BCS Superconductivity Development and Controversy

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Discussion Overview

The discussion centers on the BCS theory of superconductivity, its historical development, and ongoing controversies regarding its validity and applicability, particularly in relation to high-temperature superconductivity (HTS). Participants explore various theoretical perspectives, empirical findings, and challenges in understanding superconductivity mechanisms.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • Some participants note that the BCS theory was not fully developed until 1957 and reference various texts for deeper understanding.
  • Others discuss the historical debate between Bernd Matthias and P.W. Anderson regarding the validity of BCS, highlighting predictions and discrepancies in superconducting behavior.
  • A participant mentions that the critical conditions for superconductivity remain inadequately addressed in existing theories, citing attempts by Frohlich and Bardeen.
  • Concerns are raised about the empirical formula proposed by Anderson, with some arguing it fails to accurately predict superconducting transition temperatures for certain elements.
  • Another participant suggests that modern calculations using Eliashberg theory can provide more accurate predictions for superconducting parameters, challenging the reliance on older empirical discussions.
  • There is mention of ongoing controversies in quantum-mechanical explanations of superconductivity, with various historical figures contributing to the discourse.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the validity of BCS theory and the adequacy of existing models to explain superconductivity, indicating that the discussion remains unresolved.

Contextual Notes

Some claims rely on historical discussions and empirical formulas that may not reflect current understanding or methodologies in superconductivity research. The limitations of BCS theory in addressing high-temperature superconductivity and the critical conditions for superconductivity are also noted.

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[Moderator's Note:
This thread is split from a textbook thread:
https://www.physicsforums.com/showthread.php?p=4275234#post4275234]

Greg Bernhardt said:

Exellent book. Especially 1953 year edition.

Kittel said:
Recently there have been a number of attempts to give a quantum-
mechanical explanation of superconductivity. We mention work by
Heisenberg,28 Tisza,29 Slater,30 Born and Cheng,»1 Frohlich,32 and
Bardeen.32 At the present time all these theories are highly contro-
versial, and the difficulties do not lend themselves to analysis in an
introductory textbook.

It has no subsequent ideas of Cooper pairing, preventing us of from understanding of HTS.

Kittel said:
In every theory the apparent contradiction between the Bloch theorem and the observed persistence of currents in a superconducting ring is explained by the presumed metastable nature of the current distribution.

Anticipating words!
Bloch theorem must be corrected!
 
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Did you know that the BCS theory of superconductivity wasn't fully developed until 1957? It is covered in later editions such as the 3rd (1967), but lightly since this book is an Introduction to solid state physics. For full coverage, see Kittel's Quantum Theory of Solids, or these excellent books: Harrison, Solid State Theory, or Tinkham, Introduction to Superconductivity.
Also, note that the mechanisms of high temperature superconductivity (HTS) are still being worked out.
 
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marcusl said:
Did you know that the BCS theory of superconductivity wasn't fully developed until 1957? It is covered in later editions such as the 3rd (1967), but lightly since this book is an Introduction to solid state physics. For full coverage, see Kittel's Quantum Theory of Solids, or these excellent books: Harrison, Solid State Theory, or Tinkham, Introduction to Superconductivity.
Also, note that the mechanisms of high temperature superconductivity (HTS) are still being worked out.

I many do know.
Date of 1957.
Discussion between Bernd Matthias and P.W. Anderson about validity of BCS, published in Science 144, 373 (1964). See "A career in theoretical physics" by Philip W. Anderson.
[QUOTE=""Matthias]These include the prediction that the Knight shift in superconductors vanishes, that higher transition temperatures exist, and that the isotope effect, with a value of M(-1/2) is general; in addition, the theory has also incorrectly predicted the electronic heat conductivity.
Unfortunately, one question remained almost totally ignored in most theories and experiments; namely, What are the critical conditions for the occurrence of superconductivity itself? Derivations of a criterion were first attempted by Frohlich and Bardeen, and later by Bardeen, Cooper, and Schrieffer. The latter group actually gave an equation for the transition temperature itself; this equation, however, contained an interaction constant that cannot be calculated at present Apart from this difficulty, the critical condition* for superconductivity could not be predicted by this equation either. Fог example, асcording to the equation, yttrium and lanthanum should have (the same transition temperature, that of yttrium being possibly a liltle higher, since both have the same N(0) and almost the same V and Debye temperature. However, yttrium is not superconducting down to 0.07'K and alfa lanthanum is superconducting at about 5K. This difference is discussed later. Moreover, this formula, cited by Anderson, is not only crude, as he says, but also incorrect for the transition elements, since the dependence of Tc on N (0) is in most cases the exact opposite of that stated in the formula. For example, the T, of yttrium, rhodium, and platinum decreases with an increase in N{0). Since the formula was proposed it seems to have been discarded completely because it does not present the criteria for the occurrence of superconductivity which, on the other hand, are easily given by a simple empirical rule (9).[/QUOTE]
P. Aynajian, T. Keller, L. Boeri, S.M. Shapiro, K. Habicht, B. Keimer,
“Energy gaps and Kohn anomalies in elemental superconductors”,
Science, vol. 319, pp. 1509-1512, 2008.
http://www.sciencemag.org/content/319/5869/1509.abstract

BCS theory of superconductivity: it is time to question its validity ...
http://iopscience.iop.org/1402-4896/80/3/035702/ by JE Hirsch - 2009

Jan 26, 2009 – BCS theory of superconductivity: the world's largest Madoff scheme? JE Hirsch. http://arxiv.org/abs/0901.4099

http://en.wikipedia.org/wiki/User:B...ty,_superfluidity_and_zero-point_oscillations

And i had the luck to read paper by Minich recently, prepared for Nature.http://love.minich.ru
 
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M@2 said:
Discussion between Bernd Matthias and P.W. Anderson about validity of BCS, published in Science 144, 373 (1964). See "A career in theoretical physics" by Philip W. Anderson.

Come on, you won't base your argument on some discussion from 1964 of an empirical formula.

The superconducting parameters for e.g. Yttrium, which was mentioned as problematic by Anderson, can be calculated nowadays with reasonable accuracy from first principles using Eliashberg theory, see, e.g.:

http://www.google.de/url?sa=t&rct=j...q4DQCw&usg=AFQjCNEvglgAsARL1-tZQmA0naFK5qEp-g