is bulls**t.

If, in the unlikely event, it is real, then they really need a technically savvy publicist who can get a useful demonstration video together.

[switchabl]

The issue I have is why the video was even presented at all.  Anybody even vaguely familiar with the principles involved will know there is no need for superconductivity to explain the behaviour.

You'd have to ask them. As a basic sanity check, it certainly makes sense to check that the sample is repelled by a magnet. They may simply have wanted to document that - badly in this case because it isn't really clear from the video. But someone linked a different video that shows (partial) levitation above a magnet, so I don't think there is any doubt that the material is at the very least strongly diamagnetic.

I don't know if this was maybe rushed out, the papers aren't exactly polished either (to put it mildly). In the end the only thing that matters is if it can be replicated or not. If it holds up, we will eventually get a proper peer-reviewed paper. If it doesn't, ... 

[thm_w]

The issue I have is why the video was even presented at all.  Anybody even vaguely familiar with the principles involved will know there is no need for superconductivity to explain the behaviour.

The only purpose I can see is to "wow the uninformed" - which leads me to think the whole exercise is bulls**t.

If, in the unlikely event, it is real, then they really need a technically savvy publicist who can get a useful demonstration video together.

Did you read the title of the video? "Magnetic Property Test of LK-99 Film".
It doesn't say "proof video of superconductivity!!! *WOW* MUST SEE"

Its a simple test showing the magnetic properties of the material, that is it, as I stated above already.