PHASE INTERGROWTH EFFECTS ON THE MAGNETIC AND TRANSPORT-PROPERTIES OFBI2SR2CACU2OY THIN-FILMS GROWN IN-SITU BY LASER-ABLATION

Bi2Sr2CaCu2Oy (2212) films, grown in situ by laser ablation, show the presence of the intergrowth phenomenon: the random stacking of 2201 (B i2Sr2Cu1Ox) and 2212 cells. The precise fraction of the 2201 phase int ergrowth depends on the growth conditions. We have measured the influe nce of such structural defects on electrical transport and magnetic pr operties. The main consequences of the intergrowth are a broadening of the superconducting transition and a decrease ol the critical tempera ture. The irreversibility line of the films has been deduced from ac s usceptibility measurements in magnetic fields H parallel to the c axis of the films using a superconducting quantum interference device magn etometer. A strong shift of the irreversibility line to low fields and temperatures is reported with increasing the percentage of 2201 stack ing faults.