Magnetic Penetration Depth in a Superconductor

Abstract

It is shown that the notion of the finite pairing interaction energy range $T_d$ results in a linear temperature dependence of the London magnetic penetration depth $\Delta \lambda /\lambda (0)=(T/T_d)(2/\pi )\ln 2$ at low temperature, in the case of the s-wave pairing state.

5 pages, Latex