Q: Does Cooper pairs only flow at surface at $T=0\rm K$? Then, how about at the temperature above 0K? We know that Cooper pairs generate at critical temperature, and as more as reducing the temperature. But where are they? We also know them exhibit around Fermi surface as the wave-function. So, it means that cooper pair only appears near the superconductor surface? Can it be formed inside the superconductor?
