Superconducting coherence length

A Superconducting coherence length, usually denoted as $\xi$ , can be interpreted in two different ways:

It gives approximate spatial dimension (size) of the Cooper pair,
It sets the length scale on which the superconducting order parameter changes considerably.

The superconducting coherence length ( $\xi$ ) is one of two parameters in a Ginzburg-Landau theory of superconductivity.

It is given by:

\xi ={\sqrt {\frac {\hbar ^{2}}{2m|\alpha |}}}={\frac {\hbar ^{2}k_{f}}{2mE_{gap}}}={\frac {2\hbar v_{f}}{\pi E_{g}}}

See also