[tt] the physics arXiv blog

Sat Apr 12 20:14:01 UTC 2008

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From: the physics arXiv blog <howdy at arxivblog.com>
Date: Fri, 11 Apr 2008 16:15:00 -0500 (CDT)
To: eugen at leitl.org
Subject: the physics arXiv blog
Reply-To: the physics arXiv blog <howdy at arxivblog.com>

[1]the physics arXiv blog

   [2]Nanoclusters break superconductivity record

   Posted: 11 Apr 2008 12:15 AM CDT

   [3]Al nanoclusters 

   Wow! Every now and again a paper on the arxiv leaps out at you and
   today there's work from Indiana University in Bloomington that has got
   my eyeballs on stalks.

   Get this: a team led by Martin Jarrold is claiming to have found
   evidence of superconductivity in aluminium nanoclusters at 200 K .

   Yep, 200 K. The current world record for high temperature
   superconductivity is 138 K for a cuprate perovskite so that's a
   massive jump.

   The background to this is that two years ago Yuri Ovchinnikov at the
   Landau Institute for Theoretical Physics in Moscow and Vladimir Kresin
   at the Lawrence Berkeley Laboratory in California predicted that metal
   nanoclusters with exactly the right number of delocalised electrons (a
   few hundred or so) could become strong superconductors.

   Now Jarrold and his buddies (Kresin and Ovchinnikov among them) have
   found the first evidence that this prediction is correct in individual
   aluminium nanoclusters containing 45 or 47 atoms . And they found it
   at 200 K.

   A few caveats. Before a claim of superconductivity can be made,
   physicists require three unambiguous and repeatable lines of evidence.
   The first is obviously zero electrical resistance. The second is the
   Meisner effect in which the superconductor reflects an external
   magnetic field. And finally there must be evidence of a
   superconducting phase transition, such as a jump in the material's
   heat capacity when superconductivity occurs.

   What Jarrold's team have measured is the last effect-a massive change
   in an individual nanocluster's heat capacity at 200 K. That's an
   important pillar of evidence which is consistent with
   superconductivity but it is not yet a slam dunk.

   Jarrold and his team are simply time-stamping their efforts by
   publishing on the arxiv and you can bet your bottom dollar that
   they're looking for other evidence right now.

   Even with that proviso, this looks to be an important breakthrough
   which should be straightforward for other groups to replicate. The
   group's work is not yet peer-reviewed. That'll be an important step
   too.

   Jarrold will be only too mindful that the field of high temperature
   superconductivity is littered with the corpses of physicists who have
   made premature claims.

   But for the moment, sit back and admire. 200K...wow! That's room
   temperature in Siberia at certain times of the year.

   Ref: [4]arxiv.org/abs/0804.0824: Evidence for High Tc Superconducting
   Transitions in Isolated Al45 and Al47 Nanoclusters

   Earlier ref: [5]arxiv.org/abs/cond-mat/0603733: Shell Structure and
   Strengthening of Superconducting Pair Correlation in Nanoclusters

   [6][arXivblog?i=FxiN2F] 
   [7][arXivblog?i=Gu0x5sG] [8][arXivblog?i=tD4ljrG]
   [9][arXivblog?i=SNWo2wg] [10][arXivblog?i=jGHBWwG]
   [11][arXivblog?i=5r6cQ4g] [12][arXivblog?i=jvOyhdG]
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References

   1. http://arxivblog.com/
   2. http://feeds.feedburner.com/~r/arXivblog/~3/268153953/
   3. http://arxivblog.com/wp-content/uploads/2008/04/al-nanoclusters.jpg
   4. http://arxiv.org/abs/0804.0824
   5. http://arxiv.org/abs/cond-mat/0603733
   6. http://feeds.feedburner.com/~a/arXivblog?a=FxiN2F
   7. http://feeds.feedburner.com/~f/arXivblog?a=Gu0x5sG
   8. http://feeds.feedburner.com/~f/arXivblog?a=tD4ljrG
   9. http://feeds.feedburner.com/~f/arXivblog?a=SNWo2wg
  10. http://feeds.feedburner.com/~f/arXivblog?a=jGHBWwG
  11. http://feeds.feedburner.com/~f/arXivblog?a=5r6cQ4g
  12. http://feeds.feedburner.com/~f/arXivblog?a=jvOyhdG
  13. http://feeds.feedburner.com/~f/arXivblog?a=b5eZAWg
  14. http://feeds.feedburner.com/~f/arXivblog?a=j8UzJLG
  15. http://arxivblog.com/
  16. http://www.feedburner.com/fb/a/emailunsub?id=8632699&key=kesJ612ZsV
  17. http://feeds.feedburner.com/arXivblog
  18. http://feeds.feedburner.com/arXivblog

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Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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