Direct Measurement of the Temperature-Dependent Magnetic Penetration Depth in Y-Ba-Cu-O Crystals

Abstract

The temperature dependence of the magnetic penetration depth $\ensuremath{\lambda}$ is determined directly from low-field dc magnetization measurements on single-crystal Y-Ba-Cu-O (${T}_{c}=89.7$ K, $\ensuremath{\Delta}{T}_{c}=0.2$ K). The results are consistent with the behavior expected from a BCS ($s$ wave) superconductor.