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If helium is 'superfluid' at low temperatures

  1. May 7, 2009 #1
    if helium is 'superfluid' at low temperatures then is it correct to think of amorphous solids as 'superviscous'?
     
  2. jcsd
  3. May 12, 2009 #2
    Re: superfluid/superviscous

    Sounds clever, regard with suspicion...
     
  4. May 12, 2009 #3
    Re: superfluid/superviscous

    What would be the properties of a superviscous amorphos soild?
     
  5. May 12, 2009 #4
    Re: superfluid/superviscous

    Superfluidity is a quantum effect, where the glass transition is a classical effect, as far as I know.
     
  6. May 12, 2009 #5
  7. May 12, 2009 #6

    f95toli

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    Re: superfluid/superviscous

    I am not sure why you think superinsulators have anything to do with this; they are essentially just grainy films where the charging energy of single grains are larger than the availalble thermal energy which means that the charge carriers "freeze out" at low temperatures (it is a bit more complictated than this, since there are some collective effects involved, but that is the essence of it); it is essentially a classical effect and there is no macroscopic coherence involved.

    And yes, I do know that the Novosibirsk people like to say that that the conductor-superinsulator transition is analogous to the normal-superconductivity transition; but there are significant differences.
     
  8. May 12, 2009 #7
  9. May 12, 2009 #8
  10. May 13, 2009 #9

    f95toli

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    Re: superfluid/superviscous

    Well, the Wikipedia article isn't very accurate in this case. It is true that the effect is observed when the grains are superconducting; but this does not change what I wrote above. If you want you can think of the system as a network of Cooper pair boxes (which is why you need the grains to be superconducting); but the interaction between these are -as far as I know- still just classical (there is a synchronization of the phase BETWEEN the grains; but there is still no GLOBAL phase; the system is not described by a "single wavefunction").
    Note that the idea is far from new and as far as I remember there is even a brief discussion in Tinkham.

    I am familiar with the article, and I've also attended a few talks by among others Baturina so hopefully I have some idea about how this work (at one point we were considering using superinsulators in one of our own projects).
     
  11. May 14, 2009 #10
    Re: superfluid/superviscous

    now there is something called 'superglass'.

    http://www.nanowerk.com/news/newsid=10389.php

     
    Last edited: May 14, 2009
  12. May 14, 2009 #11
    Re: superfluid/superviscous

    http://209.85.173.132/search?q=cach...%"&cd=12&hl=en&ct=clnk&gl=us&client=firefox-a
     
    Last edited by a moderator: Apr 24, 2017
  13. May 23, 2009 #12
    Re: superfluid/superviscous

    wikipedia:

    2 components? one that flows with exactly zero viscosity and one that doesnt. sounds kinda like a supersolid, doesnt it?


    https://www.physicsforums.com/showpost.php?p=2206263&postcount=7

    maybe superflow (the component that flows with exactly zero viscosity) isnt 'real' either. in the sense of not consisting of the real flow of real atoms. the atoms somehow just behave as though they were flowing. (of course, the real atoms of the superfluid can and do really flow but that would be the component that does not flow with zero viscosity. the viscosity is unusually small though). somehow momentum 'flows' around the interior of the superfluid without the atoms (necessarily) moving. obviously this would be a purely quantum mechanical phenomenon. this would explain supersolids too.

    also:
    http://en.wikipedia.org/wiki/Superfluid
    http://en.wikipedia.org/wiki/London_moment
    in other words the electrons (or rather cooper pairs) are stationary.
    compare that to:
    http://www.nanowerk.com/news/newsid=10389.php

    I suspect that all of this might somehow be related to the concept of 'effective mass' where a particle (in the interior of some material) behaves as though it had less mass than we know it really does.

    finally:

     
    Last edited: May 23, 2009
  14. May 23, 2009 #13

    f95toli

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    Re: superfluid/superviscous

    No offense, but your post makes no sense at all.
    If you don't believe superfluidity involved "real movement" you should check out some of the videos of superfluids on Youtube or -even better- find a nearby university that holds public demonstrations where effects like superfluid helium "creeping out" of a container (via the Rollin film) are shown. I used to supervise a demonstration of superfluidity to undergraduate students, it is quite a nice demonstration and most of the effects are quite easy to see.

    Note also that there are quite a few engineering applications where this is used; one way to separate He-3 and superfluid He-4 is to use a "superleak"; basically a barriers with holes so small that only superfluids can pass through (and once you heat up the He-4 it becomes a normal liquid again). This is used in e.g. dilution refrigerators.

    Also, you shouldn't take the London theory too seriously. It is a phenomenological theory which is often useful but it doesn't even try to describe what goes on at the microscopic level, for that you need more sophisticated theories based on QM.
     
  15. May 23, 2009 #14
    Re: superfluid/superviscous

    what are you talking about?

    the article says that superfluid helium behaves as though it has 2 ocmponents. the real atoms would be the second component. the component that flows with little but not zero viscosity.


    edit:I have editted my post below to make its meaning more plain.
     
    Last edited: May 23, 2009
  16. Jun 1, 2009 #15
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