Magnetic penetration depth of high-Tc superconductors

The magnetic penetration depth in the local limit λ(T) for a high-Tc superconductor has been calculated within the electron pairing induced by holes model proposed by us recently. The derivation of the formula for λ(T) is based on a new expression for the current-density operator which takes into account the nonparabolic band structure of the conduction electrons. Our numerical results for the temperature dependence of λ(T) when the hole concentration δ=0.263 (which corresponds to 90-K superconductors) are near to the BCS results for a conventional superconductor and also agree qualitatively with the experimental data on the single crystal of YBa2Cu3O7. Our value for the zero-temperature penetration depth is also close to the experimental values for the single crystals of the above material