Can BCS theory explain type-II superconductor?

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Discussion Overview

The discussion revolves around the applicability of BCS theory to type-II superconductors, particularly in relation to high critical fields (Hc2) and low critical fields (Hc1). Participants explore whether BCS theory can adequately describe type-II conventional superconductors and the distinctions between type-I and type-II superconductors.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that BCS theory cannot explain high-temperature superconductors, which are primarily type-II, and question its applicability to type-II conventional superconductors.
  • Others reference discussions that focus on type-I superconductors, suggesting that BCS theory may not be as effective for type-II superconductors.
  • A participant mentions that understanding high-temperature superconductivity remains a significant challenge, with alternative theories proposed, such as resonating-valence-bond theory and pairing mediated by short-range spin waves.
  • Another participant highlights that the theory of type-II superconductors was significantly developed by the Russian school, particularly by Gorkov and Abrikosov, and argues that BCS theory can describe type-II superconductors, albeit in a less direct manner.
  • Some participants clarify that there are indeed type-II conventional superconductors, distinct from high-Tc superconductors, and note that extensions to BCS theory exist to account for type-II superconductors.
  • A participant acknowledges a misunderstanding of the original question, indicating that their previous response was misaligned with the topic of type-II superconductors.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of BCS theory to type-II superconductors, with some asserting its relevance and others questioning it. The discussion remains unresolved regarding the extent to which BCS theory can explain type-II superconductors.

Contextual Notes

Participants reference the limitations of BCS theory in explaining high-temperature superconductors and the need for extensions to account for strong-coupling superconductors. There is also mention of gauge invariance in the context of magnetic fields and superconductivity.

Who May Find This Useful

This discussion may be of interest to those studying superconductivity, particularly in the context of BCS theory and its limitations, as well as researchers exploring high-temperature superconductors and their mechanisms.

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I know that BCS theory cannot explain high Tc superconductor.
Most high Tc superconductors belong to type-II ones.
Can BCS theory explain type-II conventional superconductor?
How to predict high Hc2 and low Hc1 for type-II conventional superconductor in BCS theory?
 
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Nope! Understanding the mechanisms behind high Tc superconductivity remains one of the biggest problems in solid state physics (my solid state lecturer described it as "insta-nobel worthy").

There are two main theories, resonating-valence-bond theory and pairing in mediated by short-range spin waves known as "paramagnons". The latter has more support, IIRC.

Further reading: http://link.springer.com/chapter/10.1007/0-306-47081-0_7
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.67.3448
http://www.nature.com/news/2011/110720/full/475280a.html
 
To my knowledge, the theory of type II superconductors was developed to a high degree by the russian school around Gorkov and Abrikosov, who also received the Nobel prize for that work a few years ago.
With the original theory of BCS, it was not completely clear as to whether magnetic fields can be described correctly and in a gauge invariant way. The Gorkov equations maintained gauge invariance explicitly so that a detailed treatment of magnetic fields in superconductors became possible. However, the Gorkov equations describe the same physics as BCS, though in a more elegant way. So, yes, BCS theory is able to describe also type II superconductors.
 
e.bar.goum said:
Nope! Understanding the mechanisms behind high Tc superconductivity remains one of the biggest problems in solid state physics (my solid state lecturer described it as "insta-nobel worthy").

There are two main theories, resonating-valence-bond theory and pairing in mediated by short-range spin waves known as "paramagnons". The latter has more support, IIRC.

Further reading: http://link.springer.com/chapter/10.1007/0-306-47081-0_7
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.67.3448
http://www.nature.com/news/2011/110720/full/475280a.html

This is misleading. There ARE Type II conventional superconductors, and these are not the high-Tc superconductors.

As DrDu stated, there are "extensions" to the BCS theory that takes into account the existence of Type II superconductors. This is not unusual or unexpected, since the original BCS theory was to account only for "weak-coupling" superconductors. Strong-coupling superconductors, such as lead, required further tweaks to BCS theory.

Zz.
 
ZapperZ said:
This is misleading. There ARE Type II conventional superconductors, and these are not the high-Tc superconductors.

As DrDu stated, there are "extensions" to the BCS theory that takes into account the existence of Type II superconductors. This is not unusual or unexpected, since the original BCS theory was to account only for "weak-coupling" superconductors. Strong-coupling superconductors, such as lead, required further tweaks to BCS theory.

Zz.

Yes, I totally misread the OP. My apologies!

ETA: My response makes sense if the question was "Can BCS explain high Tc superconductors?" Which it clearly wasn't.
 

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