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Electronic Structure of LK-99

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Re: Electronic Structure of LK-99

#391

Post by jacquesm »

marcosdumay wrote: post #368
baq wrote: post #307

Earlier quoted context omitted.

Measuring zero resistance turns out to be quite difficult because your measuring apparatus tends to have some resistance in itself. Perhaps heating it up while it levitates would be a better idea. Put the magnet in an oven together with the sample and bake?

Magnets have an annoying tendency to stop working when they are heated. And it's ridiculous that I'm saying that on the context of testing a superconductor. But well, here we are.

Indeed, that statement would have been really funny just a few weeks ago. Now you're going to have to wonder whether the magnet or the superconductor will fail first.

Neo magnet fabrication is fascinating by the way, the somewhat magnetized blanks are not all that impressive from a magnetic field strength point of view, but then you zap them with a strong enough field and they then suddenly are the best thing since sliced bread.

This technique was first developed for 'regular' ceramic magnets.

https://idealmagnetsolutions.com/knowledge-base/how-neodymiu...

An uncoated magnet will oxidize very fast, so you always have to ensure that the coating on any magnets you use is perfect or the magnet will surely fail.

Re: Electronic Structure of LK-99

#392

Post by jacquesm »

archontes wrote: post #390
marcosdumay wrote: post #368

Earlier quoted context omitted.

Magnets have an annoying tendency to stop working when they are heated. And it's ridiculous that I'm saying that on the context of testing a superconductor. But well, here we are.

You could always use an electromagnet.

A superconducting one?

Re: Electronic Structure of LK-99

#393

Post by postalrat »

mannerheim wrote: post #215
tanseydavid wrote: post #191

Earlier quoted context omitted.

>> and remember that Air Force pilots aren't supreme authorities for objectively assessing parallax and assigning airspeed to all moving objects while flying a fucking cracker attached to a rocket. They don't need to be "supreme authorities" on anything -- they have insane technology acting as their eyes and as their objective measuring and tracking systems.

The technology itself in the 'Go Fast' video shows the object isn't moving fast. The distance from the object and the direction of the camera are available in the video, and using this you can calculate the altitude and speed of the object in question. https://www.youtube.com/watch?v=PLyEO0jNt6M

You can calculate it to go many speeds depending on what assumptions are made. Just because mick west shows something is possible doesn't prove what's in the video.

Re: Electronic Structure of LK-99

#394

Post by raducu »

jjk166 wrote: post #355
evergreener wrote: post #344

Earlier quoted context omitted.

Is there an intuitive explanation of why shrinkage of a material is beneficial for superconductivity. Naive question, particles physicist by training.

When a material shrinks, it can create immense internal stresses equivalent to what it would experience at extreme pressures. Compare to say a Prince Rupert's drop.

That's very interesting! I remember a while ago I read about a room temperature superconductor... but it required enormous pressures.

Re: Electronic Structure of LK-99

#395

Post by jacquesm »

MrBuddyCasino wrote: post #267
bluecoconut wrote: post #12

I got my PhD studying band structure of high-tc superconductors (experimentalist, ARPES). These Cu d-d interactions right at the fermi energy give me huge hope. Feels very familiar to other superconductors (re: all the cuprates). (Note: I specifically worked in a lab that was measuring a lot of the d-wave character / gap-energies of various superconductors) All in all, I'm now much more bullish on LK-99 being real su…

This is probably the most stupid question to ask, but while were are still trying to confirm superconductivity instead of understanding its precise mechanism of operation, why the focus on levitation on band structure to confirm the news instead of just "yep this chunk has actually zero Ohms"?

Because the levitation thing works with tiny fragments too whereas the 'zero Ohms' measurement only works when you have enough of it to form a long enough wire of it that you could tell the difference between 0 and 0.000001. Measuring very small resistances is usually done by letting a known current run through them and then to measure the voltage across the sample using known resistance leads. For a superconductor that has a tiny available sample which is already conductive even if it is not superconducting is fraught with error and may well give you the wrong answer due to a tiny measuring error.

But the Meissner effect is a unique signature of a diamagnetic material and will provide you some evidence even if the sample is tiny. So I understand why they have not yet resorted to other measurements, if there is no Meissner effect you don't need to continue with the hard work of trying to make a wire (which may well be a serious challenge for this stuff, the yield will have to come up significantly before that's a real possibility).

hth

Re: Electronic Structure of LK-99

#396

Post by jacquesm »

poopbutt7 wrote: post #142
dekhn wrote: post #39

Earlier quoted context omitted.

Pons & Fleischman was exciting for about 3 days. Some folks kept looking for decades after.

