Talk:Superconductivity

What do others think? - YBCO 92K 93 K ?

Back in March I (Eric Kvaalen) edited the article to change a temperature from 92 K (which has no reference) to 93 K (given in the title of a reference) and to explain a graph in its caption (see my edit). Tarl N. reverted my changes, and we had the following discussion on my talk page:

I reverted your changes; please discuss them. Which reference are you citing for 93K? The original discovery in 1987 had wide error margins. Tarl N. (discuss) 15:20, 9 March 2018 (UTC)

Tarl_N., I specific'ly went to that article because I redd something in New Scientist that gave −173°C as the temperature for "cuprate superconductors", which is 100 K, and I didn't remember seeing such a round number for cuprate suuperconductors before. I looked at the YBCO article and at the High-temperature superconductivity article, and I saw the paper giving the range 80 to 93 K. Then I looked at the Superconductivity article, and I found that someone way back in 2003 had put in the figure of 92 K, with no reference. Later someone put in a reference to the original paper, which in its title says 93 K (though it gives the range in the abstract). The Wikipedia article has a graph made by a woman in Denmark for her Master's degree thesis, which shows YBCO at over 100 K. It uses various colors and symbols for different kinds of superconductors. So I edited the article to include an explanation of the colors, and to correct the figure of 92 K to 93 K. And I wrote in parenthesis in the caption that her point for YBCO is higher than what's in the text. I think that's better than deleting the whole graph! And I don't see what's wrong with putting 93 K when that's what the original paper says in its title. Why should we (or you) put it back to 92 when there's no support for that and we know that the range goes higher than that? Eric Kvaalen (talk) 13:40, 10 March 2018 (UTC)

O.k. - points:

• • The 1987 paper says "from 80 to 93 K". The issue is that each batch made at the time had different transition temperatures, and they couldn't come up with a single number, they cited a range of what they had seen. That does not say they saw 93 K, they saw a range between 80 and 93. That does not mean they saw 93 K, and indeed, if my recollection serves (it has been 30 years since I read that paper), they saw 92.something.
  • We know now that the reason for the variation is that the transition temperature varies very sharply with the oxygen content, and with the methods they were using at the time, it was hard to control for that.
  • Specifying a single critical temperature for YBCO is incorrect; the temperature will vary considerably between O(6.5) and O(7). I don't know if they have explored values higher than 7, they are hard to reach. In any case, for that material it's probably best to say "up to" a value.
  • The graph in question was derived from an earlier graph by the same author, here. It looks like the author simply mispositioned that point - it's a low resolution graph, intended to show relationships not precise values. Perhaps you should ask.
  • I would prefer you not add confusion to captions. That simply makes the article harder to read, and presumably nobody is extracting precise values from low resolution graphs.

Regards, Tarl N. (discuss) 17:20, 10 March 2018 (UTC)

I don't think the original graph was by Pia. It dates back to 2011 and she only did her Master's in 2015. She says hers is "based on the Wikimedia Commons figure "Sc history.gif" at https://commons.wikimedia.org/wiki/File:Sc_history.gif where the timeline stopped at 2010 and did not contain more than one iron-based compound." So she made her own improved version for her thesis.

So what do we do? Leave the article as it is with an arbitrary number of 92 and no explanation for the different colors and symbols in the graph?

Eric Kvaalen (talk) 17:48, 10 March 2018 (UTC)

Yup. Unless you have WP:RS to justify removing things, I'm simply not going to allow you to make changes you don't understand. Tarl N. (discuss) 18:02, 10 March 2018 (UTC)

What do other people think? Eric Kvaalen (talk) 13:05, 24 July 2018 (UTC)

Request for Comment (2019-05-01)

The following discussion is an archived record of a request for comment. Please do not modify it. No further edits should be made to this discussion. A summary of the conclusions reached follows.

Changes have been undisputed for over two weeks, temperature has been set as 'above 90 K'

---

Should my edit be allowed (see discussion in previous section, #What do others think?). Eric Kvaalen (talk) 13:12, 1 May 2019 (UTC)

• Ugh. Why start an RFC out of the blue for something that happened a year ago? Anyway, the part of the caption detailing which shapes refer to which types is fine to add. The part mentioning a missing point on the graph should not be added. Either update the graph or just live with it. As for the temperature thing, I don't think I know enough to really weigh in, but based on the discussion, since there's apparently a good bit of variation, does it really matter if it's off by one degree? Why not just update the text to reflect that there's uncertainty in the actual value (sticking to sources, of course)? –Deacon Vorbis (carbon • videos) 14:25, 1 May 2019 (UTC)

  Seems to me that with the variation in temperature, and possible round up in generating the 93, there is no reason to change to 93. Note that the text up to 93, in the case that it was actually 92.6 rounded up to 93 (just a guess), is wrong. I suppose if it says up to about then I wouldn't argue either way, but even in that case I vote for 92. (By the way, I was at the famous APS meeting in 1987, but went to the talk about Chernobyl instead.) Gah4 (talk) 00:16, 2 May 2019 (UTC)

  If it was 92.6 then we are justified in saying 93, just as the authors do. It seems to me that either we have to say 93 or we have to give the range. There's no justification for 92 from the reference. And since what interests researchers is how high we can get the temperature, then it seems to me better to just give the 93 K that is given in the title of the reference rather than to complicate things by giving the range.

