Understanding Cooper Pairs and Superconducting Materials

In summary, Cooper pairs form below the critical temperature of the material, regardless of whether or not the superconductor is carrying a current. However, there is some evidence that suggests this process may be more complex in high-temperature superconductors, with experimental data indicating the presence of ordering above the critical temperature. This cannot be explained by the BCS theory, which is not valid for high-temperature superconductors. In conventional superconductors, the Cooper pairs start to form at the critical temperature.
  • #1
vabamyyr
66
0
Hi, I have one question about superconducting materials.

Do Cooper pairs form below critical temperature of material or do they form below critical temperature AND if the current exists?
 
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  • #2
Tc is by definition the temperature at which the Cooper pairs start to form, leading to the creation of an energy gap. Whether or not the superconductor is carrying a current or not is irrelevant.
Note that there is a small caveat; there is some evidence that suggests that this process is not as straighforward in the high-temperature superconductors; there is experimental data that suggests that some form of ordering exisits also above the critical temperature. However, this is still quite controversial.
Also, it is NOT something that can be explained using the BCS theory (which is not valid for HTS anyway). For conventional ("BCS") superconductors the Cooper pairs start to form at Tc.
 
  • #3
thank you for the answer
 

1. What are Cooper pairs and how do they contribute to superconductivity?

Cooper pairs are pairs of electrons that are bound together by the exchange of phonons, which are vibrations in the crystal lattice of a superconducting material. This binding creates a net zero electrical resistance in the material, allowing for the flow of electric current without any loss of energy.

2. How do superconducting materials differ from normal conductors?

Superconducting materials differ from normal conductors in that they exhibit zero electrical resistance and perfect diamagnetism (the ability to repel magnetic fields). They also have a critical temperature, below which they become superconducting, and a critical magnetic field, above which they lose their superconducting properties.

3. What is the Meissner effect and how does it relate to superconductivity?

The Meissner effect is the expulsion of magnetic fields from the interior of a superconductor as it transitions into its superconducting state. This effect is a result of the perfect diamagnetism exhibited by superconducting materials, which causes them to repel magnetic fields and create a perfect shielding effect.

4. What are the different types of superconductors?

There are two types of superconductors: Type I and Type II. Type I superconductors are typically metallic and exhibit the Meissner effect at low temperatures. Type II superconductors, on the other hand, have a higher critical temperature and can exhibit both the Meissner effect and the mixed state, in which magnetic flux lines are able to penetrate the material in a limited way.

5. What are some practical applications of superconducting materials?

Superconducting materials have a wide range of practical applications, including in medical imaging (MRI machines), energy transmission and storage, and particle accelerators. They are also being researched for potential use in quantum computing and levitating transportation systems. Additionally, superconducting materials are used in some specialized electronic devices, such as superconducting quantum interference devices (SQUIDs).

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