Small field behavior of critical current in Y1Ba2Cu3O7 sintered samples.

Critical currents carried by sintered Y1Ba2Cu3O7 superconducting samples have been measured at different temperatures close to the critical temperature Tc. The effects of an applied magnetic field perpendicular to the current direction have been investigated. A strong reduction of the dc current for field values smaller than the lower critical field Bc1 has been observed. The magnetic field dependence is discussed in terms of weak coupling between grains. The experimental data show an excellent agreement, at low field values, with the theoretical dependence valid for an array of Josephson junctions. [ABSTRACT FROM AUTHOR]