High-field magnetization of doped Bi-series oxide superconductors

The high-field magnetization measurements of Zn- and Ga-doped sintered Bi-based compounds were carried out in a 40 T high-field facility. The critical current density and the flux pinning force of the Bi-series oxide superconductors were calculated using Bean’s critical state model. It is found that both the critical current density and the flux pinning force of the Zn-doped oxide compounds are decreased slightly with increasing Zn content. However, the critical current density and the flux pinning force of the Ga-doped oxide superconductors diminish significantly with enhancement of dopant content. It seems that the superconductivity of Bi-series superconductors is much more severely destroyed by a trivalent dopant than by a divalent one.