  As for why I started a Request for Comment after a year, it's because no one commented during that year, and I think it was very unfair of Tarl to block my edit. He seemed to be mad at me because of another discussion.

  Eric Kvaalen (talk) 16:51, 3 May 2019 (UTC)

• No. My objection was complicating the captions unnecessarily. The purpose of the timeline in this article was to show when various temperatures were achieved. Further detail about the graph belongs either in the text of the article, or in the additional information for the image itself (scroll down from [1]). The original caption from the thesis (figure 2.4) was: The history of some of the discovered superconducting compounds. Note in particular the BCS superconductors (green circles), the cuprates (blue diamonds), and the iron-based superconductors (yellow squares). Note also the change in the axes at around year 1980 and Tc ~ 50 K. I would consider the last sentence to be useful for the caption in this article, the earlier stuff being placed elsewhere. Tarl N. (discuss) 01:32, 2 May 2019 (UTC)

  If a graph uses different colors, then it should be explained. I did the work of looking up the reference and finding the graph. Why shouldn't I be able to share the results of my work with other Wikipedia readers? Why should they have to do all that just to find out what the colors mean? We're just talking about 18 words added to the caption! Eric Kvaalen (talk) 16:51, 3 May 2019 (UTC)

  Explaining the colors is just fine - but it doesn't have to be in the caption. The long caption I quoted above was for a full-page image, not the relatively tiny thumbnails we use in Wikipedia - I've seen cases of captions being larger than the images. Adding that information to the image page itself, or in the text of the article is fine. But this is going beyond your original question, which was trying to forum-shop an answer to "can my edit go in now?" Tarl N. (discuss) 19:25, 3 May 2019 (UTC)

  I don't know what "forum-shop" means. Shopping in the Forum Romanum? All right, so we agree that the explanation of the colors should be given. Now I would like to know what others think about whether it should be in the caption or in the text. Eric Kvaalen (talk) 06:14, 4 May 2019 (UTC)

  See WP:FORUMSHOP. DMacks (talk) 13:53, 4 May 2019 (UTC)

  @Tarl N.: The strangeness of the delay aside, starting an RFC to gain wider community input is not forum shopping. –Deacon Vorbis (carbon • videos) 15:21, 5 May 2019 (UTC)

• Regardless of whether the shapes/colors are explained in the image-caption or article-text here in the article, they should be part of the image-file's own description at File:Timeline of Superconductivity from 1900 to 2015.svg. Otherwise, someone who uses in any other context will have no idea what it all means. The image description page is a great place for extended detail about the image that goes beyond what might be appropriate in detail or scope in a certain article. DMacks (talk) 14:00, 4 May 2019 (UTC)
• Storm in teacup. I agree with the likes of DMacks and Deacon Vorbis in general. For my part "above 90K" would be fine; who among our readers would fail to understand that constructively in context? JonRichfield (talk) 08:49, 5 May 2019 (UTC)

All right, I'm putting in "above 90" and putting the explanation of the colors in the file along with a note in the caption to say so. Eric Kvaalen (talk) 16:47, 8 May 2019 (UTC)

Close this RFC. This RFC is asking about an edit that was made and reverted a year ago, and is therefore a disruptive RFC. Robert McClenon (talk) 10:37, 10 May 2019 (UTC)

Close this RFC. (via FRS) I wholeheartedly agree. This is clearly unproductive. StudiesWorld (talk) 10:07, 12 May 2019 (UTC)

Well, no, it was productive. Eric Kvaalen (talk) 16:06, 12 May 2019 (UTC)

Well... While there's definitely a good argument against this RFC being productive It does look like it could go somewhere (If it hasn't already gotten there tbh) As for my opinion I have to agree with Eric Kvaalen's ideas entirely. --NikkeKatski [Elite] (talk) 17:18, 18 May 2019 (UTC)

I am removing this RfC because the discussion has stopped as of the 18^th of May, 2019. In addition, the discussed edit has been unchanged for over two weeks. - AquilaFasciata (talk | contrib) 17:03, 23 May 2019 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

IISc paper

Has anyone read the paper for which we keep reverting the inappropriate additions? I don't know where to find it, and the comments being made in support of it: Their material will have superconductivity suggest to me this is not only not peer reviewed, but speculative. Tarl N. (discuss) 19:27, 9 June 2019 (UTC)

A new IP editor, 2405:205:2294:E57E:44A9:1D12:8A38:60A0, has inserted the same content, in the same format, as Lokeshguta149 is pushing. It is his only edit. 2405:205:2294:E57E:44A9:1D12:8A38:60A0: are you the same person as Lokeshguta149? A single editor using multiple accounts pretending to be different people to deceive and push content is called WP:SOCKPUPPETRY, and can get you banned. Any more of this and I will report you to an administrator. --Chetvorno^TALK 19:57, 9 June 2019 (UTC)

