Highly enhanced flux pinning in Pb and rare earth codoped Bi-2212

Abstract

The effect of codoping of Pb and rare earths rare earths REs =La, Gd, and Yb in Bi-2212 superconductor on structural, transport, and flux pinning properties was investigated in comparison with solo doping of REs. While the solo doping led to marked improvements in critical temperature TC , critical current density JC , and in-field JC JC-B , the codoping exhibited very large enhancements in JC and JC-B at a relatively high temperature of 64 K. Pb doping at Bi site improved the coupling between the two dimensional pancake vortices and the strongly coupled vortices were effectively pinned by the defects created at Sr/Ca sites by RE doping. © 2007 American Institute of Physics.