Magnetic Properties of Pb-Doped Bi-Sr-Ca-Cu-O Superconductors

The D.C. magnetization of Bi-Sr-Ca-Cu-O compound was significantly increased by Pb-doping. However, the hysteresis Δ M in magnetization curves rapidly decreased with increasing magnetic field, and became almost zero above 0.5 T. This small hysteresis may be related to the thin layers of superconducting phases. Low-temperature tails in superconducting resistive transition curves measured in magnetic fields were drastically decreased by the Pb-doping. H c2 values at 77 K and 0 K obtained by extrapolation using the transition curves were 60 T and 140 T, respectively, when defined at the midpoint of the transition.