Magnetic penetration depth of high-Tc superconductors.

Abstract

The magnetic penetration depth in the local limit {lambda}({ital T}) for a high-{ital T}{sub {ital c}} superconductor has been calculated within the electron pairing induced by holes model proposed by us recently. The derivation of the formula for {lambda}({ital 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 {lambda}({ital T}) when the hole concentration {delta}=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 YBa{sub 2}Cu{sub 3}O{sub 7}. Our value for the zero-temperature penetration depth is also close to the experimental values for the single crystals of the above material.