Magnetization studies of high critical current density YBa₂Cu₃O_7-x prepared by powder melting process

The field dependence of magnetization of bulk powder melting process (PMP) samples with transport critical current density as high as 7 · 10⁴ A/cm² in B = 1 T at 77 K (by pulse technique) was measured. The decrease of magnetization hysteresis loops proportional to decrease of sample size was found, what means that superconducting current flows throughout the whole sample and weak links problem does not exist in PMP samples. The values of measured magnetization critical current density agree quite well with transport measurements results.