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Critical current density and flux pinning in a Bi1.7Pb0.4Sr2−xLaxCa1.1Cu2.1Oy system

The critical current density of Bi2Sr2CaCu2O8+δ (Bi-2212) superconductors can be enhanced either by changing the charge carrier concentration (holes) to the optimum value, from the overdoped state, or by creating flux pinning centres to inhibit the flux flow in magnetic fields. In this work we substitute the rare earth La at the Sr site of Pb-doped Bi-2212 [(Bi, Pb)-2212]. La3+ ions at the Sr2+ site decrease the hole concentration to the optimum value and enhance the superconducting properties. Also La at the Sr site creates point defects which act as flux pinning centres. These dual effects of La at the Sr site highly enhance the transport JC in self and applied magnetic fields.