Can BCS theory explain type-II superconductor?

In summary, BCS theory is unable to fully explain high Tc superconductors and there are two main theories, resonating-valence-bond theory and pairing mediated by short-range spin waves, that attempt to do so. BCS theory can, however, describe type II conventional superconductors with the help of extensions developed by the Russian school around Gorkov and Abrikosov. These extensions maintain gauge invariance and provide a more elegant treatment of magnetic fields in superconductors.
  • #1
time601
15
1
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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  • #3
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
 
  • #4
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.
 
  • #5
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.
 
  • #6
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.
 

1. What is BCS theory and how does it relate to superconductivity?

BCS theory, or the Bardeen-Cooper-Schrieffer theory, is a widely accepted explanation for the phenomenon of superconductivity. It describes how electrons in a material can pair up and move through the material without resistance, resulting in superconductivity. BCS theory explains the behavior of type-I superconductors, but has limitations when it comes to type-II superconductors.

2. What are the main differences between type-I and type-II superconductors?

Type-I superconductors have a single critical temperature at which they transition from a normal to a superconducting state, and they completely expel magnetic fields. In contrast, type-II superconductors have two critical temperatures and can partially allow magnetic fields to penetrate the material. Type-II superconductors also have a more complex and varied behavior in the presence of magnetic fields.

3. Can BCS theory explain the behavior of type-II superconductors?

No, BCS theory alone cannot fully explain the behavior of type-II superconductors. While it can provide a basic understanding of the phenomenon, it does not fully account for the complex interplay between superconductivity and magnetic fields in type-II superconductors.

4. What are some other theories that attempt to explain type-II superconductivity?

There are several theories that attempt to explain type-II superconductivity, including the Ginzburg-Landau theory and the Lawrence-Doniach model. These theories take into account the effects of magnetic fields on the superconducting state and provide a more comprehensive understanding of type-II superconductors.

5. How do scientists currently approach the study of type-II superconductivity?

Scientists use a combination of experimental and theoretical approaches to study type-II superconductivity. This includes using advanced techniques such as scanning tunneling microscopy and superconducting quantum interference devices to observe the behavior of type-II superconductors, as well as developing and refining theories to better understand this complex phenomenon.

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