Observation of giant T<SUB>c</SUB> depression effect in Y<SUB>1</SUB>Ba<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-d</SUB> doped simultaneously with Zn and Fe

The case of simultaneous doping of Fe and Zn in Y1Ba2Cu3O7-d is examined in the context of the issue of Tc depression by magnetic impurities in the high Tc superconductors. It is observed that codoping of Fe (magnetic) and Zn (diamagnetic) impurities in Y1Ba2Cu3O7-d leads to giant Tc depression, with an almost complete loss of superconductivity for the total dopant concentration above a certain value; while separate doping of Fe or Zn at the same total concentration yield well defined superconducting transitions; though with reduced Tc as compared to the pure 92 K material