Position dependence of irreversibility line on thin plate Gd-Ba-Cu-O bulk superconductor

We measured the profiles of the trapped field, BT, on a thin Gd-Ba-Cu-O superconducting bulk plate with 45 mm in diameter and 2 mm in thickness magnetized by the pulsed field, where Gd-Ba-Cu-O consists of a superconducting matrix phase of GdBa2Cu3O7−δ and a nonsuperconducting secondary phase of Gd2BaCuO5. The vortices were mainly trapped at the periphery in the growth sector regions (GSRs) for low applied fields, and around the growth sector boundaries (GSBs) and under the seed crystal (SC) position for high applied fields. The irreversibility line, which was determined from the resistivity measurements, of the sample cut from the GSR was rather lower than those of the samples cut from the GSBs and the SC position. This result revealed the weak vortex pinning strength in the GSRs and was consistent with the BT profiles by PFM. The obtained results suggest that the resistivity can also probe the distribution of the vortex pinning strength.