[HN Gopher] Physicists discover a "family" of robust, supercondu... ___________________________________________________________________ Physicists discover a "family" of robust, superconducting graphene structures Author : filoeleven Score : 87 points Date : 2022-07-09 16:17 UTC (6 hours ago) (HTM) web link (news.mit.edu) (TXT) w3m dump (news.mit.edu) | yababa_y wrote: | Has some high powered algebraist or topologist tried figuring out | what is happening here mathematically? what structure is | generated by all possible rotations that we are sampling here? | multiplied by the many layers, what about nonuniform sheets? i'm | imagining channels of various shapes on the inside... such a | simple concept, yet such fascinating machinery for the | measurements. i feel proud when i get a logic analyzer trace off | an fpga pin! | marcosdumay wrote: | Hum... The article actually says it at some point: | | https://en.wikipedia.org/wiki/Moir%C3%A9_pattern | | https://everettyou.github.io/2018/05/21/Moire.html | | I imagine there's no ELI5 explanation of a flat band from | condensed matter physics. | notfed wrote: | > The findings could serve as a blueprint for designing | practical, room-temperature superconductors. | | Cool, up to what temperature? | | > 1.7 kelvin | | Ok. | bastawhiz wrote: | It seems like graphene production at scale has been a few years | away for a decade or so now. Is there reasonably a future where | all these incredible graphene-related technologies come to | fruition within our lifetimes? Or is this just another cold | fusion of a technology? | parkingrift wrote: | Aluminum was extremely difficult to manufacture before the | Hall-Heroult process. Only a true pessimist would assume we | would never solve manufacturing problems with graphene. | willis936 wrote: | A few things: | | 1. REBCO was discovered in the 80s but took decades to work out | the kinks in mass production of reliable tapes. | | 2. Cold fusion is psuedoscience. These results are real. | Speculating that a technology be vaporware is a very different | and weaker claim. How do you know that people will not solve | the engineering problems preventing mass production? Because it | wasn't immediately obvious how to do it in the past? | EarlKing wrote: | Cold fusion got rebranded as Lattice Confinement Fusion. | raziel2701 wrote: | Who knows, the academic research is often focused on finding | out new physics and relies on hero samples. The many failed | attempts to solve the engineering challenge of scalability and | reliability in graphene are not very visible to the world. | gtsop wrote: | It is a disgrace to intellect when scientific knowledge comes | with references to magic (even in quotes). Can't we just say | "exact", "proper", "special", " specific", "just right"? Why | magic? | willis936 wrote: | The term "magic number" pops up in many domains. Often it's | because the underlying mechanism that yields the empirical | result is unknown. If that's the case here then that context | should not be lost because of a semantics argument. | DennisP wrote: | "Magic" doesn't necessarily mean supernatural. Google quotes | the Oxford English dictionary to include these definitions: | | - something that has a delightfully unusual quality. | | - very effective in producing results, especially desired ones. | | I think those definitions make "magic" a better term in this | case than any of your alternatives. | ben_w wrote: | If I say during a code review that "magic numbers should be | documented", I expect the other person to know the phrase and | not think I'm talking about _The Book of the Sacred Magic of | Abramelin the Mage_. | | I expect similar things in other domains. | jamiek88 wrote: | Fascinating. | | Sadly this still needs to be at super low temperature. | | This family of superconductors brings us no closer to to room | temperature superconductors which would change the world. | klyrs wrote: | What's really neat about this result is that they're probing a | link between the band structure of materials and | superconductivity. So while no, this isn't at room temperature, | stacked graphenes provide a controllable family of | metamaterials that can be probed to learn more precisely the | conditions for superconductivity. If hot* superconductors | exist, we'll have a better chance at finding them if we | understand how superconductivity works. | | * we don't need "room temperature" superconductors for room | temperature operation. Superconductors have a shared budget[1] | of temperature, current and magnetic field -- if we want these | so-called superconductors to actually carry current at room | temperature, room temperature isn't enough! | | [1] http://hyperphysics.phy- | astr.gsu.edu/hbase/Solids/scbc2.html... | raziel2701 wrote: | What are you talking about not needing room temperature | superconductors for room temperature operation? | | If at 300 K a material has zero resistance then that material | will carry current at room temperature. | klyrs wrote: | Like I said, there's a shared budget for temperature, | magnetic field and current. If you're sufficiently close to | the critical temperature, it only takes a small current to | "blow the budget" which turns your material back into an | ordinary conductor/resistor. If you remove the current or | lower the temperature, there's a nonzero switching time | before the material will return to its superconducting | phase. | | There are some neat applications of this phenomenon in | superconducting electronics. Cryotrons use transformers to | produce large fields from small currents to switch a | higher-current-capacity line from superconducting to | normal. N-trons and other "current crowding" devices | perform a similar trick using currents in a pinched region | attached to the high current line. I can't remember the | precise details, but different superconducting films are | more or less inclined to "localize" the normal-phase region | induced by local current/heat. | | Sadly, those neat devices are apparently quite finnicky | because switching emits heat into their environment, and | also depends on temperature of that same environment. As | far as I know, cryotrons are used for high power | electromagnets to rapidly and safely dump the energy -- | they don't appear to be useful for superconducting | computers, for example. | jacobn wrote: | You need one that can handle higher than room temperature | for it to be able to carry meaningful amounts of current at | room temperature. See the link provided in parent for why | this is. | willis936 wrote: | I think it's difficult to get away from the prospect of a | practical widespread use of superconductors without active | cooling. Even if ohmic losses in the superconductors is not | present: environmental temperatures change, especially in | uncontrolled (outside, in the sun) environments. Running room | temperature water adds cost and complexity, but a lot less | than refrigerant (especially cryogenic). | | I think mass produceable room temperature superconductors | would still reshape the world, even if they still required | active cooling. | loufe wrote: | Thanks for your comment, if they broke the temperature | requirement that would be BIG news. | mensetmanusman wrote: | Higher temperature superconductors are already changing the | world. Doesn't have to be room temp. Some were used to help an | MIT project reach >20 Tesla magnetic field, which wasn't | possible before... | | I think a great application for these higher temperature (and | higher B-field, current) superconductors is reaching higher | magnetic fields for fusion :) | RF_Savage wrote: | Or just MRI machines that can function without the | increasingly expensive liquid helium. | marcosdumay wrote: | The main point I get is that the mechanism for this kind of | superconductivity can be predicted fairly well on computers. | That means that if it leads to room temperature | superconductivity, we have an actual path to get it. | | And, also, there is always those old too noisy experiments that | detected superconductivity on certain grains of graphite on | temperatures up to 700K... That never gathered enough | confidence, no matter how many times they were repeated. But | maybe there's something there. | | EDIT: Anyway, the other article on the front-page about this | experiment explains it much better. | peter_retief wrote: | Really, I thought it "was" at room temperature? ___________________________________________________________________ (page generated 2022-07-09 23:01 UTC)