LOW-FIELD AC SUSCEPTIBILITY IN HG-1223 POLYCRYSTALS

The complex AC susceptibility of HgBa2Ca2Cu3O8+delta(Hg-1223) has been studied for DC magnetic fields 0 Oe less-than-or-equal-to H(DC) less-than-or-equal-to 50 Oe and AC magnetic fields 0.1 Oe less-than-or-equal-to h(AC) less-than-or-equal-to 70 Oe allowing the determination to be made of the irreversibility line both in the (H(DC), T) plane and in the (h(AC), T) plane. The critical dynamic field h(c)* has furthermore been obtained in the low AC field limit. All these results are consistent with a strong increase of the intergranular pinning strength which is one order of magnitude higher than in similar as-sintered 123 compounds, suggesting possibilities for the critical currents.