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Origin of correlated isolated flat bands in LK99

arxiv.org

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Re: Origin of correlated isolated flat bands in LK99

#101

Post by porphyra »

jacquesm wrote: post #25
m3kw9 wrote: post #11

Earlier quoted context omitted.

Depends if this can scale, and can withstand environments and carry enough current density etc. If it’s brittle as f, then it limits its applications for example.

That's not that important. What is important is that if it is true that this is the first member of a new class of superconductors, a whole new family if you will and that once the principles are better understood materials scientists can go about their search in a smaller parameter space of which they have proof that at least one set yields results. Compared to the steps that have been happening in the last decades…

On one hand, yes, a new family will be discovered. On the other hand, high temperature superconductors like YBCO are very brittle and it does limit the applications. Traditional liquid helium-cooled superconductors still have to be used in many places.

Re: Origin of correlated isolated flat bands in LK99

#102

Post by rex_lupi »

semajian wrote: post #59
yellowcake0 wrote: post #24

There's a lot of optimism in this thread, but does DFT (or any theoretical model really) actually have much predictive value in quantum chemistry? I've always gotten the impression that in this field the proof is in the pudding.

There are so many bad DFT papers out there because it's cheap to do DFT compared to growing and measuring samples carefully. DFT is notoriously unreliable as a predictive tool in strongly correlated systems, though when electron correlations are small it works well. I mean, I want this to be true, but I put little stock in DFT that doesn't calculate observables. So yes, you're right.

Absolutely, Came to say this.

Re: Origin of correlated isolated flat bands in LK99

#103

Post by Culonavirus »

floxy wrote: post #61
jakeinspace wrote: post #40

Earlier quoted context omitted.

Sorry, but how does one create a transistor from a superconductor? Maybe I’m missing something here.

Most superconducting logic families aren't using transistors at all. They use Josephson junctions, which are just two pieces of superconductor separated by a non-supercondutor. RSFQ (Rapid Single Flux Quantum) uses millivolt-high picosecond-long pulses to represent logic 1 and their absence as logic zero, instead of using voltage level as in CMOS. https://ieeexplore.ieee.org/document/783712 (770 GHz toggle flip-flop…

Sooo, a 770 GHz processor? Do I understand it correctly? Jesus.

Re: Origin of correlated isolated flat bands in LK99

#104

Post by jacquesm »

porphyra wrote: post #101
jacquesm wrote: post #25

Earlier quoted context omitted.

That's not that important. What is important is that if it is true that this is the first member of a new class of superconductors, a whole new family if you will and that once the principles are better understood materials scientists can go about their search in a smaller parameter space of which they have proof that at least one set yields results. Compared to the steps that have been happening in the last decades…

On one hand, yes, a new family will be discovered. On the other hand, high temperature superconductors like YBCO are very brittle and it does limit the applications. Traditional liquid helium-cooled superconductors still have to be used in many places.

One of the reasons it is so brittle is because it is still very cold even though it is high temp for a superconductor. Many materials will become brittle when cooled down that far. This is one of things people hope for with higher temp superconductors: that they will be less brittle. But less brittle usually also implies that a material changes shape easier and that in turn may affect the superconductivity. For instance when a large current runs through a superconductor that leads to strong magnetic fields and those strong magnetic fields will actively push against each other trying to destroy the conductor. A non-rigid superconductor would behave in ways that are not really helpful for instance by pushing it out of its superconducting domain (which would result in some pretty spectacular fireworks because suddenly all that power is available to heat up a small segment of the no-long-superconductor). So there is some chance that all materials that exhibit (useful) superconductivity will end up being somewhat brittle, and will need to be mechanically re-inforced.

Re: Origin of correlated isolated flat bands in LK99

#106

Post by u320 »

losteric wrote: post #26
caesil wrote: post #7

Out of curiosity, since this seems like a real inflection point toward trending in that direction, if it becomes increasingly likely that LK-99 or similar material is indeed a high-TC superconductor, what will savvy people be positioning themselves to do? What are good investments? What companies will be started, or what will existing companies be pivoting toward?

Posting for Cunningham's law :) * Green energy suddenly becomes way more viable. Megaprojects in the most efficient sites can send energy long-distance and store it with effectively no loss, somewhat mitigating regional variations (especially if we have a high-trust world order where a united global grid is viable). (I read LK99 might have some limitations carrying lots of current but presumably other approaches woul…

Transmission losses aren't really a big problem for the grid. Cost, geopolitics, and resiliency matters more. I don't expect superconductors to change much here.

Re: Origin of correlated isolated flat bands in LK99

#107

Post by jacquesm »

yellowcake0 wrote: post #24

There's a lot of optimism in this thread, but does DFT (or any theoretical model really) actually have much predictive value in quantum chemistry? I've always gotten the impression that in this field the proof is in the pudding.

But it isn't used for its predictive value here, it is used to verify that which is already known (or at least, strongly suggested to be known). That's different than coming up with a compound based on some hunch, this is modeling a compound with a known structure to check that for properties consistent with the expectations.

That's radically different from searching for a compound with particular properties, that is a much more error prone process.

Re: Origin of correlated isolated flat bands in LK99

#108

Post by synaesthesisx »

Something incredible to note: it took around 5 years from when the transistor was first developed, to when it started to get integrated into consumer goods. LK-99 appears promising (and at the very least, may lead to other tangentially interesting discoveries), and if this is “it”, we could see commercial applications far sooner, especially if the synthesis is relatively straightforward. We couldn’t be on a more exciting timeline.

Re: Origin of correlated isolated flat bands in LK99

#109

Post by WhereIsTheTruth »

dtx1 wrote: post #3

Even if LK99 turns out to be a dud, it's proven that there's a great need and great opportunity for more direct communication from scientist on their experiments via the internet. Live Stream of the Synthesis, Twitter Threads giving life updates of different teams, etc.

I disagree, what you are asking would just be a way to siphon information, and encourage that kind of rush behavior

Korea should protect its students and their work a little more if they want their own TSMC, Texas Instruments of Korea doesn't sound right

Re: Origin of correlated isolated flat bands in LK99

#110

Post by bscphil »

u320 wrote: post #106
losteric wrote: post #26

Earlier quoted context omitted.

Posting for Cunningham's law :) * Green energy suddenly becomes way more viable. Megaprojects in the most efficient sites can send energy long-distance and store it with effectively no loss, somewhat mitigating regional variations (especially if we have a high-trust world order where a united global grid is viable). (I read LK99 might have some limitations carrying lots of current but presumably other approaches woul…

Transmission losses aren't really a big problem for the grid. Cost, geopolitics, and resiliency matters more. I don't expect superconductors to change much here.

This seemed likely the case to me as well. I'd be interesting in hearing any counterarguments (or better still, actual studies) concerning distribution efficiencies.
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