Well, the edit summary is identical too, and the IP is located in New Dehli, so by WP:SPI standards, we can say it quacks like a duck. However, under WP:AGF, I'd assume the editor simply forgot to log in. Tarl N. (discuss) 03:44, 10 June 2019 (UTC)

For what it's worth, looking up the author names specified at IISc preprints I see this paper: Recent advances in the preparation of nanocrystal solids, the only paper jointly authored by the indicated researchers. It's from 2015, and from the description, has nothing relating to the spam/promo we're seeing here. It's behind a paywall, and I don't have the energy to fetch it through my university, since it is unlikely to have any bearing on what has been posted. Tarl N. (discuss) 04:01, 10 June 2019 (UTC)

I've requested page protection, since this spammer is now using changing IPs on a wireless network. Tarl N. (discuss) 16:12, 10 June 2019 (UTC)

The article in question is at arXiv:1807.08572. See also arXiv:1906.00708 and arXiv:1808.02929. Brienanni (talk) 07:07, 10 June 2019 (UTC)

Thanks, in particular for that last paper referenced. Let's wait until peer review gets through these. Tarl N. (discuss) 16:14, 10 June 2019 (UTC)

@Tarl N. and Chetvorno: Could editors here keep an eye on Room-temperature superconductor. The Indian Institute of Science stuff is still there, maybe it's appropriate for that article but I don't think this patent stuff was [2] and it lasted quite a while. And yes I appreciate this is technically OT here since it isn't about improving this article but while I raised concerns at WP:FTN a couple of months back (hence the edits), I wonder if this is the better place to get the attention of editors experienced in the field. Nil Einne (talk) 08:22, 30 July 2019 (UTC)

Rutger's Formula

Hello,

My draft for a stub on Rutger's Formula was declined. According to a frequent editor, this was mostly due to "lack of context". I think it might work instead as a section of this article.

Is this a possibility?

Miguelmurca (talk) 10:21, 14 October 2019 (UTC)

Google seems to find more refs (which seems to be the main reason the draft was declined) - but the content seems to be mostly about the derivation of the formula - which seems too detailed for this article. Can I suggest adding more refs to the draft, extending its introduction, and putting a very brief mention to Rutger's formula where/if this article talks about a step change in specific heat. - Rod57 (talk) 18:39, 4 January 2020 (UTC)

@Miguelmurca: I would suggest that the article needs some english language verbiage; notably, what does it mean? "discontinuity in the specific heat". I've had undergrad physics, I think I understand it, but this is wikipedia, not a textbook. Explain in words what happens to specific heat at Tc (a graph would be useful), and why we care about it across that boundary. Also, some history. Who was Rutger, and why is the formula named for him? All of this, obviously, with citations. I will also mention that you are likely to run into some paranoia about naming, so make sure it's clear with secondary sources that the name is widely accepted. Regards, Tarl N. (discuss) 21:42, 4 January 2020 (UTC)

Addendum, it seems likely that the draft is misnamed - "Rutgers Formula" looks to not have an apostrophe. Which suggests it's named after the university, rather than a person. Tarl N. (discuss) 21:48, 4 January 2020 (UTC)

Should we mention Migdal-Eliashberg theory or Eliashberg theory

Should we mention Migdal-Eliashberg theory : Accuracy of Migdal-Eliashberg theory and Coulomb pseudopotential 2011? Starts:

"The Migdal-Eliashberg (ME) theory provides a very successful method for describing conventional superconductors, where the pairing is driven by a phonon-induced attraction. This theory is based on Migdal’s theorem, stating that vertex corrections can be neglected if the phonon energy scale (𝜔0) is much smaller than the electronic energy scale (𝐷). This should be true even if the dimensionless effective electron-phonon coupling 𝜆 is much larger than unity, as long as (𝜔0/𝐷)𝜆 ≪ 1. Thus vertex corrections are neglected in ME theory, which is a huge simplification."

Breakdown of the Migdal approximation at Lifshitz transitions with giant zero-point motion in the H3S superconductor talks of the Migdal approximation to standard Eliashberg theory. - not sure how to summarise it ? Is it just a way to simplify the calculations within BCS ? or does it apply in any way to any of the unconventional superconductors ? If it doesn't belong in this article, where should it go ? - Rod57 (talk) 18:00, 4 January 2020 (UTC)

Eliashberg Theory 2013 looks like a review of Eliashberg theory (1961) and mentions various approximations (including Migdal 1958). Perhaps Eliashberg theory is a theory for SC where electron-phonon interaction can be strong (whereas BCS is better only when electron-phonon interaction is weak) ? - Rod57 (talk) 18:29, 4 January 2020 (UTC)

Proposed sidebar series for superconductivity

Hi all, I created Template:Superconductivity which mostly contains all the links in the see also section of this article arranged in categories. I am no longer fully convinced it is needed, but thought it was a great idea when I started. (There are a lot of a articles here that relate to superconductivity and you have to follow a lot of links sometimes to find specific information) I would like to know what others think. If you like the idea, feel free to edit Template:Superconductivity to help make it more useful. Thanks! Footlessmouse (talk) 05:51, 15 August 2020 (UTC)