Critical current of a high T_c Josephson grain boundary junction in high magnetic field

The critical current (Ic) of YBa2Cu3O 7-δ grain boundary Josephson junctions was measured up to magnetic fields of 5 T. Magnetic field history dependent Ic values were observed even after correction for self-field effects stemming from hysteretic shielding currents in the grain adjacent to the boundary. A novel feature observed is an anomalous increase in Ic in high magnetic fields of several Telsa.