High-field magnetization of YBa 2Cu 3−xM xO 7 (M≠Pb, Sn) at 4.2 K

Abstract

Magnetization measurements on lead- or tin-doped YBa 2Cu 3O 7 have been performed at 4.2 K in magnetic fields up to 29 T. The critical current densities are deduced from the irreversible magnetization and the pinning forces are evaluated. The effect of both lead and tin doping on the critical current density is quite appreciable. In particular, the critical current density of the sample doped with lead is more than twice that of the undoped sample. This effect is thought to be associated with the enhancement of the intergranular coupling of grains through the formation of BaPbO 3 phase at the interface of the 123 superconducting phase. The relationship between the critical current density and a micrograph of the tin-doped sample is also discussed.