Understanding Cooper Pairs and Superconducting Materials

[vabamyyr]

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?

 

[f95toli]

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.

 

[vabamyyr]

thank you for the answer