[flagged]

Super conductors exist. Room temperature net out fusion does not exist, and may never exist, and there are no known pathways in physics that would lead to it. Super conductors do not require any new physics, they require a material that may or may not exist but given the steady progression in the temperature range over which superconductivity has been observed there is a good chance that it exists, we just haven't found it yet.

Note that the 'room temperature' thing is a human requirement, and not one grounded in physics of conductivity per se, and that we started around 3 Kelvin (or -270 degrees Celsius)

https://www.scientificamerican.com/article/superconductors-t...

To 200K or -70 Celsius) degrees for the latest confirmed superconductor:

https://physicsworld.com/a/hydrogen-sulphide-is-warmest-ever...

In about 100 years. That is on average a two degree per year increase over that period. But the rate of improvement isn't linear and the closer you get to zero the bigger the market is and so the larger the amount of funding available to search for the bit that will close the gap.

This is why we will likely have room temperature superconductors somewhere in the near future, assuming it doesn't already exist. Obviously there is no guarantee that anything that hasn't been discovered yet exists. But in this case, given the arbitrariness of the boundaries set and the fact that those are mostly dictated by chance conditions on planet Earth (if we were living on the dark side of the moon we'd already have room temperature superconductivity...).

Re: Electronic Structure of LK-99

#397

Post by cynusx »

mensetmanusman wrote: post #334
jpmattia wrote: post #117

Earlier quoted context omitted.

> To me it's just "a lot of the same stories" that are told about cuprates, and less of a "I can explain the mechanism". Fair enough, and thanks for the readout. I realized after posting I essentially demanded an explanation as to why the cuprates are high-Tc, which is probably its own Nobel prize.

The internet is one of those places where if you are wrong, someone might well write a Nobel-worthy response just to win the argument. https://www.wired.com/story/how-an-anonymous-4chan-post-help...

Nice one, reading that post makes me wonder if the proof could be furthered when considering parallels from compression algorithms.

Compression algorithms detect recurring blocks and remove them with a special symbol and I think the shortest path would be uncompressable with compression algorithms.

Re: Electronic Structure of LK-99

#398

Post by jacquesm »

cooper_ganglia wrote: post #120
tnecniv wrote: post #83

Earlier quoted context omitted.

I identify with that. It didn’t help that around the end of Covid I went through a terrible break up and all my grad school friends finished their degrees and moved while I was still working on mine. It felt like I went to the bathroom at a party and came back to an empty room and I had to stay and clean up. I knew I’d be done in a year or two, so it felt weird to try and find a new social group when I was on short t…

I can relate to both comments. Covid really sapped the life out of me. Some relationships broke down during isolation, I lost friends, my fiancée left, I felt stuck in a job that I hated... The research into LLMs and diffusion models started to wake me up, but this superconductor research has, for some reason, really awoken something in me. I feel excited about the future– my future! – for the first time in a while.…

Hang in there, that's how life is, sometimes you're up, sometimes you're down but there will almost always be something interesting waiting for you in the future that makes you forget the miserable time that came before.

Re: Electronic Structure of LK-99

#399

Post by jacquesm »

jlokier wrote: post #359
pests wrote: post #350

Earlier quoted context omitted.

Haven't mRNA vaccines been in development for over a decade though?

LK-99 has been in development for longer, 24 years, if you believe a quote copied in many current articles and below. You may have heard before, "it takes years of work to become an overnight success..." > Lee & Kim had been working on the material on and off since Kim was in graduate school in 1999 (LK-99 geddit?). Lee never makes tenure and is still stuck as an adjunct professor 19 years later. Kim goes off to work…

Assuming it's all true what I like about their story is that they've basically been doing a guided brute force of candidates rather than to just sit around and theorize they got their hands dirty in a way that really impresses me.

Re: Electronic Structure of LK-99

#400

Post by jacquesm »

itsoktocry wrote: post #320
groby_b wrote: post #49

Earlier quoted context omitted.

Emotionally, it was horrible. Societally, it was depressing to see that we'll never be able to tackle any true large problems, we can't even agree on wearing a piece of paper to protect fellow humans. But scientifically? Yeah, I'll go with "exciting". The field seemed to move at a tremendous speed, or at least that's how it looked to me as an outsider. Sequencing within less than a week, extremely rapid movement on t…

> But scientifically? Yeah, I'll go with "exciting". The field seemed to move at a tremendous speed, or at least that's how it looked to me as an outsider. The practical science may have been exciting. Unfortunately "The Science" has been forever tainted thanks to secrets, tight-lips, mis-direction and "just trust us". I think Covid was a net-negative for science.

Science served us well enough that we're all still commenting here. It's the prevention paradox all over again, if science had not done its work you'd be in a much better position to appreciate the difference that it - and healthcare - made but then you might not have made it at all... science definitely did not let us down.

Who did let us down: the people that were making things worse from day #1 by stirring the pot against science.

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