Calculation of Magnetic Penetration Depth Length λ(T) in High Tc Superconductors

The notion of a finite pairing interaction energy range via Nam, results in the incomplete condensation in which not all states participate in pairings. Thestates not participating in pairings are shown to yield the lowenergy states responsible for the linear T dependence ofsuperelectron density at low T in a s-wave superconductor. Wepresent extensive quantitative calculations of $\lambda$(T) forall T ranges, in good agreements with experiments. It is notnecessary to have nodes in the order parameter, to account for thelinear T dependence of $\lambda$(T) at low T in high Tc superconductors.