Temperature dependence of the anisotropic magnetic penetration depth and lower critical field of single-crystal Pb2Sr2(Y,Ca)Cu3O8+δ

The temperature dependence of the penetration depth of single-crystal Pb2Sr2(Y,Ca)Cu3O8+δ has been determined in the vicinity of Tc (∼75 K) using intermediate-field reversible-magnetization measurements. The ab-plane penetration depth in the restricted region near Tc was found to follow clean-limit BCS behavior from which an estimate of 2575 Å for λab(0) was obtained. The effective-mass anisotropy parameter, γ=(mc/mab)1/2, was found to be 2.5, which together with the former result yields a value of 6425 Å for λc(0). In addition, the temperature dependence of the anisotropic lower critical field was determined from observations of the onset of deviation from perfect diamagnetism. The estimates obtained for the zero-temperature lower critical field, Hc1(0), were 95±10 G for H⊥c and 505±20 G for H∥c.