Enhanced Critical Current Density In Overdoped Hgba2cacu2o6+Delta Superconducting Thin Films

Overdoped HgBa2CaCu2O6+delta (Hg-1212) high-temperature superconducting thin films have been synthesized in a fluorine-assisted cation-exchange process followed by postannealing in flowing oxygen. The overdoped Hg-1212 thin films have lowered superconducting transition temperature T-c of about 114-115 K. Critical current density J(c), however, is nearly twice as that for optimally doped Hg-1212 films. The enhancement in magnetic irreversible field H-irr has also been observed in the overdoped Hg-1212 films, while a similar scaling law of H(irr)similar to(1-T/T-c)(n) with n=1.2-1.3 in field range below 1 T was observed for both optimally doped and overdoped samples. Such a fluorine-assisted cation-exchange process, hence, provides a simple practical route for achieving high-current carrying Hg-1212 films on oxide and metal substrates. (C) 2003 American Institute of Physics.