from Hacker News

Electronic Structure of LK-99

by spekcular on 8/2/23, 12:57 AM with 432 comments

  • by bluecoconut on 8/2/23, 1:31 AM

    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 superconductivity after seeing multiple different labs compute similar band structures. The video of multiple directions of magnet showing some levitation also inspires a lot of hope.

  • by samhuk on 8/2/23, 9:21 AM

    My ultimate take-away about LK-99 since the start has been that, even if it doesn't turn out to be a holy-grail or whatever, the novel ideas behind the material are incredibly interesting.

    The idea of causing tiny (~0.5%) crystal lattice shrinkage with cuprate percolation is a really interesting idea.

    So far, only huge pressures or very low temperatures (i.e. Physics) have been used to cause that shrinkage, therefore perhaps LK-99 could, at the least, mark the time that Physicists hold up their hands, admit that they have failed, and let the Chemists give it a shot.

    I'm slightly oversimplifying the situation, of course, and the disciplines of science cannot be so distinctly separated, but, y'know.

  • by dralley on 8/2/23, 1:45 AM

    My understanding is that the "99" in LK-99 is the year it they first synthesized the material, i.e. 1999.

    Assuming this is all true, why is it just now coming to light? Did they just not know what they had? (I have not been following this closely, maybe this has already been explained)

  • by westurner on 8/2/23, 1:50 AM

    "Electronic structure of the putative room-temperature superconductor [ Pb_9 Cu( PO_4)_6 O ]" (2023) https://arxiv.org/abs/2308.00676 :

    > A recent paper [Lee {\em et al.}, J. Korean Cryt. Growth Cryst. Techn. {\bf 33}, 61 (2023)] provides some experimental indications that Pb10−xCux(PO4)6O with x≈1, coined LK-99, might be a room-temperature superconductor at ambient pressure. Our density-functional theory calculations show lattice parameters and a volume contraction with x -- very similar to experiment. The DFT electronic structure shows Cu2+ in a 3d9 configuration with two extremely flat Cu bands crossing the Fermi energy. This puts Pb9Cu(PO4)6O in an ultra-correlated regime and suggests that, without doping, it is a Mott or charge transfer insulator. If doped such an electronic structure might support flat-band superconductivity or an correlation-enhanced electron-phonon mechanism, whereas a diamagnet without superconductivity appears to be rather at odds with our results.

    Superconductivity: https://en.wikipedia.org/wiki/Superconductivity

    Superconductor classification: https://en.wikipedia.org/wiki/Superconductor_classification

    Room-temperature superconductor: https://en.wikipedia.org/wiki/Room-temperature_superconducto...

    Diamagnetism: https://en.wikipedia.org/wiki/Diamagnetism

  • by NotSuspicious on 8/2/23, 2:15 AM

    One of the things that has most pissed me off about these papers is that VASP is proprietary and requires a license to use.

  • by lucideer on 8/2/23, 9:56 AM

    For anyone interested in this topic, there's a thread on Twitter that's been garnering some attention: https://nitter.net/Errorreporrt/status/1685835688216821760

  • by UberFly on 8/2/23, 1:48 AM

    Several commenters here have mentioned demonstration videos. Does anyone have a link(s) to these? Many thanks.

  • by carabiner on 8/2/23, 2:08 AM

    More DFT? Haven't we concluded that has little predictive power?

  • by itsthecourier on 8/2/23, 1:11 AM

    So theorically they agree with LK-99 reaching superconductivity?

  • by chaorew on 8/2/23, 8:22 AM

    oh, I don't believe it. At present, it is very likely that it is purely theoretical, and there is still a long time before it can be applied.

  • by nemo44x on 8/2/23, 1:57 AM

    2023 will go down as a miracle year not unlike 1905. Between AI, this, and… what’s next?

  • by appplication on 8/2/23, 1:36 AM

    This ongoing research saga pretty much the most excited I’ve been about anything since before Covid. It feels like the science equivalent of watching your favorite sports team on an epic rise towards winning a world championship.

    Even if this turns out to flop, I hope history remembers the original authors favorably. They really did find something that by all accounts could plausibly be a room temp superconductor. And of course this seems to have turned over quite a stone. Peripheral research as a result of this will likely continue for years, even if superconductivity is disproven.

  • by jeffbee on 8/2/23, 1:33 AM

    The most interesting phenomenon revealed so far is that the room-temperature superconductor people and the generative-LLMs-are-God people draw on the same limited global pool of credulity, such that HN cannot be flooded with both ChatGPT worship and superconductor speculation at the same time.

  • by arookery on 8/2/23, 2:39 AM

    Super exciting moment, seeing scientists actively exploring the superconducting properties of LK-99.

  • by qiqitori on 8/2/23, 2:29 AM

    The material containing lead is very unfortunate. I have no doubts that (if it indeed turns out to be a superconductor) humans will use it anyway in any context where it provides even a slight benefit (cf. just in the lead department: leaded gasoline, leaded solder, etc.).